Manufacturing guy-at-large.

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The beginning of a workflow

Added on by Spencer Wright.

Note: Special thanks to Bradley Rothenberg (of nTopology) and Ryan Schmidt (of MeshMixer/Autodesk) for their continued help on this workflow. Also, both of them make awesome (and very weird ;) software that you should check out.

A scenario: You've got a part that you want to manufacture with metal powder bed fusion. You've got a few mechanical features that you know you need (to mate up with other parts in an assembly) and a general sense of the design space that's available for the part you're designing. You know the mechanical properties you need (via an ISO test that the part needs to pass) and you've got a target mass (which is basically "less than the competition"), and a target cost (which is basically "similar to the competition, taking into account a ~35% margin for me").

I've spent a lot of the past week going back and forth between Inventor, MeshMixer, and nTopology Element, trying to make a 3D lattice structures that are both mechanically effective and easy to manufacture. My workflow has been decidedly emergent, and it's also been counterintuitive at times; I've often found myself working backwards (away from my final design intent) in order to create the conditions where I can make progress down the line. My end goal is to design a bike stem that's sub 125g and which has minimal post-processing costs and requires minimal support structures (I'll deal with the actual dollar cost later, as it'll depend on a bunch of factors that aren't under my direct control).

I've got 27.7 cubic centimeters of titanium to play with. Where do I put it?

I began in Inventor. Setting up a design space is, counterintuitively, kind of a hard thing to do. Very few parts that I've designed have hard and fast design space boundaries; most of them could always be a little bigger, or a little smaller, and the rest of the assembly would stretch or squish to accommodate it. Nevertheless, I need to start somewhere, so I created a T-spline form that was close to what I thought I'd want:

I export it as an STL at low resolution (where we're going, resolution doesn't matter :) and bring it into MeshMixer:

From here, things start to get complicated. The way I see it, this part essentially has three components: 

  1. The mechanical features. This includes the two clamp cylinders (one, the handlebar clamp, is 31.8mm in diameter and split; the other, the steer tube, is 28.6mm and slit along the back side) and the four bolt holes (all M5, and all with one counterbored part and one threaded part) that do the clamping.
  2. The design space's exterior surface. In general, the stiffness of the part will be determined by how much volume it takes up, and I should generally make the part as stiff as possible. Therefore the exterior surface of the part is going to be made up of a big non-Euclidian 2D lattice.
  3. The volume of space between the mechanical features and the exterior surface. I'll want some bracing here to tie the whole part together and transfer loads from the mechanical parts over to the exterior lattice.

For this design, I'm using lattice structures throughout the part. I won't design any skins (I'm generally anti-skin, unless you've got fluid separation requirements in your design), instead opting to let the lattices vary in density from zero (in the middle of the part) to 100% (in areas like the threaded and counterbored bolt holes). 

Because the different surface regions of the part (the mechanical features and the exterior surface) will have different mechanical requirements, I begin by duplicating my lattice in MeshMixer and isolating each of them in its own object:

I then go through each region and remesh it in MeshMixer. A few notes here:

  • I generally begin by remeshing the entire object at a medium-high resolution, just to get rid of the dense lattices that Inventor creates at edges and small fillets. 
  • I then choose the area that I want to be at the highest resolution (which is almost always lower than the one I chose in the first step) and remesh it. On the part's exterior, that was the bolt counterbores.
  • Then I work my way down to the lowest resolution areas. On the part's exterior, I targeted edges in the 15mm range, but I play around with the remesh settings a *lot* until I get something I like.
  • Then I'll go back and find areas that are still a bit high-res and remesh them again until they look good. There's a bit of back and forth here, and I haven't really figured out a one-size-fits-all workflow yet.

I DON'T worry about geometric accuracy much during this process; I assume that I'll need to clean up the geometry at the end (after I've generated the full lattice structure - more on this in a future post) anyway.

Then I export the lattices as OBJs, bring them into nTopology Element, and see what they look like:

At this point, I decided that I really wanted to stretch the entire exterior lattice out so that more of the beams would be horizontal. The part will probably be built on its end, so these will be easier to build as a result. So I go back into MeshMixer, transform the part down (it happens to be the Z axis here) by 50%, and remesh the outer skin. Then I transform it back up to 100%, stretching everything out.

As you can see in the last few shots, the lattice has been stretched significantly. I've also remeshed a few of the higher resolution areas individually, evening them out a bit. Back in nTopology Element, you can see the difference between the old lattice (the last shot below) and the new one:

Meanwhile, I've used nTopology element to create (and warp) an Oct-Tet volume lattice for the interior of the part. This may look odd (and to be sure it needs some work) but a lot of these beams will be surprisingly useful once the whole part is put together. The red stuff here is a zero-thickness representation of the mechanical features' lattice structures; the white/yellow structure is the volume lattice:

When you put the whole thing together, it starts looking pretty good:

Now, there's still a lot wrong with this. There are a *lot* of overhanging faces. The threaded bolt holes aren't very well connected to the outer mesh, and there's probably too much material on all of the flat faces (where the slits/slots are). I'm also over my mass target - my total is 34.1 cubic centimeters, and my target was 27.7.

But there's a lot right with the design, too. My beams are about the right size throughout, and I've been able to (more or less) distribute my mass where it will matter most. And while the aesthetics of the part aren't exactly what I'd like them to be, they're not far off either. 

So, a few things I need to work on:

  • First, I need to make overhanging faces easier to eliminate. Some part of this *needs* to be happen when I remesh a surface (assuming I'm using the surface topology to determine the lattice topology). Ditto with volumes - I need to be able to stretch the lattice out so that it isn't horizontals all over the place.
  • I also need to be more careful about directing my volume lattice where it'll be more effective. It's possible I should break it up into a few regions - some near the mechanical features, and one in the middle of the part - but I'm concerned that if I do that, I'll never get the two to tie together. Either way I need a denser volume lattice at the bolt holes, and I need to be able to tie the volume lattice beams up to the other regions of the part.
  • I should probably play with modifying my mechanical features back in Inventor to make them more conducive to lattices. This might involve warping the clamp cylinders somewhat to reduce overhanging faces... or drilling the threaded holes through the part so that they connect to the exterior surfaces... or puncturing the flat faces so that they aren't as massive as they are in the current design.

Clearly, there's a lot to do here still. But I'm beginning to get the hang of this workflow, and hoping to have some printable (and extremely lightweight) designs to make soon :)

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Quick & closer

Added on by Spencer Wright.

From the end of the day yesterday:

This is still not manufacturable, and is still missing all the mechanical features too. But it's getting there! By combining a skin lattice (which my part definitely needs in at least some regions, for instance the clamp faces) and a minimal, bonelike volume lattice, I hope to be able to create something that's significantly lighter than a comparable tube-to-tube (e.g. welded) structure.

The next step, I think, is to reintroduce the mechanical features (at least some of them) into the model *before* I remesh the surfaces. I would really want the mesh density to be created relative to the kinds and intensities of the forces that the part is going to be under: for instance, all of the bolts and clamp faces will want higher density meshes around them, etc. At the moment my best bet is to do that manually, by selecting areas I want to be at higher densities and just remeshing them to suit my intuition. 

More soon :)

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Remeshing

Added on by Spencer Wright.

I get the feeling I'll be doing a *lot* of this in the coming month:

Here I've taken an STL from Inventor and brought it into MeshMixer, where I'm remeshing the outside skin. I'm doing this so that I can then create a surface (as opposed to a volume) lattice in nTopology Element. If I tried to create the mesh directly from Inventor's STL, it would be much to fine and have a bunch of artifacts from the way that Inventor processes T-Spline surfaces (Inventor breaks the surface up into panels, and then subdivides each one individually - you can see the panel boundaries in the beginning of the gif), and would also be *way* too fine to be used as a scaffold for a surface lattice. By remeshing at a lower resolution - and playing with MeshMixer's remeshing settings a bit - I can get to a topology that's way better.

The design that I'm pointing towards here still isn't manufacturable - and is missing a bunch of mechanical features that the end part will need too - but it's starting to come together a lot better:

Special thanks to Ryan Schmidt (of Autodesk/Meshmixer) and Bradley Rothenberg (of nTopology) for pointing me in this direction - and for helping me out with the even cooler stuff I hope to do in the next week :)

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Fresh AM titanium/carbon fiber bike frame designs

Added on by Spencer Wright.

This has been a long time coming.

For what it's worth, I had the idea before either Triple Bottom Line or Bastion launched - but I'm fully aware that that doesn't buy me shit. At its core: build titanium 3D printed bike frame components, and use carbon fiber tubing for areas that are too big to practically print. This avoids the crazy crowded build chamber (and inefficient glue joints) that Renishaw/Empire's bike required, and utilizes AM for what it's good at - making customizable, low-mass parts that fit easily on a build plate.

