Many injection molding factories encounter similar problems, where the product quality is not a problem, but the glossiness of the product is not up to standard, ultimately leading to Injection molding processing The occurrence of scrap products is not only due to problems with the plastic itself, but also related to issues with injection molds, production, design, and other aspects.

1. In terms of injection molding production process
There are several options to try, which can be changed by adjusting the mold temperature, shrinking/holding pressure, filling speed, and material temperature to affect gloss. In most cases, these adjustments will not have a significant impact and will reduce the entire production process window, thereby increasing the likelihood of other issues arising. Therefore, it is best to find the most robust process for the parts and maintain the smoothness of the cavity mold surface.

2. In terms of injection molds
When dealing with gloss issues, do not immediately change the surface finish of the mold steel. Instead, first adjust the process parameters to change the glossiness of the product. Lower temperature molds, colder melts, lower shrinkage/holding pressures, and lower filling speeds may all make your plastic parts shine brighter. The reason for this situation is that the mold temperature is low, the applied pressure is small, and the plastic has not replicated the microscopic details of the surface smoothness of the mold steel.

On the contrary, the higher the temperature of the injection molding mold and melt, the higher the compression/holding pressure, and the faster the filling speed, the darker the gloss of your parts will be. The influence of melt temperature is not as great as that of filling speed, because the filling speed and the resulting shear force have a much greater impact on material viscosity.

On the other hand, if the surface glossiness of the product is too high, it can be considered to reduce the surface polishing of the mold steel or to achieve sandblasting in the mold cavity. Both methods will create small pits on the steel, increasing the surface area and allowing the injection molded product to absorb more light, making your parts appear darker.

3. In terms of injection product design
Another major reason for the issue of gloss is the design of the product, especially the location where the wall thickness of the product changes. It is difficult to maintain consistent glossiness of the parts when the wall thickness changes. Due to differences in flow patterns, thinner wall segments are relatively less likely to be subjected to excessive plastic material pressure, resulting in higher glossiness in that area.

Insufficient exhaust can also produce inconsistent surface gloss. Depending on the material and process, insufficient exhaust can lead to dark and bright spots.

The above three points are important factors that affect the glossiness of injection molded products. As long as injection molding manufacturers consider these issues before producing products, they can avoid the problem of glossiness in injection molded products.