How to Design for Additive Manufacturing (5-minute overview)

How to Design for Additive Manufacturing (5-minute overview)


Hi, I’m Alex Crease here at Markforged,
and today we’re going to be talking about an overview of designing for
additive manufacturing Designing for additive manufacturing is a subset of
designing for manufacturing which basically means adjusting your design to
make it cheaper, faster, or more effective to manufacture. Executing proper design
for manufacturing techniques can increase yield and save time and costs
when building your manufacturing process As an example when you design a part for
CNC milling there are a few things to think about Things like your mills make
and model capabilities and it’s working volume are all machine-driven. High
tolerance features tool changes and setups are all part driven. Beyond that
there are details like spindle speed, materials, and tool type that further
impact the manufacturing process If you have a complex part, it’s easier to make on a more complex machine But those machines are more expensive. A well-designed part makes use of the manufacturing technologies at hand to
simplify and streamline its production So this can involve minimizing tool
changes in set-up time Adding features to make indexing easier, and more. Some of these are machine-specific, and some of them have to do more generally with the
manufacturing process and the material behavior Now designing for 3d printing
is similar in that some aspects are process dependent and some are printer
dependent. You can get lost in the details of specific practices like
overhangs, feature size, layer resolution, things like that These are all highly
printer dependent and we won’t cover those right now. What we’re going to do
is focus on design for additive manufacturing from a very high-level,
highlighting what unique advantages it brings to the table, and how you can use
it to make a functional part 3d printing being an additive versus a subtractive process opens up a wide range of design opportunity but also comes with its
limitations that should be accounted for in your design. First of all, 3d printing
is a layer by layer process cross-sections of parts are extruded on
top of one another to build up your model which uncovers one of additives
biggest advantages. A complex part is just as simple to set up as a basic one.
Let’s take these two designs as an example A simple part with a vertical
hole like so requires a simple machining setup if you were to be milling this
whereas an angled hole requires either a more complex machine or a more involved fixturing set up when you 3d print the
same two parts, you just send your part to the 3d printing software and hit go.
The printer does all the setup for you so a geometrically complex part takes
the same amount of time and effort to set up as a simple one. One of the
drawbacks of a deposition based plastic printing process is that the parts are
anisotropic, so the material strength will be different along planes parallel
to the print bed than along the axis that’s normal to it. Think of it like a
stack of post-its. It’s hard to break this way, across the surfaces, but it’s
easy to pull apart at the seams between the discreet slices of material. So with additive, it’s important to put thought not into just a part’s printability, but
its performance and how it meets your functional requirements. What about your
part benefits from 3d printing Which features add value when printed versus made in other ways. We can summon up with this example here–a simple tetrahedron
shape. The first iteration of this is a basic kind of blocky shape. It works, but
it’s basically like a block CAD model It’s easy to get to this stage, call it
good, and hit print. This right here is a nine-hour print and cost twelve dollars
and 63 cents. Say we expect to go through multiple copies or revisions of this
model, we may want to make some improvements so to save time and cost. We can reduce the print cut time by doing something like this–we cut out a lot of
the material in the center but maintain the structural integrity of the part
with ribs instead of a solid block So this print here takes six hours and cost
six dollars and twelve cents, but from a structural standpoint, this part is
anisotropic. When we apply a load to this part It can sheer along the layer lines. So
let’s take a step back here for a minute and talk about the requirements of this
part. What’s important here? We care about the strength since this may need to endure a large load and we also care about these angles here–to make it a
regular tetrahedron. So these angles are complex geometries that need to be
precise, and the part can’t break on these beams here. If we want to rapidly
iterate on this part and modify aspects of the design, we have to do so in cycles
of six hours or more. This is where we can really use 3d printing to our
advantage Why not isolate the critical complex
components, which in this case are the corners Here’s the updated revision of
this part where we’ve done just that We circumvented the anisotropic of the
part with these dowels while conserving the overall geometry. If anything needs
to be changed about the part, each corner unit is a half-hour print job and cost
50 cents, so you can iterate much faster on each joint if you need to, and if
you’d like to change the size of the part all you have to do is swap out the
dowel pins without reprinting the corners Here,
3d printing is perfect for this design because we’ve isolated the geometrically
complex features, so that’s the key to designing for additive. Identify what
about the design can lend itself to the layer-by-layer process.
This affects costs and print time, improves workflow and part functionality,
and makes it easier to iterate and modify Think about which features of a
design you’re working on would benefit from additive and use that to simplify
how you’re creating your design Hope this helps you get started, happy
printing!

5 Replies to “How to Design for Additive Manufacturing (5-minute overview)”

  1. Interesting take. Do you think that 3d printing will be a supporting technology for a long time? Or do you think that soon, it'll be the manufacturing technology that everyone just need?

  2. This video is awesome! Did you decide to test just the corners of the structure at the end because joints tend to be the weakest points of parts or is there some other reason? Is that why you said they are the critical structures of the part? Why not test the sides as well?

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