I thought about this for a *long* time, but only this week spent some time modeling my design spaces in Inventor and poking at the lattice generation process in nTopology Element. This is still far from manufacturable, but it was great to spend a day working through how to design and customize each design space in a way that was repeatable and simple. 

In short, the frame would have four (or possibly three, if I integrate the brake bridge into the seat lug) printed titanium components; the rest is carbon fiber tubing. I'll likely also add a printed seatmast topper (probably with integrated saddle rails).

I spent a *tiny* amount of time setting up lattices for each printed component in nTopology Element today. This is extremely preliminary, but I really like the look and think that the basic idea - that the printed components are optimized for lattice shape and thickness, but in general never reach 100% density - is a good one.

You can *bet* that I'll be working on this more in the next week. Stay tuned :)

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Goals

Added on by Spencer Wright.

I've been thinking of the things I want to focus on in metal additive manufacturing, and came up with these two goals:

  1. Reduce the time & effort that independent designers spend developing & validating metal AM parts.
  2. Reduce the time & effort that service providers spend getting their shops capable of reliably making their customers' parts at a profit.

The reason I *don't* mention OEMs here is because I assume that if 1. and 2. are achieved, then the OEMs will be just fine, as they'll have a healthy supply of both engineering talent and manufacturing capabilities available to them. That's not to say that I don't want to help OEMs too, but in my opinion you can have a bigger long term impact (and help save yourself from the client-driven feature creep common in industrial solutions) if you keep small shops' needs in mind.

I have some initial thoughts on how I'd begin to address these, but I'm still in the process of developing them. If anyone has ideas, I'd love to chat about them - drop me a line!

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Supply chain complexity : process reliability

Added on by Spencer Wright.

A serious question - please post comments if you have thoughts!

Does the ratio of service providers to OEMs in an industry correlate indirectly with the defect rates in its critical components?

In other words, as the manufacturing processes required to produce a product become more reliable, is production shifted away from OEMs?

You won't be surprised that my question relates to metal AM - and the degree to which OEMs can generally outspend (in both R&D and acquisitions) the smaller job shops. When a critical process in the industry is unreliable, OEMs can invest the capital expenses to either solve the problem (through R&D and often resulting in trade secrets) or acquire companies who have. But as the process matures, smaller service providers can be more competitive, as their overhead is (citation needed) in many cases lower.

As a result: Until the process (for example, metal powder bed fusion) is fully industrialized and reliable, it's very difficult for small shops to enter the market. But once the technology is well understood, mom & pop shops are able to flourish. 

A concrete example: Today, OEMs like GE, Airbus, and Philips dominate the metal additive industry, and the proprietary R&D they do makes insourcing components more cost competitive than buying them from service providers. If you start a job shop today, it might be 12-18 months before it reliably creates revenue. But if & when additive becomes a more predictable process, the time to revenue (and profit) will be shortened, and OEMs will find it increasingly attractive to outsource their parts.

^ This is a half baked theory - I'd love to hear your perspective!

Edit:

  1. This question prompted a good discussion on twitter!
  2. Another note to the example above: Arcam EBM is (and I don't mean this as a criticism) less fully industrialized than laser metal powder bed fusion. 
    There are (by my count) 23 firms in the US who own Arcam machines; three are job shops, one is owned by Arcam, and the rest are OEMs or research institutes. On the other hand, there are many dozens (by my count at least 70) of service providers who have laser based machines. If the ratio of OEMs to job shops were consistent across the technologies, you'd expect there to be over 500 firms in the US running laser machines in house - which sounds *much* too high to me.
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Notes on Magics

Added on by Spencer Wright.

This month I'm doing a deep evaluation of Materialise Magics 19 and SG+, and trying to understand both the major features of the software and the philosophical perspective that Materialise views additive manufacturing through. I'll post more thoughts on the overall process chain later, but for now I wanted to work through some of the observations I've had in my first encounters with Magics.

For background: The cost of this software is in the neighborhood of $20,000. It's generally NOT purchased by people who don't themselves own industrial (i.e. $250k+) 3D printers. But I feel very strongly that without some knowledge of how it works, independent designers will be doomed to creating inefficient, difficult to manufacture designs. So, I signed myself up for a 30 day demo and got working :)

Note: Throughout this post, I'll be showing screenshots of my titanium seatpost part. I've already had one of these parts EBM printed by Addaero, and expect to have versions of it printed in both EBM and laser metal powder bed fusion (which I'll refer to as "DMLS" throughout this post) in the near future. In order to simplify the descriptions below, here's a key to the part's features:

My part's nomenclature.

Overview

I believe Magics to be a classic example of a piece of industrial software whose development has been driven by customers who are large, powerful, and often have divergent interests. 

In many ways its functionality probably benefits as a result. Materialise has close relationships with a number of industrial 3D printing machine manufacturers (notably Renishaw, SLM, and EOS, all of whom have agreements in place to allow Materialise access to their machines' build parameters, and develop build processors to work natively on those machines). They also collaborate closely with many of the large manufacturers (both OEMs and service bureaus) who build 3D print parts on the machines that Magics supports. Through these relationships (and through their own internal parts business), Materialise can get an up close view of what their biggest users need out of the software, and prioritize their efforts accordingly.

On the other hand, by relying heavily on key accounts to drive the product's development, Materialise gives up much in the way of product vision - accepting, instead, a steady stream of feature creep. Every additional feature (while I'm sure they're all valuable) makes the entire application more difficult and clunky to use, and it often feels like Materialise has given two different customers two distinct ways of doing the same thing - simply because each one demanded that the workflow fit their way of working. This kind of path is ubiquitous around the world of industrial software, and Materialise is, to be fair, ultimately at the whim of its (enormous) industrial stakeholders. But as someone coming in from the outside, the result feels schizophrenic.

The core issue is that independent designers like myself are seen as customers, while Magics' development is driven by client relationships. Again, this isn't Materialise's fault, and nor is it ipso facto bad. But I don't believe that the incentive structures that drive Magics' development are optimal for the industrialization of additive manufacturing, either. I'll explore this topic more in a later post; for now, just ponder this. In the meantime, here are my initial observations of how this big, important, and powerful piece of software works.

One important note: Materialise is a member of the 3MF consortium, which is working to create a file format which apparently contains "the complete model information" within "a single archive." My hope is that 3MF allows for more of the process chain to be accessible from a single interface, and that Materialise is a key part of that development. I'm looking forward to learning more about 3MF in the near future; stay tuned for more.

UI

Magics has two or three ways to do basically everything. At the top of the window is a drop down menu bar. It changes depending on context, but generally has a lot of functionality; in the default view, it has eleven menus - a mix of standard stuff (File/Edit etc) and context dependent stuff (Fixing/Scenes etc).

Directly below that is a tool bar, which mostly contains standard tools (undo/redo, Print 2D, Zoom/Pan/Rotate, etc). As far as I can tell, every command in the tool bar is also accessible via the menu bar AND via keystrokes & mouse gestures.

To the right of the tool bar is a series of tabs, which toggle the appearance of another tool bar below. These are a bit more context dependent, and as far as I can tell the correspond 1:1 with what's shown in the "Tools" drop down menu above. Most of these functions, though, *can't* be accessed by keystrokes or mouse gestures.

Overall, Magics' multiple, competing UIs are not unlike most of what's out there in industrial & B2B software today. Most companies (including Materialise) tend to bill this as a feature: the user can interact with the software in a wide variety of ways (keystrokes, mouse gestures, drop down menus, or toolbars), so almost anyone will be able to get comfortable with the interface quickly.

Personally, I prefer opinionated UIs in industrial/B2B software. The best one I'm aware of is McMaster-Carr's, which is built specifically for MRO professionals and makes everyone else adjust their mindset to that of someone looking for replacement parts. I'm not an MRO professional, but once you figure out how they work, the experience is wonderful. 

Magics doesn't act this way, though. The UI doesn't guide me at all; it simply offers a multitude of options, and lets me decide which one I prefer.

Orientation

Magics' "Orientation Optimizer" is very straightforward, and seems in some cases like it'd be useful. I used it only briefly, but to be honest I had already decided more or less the orientation I wanted the part to be printed in. As it happens, the Orientation Optimizer confirmed my plan, but I take that confirmation to be a bit of a false positive. As I discuss below (and have written about extensively in the past), setting an orientation angle really requires an understanding of the part's design intent and manufacturing life cycle, and Magics lacks these. As a result, it can only optimize for the factors that it understands: in this case, some combination of Z-height, XY projection, Support Surface, and Max XY Section. I chose the middle two of these, and Magics gave me exactly what I already knew I wanted.

