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  • Long Glass Fiber Composite Replaces Metal in Knife Handle

Knife HandlesLeatherman Tool Group’s customers were very clear about what they wanted in the company’s upcoming line of knives. They needed to be lightweight. They needed to be dent resistant. They needed to stand up to an array of chemicals from oils to insect repellent. And, they needed to look sharp as well as be sharp.

“Metal scales (industry jargon for knife handles) couldn’t meet such varied criteria; many customers wanted ruggedness and strength, plus the light weight of plastics,” said Michael Duncan, Leatherman’s Sourcing Engineer.

Leatherman considered using a carbon fiber material, but found that the cost, including the frequent need for machining after molding, would have made the knives too expensive to produce.

Duncan discussed the challenge with Dean Christensen, Sales V.P. at Leatherman’s molding partner, KASO Plastics, Inc. KASO had worked with RTP Company regularly for many years, and by chance, was at that moment running a part using an RTP Company specialty compound that Christensen believed could also meet Leatherman’s stringent demands.

“We knew of a couple of materials that had the desired properties, but the RTP Company material leapt right out at all of us — the price difference was huge; it was like a quarter of the cost of carbon fiber,” said Christensen.

The material was an RTP 200 Series very long glass fiber reinforced nylon 6/6 composite and, according to Duncan, the material met all of Leatherman’s criteria and was instrumental in allowing them to bring two new knife lines — Crater and Expanse — successfully to market. The latter line has a hybrid metal/plastic scale, an important aspect of the RTP Company very long fiber material is that it mechanically bonded well with this metal component in the mold after a simple pre-surfacing treatment, Duncan noted.

“RTP Company’s very long fiber composite was easy to process and worked out well for us in both lines,” said Duncan. The key to obtaining the best performance from a very long fiber material is good tooling that is designed and built to align the fibers correctly during processing. “RTP Company delivers a high quality product that is extremely consistent order-to-order,” added Christensen.

Duncan had worked with RTP Company while in a previous job in the electronics industry and was glad to be reacquainted with the company through this application. “They’re very knowledgeable about different resin types, and they’re more responsive than any other plastics supplier I’ve dealt with,” Duncan said. “I look forward to working with RTP Company more in the future.”

KASO Plastics, Inc. has been a full-service custom injection molder in Vancouver, WA since 1962. For more information, visit their website at

Leatherman Tool Group, based in Portland, OR has been making high quality multi-tools since 1983. For more information, visit their website at