Dictionary
EnglishShort definitionJetting is an injection molding defect characterized by irregular, worm-like flow lines on the part surface when the plastic melt enters the cavity too quickly without immediately contacting the mold wall. It is often linked to gate design, melt temperature, or injection speed and can weaken appearance and surface consistency.
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Burn marks (injection molding)Burn marks in injection molding appear as dark brown or black areas on molded parts when plastic or trapped air overheats during filling, often near the end of the flow path. They usually indicate poor venting, overly aggressive process settings, or problematic flow geometry and can affect both appearance and material integrity.
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Injection molding parametersInjection molding parameters are the specific settings and conditions that are defined in the injection molding process to control the production of plastic parts. These include die and plastic temperatures, injection pressure, injection speed, dwell time and cooling times. The precise setting of these parameters is crucial for the quality and consistency of the parts produced, as they influence factors such as surface quality, dimensional accuracy and material properties. In practice, optimally tuned injection moulding parameters enable efficient production, reduce scrap rates and improve material utilization. They are therefore of great importance both from an academic perspective and in industry in order to produce competitive and high-quality plastic products.
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Short shot, also called incomplete injection, occurs when the mold cavity is not fully filled with molten plastic, leaving missing sections or incomplete contours on the part. Common causes include insufficient shot volume, low injection pressure or speed, low mold or melt temperature, restricted flow paths, or poor venting.
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Weld lines (knitting lines)Weld lines, also called knitting lines, are visible linear areas on injection-molded parts where two melt fronts meet but do not fuse completely. They can reduce local mechanical strength and visual quality, especially around holes or complex flow paths, and are influenced by melt temperature, tool design, venting, and flow balance.
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Burn marksBurn marks are dark discolorations or streak-like markings on injection-molded parts caused by local overheating of the plastic melt or trapped air inside the mold cavity. They reduce visual quality and often point to poor venting, excessive injection speed, or overly high melt temperatures.
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Injection MoldingInjection molding is a manufacturing process in which molten material - usually plastic or metal - is injected into a mould or tool under high pressure. This process is mainly used in plastics and metal processing to produce precise and complex components in large quantities. Injection allows detailed shapes to be produced with tight tolerances and consistent quality, which is essential for series production. The technology enables efficient production processes, reduced material waste and quick changeover between different product variants. In industry, injection plays a central role in the production of components for the automotive, electronics, consumer goods and many other sectors. The optimization of the injection process contributes significantly to the competitiveness and innovative capacity of manufacturing companies.
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