The orientation that Magics suggested for my part

This tool is probably more useful in high mix environments (service bureaus), but most of the people in the industry I've spoken to say that when they use it, it's just as a starting point; the final orientation is almost always set by a human being.

Support generation

Generating support structures in Magics is really straightforward; it's possible (though almost definitely not ideal) to simply choose a machine, plop a part on the build plate, and hit "generate support." Magics has some understanding of the technology you're using (in my case, either EBM or DMLS), and it creates support geometries that are (reasonably well) tuned for the process. 

But before you even get that far, Magics has a nice feature that allows you to preview which surfaces will need to be supported - the "Supported area preview." Presumably this would be used while the operator is setting the part's orientation in the build chamber. It allows you to view downfacing edges as shaded, and it shades them on a color gradient depending on what you want to see. Here I'm looking at the underside of the part, and varying the angle that Magics highlights:

On my part and in this orientation, there are two large areas that need support structures (inside the saddle clamp cylinder, and from the shoulder straps down to the build platform). But if you look closely, you can see that there are also a series of tiny areas with downward facing surfaces:

  • At the v-necks, there's an surface below 30˚ whose area is .91mm^2. If you change the selection angle to 50˚, the area grows to 2.58mm^2.
  • At the window tips, there are surfaces with 30˚ whose areas are about (they vary slightly from window to window) .22mm^2. If you change the selection angle to 50˚, the areas grow to about .73mm^2.

For comparison, the cross sectional area of a "medium" grain of sand (as described by ISO 14688) is about .4mm^2. Which is to say that these are relatively small surfaces. My hope is that even though they face downwards, they won't require support structures at all.

When you enter the support generation module and hit "generate support," Magics simply looks at the faces that face downward, chooses a support type that's appropriate for the surface size & shape, and projects that support directly downward. Here are the automatically generated supports for both my part in EBM and DMLS:

Throughout Magics' UI, there are "tool pages" on the right of the window that offer a variety of context dependent functions. When you're in the support generation module, there's a section of "Support Pages" there that let you analyze and modify the support structures in your build. Looking at the support pages in the pictures above, you'll notice that I've got the "Support List" page open, and that there are 12 supports listed in that view. For each of these, a variety of data is displayed: ID; type of support; some basic geometrical data, and an "On Part" column. You'll also notice that the supports that are "On Part" are keyed red in the list. This is a very useful piece of information: those supports, when they were projected downwards, ended up falling onto the part itself. The result is that when the part is printed, those supports will tend to be more difficult to remove. In the case of the MLab build above, supports 3 and 4 run the full inner diameter of the saddle clamp cylinder. In the Arcam A2X build, supports 3 and 4 are in the same situation - but a whole series of point supports (7-12) are also partly trapped in the part's windows.

In my experience, this is *not* desirable. Especially with EBM, supports that fall onto the part itself are a real pain in the ass to chip out (for a bit of context, see the photos I took of the first parts I had EBM printed). In addition, they tend to make the surface they're hitting rough, and as a result the part often requires more post processing.

In order to avoid this, I need to modify the support parameters. By going into the "Advanced" section of the Support Parameters Pages and checking off "Angled supports," I can pull the two big Block supports (ID 3 and 4) away from the part:

(I'm working on similar edits to the EBM build, but want to get a little clarification from Arcam on those point supports first.)

I can do a variety of other things to these supports, including "Rescale platform projection," which essentially flares the support in/out as it goes down to the platform. There are also a slew of parameters (hatching, hatching teeth, teeth synchronization, perforations, etc) which seem mostly designed to make the supports easier to remove from the part. All of these can be preset in the Machine Properties screen (which, frustratingly, isn't accessible when you're in Support Generation mode) or adjusted on a support-by-support basis from the "advanced" tool pages.

To be sure, I'm only scratching the surface on Magics' support generation features here. Magics will let you play with a *ton* of support parameters. I get the impression that there's a lot of nuance here, and that there are many parameters that you'd only play with in edge case builds. Regardless, the number of possibilities generated by varying just a few of the options is staggering; in order to know how they affect part quality, you'd need to run thousands upon thousands of test builds.

Eventually, it's very likely that Magics (or whatever replaces it) will have thermal & residual stress simulations built right into the software. Today, however, machine operators have remarkably little info about the finished part before they actually print it. Except...

Build time estimation

This is a key part of the additive design-for-manufacturing process. Knowing how long a part will take to print is a *huge* factor in what it costs, and is critical in comparing two build configurations for the same part.

Magics has a build time estimator, but it's not plug-and-play. Instead of shipping pre-loaded with estimates of how long a given machine will take to build a part, Magics requires the user to run "Learning Platforms" - and you need to own your own machine to do that. And, of course, I don't own a metal powder bed fusion machine.

I was *really* excited to get a build time estimation, but no dice.

The reason for this is that in order to estimate build time, you need to know how both the slicer and scanning strategy work - as well as mechanical factors like scanning speed and recoating time. And while certain machine manufacturers (see below) share this information with Materialise, for many it simply isn't worth it. They see those process parameters as valuable, and don't see the benefit of sharing that data with a third party software developer. Moreover, most of them can provide very accurate build time estimations in their own software, and the manufacturing engineers that use the machines take it as given that they need to use that at some point in the process anyway.

This strikes me as a big failing. Magics needs a way of sharing data about their builds: a public repository of machine parameters and build times. Without that - or without, on the other hand, convincing the machine manufacturers to share that data themselves - Magics is left with a huge disconnect between the build setup and the end product. This undercuts Magics' claim to be "The link between your CAD file and the printed part." If it lacks basic data on build speed for the most common machines in the industry, what exactly is it linking to?

So: As of the time I'm writing this, I've got emails out to a handful of the biggest metal powder bed fusion machine manufacturers in the industry, asking for Magics learning platforms. If anyone out there can share that data with me, please send me a note!

Build Processors

My demo doesn't include these, but they're worth touching on. For a few big machine manufacturers (Renishaw, SLM, and EOS), Materialise has developed build processors that are tuned to those machines' capabilities and specifications. Presumably, these companies provide Materialise with in-depth data about how their machines work, some of which is either patented or proprietary. Materialise then builds software modules that, through a few intermediate steps (the most notable of which are slicing and subdividing/hatching), produce a job file that can go directly to a machine.

Materialise bills the build processors as reducing complexity in the manufacturing life cycle, and allowing both Materialise and the machine manufacturers "to focus on their core competencies." Having not played with them myself, I can't really comment. I hope to learn more soon.

A few things Magics *can't* do

To reiterate: It's my impression that Materialise built Magics to fill a really big hole in the existing work chain, and the bottom line is that that work chain is something that no single party (let alone Materialise) created. It's also, in my opinion, *not* the right work chain for the future of additive manufacturing, and Magics' role in it highlights a lot of the problems in the industry today. Here are a few things that I noticed that Magics can't, for various obscure and not-so-obscure reasons (many of which are decidedly *not* Materialise's fault), do.

Understand the underlying design

This is something I've touched on in previous posts, but it struck me again when I was in the "supported area preview" screen. It's *very* likely that I could, with a relatively small amount of work, edit the underlying geometry in order to reduce the number of supports needed significantly. But I'm not aware of a way of showing downfacing regions in solid modeling software (Solidworks/Inventor, etc), and it's rather cumbersome to bounce back and forth between Magics and Inventor to try to optimize the design for additive. 

All across the industry today, I hear people talk about design software that understands the intent of the designer, and responds to accommodate it. This may be feasible in the near future, but the bottom line is that Magics (as it stands now) is *not* part of that process chain. Once a designer transitions from parametric modeling to surface tessellations, all of the geometry data is lost. If manufacturability feedback (like the supported area preview screen) is provided in software that reads surface tessellations (as Magics does), then going back to edit the underlying parametric model is *always* going to be cumbersome - and necessary.

Understand/display surface quality issues due to orientation

In all additive processes that I'm aware of, surface finish will vary significantly depending on the orientation of a surface relative to the build direction. Given the layer thickness of the printed part, this is relatively straightforward to simulate - not to a high degree of precision, but with a good amount of accuracy, at least. Magics doesn't do this, and it leaves me feeling like I'm missing a key piece of information about the printed part. Sure, I can imagine what the part will look like if I just think about it for a minute, but it does strike me that having some indication of areas with high stepover (which will occur wherever a surface is oriented close to the XY plane) would be really helpful - and not particularly hard to implement (caveat: everything I said above about feature creep, etc).

