1、 Causes of uneven color:
1 poor dispersion of pigment
2. Insufficient thermal stability of materials
2、 Associated knowledge
According to the properties of materials, like granular pigments and other thinly colored materials, the materials flow in parallel
As a result, there is an irregular directionality in the gate edge and other parts, and the results show that
Different colors. It's usually very difficult to remove the uneven color of the fusion part no matter what color material, especially
Don't use multiple gates.
2. The products with granular pigment are more likely to produce uneven color than those with toner.
1 short term: change gate position to change uneven color position
Long term: improve the coordination of soft pigments.
4、 Due to material differences
The crystallinity of crystalline resin (PP, PE, PA, etc.) varies due to different cooling rates, because of the crystallinity,
The transparency is good when the cooling speed is small. Because the transparency varies with the thickness, it is necessary to use soft
Paint to cover up the change
(15) Processing of plastic products -- a method to eliminate the poor finish of products
1、 Causes of poor finish of products
1. The mold finish is not high
2 mold temperature too low
2、 Associated knowledge
1 because the finish of the product surface (the total area in contact with the mold) is determined by the finish of the mold surface,
If the mold finish is not good, because the small concave and convex surface will make the product finish worse, so in the transparent
In the products of materials, the transmittance and transparency of light will decrease.
Because of the high temperature of the mold, the finish will be better, so a large number of warm water circulation is used in the mold to keep the mold temperature
At a certain value, the heat of the product is transferred immediately, which can shorten the cycle and reduce the residual stress
In order to obtain the mould with high finish, the surface of the mould product is plated with hard chromium, but after the mould is damaged
It's difficult to repair.
1 instant: increase mold temperature
2 short term: improve the surface finish of mold products
3 long term: use hard mold material and diamond grinding powder for grinding.
4、 Due to material differences:
1. Because the materials with poor fluidity contact with the mold product surface, that is to say, solidify immediately, and cannot contact with the mold product surface
Good to talk about. In addition, the insufficient pre drying materials and the evaporation of the volatiles in the materials will condense in contact with the mold
After existing between the product and the mold, the product becomes poor finish.
2. Materials with good molding finish: GPPS, ABS, PP