Plastic Failure Analysis
From Fault Detection to Solution
Injection Molding Defects
Various molding defects can occur during injection molding. These include, among others, streaks, sink marks, blistering, weld lines, glossy spots, matte spots, warpage, etc. Some of these defects lead to complaints regarding the product’s optical appearance. Other defects cause a deterioration of mechanical properties and even lead to premature failure. In some cases, further processing, such as subsequent electroplating, is also negatively affected.
The failure analysis of injection molding defects begins with defect classification. This is carried out based on defect characteristics on the component surface or by examining cross-sections. Based on various defect characteristics, the physical causes that led to the damage pattern can be narrowed down. An analysis of influencing factors provides insights for defect reduction or prevention. Usually, tips for modifying process engineering parameters can be provided. Our plastics testing laboratory specializes in the analysis of damage cases in injection molded parts.
Plastic Electroplating Defects
Nowadays, PC/ABS materials are mostly used for plastic electroplating. The quality of electroplated plastic surfaces is also influenced by the manufacturing conditions of the plastic parts themselves. Increased reject rates frequently occur due to pimples, specks, blisters, or insufficient layer adhesion. The causes for these defects are to be found in both the injection molding process and the electroplating process.
Injection molding defects on the raw part are usually also visible on the finished electroplated component. However, hidden defects not observed on the raw part can be amplified and thus become visible through the electroplating process. Additionally, defect patterns can arise from deposition disturbances during electroplating, aging of the baths, or unsuitable electroplating conditions. A systematic, microscopic analysis of the finished part and the raw part helps to determine the cause of defects in electroplated plastic parts and to reduce reject rates.
Contamination of Components
Contaminations can be introduced at all process steps. Even the raw materials can contain foreign substances. Contaminations can also be introduced during processing or transport. Depending on the type of contamination, various spectroscopic and microscopic methods are used for failure analysis.
For the analysis of liquid raw materials, NMR spectroscopy is suitable for detecting organic impurities. With this method, even small amounts of foreign substances can be analyzed. For inorganic impurities in liquids, XRF spectroscopy is suitable for detection in the trace range.
In the case of surface contaminations on a component, the defective areas can usually be analyzed with scanning electron microscopy and/or IR spectroscopy. From the composition as well as the morphology of the contaminations, clues about the source of the contamination can often be obtained. For inclusions, suitable sample preparation and conditioning are necessary.
Some contaminations are not visible but lead to problems during further processing. Typical examples are adhesion problems of coatings or bondings, for the investigation of which extremely surface-sensitive methods are useful.
A systematic failure analysis using investigation methods specifically tailored to the damage case makes it possible to characterize the composition and type of contaminations on plastic parts and often to determine their cause. We conduct a failure analysis optimized for your specific inquiry and can thus help reduce reject rates.