PPS picked for complex medical parts

To provide the stability and autoclavability needed in the complex handles of Surgical Innovations’ MIS (minimal invasive surgery) forceps, Ticona’s Fortron polyphenylene sulfide (PPS) was chosen over nylon, polyetheretherketone (PEEK) and liquid crystal polymer (LCP).

The handles contain eight molded components including a central core with stainless steel inserts and a cone that transmits rotation and insulates against high-voltage during electrocautery.

In creating the forceps, the British medical device manufacturer rejected glass filled nylon, because it lacked sufficient dimensional stability during steam sterilization at 134C and 2.2 bar. As well, PEEK proved too costly, and LCP could not meet weld strength and surface appearance requirements.

The material selected was a 40 percent glass fibre-reinforced linear PPS (Fortron PPS 1140 L4). This resin had high strength (tensile strength at break is 195 MPa and flexural strength is 285 MPa), costs about 90 percent less than PEEK and has much less water absorption (at 0.02 percent) than nylon.

“The resin’s margin of stability and strength should allow us to reduce or eliminate the metal inserts, which will lower costs and simplify molding,” says Stuart Moran, engineering director at Surgical Innovations.

Ticona 507/457-4069

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