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Minnesota Wire selects Teknor for TPV replacement

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Jeff Lewison shows off the iStretch cable that Minnesota Wire recently introduced.
Jeff Lewison shows off the iStretch cable that Minnesota Wire recently introduced.

ST. PAUL, Minn.—Minnesota Wire Co., a specialist in the custom design and production of cable assemblies for medical devices, selected Teknor Apex Co. to replace its thermoplastic vulcanizate elastomers.

Minnesota Wire replaced the TPVs that are standard in such applications with new styrenic thermoplastic elastomer compounds from Teknor Apex. Marketed under the Medalist MD-8421, MD-8431 and MD-8451 brand names, the TPE-S materials were created specifically for the medical market.

The elastomers can be used for insulation, jacketing, and molding fittings and connectors. The Shore A hardness levels of the compounds are 92, 69 and 82, respectively, and have a maximum continuous operating temperature rating of 105° C, Teknor Apex said.

“Part of our time is always looking out for new materials, and so when Teknor Apex had this product launch, it fit a niche,” said Jeff Lewison, a designer/test engineer at Minnesota Wire.

Lewison said Minnesota Wire had “a need in this niche for improvement.” The company sought a company that could meet the need and found Teknor Apex. Minnesota Wire had used some of Teknor Apex's products in the past, but in general, all-purpose fields, not in the medical sector. This is the first time the companies have come together for any formulating.

Minnesota Wire talked to Teknor Apex, Lewison said, tested the product, made some formula changes and “have a product now that we're pretty excited about.”

He said it was about finding better materials with better properties and replacing what was there. A few other companies were looked at, but in the end, Minnesota Wire selected Teknor Apex because of its compounds' physical attributes “and its ability to handle the wide variety of chemicals and sterilization properties.”

Ross Van Royen, senior market manager for regulated products at Teknor Apex, said “we went back to our tried-and-true compounds, which are our Elexar grades for wire and cable applications.”

He said the Elexar compounds have had many years of success mainly—but not exclusively—in industrial uses, so “what we did was reformulated those specifically for medical applications.”

Ross Van Royen, senior market manager for regulated products at Teknor Apex.
Ross Van Royen, senior market manager for regulated products at Teknor Apex.

Van Royen said Minnesota Wire approached Teknor Apex “because they really liked the way our materials pro-cessed ... so we didn't want to start from scratch.”

The company took its materials and modified them to meet all the requirements under medical products.

Lewison said Teknor Apex was selected because of a “couple of key attributes.” One of the biggest reasons was because the TPE-S compounds are aesthetically pleasing “for the end user, for the patients and for the doctors.”

It also feels better on the skin, Lewison said, and is a little easier to clean. “(The) coefficient of friction on the surface is a lot lower so it slides nicer,” he said. The compounds' “ability to withstand steam autoclaving and still have a very high elongation and tensile properties” is a reason Teknor Apex was able to fill the need for Minnesota Wire.

“You don't see a big drop in those properties when it gets steamed or gets autoclaved or sterilized,” Lewison said.

He added that the new material also lowered Minnesota Wire's scrap rate, while increasing speeds, so overall there was many benefits to the new compounds. “Once they nailed the formula, it was a pretty easy change for us,” Lewison said.

Van Royen said the new TPE-S lines are widely available and that it's not an exclusive partnership with Minnesota Wire.

“These materials are based upon products that have been sold into the marketplace for well over 20 years. They are well-proven, well-accepted, high performing materials,” he said.

Van Royen said the company expects them to do equally well in the medical field.

Lewison said Minnesota Wire also recently launched its iStretch cable, which is a cable that elongates so it has “extremely high reliability.”

He said the company was recently in California shooting a show with National Geographic on this product where two technologies battled against each other. He said the iStretch cable will be big in the safety area, especially with robotics and companies that have moving parts.

“iStretch is a great replacement because it grows and contrasts with the swelling of the materials.”

Minnesota Wire said the conductivity and the electrical properties are not affected, so this can be a replacement product in a variety of areas.