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A Better Way to Test Quality in Plastic Welds

October 15, 2020

Evaluation of plastic weld quality is a multi-industry challenge. Typical methods of weld evaluation such as mechanical or leak testing can determine whether a weld can accommodate a defined application requirement, but do not indicate whether the weld itself is good. A good weld is one in which the polymer chains from either side have diffused across the joint. However, the success of the intermolecular diffusion cannot be determined via the standard mechanical and leak tests. 

Through previous work at EWI, we have determined that the most effective method for evaluating diffusion is a technique developed internally several decades ago. The process, first published in a paper presented at the Society of Polymer Engineers (SPE) Annual Technical Conference (ANTEC) in 2018, involves heat treating of polished cross sections. While this method has been used at EWI to good effect for years, it has always involved a manual process with a hot air gun. To make the process more consistent, internal research was conducted to apply controlled infrared (IR) lamp heating to perform the heat treating process. Selected cross-sections from previous internal research projects were re-polished and then heat-treated using the IR lamp to establish material-based heat-treating settings. The results and recommendations will be submitted for publication in the proceedings and presented at SPE’s ANTEC conference in 2021.

Before heat treatment
Too much heat treatment
Good heat treatment

To learn more, contact Miranda Marcus at [email protected].