In automobile manufacturing, the quality of car part injection moulds directly affects the overall performance of plastic components. Despite continuous advancements in injection moulding technology, various issues still arise during the actual production process. This article will explore common failures in car part injection moulds and their solutions to help manufacturers improve production efficiency.
The locator pin in car part injection moulds primarily serves as a guide to ensure the precise alignment of the core and cavity. However, the locator pin is prone to damage during the injection process, especially in the following situations:
If the wall thickness of the plastic component is uneven, the flow of material through thin walls will accelerate, causing significant pressure.
For example, the sidewalls of a trapezoidal mould may experience different counteracting forces, leading to misalignment during injection.
To prevent damage to the locator pin, high toughness locator keys can be added to the diagnostic surfaces of the mould. Cylindrical keys are recommended. Ensure that the locator pin holes are perpendicular to the parting line, which can be achieved by using a milling machine for single-pass boring to ensure concentricity. Additionally, the heat treatment hardness of the locator pin and guide posts should meet the design standards to enhance durability.
In large and medium-sized car part injection moulds, the shifting of moving and fixed moulds often leads to poor injection results. This misalignment is generally caused by the following reasons:
Different filling speeds in various parts of the mould may result in different counteracting forces.
The weight of the mould can affect its alignment during assembly.
To solve the issue of shifting moving and fixed moulds, high-toughness locator keys can be incorporated into the mould design. It is essential to ensure that the positioning of the moving and fixed moulds is completed in one pass on a milling machine to guarantee concentricity. Proper heat treatment and hardness standards will significantly improve the durability of the locator pins and prevent damage during demoulding.
Bending of the moving plate is another common failure, primarily caused by the back pressure generated during the injection of molten plastic, which typically ranges from 600 to 1000 kg/cm². If the design is not carefully considered and low-hardness materials are used, the plate may bend, affecting the injection moulding process.
To prevent bending of the moving plate, it is recommended to select high-quality stainless steel materials to ensure that the plate has sufficient thickness. In addition, support columns or support blocks can be placed underneath the moving plate to enhance its load-bearing capacity and reduce bending. The design should also adhere to strict engineering standards to ensure the overall stability of the mould.
Common failures during the processing of car part injection moulds mainly include damage to the locator pin, shifting of moving and fixed moulds, and bending of the moving plate. By implementing reasonable design and processing measures, such as adding high-toughness locator keys, ensuring concentricity, and selecting quality materials, these issues can be effectively addressed. For automobile manufacturers, continuously optimizing the design and manufacturing processes of car part injection moulds is key to improving product quality and production efficiency.
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