Automotive Engineering - August 2022 - 22

Optimizing design for
additive manufacturing
The rules for designing for DfAM require
design engineers to take a different
approach than used for traditional DfM.
Avoiding the pitfalls of 3D printing requires knowing the process limitations
- and how to work around them. An expert at a leading AM specialist shares
insights on getting it right.
by Nick Allen
A
s additive manufacturing (AM) technology and its applications
expand, engineers are recognizing that different industrial
3D printing processes have different constraints
that can affect designed parts in production. Some constraints
are universal across the different processes, and some are
more specific to the type of process used. It is thus essential to understand
the technology you are working with to maximize its potential
as a production method. With this understanding it is possible to
design around the general limitations of AM as well as the specific
process constraints that could impact a product or part.
While design for manufacture (DfM) is not a new concept, the rules
for designing for additive manufacture (DfAM) require design engineers
to take a different approach. This article is dedicated to sharing
some of the most common pitfalls encountered when designing parts
for the selective laser sintering (SLS) and multi-jet fusion (MJF) 3D
printing processes and how to avoid them.
Wall thickness
Wall thickness is a critical consideration for parts being designed for
AM both in terms of the part itself and any post-processing that may
be required. We recommend a maximum wall thickness to prevent
shrinkage deformation during cooling, while our minimum wall thickness
is recommended to ensure parts withstand our automated postprocessing
techniques without damage.
* 1 mm (0.039 in.) is our guaranteed minimum wall thickness for
unfinished parts, but it is important to note exceptions where
22 August 2022
thickness should be increased. Exceptions include
vulnerable unsupported structures, skeletal structures,
weight-bearing walls and specific functional/
performance requirements.
* 1.5 mm (0.059 in.) is our guaranteed minimum thickness
for parts that will be post-processed using our
polishing or shot peening options. Again, there are
exceptions for vulnerable unsupported features,
weight-bearing walls and performance requirements.
* Our recommended maximum wall thickness is 5 mm
(0.196 in.). Anything beyond 10 mm (0.393 in.) may
require the wall of the part to be hollowed out to
prevent shrinkage deformation, build failures and
excessive print times.
In most cases, 3 mm (0.118 in.) wall thickness provides
a rigid part with a little or no flex, while 1.5-mm
walls result in some flex depending on length and/or
structural support.
Surface details
The nature of the powder bed fusion (PBF) processes
that 3DPrintUK uses means that parts come off the
printer with a granular surface, and sometimes layer
lines can be visible. This is why post-processing options
such as polishing or shot peening are often required,
to achieve a smoother injection moulding-like
AUTOMOTIVE ENGINEERING
3DPRINTUK
Automotive Engineering - August 2022

Table of Contents for the Digital Edition of Automotive Engineering - August 2022
