An Ohio processor is growing 15-20% per year in part due to proprietary technology to injection mold tight-tolerance medical components from tough-to-process fluoropolymers. One of its biggest breakthroughs has been development of a direct gating technology that eliminates runner waste.
In an interview with PlasticsToday, Ken Kelly, general manager, said that Performance Plastics has added three Roboshot electric molding machines from Milacron recently and is on track to buy another. "We have $1 million in additional medical business coming in the third quarter," he said.
|Fluoropolymer parts can be molded with many features and tight tolerances.
So far the focus is on Class 1 medical devices, but the company is bidding on Class 2 work where the inertness of the highly crystalline fluoropolymers could play a critical role.
Behind the growth is a ten-year project to perfect the molding of fluorinated ethylene propylene (FEP) and perfluoroalkoxy (PFA), which are highly inert and compatible with most organic compounds, while also possessing good barrier, friction and wear properties. The materials have high continuous-use temperatures that can withstand repeated steam sterilization.
Fluoropolymers are also well known for their extremely low coefficient of friction properties that can reduce liquid, gel and powder adhesion and stick slip without the need for silicone coatings. Any reduction in chemical contaminants is a major plus in the current medical environment.
Those properties make FEP and PFA great candidates for medical applications. There's a perception obstacle, however.
"Many people still think that sintering or machining are the only viable processing alternatives for fluroropolymers because of corrosion and thermal issues during the traditional injection molding process," Kelly said. Part of that perception is based on the fact that polytetrafluoroethylene (PTFE) cannot be melt processed. But many people are not aware of the work that can be done with FEP and PFA.
The issues with fluoropolymers are significant.
Highly toxic gases
Temperatures of molds and equipment can range from 300°F to 800°F. Highly toxic gases produced have an extremely corrosive effect on both molds and machines. Issues include mold deterioration, runner system scrap rates, melt fracture, unpredictable shrinkage rates, delamination and dimensional limitations of traditional gating methods.
Kelly said that Performance Plastics has had a focus on developing parts from fluroropolymers, PEEK, Torlon and other performance plastics since it was formed in 1982. Around 2002, engineers at the company began asking: "How can we scale this up to make tens of millions of parts?"
Original focus was on metals that could be used in tools, hot runner systems, screws and barrels that could handle corrosiveness of fluroropolymers, while also providing hardness for long life.
Performance Plastics developed proprietary alloys and is now on a second generation material called PPL Tip Alloy B that shows an improvement of 250 times the resistance when compared to SS420, a stainless steel alloy commonly used in tools to prevent corrosion.
Kelly said that the PPL alloys for tip and mold have hardness values ranging from 46 HRC to 56 HRC to maintain surface integrity and excellent corrosion resistance. Composition of the alloys is a trade