One lesson learned from the economic recession is that
One company that barely felt a blip in business was Accumold, a company in Iowa that molds parts with an average shot
size of just two grains. One grain equals 0.000142857143 lb. Accumold started in
a rented garage in 1985 with a focus on micro-sized parts that other companies
The original custom Micro-Molderģ was designed to manufacture parts with minimal waste and short
cycle times for electronic component manufacturing. The company still focuses
on tiny parts for industries that require fast turnaround and complex parts.
They include microelectronics, automotive, fiber optics, medical and military.
"In terms of the volume of the part, our limits are around
0.005 cubic inches," says Greg Peterson, a former tool designer who is now the
technology manager at Accumold. "Anything less than a half-inch square and on
down, we would consider a candidate for micro molding."
The smallest part Accumold produces is about 800 microns
long by 380 microns by 300 microns. "But it's not only about the size; it's
also about the efficiency of the process. "We don't have a runner that's 7,000
times larger than the part," says Peterson. "It's maybe a dozen times larger."
Ten or 20 microns are pretty common values for tolerances held on Accumold parts, he says.
The Secret Sauce
Accumold has more than 70 injection molding machines,
including about 40 it made especially for demanding jobs. Accumold reveals no
technical details about its machines or process, and has filed for no patents,
to keep the technology secret. The conventional presses are in the 12 to 35 ton
range, and include Sumitomo electrics and Boy hydraulics. Its own machines aren't
classified by tonnage because clamping force becomes irrelevant on micro parts.
All molds are made from tool steel and are delivered in two to three weeks.
Accumold recently developed a two-shot micro system. "Our
customer had been doing this on a machine that was the size of a semi trailer,"
says Peterson. "We reduced it to a small footprint - less than a VW Bug. The
nylon part is about 3/16-inch square with an eighth-inch diameter co-molded
elastomeric sound seal. In another new development, Accumold expanded its
insert molding capabilities with an automated system.
One of Accumold's hot growth areas is lead-frame packaging
for electronics parts. Plastic is molded on and around several types of metals,
including tin, copper, silver and gold to form an air gap seal. In some cases,
plastic is replacing ceramic as the packaging material. According to Accumold,
thermoplastics can provide 85 percent of the performance of ceramic at 25
percent of the cost.