Micromolding: 'It has to be perfect'

The industry's buzzing about exciting new business opportunities coming in the field of micromolding-that is, precision molding of extremely small parts and components in exotic engineering materials (see, for example, May 1998 IMM). But micromolding is nothing new to some. Take Accu-mold Corp., for instance. Accu-mold has been building "micromolds" and micromolding machines for more than a decade. Today, in its 7500-sq-ft plant in Ankeny, IA, it houses about 6 million parts in its shipping and receiving "warehouse," a room that's smaller than your average conference room. Typically, Accu-mold produces up to 85 million parts a year-85 million parts out of a 7500-sq-ft plant! You can fit an entire production run of some of its parts in a plastic yogurt container . . . a small one.

Gary O. Grams, president of Accu-mold, and fellow owners/directors Leo Beebout, CEO and business manager, and Roger Hargens, vice president and director of worldwide marketing, have Accu-mold humming at a 20 percent/year growth rate and $3 million in average annual sales. Sales are expected to shoot to $10 million in the future based on work that's already been contracted.

Full-service, art-to-part micromolding and high-tech leadframe molding are Accu-mold's specialties. It serves mainly electrical/electronics, telecommunications, and veterinarian/medical markets with large volumes of small precision parts accurate enough to work in high-speed automated assembly systems. The majority, some 65 percent, of its production is for export to countries like Taiwan, Japan, Mexico, Ireland, and Costa Rica. Customers include Bourns, the world's largest manufacturer of potentiometers; BI Technology; Starkey Labs; Vashay-Dales; Tocos; John Deere; and Kyocera America. It can provide JIT delivery, even to some offshore locations.
Consistent part quality is key. Accu-mold's molds and machines work very well. They are backed up by SPC and sophisticated inspection systems. Control documentation travels with a mold and shows workers how to check a part. But Grams says, "Inspection isn't where it starts. It starts in the process. The dimension we check is a process dimension. If the process is in control, parts are usually good."

Microprocess Control

Employing 33 people, Accu-mold operates 25 molding machines, including eight Boys, 22 to 25 tons, and one 28-ton Arburg for "big" parts. Accu-mold also has two 2-oz DynaCast die casting machines for mid-sized parts. Grams likes Boys for their price, reliability, and service. Accu-mold has had a very good relationship with Boy over many years. It is also looking hard at Boy's new small-tonnage 12M Procan series machine. Accu-mold works closely with all of its key suppliers. For example, some folks from Conair came out recently to see its operation, and Conair is now developing a micromolding drying system with a 2 lb/hour throughput.

The rest of the company's molding machines are trade marked "Micromolders." These are proprietary ultrahigh-speed hydraulic/pneumatic presses designed by Accu-mold and built in-house. Grams says that the real secret in running small parts in exotic materials is to "get material in and out fast and don't degrade the material." Micromolder machines operate at very high injection pressures. Cycle times typically are around 2 to 8 seconds. Parts are produced with zero flash. We asked Grams if Accu-mold would ever consider selling machines or licensing their manufacture. Accu-mold has not seriously considered it. By the way, all of the capital equipment at Accu-mold was paid for in cash; it has no bank debt.

Accu-mold also builds all of its own molds. Most are single-cavity molds to ensure consistent quality, but molds with up to 20 cavities have been built. Three-plate molds with slides have been produced for leadframe molding. Lead times usually are four to six weeks, or sooner, or about 14 weeks for leadframe tooling deliveries. About 25 percent of its molds are built for others. Accu-mold has in-house 250 active molds, some smaller than the head of a golf club. Again, that's 250 molds in a 7500-sq-ft plant. And its molds are built to last. There may be follow-up charges for engineering revisions, but once the job goes into production there's no charge for maintenance, largely because they seldom wear out. Nor does the other Accu-mold equipment. The parts are too small.

EDM is the secret in Accu-mold's core and cavity production. It builds all of its own jigs and fixtures, and has standardized on Handsvedt sinkers and a newer Mitsubishi wire EDM machine. "Our burn setting has to be less than the tolerance of the part. We burn-in our logo in some cases with .020-by-.014-inch letters," Grams says. It makes all of its electrodes of copper tungsten. "Graphite can't hold the tolerances." Mold bases are ground on one of the company's eight Okamoto grinders or its Brown & Sharpe. It also uses Hasco bases. Lathes are from Hardinge. Most of the work is in A-2 steel.

Polishing is a science at Accu-mold. Diamond-compound and toothpick-sized dental tools are used to polish off the .0001-inch sides left by EDM. Ejector pins are hand lapped down to .012 to .013 inches in diameter. Polishing is done through Nikon toolmaker microscopes. Even though the parts are small, venting is the most critical thing in Accu-mold tooling. Vent designs are proprietary. Accu-mold also has proprietary mold making technology for producing knitline-free moldings.

Think Small

As you might imagine, product handling of micromolded parts can be quite challenging. Some of Accu-mold's parts are so small and lightweight that static electricity makes them float in the air. It's possible to lose some 10,000 parts out of a 28,000 parts/day run if parts are improperly handled. The company has developed its own top-secret handling systems during the past decade. Automated assembly systems also are designed and built in-house, as are parts separators.

Accu-mold runs little commodity resins. It runs mostly filled and unfilled high-temperature engineering materials like PPA, PAEK, and LCPs. It also runs custom, confidential formulations from compounders like RTP.

"Sales and marketing activities are being intensified," says Hargens. Accu-mold has brought a couple of marketing alliances on board, and it has found that its new web page (www.accu-mold.com) has opened new doors into a number of different market areas around the world. Accu-mold sees its leadframe business as its biggest growth opportunity. "Convincing people that we are for real and getting them to understand our capabilities is our biggest challenge," Grams, Beebout, and Hargens say in closing. "What folks have to realize is that doing the impossible isn't impossible, it just takes a little longer."