Understand the place of additive in the process chain

This may seem like I'm splitting hairs, but I think it's worth reiterating: Magics bills itself as "The link between your CAD file and the printed part." It is NOT concerned with the end product, which in almost all cases will have additional (subtractive) processes performed on it.

Why does this matter? When I had this part EBM printed recently, both the saddle clamp cylinder and the seatpost cylinder came out undersized. I know now that one of two things needs to happen there: either I need to compensate for the printing process in the underlying model (by making the designed dimension larger than I actually want it to be), or I need to remove material from the as-printed part (by machining, grinding, or similar).

Magics doesn't know any of this. If it did, it might be able to give me intelligent advice on what surfaces to take extra care with - and which I should ignore, as they'll be machined away in the end regardless.

In the end, Magics is a piece of CAM software - but it only deals with one step in the production chain. Changing this is a monstrous, complex task, but it's one whose impact will be hugely positive.

So

Magics is pretty cool - it does a *ton* of really useful stuff. You'll note, also, that I'm basically not interested at all in its "fix" feature, which (I'm told) is used a lot with models that come out of Rhino.

But it's also representative of a lot of what's going on in industrial additive manufacturing today. This isn't Materialise's fault; it's just the way things evolved, and is the result of (I'm sure) a lot of collaboration, competition, and plain old hustling (all of which I fully support) in the industry over the past few decades.

Regardless, Magics is a place where you can see a lot of the implicit assumptions that industrial additive manufacturing has been built upon. More on this soon.

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Improved laser build

Added on by Spencer Wright.

Learning new software is fun. This is me after a few hours playing with Materialise Magics 19 and SG+.

I've made a few modifications to the standard build:

  • Changed the surface selection angle to 50°. This build is set up for laser metal powder bed fusion (aka DMLS), which will print angles a bit below that, and it's very possible that 50° isn't optimal.
  • Changed the upper supports so that they're angled. In my last post you'll notice that if these are vertical, they'll rest on the bottom face of the cylinder. While that may be fine structurally, it means that I'd have that much more to clean up, and I think I'd rather have the supports go all the way down to the build plate instead. It's *possible* that this will reduce the amount of post processing necessary on the part - you'd need to run multiple builds with different configurations to be sure.

It's worth noting that this part is too far off the build plate right now - I'm still trying to get used to Magics' UI, and figured it didn't matter for now. I should probably also orient the part at a slight angle from vertical (see my recent post, here, for more details on this); again, I'll play with that a bit more later.

Oh, and I probably want to add additional reinforcements to the short ID, to make sure that it prints round. I'm looking at a few methods of doing this, most of which would require some work back in solid CAD (Inventor), or *possibly* some volumetric mesh generation software (like nTopology). 

I'm definitely still getting used to Magics' philosophical perspective on the additive process chain, too. I have some thoughts on what this is, but will play around more before I share them :)

Stay tuned.

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This week: Materialise Magics 19 and SG+

Added on by Spencer Wright.

Just a little teaser:

This week, in addition to the networking I'm doing (remember: I'm a free agent now, and directing my efforts toward finding the best path for myself in metal additive manufacturing), I'll be diving deep into Materialise Magics 19, the industry standard software for metal 3D printing build processing. I'm excited to learn more about its capabilities, and will share more later this week. I'll be spending most of my time working on orientations & support structures schemes for my titanium seatpost head, seen here in Magics' simulation of an EOS M280:

Magics bills itself as "The link between your CAD file and the printed part." It's used by OEMs and service bureaus alike to prepare design files to be printed - often times on the very machines that I've been building parts on (one, two) over the past year. In most cases, Magics imports an STL file. It then can be used for three big chunks of work:

  1. Fixing. In many cases the files that you import are broken in some way (edges not connected; faces oriented in the wrong direction), and can't be printed as is. Magics has a suite of tools that analyze and solve these problems.
  2. Editing. There are a variety of reasons why you'd want to edit a design before printing it, but probably the most common is that it won't fit in the build chamber of the machine it's being printed on. Magics offers tools that cut, hollow, thicken, perforate, extrude, label, boolean, and support parts and their features.
  3. Build prep. This is the part that I'm most interested in, as it directly affect the workflow that I've beed dealing with on my titanium parts. Here, the user selects the machine that the parts will be printed on. Then the parts are oriented physically within the build chamber, and an analysis is run to confirm that there are no part collisions that will affect the build.

Lastly - and of particular interest - is the SG+ module for support generation in metals. This would fall somewhere between (and across) numbers 3 and 4 above, and involves creating solid and mesh support structures that anchor the part to the build plate and provide thermal sinks to ensure a successful build. The SG+ module is a critical part of the metal 3D printing process chain today. It's used extensively across the industry, and engineers who are skilled at support generation are highly prized.

This week I'll be exploring these features (especially build prep and SG+) extensively; stay tuned for updates.

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3D printing titanium: Learning to learn from success

Added on by Spencer Wright.

Dear reader — 

This report is an update to my experiences in metal 3D printing; it describes a good chunk of what I’ve been working on over the past four months. While I’d like to say that it stands on its own, I think there’s some context — especially if you’re just beginning to explore metal 3D printing — that can be gained from reading my earlier posts (starting with my long "Bin of broken dreams post") first.

For background: I believe that functional, engineered consumer products made by additive manufacturing are an inevitability. In order to prepare myself for that inevitability, I’ve been developing a line of bicycle parts made by metal powder bed fusion, a process that’s used extensively in aerospace, medical, and tooling applications. My last post described the difficulty and constraints I’ve experienced in part geometry and build orientation. Since then I’ve turned a corner, and today I can say that I’ve successfully designed, built, and tested a functional product — which at last puts me in the position of needing to learn from success.

As I’ve documented the process — and frustrations — of developing metal 3D printed parts, I’ve been pleased and surprised at the number of people who’ve reached out to me to commiserate (n.b., if you’re reading this and want to do so yourself, please drop me a line). Without exception, they have expressed solidarity. “We share all of your frustrations,” one person said. “I have been through the same pain as you,” said another. 

One of these people was Tom De Bruyne, General Manager at Layerwise. Layerwise is a Belgian company which was started out of the Catholic University of Leuven (one of the premier centers of additive manufacturing research); it was acquired by 3D Systems in late 2014. They’re famous for being one of the few service providers who built their own laser metal powder bed fusion machines, and have a ton of experience making 3D printed parts at both prototype and production scale. We struck up a conversation, and soon agreed to work together.

While popular opinion would have you think that quantity is a non-factor with 3D printing, the realities of running a service bureau are much to the contrary. To job shops, quantity is a critical factor; if a part will be produced at large volumes, every detail of its design and manufacturing life cycle must be examined. If, on the other hand, you’re printing a tool — or a prototype of a part that will be manufactured conventionally — then most shops will focus on getting the first print right without modifying its underlying geometry.

My project falls somewhere in the middle: while my design is certainly imperfect, there are many aspects of it which are very close. Moreover, it poses challenges (most notably its opposing cylinders, oriented 90° apart, and also its thin-wall construction and bolt boss) that will exist throughout any redesign, and solving them now will only improve my ability to deal with them in future iterations. 

At the current juncture, the key questions to test are:

  • Can we reliably build my current design with minimal post processing?
  • Does my current design meet the necessary performance standards (strength, security, etc.) for bicycle seatmast toppers?

In practical terms, the first question boils down to whether we can build a part that can be installed on a bicycle. This means two things: maintaining inner diameters which are round and dimensionally accurate to within +/-.006", and having a bolt boss on the long cylinder which, when tightened, is capable of securing the part to a bicycle’s seatmast.

My last prototype was built on its side, and the long cylinder’s aft wall distorted as it was sintered. We added a series of solid ribs in order to counteract the built-in stress in that wall, but it ended up like a game of whack-a-mole: each reinforcement just moved the stress somewhere else. A new approach was needed.

Unlike most of the US job shops I’ve spoken to, Layerwise bundles together many low-volume customer orders into each build; my part was printed alongside a handful of other titanium parts in one of the 15–20 machines that Layerwise designed and built themselves. This means that Layerwise is able to process a large value of parts at once, even if they’re only building prototype quantities of each design.

This poses a significant challenge: if one part fails, it can jeopardize many customers’ orders. To mitigate this risk, Layerwise constantly monitors a slew of process signatures, and can adjust machine parameters on-the-fly if they detect problems. They’re also working on a layer-based deposition control & verification system (the details of this are secretive, but it sounds similar to the optical tomography systems that other machine manufacturers are working on today). Still, each part is evaluated carefully beforehand in order to anticipate and avoid failures. Especially for short-run prototypes, it’s usually better to over engineer the support structures (and ensure a successful build) than skimp out and need to rebuild the part later.

