Part performance is critical in all applications – but crucial in fastening solutions. When it comes to plastic fasteners, thermal stability is typically evaluated by measuring the material’s percent tensile strength retention after aging. In automotive, specifications then set limits - such as greater than 50% or 75% retention of tensile strength after aging – to determine suitability of the material for a given application. It’s all standard and well-established – so why is it that fasteners often still struggle to maintain performance over time and temperature?
THE PROBLEM WITH TENSILE STRENGTH TESTING AS A PREDICTOR OF FASTENER PERFORMANCE
The answer? The lesser reported measure of elongation. The heavy focus on testing for tensile strength retention has created a bit of a paradox where heat aged fasteners are able to maintain percent tensile strength in testing but still fail in the field due to a loss in elongation. This ultimately results in part failure when, during insertion or bending, the outer surface elongates and cracks.
INSERTION/EXTRACTION TESTING TO DETERMINE FASTENER PERFORMANCE
Our Teknor Apex experts wanted to test the theory that it’s possible to better predict and improve part performance after thermal aging by enhancing and measuring percent tensile elongation, in addition to tensile strength. To test, samples were molded into fasteners and aged in an oven at 150° C for over 1,000 hours (up to 1,500 hours at one partner) allowing for a rapid screening of experiments.
These trials – composed of reformulation, insertion/extraction experimentation, and this new emphasis on elongation – produced two new product formulations. During the trials, where standard toughened PA66 and the competitive material failed insertion/extraction tests after 500 and 1,000 hours respectively at 150° C, these new formulations were able to meet or exceed critical success factors like:
HEAT STABILIZED CREAMID® PA66 REPLACES HIGH PERFORMANCE POLYMERS BY MAINTAINING ELONGATION AND MECHANICAL PROPERTIES AFTER THERMAL AGING
Now you can say goodbye to brittle parts with the new, proprietary heat stabilized and impact modified Creamid® PA66 from Teknor Apex. Download our brochure to learn more about these enhanced products that can take fastener and other thin wall application performance to the next level – all while offering the same fast cycle time and same chemical resistance as standard materials. And what’s even better? Not only does less part breakage mean less waste; but, being regrindable and recyclable makes Creamid® PA66 a sustainable alternative to resins that cannot be reused.
As a full-service plastic materials supplier, our plastics expertise doesn’t begin and end at materials, nor does our commitment to our customers. Whether you need support with an existing product or are undertaking a new project, we are the value-added supplier you need to help inform decisions and achieve successful outcomes. Contact the Teknor Apex team today to learn more.
