F E AT U R E
By Michael Siemer, P.E.
By Michael Siemer, P.E., IMDS
Pattern-based tooling (RTV molding
and urethane casting). Courtesy of
Met-L-Flo.
"Adding" to
Your Tooling
Options
Understand the benefits and applications of processes
for making tooling through additive manufacturing.
dditive manufacturing (AM) has come far
since first gaining traction in the 1990s. In
recent years, the technology has seen an
official name change from the old term "rapid prototyping," the creation of an ASTM International
committee on standards, and the announcement
that the pilot institute for the new National Network
for Manufacturing Innovation will focus on additive
manufacturing. If you are watching AM but not yet
working with it, you may be left behind.
According to ASTM F2792-12a, rapid tooling
(RT) is defined as the use of additive manufacturing to make tools or tooling quickly. Rapid tooling
went through a push in the '90s when processes
such as Direct AIM, 3D Keltool, QuickCast and
others were created. Most of these processes
faced material and process limitations, but a few
survived. Recently, there has been a resurgence
in attention to AM tooling thanks to both material
and process improvements.
A
4— AM Supplement
There are two broad categories of tooling
from AM. One involves indirect approaches that
use a master pattern to create a mold or die, such
as a silicone rubber mold made from a master.
The second category is a direct approach in
which the AM machine builds the actual tool or
tooling insert. Direct metal laser sintering (DMLS)
from EOS, ProMetal from ExOne and LENS from
Optomec or POM are examples of processes that
can directly produce metal tooling.
Additive vs. Subtractive in Tooling
In contrast to these additive approaches, CNC
machining, the conventional approach to toolmaking, is an established and well-understood
technology that is currently the worldwide
standard for producing prototype and production
injection-mold tooling. Whether the machining is
entirely milling or includes EDM, CNC machining
is not subject to the material, size and accu-