Layerwise is secretive about their custom-built machines, but they did tell me a few details. They each contain a single laser, and are built around roughly the same form factor (275mm x 275mm x 420mm) as most of the industrial machines on the market today. I also understand that Layerwise uses a recoater blade (unlike 3D Systems’ ProX line, which uses a roller), though I couldn’t confirm whether it’s a hard material (like the high speed steel blades that most EOS machines use) or a soft one (like the polymer wipers often used on Concept Laser machines). They’re able to print in about 15 materials, with the majority of their work being done in titanium. They monitor temperature, pressure, and oxygen content on-the-fly, and are working on additional variables — including full melt pool analysis.

Layerwise has in-house wire EDM, and has a daughter company that does 5-axis CNC machining. But most prototype parts, including mine, are finished by hand. When validating a part for production, Layerwise tests the full manufacturing lifecycle, building multiple full batches of parts and sending them out to be post processed. Once they’ve validated the process, they will in some cases hand off production to other 3D Systems divisions.

Reorienting

I worked with Martijn Vanloffelt, a project engineer at Layerwise, to prepare my part to be built. He used a few key tricks:

In order to maintain roundness in the saddle clamp cylinder (the shorter of the two cylinders, which was was going to be oriented more or less parallel to the build plate), Layerwise reinforced the inner diameter with three serrated discs. 

They also oriented the part slightly off-axis in both the X and Y axes. This brings me to a point that’s worth highlighting: In metal powder bed fusion, a part’s orientation has a number of effects. First of all, any surface with an angle of less than about 45° (depending on material) must be supported. As a result, it’s generally better to orient a part so that all overhangs are as steep as possible.

From NIST Technical Note 1801, a good primer on laser metal powder bed fusion.

But in addition, one must consider the angle between the part and the recoater blade. If the part lifts up at any point during the build, the recoater blade will strike it. The longer the area of contact is, the worse the result will be. Some machine manufacturers offer alternative recoaters to lower this risk (3D Systems ProX uses a roller; EOS offers a carbon fiber brush; Arcam uses a metal comb; and both Concept Laser and SLM offer soft polymer blades), but most use a piece of high speed steel (or, in the case of older EOS machines, a ceramic blade) to spread powder across the build platform. Regardless, it is usually better to orient parts slightly off axis in the XY plane, so that the blade doesn’t contact the part’s walls all at once. 

Orienting parts off axis can also help improve surface finish. When a cylinder’s axis is aligned in the XY plane, the top face will exhibit an undesirable stepped appearance; my earlier prototypes all had this feature. When a part is oriented off axis, the surface finish is generally more consistent.

I should note that none of these techniques is guaranteed to work in all cases. Layerwise has a lot of experience building a wide variety of geometries, and has developed a sense of how to anticipate and deal with issues as they come up. I got the impression that the techniques they used on my part are things they’ve used in the past, but each design is different — and even a tried-and-true method of dealing with one design isn’t guaranteed to work well on another.

The Layerwise team also put a lot of care into generating mesh supports. Like most of the additive metal industry, Layerwise uses Materialise Magics for their final build prep, and they’ve developed expertise in exploiting the software in creative ways. I’m not able to share a detailed description of the supports Layerwise created for my part, but I can say (and anyone in the industry could confirm) that they were needed in four areas:

  1. Underneath the part to anchor it to the build plate. 
  2. Inside the saddle clamp cylinder. 
  3. Inside the window in the center funnel area. 
  4. Inside the seatmast clamp bolt boss. 

Layerwise took great care to orient the part such that it didn’t require support structures inside the hidden voids in its center section. This is something that designers and project engineers alike need to think about as a part heads into production. Not only can powder bed fusion not make fully sealed voids (if you printed a sealed sphere, the entire center would be full of trapped, unmelted powder at the end of the process), but many geometries will require support structures in areas where they’re difficult or impossible to remove. For instance, a Klein bottle could be printed in metal — but no matter how you oriented it, there would likely always be support structures stuck inside its fat end. Because of the angles in my part, it was possible to avoid this — but a different design might not fare as well.

The Parts

The first part Martijn printed was a big step forward: The build completed successfully without collapsing. However, a new problem arose. The windows on the seatmast clamp area caused the two “leaves” of that cylinder to twist as they were built. By the time the window closed back up, they had become misaligned, and a witness was clearly visible where they joined back together. The part had a clear flaw — and it wouldn’t be acceptable for production.

In the next build, Martijn added a curved, perforated disc to each of the seat mast cylinder’s windows, keeping them aligned as they grew. The part that resulted was a full success, printing with clean, smooth surfaces and good near net dimensions.

Layerwise’s second build.

Considering how much support material needed to be added back into the seatmast clamp area just to get it to build properly, I’m struck again with how inefficient my design is. The windows in the sides of the part are meant to reduce both weight and cost, but a bunch of energy is put into supporting them — and then cleaning the temporary supports out again. Instead of windows, I could just as well have replaced the walls with a lattice structure that would both decrease mass and be self-supporting during the build process, bringing the part’s cost down.

This hammers home a point that has plagued my design process: Without knowing — and, optimally, having input into — how a part is going to be oriented and supported during its build, designers are doomed to creating inefficient designs. Designing for manufacturing requires an intimate knowledge of the manufacturing process, including direct access to detailed information about how the part will be oriented and supported. But in most designer/service provider relationships today, that information comes well after many of the important design decisions have been made — if it comes at all. As a result, it often takes a large investment (both in time and money) just to prove whether additive can possibly be used to create the part at hand — and once that’s been proven, many additional iterations are sure to be needed.

This is a key problem in today’s additive manufacturing supply chain: while parts are usually designed in a solid modeling environment (often Autodesk Inventor or Solidworks, each of which cost between $5–10,000), builds are oriented and supported in Materialise Magics — which costs an additional ~$20,000. As a result, independent designers are stuck with a disjointed process, which requires costly iterations and lots of communication with the service bureau who’s preparing the part to be built.

Regardless: At this point in the process, it didn’t make sense to redesign the seatmast clamp area to reduce supports. Martijn’s build had a very high likelihood of completing successfully, and it was time to put it to the test.

It worked.

Post processing 

After printing it, Layerwise did a bunch of post processing before sending the part to me:

  1. First, the entire build plate was stress relieved. Layerwise’s stress relief process is proprietary, but a typical process would involve putting the build plate in a furnace and bringing it to 600°C over a period of an hour, then holding it there for three hours before turning it off. In theory the furnace is either argon purged or vacuumed, but in practice it may contain small amounts of oxygen too. Layerwise says that the vast majority of the stress relief that they do is performed in a vacuum, but argon is typically used on prototype parts.
  2. Then the parts were removed from the build plate. Like most shops I’ve spoken to, Layerwise uses wire EDM — though bandsaws are also common.
  3. At this point, each customer’s part is separated and processed on its own. Supports are removed by a totally unsexy manual process, often involving wrenches, picks, and mallets.
  4. Where support structures have been removed additional cleanup is usually necessary. On prototype parts, Layerwise makes extensive use of rotary grinding bits.
  5. The inner diameters of my part were both ground to their final size. Layerwise told me that this process was 100% manual, and I was blown away at the precision and consistency of the surface finish.
  6. Then, any remaining features were micro shot peened with a nonabrasive ceramic medium.

At this point, Layerwise sent me the part. Still to be done, however, was to tap the female threads in the seatmast bolt boss.

Herein lies an important point: metal 3d printing does not, in general, produce usable mechanical features like threading. In conventional manufacturing, threading is often just another step on the same machine: mills and lathes can both easily create female threads. But with additive, threading almost always requires secondary processing. As a result, the design files that are loaded into Magics only contain plain-bore thru holes; any threading specifications must be documented (and manufactured) separately.

So, the part that I received simply had a 4.2mm hole in it; it was up to me to cut the M5 female threads. “No problem,” I thought. I’ve got a tap handle right at my desk, and am more than comfortable using it. 

At this point, I became painfully aware of what’s called alpha case. Alpha case is a very hard, brittle layer of oxygen rich titanium in a part’s surface (for an interesting study on alpha case depth, see this); it’s the result of the titanium having been processed at high temperatures in environments where oxygen is present. And as I tapped the hole in the first part that Layerwise printed me, I realized that it’s very, very difficult to cut.

In order to make my job easier, I purchased a set of custom progressive taps from Widell Industries. Progressive taps cut threads in three steps, increasing the thread depth as they go. As a result, the cutting force required is generally much lower.

Even using progressive taps, I was shocked at how difficult tapping the second part was. It was incredibly slow going, and produced a lot of heat. I used cutting fluid liberally, and 45 minutes later was done.

