How to increase the brightness of injection molded products from process and mold?
What affects the brightness of injection molded parts? The main reasons for the poor gloss of plastic parts are injection mold, injection molding process, raw materials, and other aspects.
Here, we introduce 12 methods to increase the brightness of injection molded products.
First, from the injection mold to increase the brightness of injection molded products
- If the mold cavity processing is not excellent enough, such as scars, microporous, wear, roughness, and other such defects, then it will have an impact on the plastic parts, producing a large degree of adverse consequences, thus causing the plastic parts luster is not good enough. Therefore, the mold should be carefully processed so that the roughness on the surface of the cavity can be significantly reduced. When necessary, there is also the option of polishing and chrome plating to achieve the best results.
- If there are some untreated oil or water stains on the surface of the mold cavity, or if too much mold release agent is used, the surface of the plastic parts will look dull and unlit. In this case, you should remove the oil and water stains and limit the amount of release agent.
- Suppose the release slope of the plastic part is too small. In that case, it is difficult to release the mold, or the release is subjected to excessive force, resulting in the smoothness of the surface of the plastic part is too small, the release slope should be increased to ensure the smoothness of the plastic part.
- If the mold exhaust performance is not good, then too much gas will be trapped in the model, leading to the final product molding with poor gloss. Therefore, it should be checked and corrected to ensure that the mold venting system has adequate venting performance to avoid trapped gas.
- Suppose the cross-sectional area of the gate or runner is too small or fluctuates widely. In that case, it will lead to excessive shear force acting on the melt during the flow, which will result in the turbulent dynamic flow of the melt, which will also lead to the poor gloss of the final product. Therefore, the cross-sectional area of the runner and gate should be increased appropriately to reduce the shear force to avoid turbulence and improve the gloss of the product.
Second, from the injection molding process to increase the brightness of injection molded products
- If the injection speed is too low, the surface of the plastic part is not dense, appearing to have bad luster, for which the injection speed can be increased appropriately.
- For thick-walled plastic parts, if the cooling is not sufficient, the surface will be hairy, and the luster will be dark, for which the cooling system should be improved.
- If the holding pressure is not enough, the holding time is short, so the density of plastic parts is not enough, and the luster is not good. For this, the holding pressure and holding time should be increased.
- If the melt temperature is too low, liquidity is poor and easy to leads to bad luster, which should be appropriate to improve the melt temperature.
- For crystalline resin, such as PE, PP, POM, and other plastic parts, uneven cooling will lead to poor luster. In this regard, the cooling system should be improved to make it uniform cooling.
- If the injection speed is too large and the cross-sectional gate area is too small, the vicinity of the pouring product will be dark and have bad luster. In this regard, the injection speed can be properly reduced, and the cross-sectional gate area increased.
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