Injection molding: Fosta-Tek Optics focuses on Engel electric IMInjection molding: Fosta-Tek Optics focuses on Engel electric IM

Because molding optical components for applications such as mission-critical military equipment is the specialty of the house at Fosta-Tek Optics in Leominster, MA, the company has demanding standards for suppliers, especially when it comes to injection molding machines.

The 420-ton all-electric Engel e-motion injection system recently delivered to Fosta-Tek meets the demands precisely. Company VP Jim LeBlanc says, "We run some complex parts in challenging engineering materials-particularly for the military-everything from little prisms for night-vision goggles and large face-shields for industrial applications, up to automotive dashboard components."

LeBlanc notes that molded parts at Fosta-Tek have to meet demanding specs, and that requires shot-to-shot consistency. "Not an easy task," he says, considering the shrink rate of resins such as polycarbonates and cyclo-olefins."

"We have to know where the melt is in the mold and use injection-compression-sometimes sequential injection-compression-to

ensure repeatability, shot-after-shot. So our molds are loaded with transducers interfaced to our machine controllers," LeBlanc adds. "The optical surfaces of the molded parts are then measured with interferometers."

Engel machines have proven themselves to Fosta-Tek. Among its 22 injection systems, are 18 Engels, including seven all-electrics that LeBlanc says have been sourced over the past 12 years. He says that it's not just the machines themselves, but also the technical support. Engel engineers have worked with Fosta-Tek on a variety of technical issues, such as coining technology, mold and screw design, and processing, and some particularly challenging mold trials were performed at both Engel and at Fosta-Tek Optics.

John Morrison, Jr., the president of Fosta-Tek Optics, notes that the all-electric machines give the company a significant advantage in repeatability, and adds, "They also take the load off of our cooling tower; they add minimal heat to the shop; they're quiet, and provide significant energy savings, as well." He says the Engel are the best that Fosta-Tek has evaluated for its applications, and expects to buy more as the business continues to grow.

Fosta-Tek Optics currently employs 155 people. Besides molding, it performs mold design and optical polishing in house, and the range of its molding machines goes from 65 to 500 tons of clamp force.