An under-the-radar Arizona-based company has developed new molding and sizing technology to produce what it calls “the strongest line of injection moldable thermoplastic composites available.”
The reinforcing material is a carbon fiber-like material that is modified in a proprietary way to improve its adhesion to the matrix polymer and avoid some of the problems with
Metal replacement fasteners are an important application for the new compounds.
traditional fibers. The filler generates high mechanical performance with lower fiber content, increasing strain and allowing the part to yield and not fracture. That’s according to Dave Wilkinson, materials engineering manager at Piper Plastics.
The company also designs and builds its own injection machines up to 700 tons in order to maximize the strength of molded parts. Wilkinson said in an interview that the focus is on pressure control and the material feed system. “Traditional screw systems break up the fiber,” Wilkinson said. The Piper system is designed to minimize degradation and improve the integration of the fiber and the plastic. The Piper process actually melts the fiber to some extent. One fiber supplier it lists on its Web site is Kureha Chemical Corp. Tool design is also a critical factor.
Technical details are confidential. Piper Plastics does not patent its technology to avoid any disclosure.
The privately owned company was founded in 1980 as a plastic machining, fabrication and distribution company. A molding group was formed in 2005 when the company was disappointed with the lot-to-lot consistency of plastics shapes, which often performed far below specifications listed on data sheets. Wilkinson said that mechanical properties at times were 50 percent of what was claimed from lab testing.
“It was difficult for our customers because in the metals world, you can take the data sheets to the bank,” said Wilkinson. The biggest market is medical where molded plastic allows more design flexibility than metal. The company’s second biggest market is aerospace where OEMs are using more plastic to reduce weight.
Piper Plastics sells finished parts, like fasteners, but will occasionally sell resin if a customer does not want to be single sourced. Matrix resins include many very high-end high-performance engineering plastics, including polyetherketone (PEEK), polyphenylene sulfide (PPS), polyetherimide (PEI), and polyphthalamide (PPA), a high performance polyamide).
Part costs are said to be significantly lower than those made with prepreg layup because of the volume efficiencies of injection molding. Tradenamed Kyron MAX, the series is available in three grade levels, depending on performance and cost requirements.
Wilkinson says the company operates up to 50 injection molding machines and has annual sales of less than $100 million. Piper Plastics has locations in Libertyville, Illinois; Chandler, Arizona; Bangkok, Thailand; and mainland China.
All data supplied by Piper Plastics.
