manufacturing processes. In addition to those with
bachelor’s degrees, there are opportunities for master’s degree holders who have the skills to set up,
operate, and troubleshoot 3-D printing machines.
In addition to training issues, there are safety issues and technical issues. Some of the safety concerns
stem from the fact that the technology is new. In an
effort to reduce the possibility that parts will fail,
some manufacturers are using parts that are heavier
than optimal. Clever new structures such as very
light meshes have different vulnerabilities from
solid, chunky components; this is especially true in
applications where parts need to rotate or are repeatedly loaded and unloaded. Understanding these
potential weaknesses, and learning to design parts to
avoid them, will take time.
On top of that, more work needs to be done to
reduce variability, so that additive manufacturing
machines and processes can produce components
that are identical given the same set of inputs. 10 To
understand why this is important, it’s helpful to
recognize a fundamental difference between 3-D
printing and other manufacturing technologies.
Take machining, for example. Machining involves
starting with a block of metal and cutting away the
parts you don’t need. It’s reasonable to expect that
after the machining process the material that’s left
has essentially the same properties as the block you
started with. But that is not necessarily the case
when a part is made with 3-D printing.
That’s because some metallic additive manufacturing involves zapping adjacent microscopic
particles of a powder with a powerful laser so that
the particles melt and fuse. The process of zapping
particles occurs over and over — millions, perhaps
billions, of times — until the part is completed.
Each particle in the resulting component is rapidly
heated and cooled many hundreds of times. What
finally emerges depends on a number of factors, in-
cluding how much each particle was heated, how
many particles were heated at one time, how many
times the particles were heated, and how quickly
they cooled. If the process is not consistent from
beginning to end, you can’t have consistent results.
To ensure that the process has been properly con-
trolled requires finished-part testing. However, some
of the necessary testing methods — for example,
how to inspect the insides of hollow parts without
having to slice them open and destroy them — are
still being invented. Ultrasound does not always
work well for metals, and another technology, indus-
trial CT scanning, is slow and expensive, and cannot
be used for all geometries. 11 Yet unless we can resolve
these issues, the savings that might be generated by
one-step manufacturing processes, especially for
parts critical to product safety, could be swallowed
up by the need for additional testing.
Quality control is challenging enough when
components are made within the same four walls;
working with third-party suppliers makes for even
greater difficulty. A part made using additive manufacturing that performs well on tests designed for
conventionally produced components may for a
variety of reasons perform poorly in service. For
example, although the properties at the surface of a
part may be the same, they could be different from
those a few millimeters deep.
Initiatives are underway to solve these problems.
ASTM International and the International Organization for Standardization are collaborating to develop
standards for additive manufacturing. 12 In the United
States, the Materials Genome Initiative, an interagency program designed to create public policy and
infrastructure for the development of advanced materials, aims to create powerful software simulation
tools and create shared material databases. 13
Some companies are pushing the boundaries of
additive manufacturing with new materials and techniques. For example, Impossible Objects LLC
of Northbrook, Illinois, is applying additive manufacturing techniques to composite materials to
produce components that are much stronger than
A part made using additive manufacturing that performs well
on tests designed for conventionally produced components
may for a variety of reasons perform poorly in service.