How to solve the surface defects of molded parts?
Generally, it is common to meet the detects on the surface of the plastic products during injection molding. For those surface defects, we can analyze them from three aspects to solve product defects.
1. Mold structure
The surface shape of the plastic part is the shape of the mold cavity, and if there are surface defects such as scratches on the cavity, it will be directly displayed on the product. If there are oil and moisture on the surface of the cavity, and it will cause the surface of the product to become dark. Therefore, the cavity should remain smooth every time before injection molding. The best way for keeping the cavity smooth and clean is to perform the polishing treatment and also remove the moisture on the cavity in time before molding.
Mold temperature has a great impact on the surface quality of plastic parts. Generally, different types of materials have large differences in glossy at different mold temperature. In the molding process, it is necessary to select the appropriate mold temperature for injection molding by the actual materials used, which can effectively reduce the probability of unexpected surface defects.
2. Improper molding conditions
In the injection molding process, whether the injection speed is fast or slow, the injection pressure is too low, the barrel temperature is too low, etc, it will cause surface defects of the plastic parts. We should adjust the parameters of the injection molding machine by the actual requirements of customers.
3. Wrong materials
Using raw materials that do not meet the requirements can also cause surface defects on plastic parts. The general solutions are :
1. If the moisture of the molding material is heavy, and we should proceed with the pre-drying process.
2. The decomposing of raw material or colorants, we should select relevant material with higher temperature resistance.
3. The poor fluidity of the raw material makes the surface gloss of the plastic parts poor. Here, you must switch to a resin with better fluidity or add an appropriate lubricant to increase the processing temperature.
4. There are impurities in the raw materials, and we should replace it and use clean material.
5. The particle size of the raw material is not uniform, and it is necessary to screen out the material with different particle sizes.