I should note here that titanium is a hard metal regardless of how it’s processed. Moreover, alpha case is preventable; in this case, it’s simply the result of the stress relief process being done in a furnace that contains some trace oxygen. Annealed titanium 6/4 has a typical Vickers hardness of about 349, but when a part has been stress relieved in an oxygenated environment, that number might jump to more than 412. By comparison, 4130 steel and 6061-T6 aluminum (both of which are used extensively in the bicycle industry) have Vickers hardnesses of around 207 and 107, respectively. In future prototypes, I would probably specify that the stress relief should happen in a full vacuum; that would at least make the tapping a bit easier.

Regardless: Finally, the part was ready to assemble:

After a total of eight build iterations, I could finally have the part tested — and learn whether my underlying design worked.

Testing

To help understand if my design would handle real world performance requirements, I worked with EFBE Prüftechnik, a German bicycle & component testing facility. EFBE tested the part to ISO 4210–9:2014, 4.5. That test entails:

  1. Clamping the seatmast topper onto a 34.8mm pillar angled at 73°, and fitting a dummy saddle rail into the saddle clamp.
  2. Applying 100,000 cycles of a test force of 1230 N, at a distance of 70mm to the center of the rail clamp, with the saddle rail tilted down/backwards by 10°.
  3. Applying a vertical static load of 2050 N to the center of the saddle rail clamp.

Marcus Schröder, managing director of EFBE, put my part through the dynamic test first. It passed.

Before he went through the static load test, Marcus asked whether I wanted to make sure I got an intact part back — or if I would rather find the failure mode in the static test. In the latter scenario, he would apply the maximum force his rig could handle and see if he could get the part to break — allowing me to redesign it accordingly. Wanting to know as much about my design as possible, I chose the latter option.

Marcus’s test fixture was capable of applying 3750 Newtons to the part. My part withstood the whole thing.

So.

Marcus used penetrating dye to confirm that the part didn’t have any micro fractures, and it came back negative. The part had met and exceeded the requirements for parts like it.

My part, covered in penetrating dye after being tested.

It’s worth noting that this test is simply that: a test. It’s meant to simulate real world conditions and guarantee that the part meets generally accepted standards. But it simulates those conditions only generally; manufacturers of these kinds of parts will often have their own in-house spec that to tune the characteristics they optimize for. But in general, a designer needs to choose a test, and then optimize his design such that the part fails just beyond the test’s requirements. If I trust the ISO spec implicitly then it stands to reason that I should remove more material from the part; after all, it passed the test with a wide margin.

Regardless, my part could be further optimized. What I’ve done to date was prove a basic concept: That metal powder bed fusion can be used to make thin walled bicycle parts. Which, to be honest, isn’t a particularly surprising result; after all, metal powder bed fusion has been used by others to create all kinds of bike parts, including both road and mountain frames. 

The question is: Can I make it commercially viable?

Practical matters

With the current design and an order quantity of 10 pieces, the as-printed parts cost about $500 to make. Meanwhile, the most expensive commercially available seatmast topper I’m aware of (made by No22) costs $300, and the fanciest seatpost I’ve ever seen (made by AX Lightness) was under $600.

Now, there are a number of interesting things to note here. First, I’m able to buy in fairly low quantities. It’s not unreasonable for me to purchase parts in batches of 10, which is about as low as any non-stock commercial product in the world— and much lower than most products that involve forging, casting or CNC machining. If I can sell my part at a high end price point, then it wouldn’t take much cost reduction before I’ve got a reasonable margin — even with a strikingly low order volume. And there are a number of ways that I can reduce cost on this part:

  1. Even keeping the part’s design the same, I can reduce the cost by 25–40% by doubling the layer thickness. This will result in a rougher surface finish, but it’s possible that the difference will be acceptable.
  2. A significant amount of time and effort can be saved by redesigning the underlying model so that the inner diameters need very little — or even zero — post processing. It’s unclear exactly how much work this will take, but it could reduce the price significantly.
  3. Moreover, the entire part can be redesigned in order to reduce both the end mass *and* the amount of support structures necessary. Both of these have a big effect on price, though it will be time consuming to find an optimal design.

All of this assumes that I stick with a laser powered process. Electron beam melting (which I’ve been experimenting with) might reduce cost further, though the design constraints there are quite different. 

It’s also possible that while this part isn’t the absolute best application for additive manufacturing, there’s another place on high end bicycles where additive works better. This is key: The cost of this part is in the right order of magnitude as my goal. Any number of small changes — whether to the machine’s build parameters, the design, or the underlying cost of the technology — could easily put the numbers in my favor.

Industry observations

As I hope you would expect by now, a few things have jumped out to me in this past few months of work — some relating to longer term questions I have about the industry.

Manufacturing design

As a designer, having more — and earlier — access to support structure generation software is incredibly helpful. Today, countless design decisions are made on little more than a hunch; it’s not until much later that the ramifications of those decisions become evident. This leads to an inefficient design-for-manufacturing process, where it’s difficult for product designers and manufacturing engineers to communicate all of the nuance needed. Until professional grade design software (and here I’m looking at Autodesk, Dassault, Siemens, and PTC) allows these implications to be understood early on, this will be a big problem. In other words, I should be able to set build orientation and design support structures directly in my CAD modeling environment.

Documentation

The designs that are loaded onto a metal 3D printer are often very different from the finished part, whether due to the addition of stock material to be removed subsequently (like my female threads), or the support structures necessary to hold the part on the build platform. But today’s modeling software generally only shows one state for each 3D model; those intermediate, near net shapes aren’t linked to the end design. This makes the design for manufacturing process even more disjointed and awkward, as it means that I’m never working on the same design documents as my manufacturing partner is. This communication structure is bound (cf. Conway’s Law) to be replicated in the end product, and the result is bad. To fix it, we need a new class of software that blends CAD (computer aided design) and CAM (computer aided manufacturing), allowing designers to understand a part’s production cycle with perfect clarity.

True design optimization

In the work I’ve described so far, I’ve relied exclusively on conventional volumetric and NURBS modeling techniques. But a new wave of design tools is out there — topology optimization and lattice generation, for instance — and they promise to create designs directly from functional requirements. Presumably these techniques would be just as applicable to my part as they are to the applications they’re already used on (mainly aerospace, biomedical, and other high tech applications). I’ve begun to explore this space, but the fact of the matter is that I’m not aware of a single consumer product today that was designed with these tools. My hope is that they both remove weight and make the part more visually appealing, but it could take a lot of work and some expensive (and experimental) software to find whether I’m correct.

Blatant editorializing: Gongkai for industrial additive manufacturing

Today, the viability of additive processes is totally opaque, producing a chilling effect on the creativity of both designers, service bureaus, and machine manufacturers. It’s my strong belief that that will only change by better understanding the efficiencies (and inefficiencies) of the additive manufacturing toolchain, and through my own work I hope to do just that.

In a series (one, two) of recent blog posts, Bunnie Huang describes the way that Chinese electronics manufacturers have been able to drastically decrease the cost of consumer electronics. To me, they provide an example for how additive manufacturing could advance much more quickly:

My most striking impression was that Chinese entrepreneurs had relatively unfettered access to cutting-edge technology, enabling start-ups to innovate while bootstrapping. Meanwhile, Western entrepreneurs often find themselves trapped in a spiderweb of IP frameworks, spending more money on lawyers than on tooling. Further investigation taught me that the Chinese have a parallel system of traditions and ethics around sharing IP, which lead me to coin the term “gongkai”… this copying isn’t a one-way flow of value, as it would be in the case of copied movies or music. Rather, these documents are the knowledge base needed to build a phone using the copyright owner’s chips, and as such, this sharing of documents helps to promote the sales of their chips. There is ultimately, if you will, a quid-pro-quo between the copyright holders and the copiers.

It would be an understatement to say that industrial additive manufacturing hasn’t adopted gongkai. Today, trade secrets & patents are the name of the game; the access I’ve been permitted (by Layerwise, DRT Medical-Morris, and countless other friends across the industry) is rarely afforded to others. It’s my feeling that this is bad, both for the technology as a whole and for the long term interest of individual players within it.

For instance: Anyone with experience could, given a part geometry and its build orientation, surmise more or less what the support structures will look like. If you have a physical part in hand, it’s even easier to reverse engineer; a part’s layer boundaries reveal its build orientation, and even with careful cleanup it’s generally possible to tell which surfaces have had support structures removed from them. In short, manufacturing forensics is, with enough experience and care, fairly reliable. And yet orientation and support structure setups are almost always treated as closely guarded secrets.

With so much uncertainty in industrial additive manufacturing today, firms are caught in something of a prisoner’s dilemma; their protective IP strategies prevent the industry from moving forward in the way that everyone ultimately wants it to. 

