Poor demoulding of mould products is often encountered during our injection moulding production process. And demoulding defects have a significant impact on the quality of injection moulded products. Therefore, solving the problem of demoulding defects in injection moulding affects the quality of the final injection moulded products. The causes of poor demoulding defects in injection moulded products mainly include the following aspects:
Regarding moulds
- The surface of the mould cavity is rough. If there are defects such as gouges, scratches, scars, and dents left on the surface of the mould cavity. The product is easily adhered to the mould, causing difficulty in demoulding. Therefore, we need to improve the machining accuracy and surface smoothness of the mould surface. Which can be improved through polishing, EDM and other methods to improve the surface quality of the mould.
- The unreasonable design of the mould structure results in uneven stress on the injection moulded parts during demoulding. Which hinders demoulding. So in the process of mould design, it is necessary to reasonably consider the structural characteristics of injection moulded products and adopt appropriate demoulding methods, such as adding demoulding agents, designing demoulding angles, etc., to reduce demoulding force.
- The uneven distribution of heat on the surface of the mould can lead to varying degrees of shrinkage in different parts. Resulting in deformation or damage to the mould during the demoulding process. If the temperature of the injection mould is too high, it is easy to stick to the mould. And obvious bright spots may appear in local areas of the product. If the temperature of the injection mould is too low, it can also cause the product to hold the mould too tightly. Which can easily strain the product during demoulding. Therefore, we need to adjust the temperature of the mould reasonably, maintain uniform heating, and avoid local overheating or overcooling.
Injection moulding machines
- The nozzle diameter and feed port diameter of the injection moulding machine do not match. If the nozzle diameter is smaller than the feed port diameter. The plastic will be squeezed at the feed port, causing poor melting and affecting product demoulding. Therefore, we need to select the corresponding nozzle specifications based on the diameter of the feed inlet to ensure diameter matching.
- Ejection force is a very important parameter in injection moulding machines. Which directly affects the quality and production efficiency of molded products. If there is no appropriate ejection force, the moulded product will be difficult to demould. We can adjust it by increasing the ejection stroke, increasing the ejection pressure, and changing the waste separation time.
The process aspect
- Improper injection molding process parameters, such as injection pressure, holding time, and cooling time, can affect the structure and surface quality of injection moulded parts and increase the difficulty of demolding. Therefore, we need to adjust the injection molding process parameters. Reasonably set the injection pressure, holding time, cooling time and other process parameters. And optimize the structure and surface quality of the injection moulded parts. Pay special attention to the impact of injection pressure on the fluidity of plastics. Maintain sufficient cooling of the structure and surface of the injection moulded parts, and reduce the difficulty of demoulding.
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