Thermoplastic parts can fail. This is no secret. However, when it has happened it is crucial to find out the reason for the failure of a part. Then, removing the cause of defect takes priority.
For the analysis of the cause of failure of injection-molded thermoplastic parts, a superior level of expertise in material science, production methods and analytical instrumentation is required. There is a wide array of failure scenarios that can occur. Possibilities range from misuse and unintentional service conditions to design faults, molding issues, StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress, overload and degradation.
Thermal analysis instruments are powerful tools for failure analysis. Here is a short list of thermal analysis techniques and which questions they can answer in your failure analysis:
- Was the material contaminated with a different material?
- Did the supplier provide the correct material composition for my thermoplastic part?
- What is the crystallinity of the material? Is there any potential for Post Crystallization (Cold Crystallization)The post crystallization of semi-crystalline plastics occurs primarily at elevated temperatures and increased molecular mobility above the glass transition.post-crystallization?
- Was the material filled with the right amount of fillers, plasticizer and modifiers?
- Was the material thermally stable to withstand service temperatures?
- Did the material absorb water?
- Did the material change its dimensions at service temperatures?
- Was there residual StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress in the molded part?
- Did the material have the same mechanical properties at service temperatures?
- Did the material degrade at a faster rate than anticipated?
- Did the material lose its mechanical properties due to liquid interactions?
These few questions give you a short overview of the wide field of questions in failure analysis that can be answered with thermal analysis instrumentation.