All around the world, intelligent, hardworking people trying to solve the most basic problems in additive manufacturing. Everyone in the industry knows what these are, and all of the major players are fighting tooth and nail to solve them first. And though it seems a long way off, I think most of them genuinely believe that they’ll see fully automated orientation & support structure generation within the next decade or two.

But today, the process of printing a part is decidedly hands-on; expertise is critical. “The people who are good at this stuff are good at it because they’ve been doing it for eight years,” one industry veteran told me recently. For sure, this industry is full of valuable intellectual property. But in most cases, *craftsmanship* is central to most firms’ bottom lines — and it is protected at all expense.

I believe that industrial additive manufacturing needs far, far more knowledge sharing. We need an environment closer to the one that Bunnie describes: 

We need “a ‘network’ view of IP and ownership: the far-sight necessary to create good ideas and innovations is attained by standing on the shoulders of others, and as such there [should be] a network of people who trade these ideas as favors among each other.”

In the coming moths, I’m looking forward to working on just that.

This post is just one in a series, and I remain convinced of what I’m working towards. With any luck — and more open collaboration with intelligent, committed people in the industry — I’ll have more to report soon :)

Thanks to

First, thanks to Martijn Vanloffelt and Tom De Bruyne, of Layerwise, for both their hard work and their willingness to help me understand how they work.

Second, thanks to Marcus Schröder, of EFBE, for both his hard work and the enthusiasm he had for testing my part — and discussing at length the testing & engineering cycle he sees in the industry today.

Thanks also to Dave Bartosik, of DRT Medical-Morris, and Dustin Lindley, of UCRI. Their continued technical help has been an incredible asset, without which I may never have begun this project.

Thanks also to Clay Parker Jones and Bradley Rothenberg for reading early versions of this piece.

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Planning for post processing

Added on by Spencer Wright.

The other day I got an email update from Rob Oliver, a machinist in Brooklyn who's helping me post process the EBM printed titanium parts that I got from Addaero recently. There's still a bunch of work to be done, but I wanted to write a bit about how we're thinking of the manufacturing plan - and the constraints that we're facing in the process.

While electron beam melting tends to produce much lower internal stress than laser powder bed fusion does, it's still a decidedly near net shape process. In further iterations I hope to get the as-printed part much closer to the final dimensions, but at this stage the parts I have deviate significantly from the intended tolerances. Specifically, most outer dimensions seem to have grown, most inner dimensions seem to have shrunk, and there are a number of locations where support structures have left unacceptable surface finishes.

My main focus right now is getting both inner diameters to within .006" of their designed size. It's difficult to get a reliable measurement of where they are now (due mostly to surface finish, and the presence of leftover support material), but they both appear to be about .040" undersized. In addition, I suspect that the shorter cylinder is slighly ovalized - though not to the extent that it'll be an issue in the end.

Although there are other conceivable options, the most obvious way to get the IDs within tolerance is milling. By using either a CNC toolpath on an end mill, or a boring bar on a conventional mill, it should be very easy to get well within .006" of nominal dimensions on both areas of the part. However, the issue of fixturing is nontrivial. I designed this part with T-splines, and its outer surfaces aren't orthogonal at all. As a result, we'll need custom tooling to hold the parts in a milling vise.

As an aside: Anyone who says that additive manufacturing eliminates the need for custom tooling has no idea what they're talking about. 

In order to securely fixture this part, Rob is machining its negative into a set of aluminum blocks, which can then be clamped securely into a milling machine vise. This technique (which I'll refer to here as "soft jaws," although technically what we're making is more of a coped fixturing block) is used extensively in subtractive manufacturing to hold irregularly shaped parts. 

The process of making soft jaws is relatively straightforward, but designing them for this part is somewhat complicated by the dimensional variation that EBM produces. Put simply, feature sizes in EBM parts tend to deviate from the design in the X and Y axes, but stay relatively true to size in the Z. That's because the Z axis is at least partly controlled by the Z stage drive system; the powder bed is lowered a predictable amount with each new layer, keeping features in the Z close to their designed dimensions. But in the X and Y, deviations in feature size are partly driven by the electron beam diameter, and partly driven by the distance that the feature is from the center of the build platform. 

As a result, my part has grown anisotropically, and Rob will need (to some extent or another; soft jaws tend to be somewhat forgiving) to compensate for the as-printed dimensions differently in the XY plane than he does in the Z.

In the end, though, the most practical way of determining the final dimensions of the soft jaws is to make a set, test them on the as-printed part, and iterate as necessary. It's conceivable that the first try will work, and it's also possible that if we make the negative a bit too big in all directions, we could use a piece of soft material (for instance, blue tape) to take up the gap.

It's also worth noting that there's an alternative path that I decided *not* to take. A common way to make parts - both with additive manufacturing and conventional - is to design fixturing features into an intermediate stage of the part. These can then be used to hold the part while secondary operations are performed; they can then be removed in a subsequent step. I considered this option, but find it undesirable for the simple reason that it would likely result in more post processing steps. Worse yet, it would probably require the surface of the part to be blended where the fixturing element had been removed, which would be either labor intensive, or unattractive, or both.

Regardless, we should have the first iteration of our soft jaws machined shortly. Expect updates!

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First EBM prints

Added on by Spencer Wright.

A few weeks ago I visited Addaero Manufacturing, one of the very few EBM (electron beam melting) service providers in the US. After my recent trials (and successes) with laser powder bed fusion, I wanted to try building parts with EBM. EBM is used extensively by aerospace and medical OEMs, but its penetration into the job shop world is way behind laser. Addaero, whose founders (Rich Merlino and Dave Hill) both worked at Pratt & Whitney before striking out on their own, is located just a few hours from New York City, and they were gracious enough to build two parts for me to evaluate the process.

I'll be writing up a longer post on the unique design considerations that EBM poses, but for now I wanted to share the pictures I took while there:

At this point, the parts Addaero made for me still need post processing before they can be assembled and tested. I'll be working on that over the coming weeks, and will update soon on my progress.

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Things that are on my plate right now

Added on by Spencer Wright.

Mostly for my own benefit & the sake of catharsis, here are the things that are consuming my attention over the past & for the next few months:

  • Planning my own wedding in October.
  • Having fun this summer.
  • Getting more exercise.
  • Writing a long blog post on the seatmast topper that I had printed (DMLS) by Layerwise, and then tested by EFBe. 
  • Writing a long blog post on the seatpost that I had printed (EBM) by Addaero.
  • Digging more into McMaster-Carr's iOS app, and comparing it to Amazon's recently rebranded Business offering.
  • Planning a sourcing trip to Shenzhen, where Zach and I will investigate a significant redesign of The Public Radio's speaker & mechanical assembly.
  • Getting more hands-on experience with metal powder bed fusion machines. Because there are none in the New York metropolitan area, this inevitably means traveling for a few days to somewhere where I have a friend in the industry.
  • Doing a deeper dive into the variety of design tools that are cropping up for additive manufacturing. This includes getting better at T-splines (Autodesk Inventor), working with topology optimization software (SolidThinking Inspire; Frustum Cloudmesh), and doing some experimenting with lattice structure generation (with nTopology).
  • Doing a deeper dive into build preparation software, namely Materialise Magics.
  • Building myself a real desk, preferably with a proper toolchest integrated into it. I also want 2x24" displays, a proper Windows computer for 3D design, a new Mac for daily use, and a place for both a Wilton "bullet" vise and my 12"x18" granite surface plate.
  • Writing a presentation on metal 3D printing that covers both my experiences over the past two years (a case study), and my broader observations on the industry. 
  • Getting said presentation accepted to an industry conference (likely either AMUG, RAPID, or Inside 3D Printing).

There are a few more longer-term things, but this is a pretty good list for now. 

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Measuring process signatures is hard

Added on by Spencer Wright.

From a NIST report titled Measurement Science Needs for Real-time Control of Additive Manufacturing Powder Bed Fusion Processes:

Finally, metallic debris from the [heat affected zone] can coat a window or viewport used in an AM imaging system, and disturb temperature measurements by changing the radiation transmission through the window. This is particularly troublesome in electron-beam melting (EBM) systems, and prompted Dinwiddie et al. to create a system to continuously roll new kapton film over the viewport in order to provide new, unsullied transmission.

This is a very important and totally nontrivial challenge. Measuring process signatures (which this report defines as "the dynamic characteristics of the powder heating, melting, and solidification processes as they occur during the build") is key to the industrialization of additive manufacturing. If the systems we have for measuring those factors are unreliable, machine manufacturers need to develop improvements for them ASAP.

