2. Part Volume
Part runs are certainly one of the key consider-
ations in determining which path to take. Haars-
ma said, “Volume is usually your first indicator.
So we use a cutoff point of 6,000 a year. If an
annualized part run is 6,000 or more, usually we
want to stamp it.” Machine time is part of that
decision, and so is lead time. “At 15,000 parts a
year, it’s going to eat up all my machine time on
a turret or laser. Our lead times are going to be
too long as well.”
Haarsma qualified that break point, saying
that it is just a rule of thumb. “We might stamp
parts with only a 3,000-a-year volume, depend-
ing on other factors.”
Kenny was reticent to adhere to a hard-and-
fast rule on volume. “Identifying upfront the
volume, life cycle, and design dynamics will lead
the team down the path, but there is no defined
rule of thumb.” When pushed, he did cite a cut-
off number. “In general, parts with volumes
of 5,000 or more annually will get a look for a
stamping operation,” he said.
Axelberg refrained from pinpointing a cutoff
volume at all. “We never draw a line in the sand.
We try to learn as much as we can about our
customer’s needs and objectives and present
more than one option if the choice isn’t clear.
There is no set number that applies across the
board, because every part comes with a unique
set of conditions. That’s what makes this business so interesting!”
Launch lead time and product development may
result in a part’s life cycle starting as a fabrication and ending as a stamping, Kenny said.
Axelberg explained how the customer’s time-
table is a major driver. “A lot of it depends on
when the customer needs the parts,” he said.
“For one of our big customers, we’ve made runs
of 20,000 pieces of good-sized parts on a laser
and press brake just because they were needed
in six weeks. There was no way we could build a
die in that time.”
Axelberg added that because the job required
a very large annualized volume, GSM worked
on a long-run, hard-tooled option that would
take over the project when it was ready. “And
then in 12 weeks, the part converts over to a
stamping. So it starts off soft-tooled and ends
up hard-tooled. We do that on a regular basis.”
Axelberg said that to some degree, laser
technology has driven the need to take that
two-pronged approach. “I think a lot of OEMs
have gotten used to the responsiveness of
fab shops with lasers and their ability to make
almost anything very quickly.” As a result,
customers may not start thinking about hard
tooling when the product is still in a test phase.
Other times the part’s final design has to be
worked out. In those situations, GSM will start
out using a laser cut/press brake form process
and then progress to a stamping tool.
Another reason a customer might not initiate
a job in enough time to accommodate stamp-
ing tooling is the nature of its industry segment,
Axelberg said. “Solar is an unpredictable indus-
try. Projects can be huge, and often because
of the complexity of financing and permitting,
they’re complicated deals. The date that the
project has to go into service is established far
in advance. All the other details can really en-
croach on that final day. So for a lot of these
jobs, once they’re finalized, boom, we have to
go now—and it’s a lot of parts.”
Axelberg said that the introduction of high-powered fiber lasers has had a big impact on
the calculus unrelated to material type. As
recently as five years ago, GSM was building
pierce and trim dies to run sheared blanks in its
stamping presses. In spite of all the manual handling, the process was still faster than cutting
the parts on a laser. “We would run rectangular
parts with square corners on our CNC punches
because that was faster than laser cutting. Not
so anymore. Now we reserve our punches for
parts with 3D features that can’t be created on
a laser, because the punches can’t begin to approach the profiling speed of the fiber lasers.”
4. Part Size
Kenny discussed another factor: part size.
He said that a large part would most likely
force the operation toward fabrication rather than stamping. “That is because tool cost
grows with each progressive operation in a
tool, and a complete tool may require more
real estate than the press has available.”
Kenny pointed out that smaller parts have smaller tooling costs, rendering a shorter ROI. “Large
parts may require a larger annualized volume to
be stamped. Alternatively, we may consider multiple processes, like laser cutting the blank, then
» This fan component is a good example of a part that
must be fabricated on a laser and press brake, rather
than stamped, because so much metal is removed and
the remaining skeleton would become distorted. Photo
courtesy of GSM.
» Some parts with circular contours must be formed in a stamping press. Photo courtesy of Kapco.
»Material utilization is a driver, especially when the
material is costly. The first drawing shows excellent
material utilization using nesting for laser cutting, with
only a 1.84-lb./part scrap rate. The second drawing shows
material utilization using stamping to blank the part.
The third drawing shows the parts blanked and formed
in a progressive stamping process. Images courtesy of
General Stamping & Metalworks.