Full disclosure: the conventional bracket was stamped in a press and then laser-welded by robots. It took about a three-car garage's worth of space, an easy $250k worth of tooling and probably 12 minutes to make. The 3d-printed bracket was laser sintered in a powdered-aluminum Selective Laser Sintering 3d printer that's about the size of a dishwasher and cost about a million and a half dollars. It also took prolly 30 hours.
So we're not there yet? But it's interesting to see where it might go. That 3d bracket, for example, could be sand-cast without too much drama.
I've become very interested in generative design lately. We had Autodesk over at our company the other day to talk about it, and after playing with the tools for a bit I've become convinced that it could revolutionize urban developments and urban design. Urban design is about figuring out what to do with a place, designing for stakeholders' desires while taking (policy) limitations into account. That has always sounded like an optimization problem to me, with constraints (policy) and goals to maximize or minimize (in the GM case lightness/cost/etc, in our case project cost/sustainability/...). I found the Alkmaar example here absolutely mesmerizing, and I'm arranging meetings with the company that did the pilot. If it still looks interesting after hearing what happened when the rubber met the road, I'm gonna be the one to helm our expedition into generative design.
Interesting. In a way, it's very similar to permaculture design principles, which claim heritage from African agriculture. Curious to hear how it works. It hasn't escaped me that generatively designed watch plates might look pretty damn cool... and are the sort of thing you can have only if you're 3d-printing wax for bronze castings, as opposed to machining the things on a VMC. I suspect you'd still need to do boring on a VMC but you could get some really cool lookin' movements that way. Stay tuned, I guess?
Generative design rests firmly on parametrically designed products - e.g. if a watch is 42mm, the hour hand length should be less than half that, so The demo example that I've been playing with is that of three towers. Each tower has an x and y coordinate for its centerpoint and a height parameter. The three towers together have a width and length parameter. Based on those simple inputs, you can have the program design three towers, adding for example the constraint that the middle tower must be 20% higher than the other two or that they have to comply to the NYC setback. The goal in this example is to maximize inner volume while also minimizing the outer surface area. I think the idea was to limit the amount of glass needed on the outside. So a good strategy is to have the towers overlap, but how much and in what formation? Basically, with the variable inputs (x,y,height,...), the parametrically defined shapes and constraints, and the desired outputs to optimize for(MaxVolume, MinSurfaceArea), the software will try many variations on the input variables and score them on the output variables. Of course, many different goals / KPIs can be considered, as long as they can be calculated based on the resulting design shape. So with this bracket example I am pretty sure that they also ran the computer-generated designs through some strucural simulation models in Fusion to see how strong it would be against certain loads. I think the interesting thing is that it is a very flexible framework for creating wayyyy more alternative solutions to a problem. It also makes the consequences of your design choices much more visible - you can actually see what it means to choose sustainability over profitability, or volume over surface area, or any set of evaluation KPIs over another set of KPIs. Currently, those design choices and consequences are hidden from view, or neglected, or made on gut feeling / expertise. If I can sit down with relevant stakeholders and say "here's 200 designs that are all up to code but each score differently on these factors you value, now what do you guys really want?", that's gonna be incredibly valuable I think. hourHandLength = watchDiam * 0.4
Yeah but the watch hand length isn't parametric. It's preferential. Parametric is "there's this much torque from the main barrel, reduce material until only the necessary structure withstands the force on the jewel holes: Autodesk's archetypal example - the one that's at all the trade shows - is the motorcycle swing arm: 
I might very well have my terms mixed up - I'm by no means well-versed in this type of engineering. (Yet?) My understanding of parametric is that it is a relational method of design; thing A's size depends on thing B. It can be made much more complex than that, and it can be types of "inputs A should lead to shapes B constrained by strenght model C and solution space D", but fundamentally it's about the relationships between design elements. Could've made that clearer, I suppose, or I'm missing something. Generative design as I have dabbled with is "given input parameters A that each can vary this amount, and given model B that takes these parameters and generates a design, measure set of result-based KPIs C and iterate over A to optimize C."
