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!