Video: The Impact of Part Orientation on Cost and Build Time in AM
In this video, Professor Timothy Simpson of Penn State University discusses with me the case of a 3D-printed part in which just turning the part to a different orientation offered the chance to save considerable cost and time. Laying the part on its side meant fewer layers and less support structure might be needed. But first, the part had to be redesigned so it could build effectively in this orientation and so support structures could be removed. Design for additive manufacturing (DFAM) includes consideration such as these.
A co-director of the Center for Innovative Materials Processing Through Direct Digital Deposition (CIMP-3D) at Penn State, Dr. Simpson is a regular contributor to our site. He is also part of the faculty of a graduate-level program in AM.
Peter Zelinski, Additive Manufacturing
I'm Pete Zelinski with Additive Manufacturing magazine, and I am here with Dr. Tim Simpson, co-director of the Center for Innovative Materials Processing Through Direct Digital Ddeposition at Penn State University. Tim, we have a metal additive part here, a 3D-printed part. What's the material?
Tim Simpson, PSU
All right, a titanium part. And we'll talk about the straightforward question of build orientation, which in a lot of ways isn't so straightforward at all. This part was built [and] oriented like this. It took a lot of build time, and the time was just part of the waste. Talk about that.
Correct. So, this was actually an upright for the Formula race car team here at Penn State, Vincent Miranda was working with my colleague, Todd Palmer, to design and optimize this. They had used topology optimization to create this very lightweight structure and EOS was printing for us at the time, and decided to orient it in this direction. One of the challenges with this now is you've got overhanging and support surfaces here that need support structures. So in the end, printing it vertically, like this, took 54 hours to build, of which about 30 hours of that was to create the supports. And it was about $2,000 in powder. $1,500 was in the support structure. So, over half of your build time and three quarters of your cost end up being scrapped and get removed from the actual part itself.
All right, so a solution: Build it this way, orient it this way, and it's not as high up off of the build platform. Fewer layers ultimately to define the form, less time, why not do it this way?
Absolutely. So in most cases, you're absolutely right. The build height determines how long it takes and, of course, how much material it takes. This was done in a powder-bed fusion system, so that's a lot of titanium. So naturally, you would want to lay it flat in this orientation [with] minimum height as well as minimum build time. But then you now start to get these geometries underneath here that are going to need support structures, and it's going to be difficult, if not impossible, to be able to get in there and remove the support material to create that lightweight structure. So, you spent all this time optimizing your design, you're going to print it out, and then you've got extra material in there that you can't remove. That's just going to increase the weight again. So in this case, it didn't make sense to lay it down flat, given this geometry that we were trying to create.
So you took it farther than this. What's the solution that did allow this orientation?
If you think about it, most of the topology optimization software out there now, essentially the computer program or algorithms that are helping you optimize these lightweight structures, they're not aware, they're not thinking about overhangs and support and build orientation. A lot of people are working on that, but it's not available yet.
We actually had a graduate student of mine that picked this up and continued the project, combining different optimization algorithms, as well as build planning software to identify, "Hey, can we sort of lightweight some of these over if we're going to print it in this orientation? How do we change some of this geometry and change some of the structure so that it still maintains the structural integrity as needed, but doesn't require as much support structures when it's being built?"
This is actually the end result there. What we've done is actually eliminated the caps, if you will, that are over that particular part; they don't need to be solid like that. We can lightweight it and then remove some material, but then we add some stiffening ribs in here to be able to do that, very small support structures now that would be easy to go in, pop out or move out as part of that. We're able to also, underneath here, change this geometry a little bit to make it slightly lighter weight. So we're able to now, as we design for additive manufacturing, think not only about the geometry, but also how are you going to build that, and the interaction between those two to try and create a lightweight structure that also doesn't need as much support structure as the parts being built.
Design for additive manufacturing. So we hear that phrase, your university has a degree program in additive manufacturing and design. Design for additive manufacturing, we think about things like organic forms and topology optimization and lattice structures for weight savings. But another crucial aspect of design, when it comes to additive, is support structures. How much of additive design involves thinking about the support of your part while it's growing?
Absolutely. So I think when we're talking about design for additive, it's as much about designing the part as it is to think about or design the build itself. Those two decisions are very, very tightly coupled now and I think that's one of the challenges with design for additive manufacturing.
I think that's one of the challenges with design for additive manufacturing. We're having to make these new trade-offs that we're not used to making, [and] we don't have the software tools combined together yet to help us make those trade-offs.
We're having to make these new trade-offs that we're not used to making, [and] we don't have the software tools combined together yet to help us make those trade-offs. So for instance, as we said, thinking about what is my build orientation, as I'm creating my structure that then is going to dictate supports, [and] where I might need support (thin wall structures, maybe thick sections). All of those are important when we're starting to do the build planning, and we need to design and make decisions there just like we do in the geometry of the file itself.
And as AM continues to advance, the differences are becoming more pronounced and more important.
Additive manufacturing offers powerful capabilities alone, but even more opportunities are opened when AM is combined with subtractive processes.
Additive manufacturing imposes inherent manufacturing and design challenges that impact the dimensions and tolerances that you can (or cannot) achieve on an “as built” part.