In mechanics, you're talking about parametric design; Solidworks and Fusion will do it all day long. "The distance from A to B is 1/2 the distance from B to C." Move C, A will move. Those interdependencies allow you to change things up pretty easily if you set your model up right. Generative design in mechanics runs exactly as you describe, but the goals are different: "Given torsion forces A, B and C, compressive forces D, E and F, shear G H and I and clamping forces J and K, generate a continuous cross-section between pins Alpha-Beta and holes Gamma-Theta that minimizes the weight of the assembly. Presume a Young's Modulus of x, a shear modulus of y, a density of z and a factor of safety of five now GO." Things had to get computationally intensive to do this. you're goal-seeking through finite element analysis which, back when I had to do it, took ten minutes of server time on a DEC Alpha just to model a bike frame made of constant-diameter tube.
"just" if you're willing to invoke 3D printing in the manufacturing process somewhere, which as listed above, puts you in a pretty spectacularly weird regime at the moment. If you look at that second swing arm, it only exists if you can cast it off an algorithm. Yeah you could probably painstakingly shape it by hand but you're not going to because you don't have any good way to verify that you put stuff in the right place and the weight savings are probably not entirely worth bothering with (I mean, a tire is going to weigh more than what you're saving there). However, as soon as your construction method becomes "make it thicker in one direction by fractions of a mm" it starts to make sense.
All the properties of a casting, waste to usable material ratio of a hog-out and a part geometry so damn complex it can only be verified by proof testing. Whats not to love about this? If you think this is the future of manufacturing i have a bridge in Brooklyn to sell you.
Oh c'mon it ain't as bad as all that. Yeah - it's gonna have all the properties of a casting, or worse properties than a casting if you're sticking with the laser sinter. Which is going to make it jaw-droppingly expensive so let's assume it's a casting. But that means you destructively test one in a hundred or one in fifty and move on. Waste to usable material ratio? If you're casting it, it's got the waste of a casting. If you're sintering it, it's got effectively none - you're fusing powder and the unfused powder goes back in the hopper. Let's presume we're rollin' HDPE. It's going to cast utterly without drama. Our material costs are entirely related to waste so the less we use the happier we are; we have no dross 'cuz it all goes back in the bin. Let's presume we're rollin' aluminum. Yeah that casting is going to be a bit of a nightmare but we can adjust for that. Either way we're in a much better regime than if we have to 5-axis the bitch or weld it up. Ductile iron? I can heat treat it and shot-peen it. It'll magnaflux like anything else. Heat sinks on Microsoft Surface Book 2s are laser-sintered 3d-printed aluminum. I know. Crazytown. But they make 'em about 300 at a time in a printing process that takes about 5 hours so... it works.
If you're sintering it, it's got effectively none - you're fusing powder and the unfused powder goes back in the hopper. That was the original thought... but turns out the powder thats was near the laser gets affected by the heat and if you pour it back in you get all sorts of additional material oddities in the next part. So you get get material properties for the first part but the scatter kills you on part #2. Idk why you would make 3D printed heat sinks... probably because you have too much money but ok it works fine in any application where you dont need structural material properties. So if you want to turn a 10c heat sink into a $5 one you can or if you need some sort of fancy decorative shape for a trim price, great but the technology is decades out for practical and cost effective structural applications. You will see this stuff pop up here and there as peoples pet projects or to show how cutting edge some company is but its just not ready for prime time, and may never be. I should caveat that all by saying that 3d printed parts like this should be great for fluid systems applications. Any time you need weird mixer geometries with internal cavities, probe holes, flow reducers and mixers 3D printed parts like this will work great.
This is news to me. Not doubting you - curious. Can you show me some links on that? I suspect so they can iterate quickly. They're complex shapes; more like exhaust vents than sinks and they're curved in two directions. They'd be problematic to cast. I agree with you largely. but turns out the powder thats was near the laser gets affected by the heat and if you pour it back in you get all sorts of additional material oddities in the next part.
Idk why you would make 3D printed heat sinks... probably because you have too much money but ok it works fine in any application where you dont need structural material properties.
Here is a decent one talking about the decreased tensile strength of products made from recycled polyamides. Though I'd like to hear HGL's input as well. Going to a different setting and hoping it's a good analogy, It seems to make sense from the organic synthesis standpoint. Once you allow it to happen, runaway polymerization is one of the easiest ways to obliterate your product (e.g. decarboxylation of salicylic acid to phenol). All you need is heat and impurities that act akin to nucleation sites for growing crystals.
That paper is about polymers, though, and the whole fun of SLS is powdered metal. I have no doubts that getting a polymer melty-adjacent makes the remelt janky. If you're talking about steel, aluminum or titanium, though, you're at basic-bitch cast level anyway.