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The six questions I think about when I think about industrial additive manufacturing

Added on by Spencer Wright.

Prompted by an impromptu back and forth with Jordan, I was compelled to write down the things I spend so much of my time thinking about. Some of these I have a better grasp on than others, but they're all problems that I'm excited to see developments on - and work on myself.

1. What are the process parameters that affect finished part shape?

I'm in the middle of a NIST report that goes through many of these. The sad thing is that knowing what the parameters are is only half of the battle; then, you need to control those parameters on-the-fly (which is not something that all machine manufacturers currently allow).

2. What are the most reliable and effective methods of measuring, recording, and processing those parameters?

Industrial additive manufacturing machines tend to be harsh environments for sensors and sensor hardware. Once we know what parameters to measure, we'll need to build measurement systems that are robust, accurate, and reliable.

3. Given two identical finished parts with two different production process chains (additive, subtractive, etc.), how can one determine which process chain will be more expensive to complete?

This is hard. I believe that it'll be easier to automate process chain comparison than it will be to automate process chain creation; in other words, coming up with a list of steps to manufacture a part will remain hands-on, but assessing the cost difference (time/money/energy) between two process chains will be increasingly automated. Regardless, these are big problems.

4. Given two different designs, each of which has the same end functionality, how can one determine which design will be more expensive to build?

This feeds into question 3. In many cases today, design decisions are made based on a hunch. If it were easier to estimate the production cost for parts with complex production process chains, designers would be able to make more informed decisions.

5. Given the same input design and two different additive build orientations, how can one determine which build orientation will produce the most high fidelity net near shape, at the lowest cost?

Also feeds into question 3. Manufacturing engineers need to pick a build orientation quickly and be guaranteed high fidelity end parts; today, those decisions are made mostly by gut. Bonus points if this data is also made available to designers, so that they can make even more informed design decisions.

6. Given the same input design and build orientation, how can one determine which support structure design will produce the most high fidelity net near shape?

Given the early effort that startups (namely 3DSIM) are putting into this question, it stands to reason that it's an easier one to solve than question 5. It's also possible that they think it'll be easier to commercialize support structure optimization software in the near future. Either way, I see this as just part of a bigger need that 5 and 6 are pointing at together: additive manufacturing engineers need better tools to set up and process builds.

These issues outline the biggest roadblocks that I've experienced on my path to commercially viable additively manufactured parts. If you have different experiences, or know of developments on what I've described here, I'd love to hear from you.

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CT Scanning of 3D printed parts

Added on by Spencer Wright.

A few weeks ago I visited CIMP-3D by invitation of its co-director, Dr. Tim Simpson. I was there partly just to visit (I love these kinds of places), but also to see first-hand the role that CT scanning can play in non destructive testing of additively manufactured parts.

CIMP-3D is located at and operated by Penn State University, and serves as part of Penn State's Applied Research Lab - and as an Additive Manufacturing Demonstration Facility for DARPA. In aggregate, they help both government agencies and commercial partners qualify and improve parts made by powder bed fusion and directed energy deposition. In their well-equipped shop, they have two powder bed fusion machines: an EOS M280 (EOS calls their process "DMLS", a term that I continue to get flack for using generically :) and a 3DSystems ProX 200 (3DSystems calls their process, which was developed out of their 2013 acquisition of Phenix Systems, "DMP" - for "direct metal printing). For their work on directed energy deposition, they also have an Optomec LENS MR-7 (a laser based powder deposition machine), and until recently had a Sciaky EBAM (a large scale wire fed electron beam welding machine, which had been sold just prior to my visit).

While I was excited in see their directed energy deposition machines, the real attraction was their GE phoenix v|tome|x m300 CT scanner. This machine is made by GE Measurement & Control division, which is part of GE's Oil & Gas business unit (it should be noted that I've done consulting for both M&C and O&G, though not for the people who make CT scanning equipment). CT scanners are *expensive* (close to $1M, depending on options), and are basically unheard of in private service providers. They can be used to analyze both the as-built form of a part (which will often deviate from the as-designed form significantly), and also any flaws (cracks and voids) which would make it unusable.

Before I visited CIMP-3D, Corey Dickman (an R&D Engineer there) was kind enough to print one of my seatmast toppers, in aluminum, on their EOS M280. It came out well, with only a small defect in the seatmast clamp area. Corey used some pretty clever support structures, tapering them in order to provide a balance between a solid grip on the plate on the one hand, and relatively low material usage on the other:

CT scanning uses a series of 2D X-ray images to reconstruct a 3D part. In CIMP-3D's scanner, the part is placed on a turntable in the middle of the machine. The X-ray projector, on the right side of the machine, shines X-rays through the part onto a sensor on the left side. Solid parts block X-rays, creating shadows on the sensor, and the result is a greyscale image where dark areas correspond with solid mass and light areas correspond with empty space. 

The scan moves pretty slowly. My part was scanned in 3500 slices, or one scan every ~.1 degrees. At this rate (and at a voxel size of 58µm), the total scan time was about an hour. Each scan takes about a second, and between scans you can see the turntable rotating slightly.

Fixturing the part in the machine presents an interesting challenge. You want it to be held securely, but you don't want any other solid things touching it - as they will cast their own shadow in the X-ray images. As a result, parts are often held in place by simply sticking them into a piece of styrofoam - as mine was.

Once the data is captured, it's loaded into a separate workstation to be reconstructed. The amount of data that needs to be processed here is staggering - my scan generated about 25 gigabytes of image data, which reconstructed into a 5.7 gigabyte model.

Once the reconstruction was complete, Griffin Jones (the R&D Engineer responsible for CIMP-3D's CT scanning) was able to do a visual analysis of the as-built part, checking it for voids and flaws. The as-built model can also be overlaid on top of the as-designed model, allowing for deviations to be easily quantified. The model can also be explored layer by layer in any orientation, allowing for a really complete understanding of what the solid part looks like:

A word on resolution: this scan was performed at a voxel size of 58µm, and each voxel is assigned a greyscale value that corresponds with the material's radiographic absorption coefficient at that location. However, any given voxel is subject to some amount of randomness as well; if a voxel has a vastly different value than its neighbors, then the operator needs to determine whether that's a result of a microscopic void, or a result of random variations. 

As a rule of thumb, Griffin assumes a void when he sees three voxels in a row with low grey values. Interestingly, the scan did reveal a few tiny voids in my part. They're mostly near the edges - specifically, the zone right at the boundary of the profile scan (the perimeter of the part's cross-section) and the infill hatching. Since the scan was performed at a voxel size of 58µm, and Griffin was looking for three voxels in a row with low grey values, the voids we detected were about 180µm - just larger than the diameter of a human hair. 

My suspicion - which would need to be verified by destructive testing - is that voids of this size are probably well within the functional requirements of my design. Of course, this particular model is aluminum, and the design is meant for titanium - but I'm looking forward to having a ti model scanned and destructively tested in the future.

For most product development teams, non destructive testing (NDT) is just one part of the process of qualifying a new part. My part, for instance, is being put through physical load testing this week - and I'll use the data I get from that test to improve my design. But for early on in the build planning process, having a tool that allows you to dive inside otherwise obscured areas of your part is incredibly helpful. Especially in the case of complex, topology-optimized parts with organic forms, it can be difficult to impossible to measure a part's deviation from the underlying design. Moreover, there may be regions that it's impossible to inspect without destroying an expensive prototype. My part has just this: the front of the neck section contains a completely hidden hollow zone. And as I move into redesigning for EBM, knowing the areas where powder tends to cake up will be even more helpful.

Thanks so much to CIMP-3D for hosting me!

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"Just Press Print"

Added on by Spencer Wright.

This is a total load of crap:

The high cost of tooling up a factory has long been a barrier to developing niche products. But now anyone with an idea and money could go into small-scale manufacturing, using computer-aided design software to create a three-dimensional drawing of an object and letting a commercial 3-D printing firm do the rest.

Some of the shit that's written about 3D printing *really* irks me. The above quote totally misses two key truths:

  • 3D printing - regardless of the technology - is highly immature. The idea that a designer can "let [someone else] do the rest" is just plain false.
  • Conventional manufacturing is actually *really* easy to do fabless; the "barrier" they refer to is a total misrepresentation.

I'm honestly excited for the future of manufacturing, but articles like this one only froth the market - resulting in less focus on the today's most interesting and pressing problems.

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A successful print

Added on by Spencer Wright.

The other day I got a package from Layerwise. In it was the second titanium seatmast topper of mine that they printed, and this one is ready to ride.

...but actually, this part might not actually be ridden - it's off to Germany to be tested. I'm in the process of writing up a longer report about how the project has gone over the past month or so - expect that soon!