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9/4/2015 | 1 MINUTE READ

RTP Offers Tribology Data for Medical Device Material Selection

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Until recently, there were no established industry tests that accurately predict friction behavior.

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An innovative friction test that accurately predicts friction behavior in single-use drug delivery plastic medical devises has been developed and is now offered by global custom compounder RTP Company, Winona, Minn. Until recently, there were no established industry tests that accurately predicted friction behavior—tribology data--in such devices, making precise material selection difficult.

            Molders, designers and OEMs are keenly aware of the issues that can arise when devices such as auto-injectors, injection pens, stop cocks, and safety syringes fail. External factors, such as long periods of inactivity, shipping, and cold-storage conditions has all impact the friction behavior of plastic-on-plastic moving parts; thus, increasing the chances of stick-slip phenomena or “stiction”, resulting in poor performance of a drug delivery device.

            Using the new test method, RTP explored PC, POM, ABS, PC/ABS, HDPE, and PBT. These resins were tested in a variety of combinations with friction-reducing additives including PTFE, PFPE (perfluoropolyether) oil, and a selection of silicones, along with RTP’s ow All Polymeric Wear Alloy—APWA Plus.Testing the friction behavior in various combinations of resins and friction reducing additives (friction pairings) involves the measurement of the static and the dynamic coefficients of friction. The threshold representing the smallest delta between the two measurements has been coined by RTP tribologists as the “Glide Factorsm”. Consitent, repeatable tests showed that the ideal friction pairings exhibited low static coefficient of friction (≤ 0.15) and a Glide Factor of  ≤ 0.015.

            The data collected from these tests can prove invaluable, eliminating the need for trial and error when choosing the correct low-friction thermoplastics. Also, single-use devices will perform more consistently without the need for external lubrications and extra processing steps, decreasing costs and time-to-market.

Want to find or compare materials data for different resins, grades, or suppliers? Check out Plastics Technology’s Plaspec Global materials database.