What About Uneven Injection Color?

Analysis of reasons for uneven color of injection molding products the main reasons for uneven color of injection molding products and solutions are as follows:

(1) colorant diffusion is not good, this situation often make the sprue near the pattern.

(2) plastic or colorant thermal stability is poor, to stabilize the parts of the color, must be strictly fixed production conditions, especially material temperature, material quantity and production cycle.

(3) For the crystallized plastic, try to make the parts of the cooling rate consistent, for the wall thickness difference of the parts, can use colorant to cover the color difference, for the wall thickness is more uniform parts to fix the material and mold temperature.

(4) The moulding and sprue form of the workpiece, the position has influence on the plastic filling condition, make some parts of the workpiece produce color difference, it must be modified if necessary.


Analysis of reasons for defects in the color and gloss of injection molded products normally, the gloss on the surface of injection molded products is mainly determined by the type of plastic, colorant and surface finish. But often also because of a number of other reasons for the surface color of products and gloss defects, dark surface defects.


The causes and solutions are as follows:

(1) poor mold finish, mold surface rust, mold exhaust is bad.

(2) if the casting system of the mold has defects, the cold feed well should be increased, and the flow passage, polishing mainstream passage, diversion passage and gate should be increased.

(3) the material temperature and mold temperature are low, if necessary, local heating method of gate can be used.

(4) Low processing pressure, slow speed, insufficient injection time, insufficient back pressure, resulting in poor compactness and dark surface.

(5) Plastic to fully plasticize, but to prevent the degradation of the material, heat to be stable, cooling to be sufficient, especially thick wall.

(6) Prevent cold material into parts, if necessary, use a self-locking spring or lower nozzle temperature.

(7) Too much recycled material, poor quality plastic or colorant, mixed with water vapor or other impurities, poor quality lubricant.

(8) The clamping force should be enough.


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