Case Study
STEEL

Pre-hardened Tool Steel
Saves Time and Money
Using NAK 55 standard mold bases allows moldmakers to focus on crucial coreand cavity work.

Sherry L. Baranek
hen Tooling Express, Inc. (TEI)— a Bellevue, ID-based moldshop that specializes in sporting
good molds — branched into the molding
part of the business to further define its
niche and improve its moldmaking process, it soon faced the challenge of finding
a quality tool steel to work with that also
would shorten deliveries by reducing
machining times and post processes suchas heat treating.
Located right outside of the ski resortarea of Sun Valley, ID, this father/son
moldmaking/molding shop employs four
full-time toolmakers/mold designers. The
shop is literally 15 minutes from the ski
slopes, and summertime fly-fishing is a
10-minute walk from the shop’s back door.
It seems only natural that the company
soon found its niche catering to the wide
world of sports. With a 10,000-square-footfacility containing six injection molding
machines ranging from 55 to 165 tons, TEI
also has second operation facilities such as
pad printing, ultrasonic welding, andminor assembly and packaging of its customer’s products.

The Overmolding Challenge
According to Vice President Evan Downard, one of the company’s earliest challenges involved building a mold for overmolded ski pole grips. “It had only been
done once before and our new customer
wanted to get very aggressive with theshut-off shapes that would show thesecondary color on the grip,” Downard
explains. “We quickly realized that the
only way to ensure success with the project
was to also control the final injection
molding process. So, eight months into ourendeavor as a moldmaking shop, we also
found ourselves as injection molders. Ourhuge success with this particular overmold job quickly lead to other jobs andwww.moldmakingtechnology.com

Photo courtesy of Tooling Express, Inc.

WInternational Mold Steel’s off-the-shelf NAK 55 MUD style bases allowed Tooling Express to get it’s customer’s products
ready on time.

helped us realize that this is our niche in
the industry.”
The object of overmolding — or insert
molding — is to place either a metal orplastic item into a mold and close on it.
“This is something that most injection
molders try to avoid,” Downard explains.
“But here we are in our own private Idaho,
doing it all day long on purpose.
“A big problem with insert molding is
the fact that you are actually closing themold on pre-molded parts or some otherinsert material,” Downard continues. “Inthe past, we have relied heavily on heat
treated tool steels to take on the task ofpinching off on insert material and stillleave shut-off surfaces intact. Taking theproblem one step further, there is often aneed to do additional machining on moldsurfaces to fine-tune the pinch off areas.”

Standard Mold Bases/Inserts Speed
Delivery
Downard found the solution he wasseeking at International Mold Steel, aFlorence, KY-based supplier of prehardened mold steels and a new line ofMUD-style mold inserts. The company’soff-the-shelf NAK 55 MUD style bases
were the best fit for TEI’s needs. “Since alarge portion of our molds are built in thisstyle base, and the fact that we can more
efficiently cut NAK 55 over the otheravailable pre-hardened mold bases, this iswhat we were looking for,” Downardcomments. “The price may be a bit higher,
but we quickly make up for that additional cost by having the ability tofinish molds earlier due to faster machining and less time spent on any unnecMoldMaking Technology ■ August, 2001 21

essary heat treating. In addition, we don’t
need to post-grind the inserts.”
Plus, the quick-change inserts load inand out of a master frame that can bereused over and over again, eliminating theneed for each mold to have its own “A”
support plate and “B” side ejection box orU-frame. “This obviously offers some costsavings due to fewer materials being
needed, but more importantly, it allows themoldmaker to focus on the more highly
detailed core and cavity work,” Downard
explains.
The greatest challenge of this type ofwork, he continues, is that most often there
is no real life part geometry to work from.
A customer’s only concern is that it works
and achieves the desired look whenassembled. When components for the final
assembly are being made all around theworld with no real hard numbers to calllaw, quite often final “tweaking” isnecessary. For this reason, weldability ofthe mold insert material is crucial, andDownard points out that it can be welded
without any evidence of the weld on thepart.
“In our latest endeavor of overmolding
plastic attachment points to the ends ofgoggle straps, the NAK 55 mold bases
have really shined,” Downard adds. “Dueto the perfect timing on delivery of themold bases and the ability to machine
faster with minimal polishing, we wereable to get our customer’s new concept
products online in time for them to takeactual production parts with them to arecent trade show.”
MMT

For more information contact Paul
Britton of International Mold Steel(Florence, KY) at (859) 342-6000 or visit
its website at www.imsteel.com.

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TECHNOLOGY Reprinted from MoldMaking Technology magazine. Contents cannot be reprinted without permission from the publisher.
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