Various moulding defects can occur during injection moulding. These include, among others, streaks, sink marks, bubbles, weld lines, shiny spots, matt spots, warpage, etc. Some of these defects lead to complaints about the visual appearance of a product. Other defects cause a deterioration of the mechanical properties and even lead to premature failure. In some cases, further processing, such as subsequent galvanization, is also negatively affected.
At the beginning of the damage analysis of injection moulding defects is the defect classification. This is done on the basis of defect features on the component surface or by examining cross-sections. With the help of various defect features, the physical causes that led to the damage can be narrowed down. An analysis of the influencing variables provides information on how to reduce defects or avoid them. In most cases, tips can be given on how to change processing parameters. Our test laboratory for plastics is specialized in the analysis of damage to injection moulded parts.
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 scrap rates often occur due to spots, specks, bubbles or insufficient layer adhesion. The causes of defects can be found in the injection moulding process as well as in the plating process.
Injection moulding defects on the raw part are usually also visible on the finished electroplated component. However, hidden defects that were not observed on the raw part can also be intensified or made visible by the electroplating process. In addition, there are defect patterns that can be traced back to deposition faults in the electroplating process, overaging of the baths or unsuitable electroplating conditions. A systematic, microscopic analysis on the finished part and on the blank helps to determine the cause of defects on electroplated plastic parts and to reduce reject rates.
Contamination can be introduced at all stages of the process. Even the raw materials can contain foreign materials. But contamination can also be introduced during processing or transport. Depending on the type of contamination, various spectroscopic and microscopic methods are used for damage analysis.
For the examination of liquid raw materials, NMR spectroscopy is suitable for detecting organic contamination. 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.
If the surface of a component is contaminated, the defects can usually be analyzed using scanning electron microscopy and/or IR spectroscopy. From the composition as well as the morphology of the contaminations, one can often obtain clues to the source of the contamination. In the case of inclusions, appropriate sample preparation and dissection is necessary.
Some contaminations are not visible, but lead to problems during further processing. Typical examples are adhesion problems of lacquers or adhesions, for the investigation of which extremely surface-sensitive methods are useful.
Systematic damage analysis with examination methods specially adapted to the case of damage makes it possible to characterize the composition and type of contamination on plastic parts and often to determine its cause. We carry out a damage analysis optimized to your problem and can thus help to reduce scrap rates.
Our test laboratory for plastics is specialised in the analysis of damage to injection moulded parts. We will be happy to provide you with a corresponding offer tailored to your problem.