We always curious how we can improve the surface glossy of injection plastic parts, today we will analysis from 2 points: Plastic Injection Mold and injection technical
1, Injection mold
If the mold cavity is poorly processed,such as scratches,micropores,wear out,roughness and so on,it must be reacted to the Plastic Injection Parts, then the glossy of plastic parts will be bad. So we should process mould elaborately, make the cavity surface smaller roughness. If necessary,it is possible to polish and chromium plating.
If the surface of cavity is oily,water stains or too many demoulding agents,it will make the surface of plastic part be darkening,no shiny.Regarding to this,it is necessary to remove oil pollution and water stains in time and limit using demoulding agent.
If the draft angle of plastic parts is too small, it will be difficult to de-mould. Or overforce when de-mould, it will make the surface be poor of glossy. Regarding to this project, it is necessary to increase the draft angle.
If the mold exhaust is bad,excess gas stay in the model,it also causes poor lustre. Regarding to this problem,it is necessary to check and correct the die exhaust system.
If the gate or runner cross-section area is too small or suddenly change, shear effect of the melt in it is too large about the shear force when liquid melt in, this is the reason of poor glossy of plastic part surface. Regarding to this, it is necessary to increase the gate and the runner cross-section area.
2.Injection technical
If the injection speed is too slow, the surface of plastic part will be not compacted and appears that poor gloss.Regarding to this,it should improve injection speed properly.
Regarding to the thick wall plastic parts, it will have problems, for example insufficient cooling,the scared surface,lustre darker, the solution is to improve the cooling system.
If holding pressure is insufficient and holding time is too short, the density of the plastic injection parts will not enough and with poor lustre. It should increase the holding time and holding pressure to solve this problem.
The melt temperature is too low making fluidity poor and easy to cause lustre, we should improve the melt temperature properly to solve this problem.
For crystalline resin,such as PE.PP.POM etc. Molded Plastic Product, it will cause the poor glossy if the cooling is uneven. About this problem, it’s necessary to improve the cooling system and make it uniform cooling.
If the injection speed is too fast and gate cross-section area is too small. It will be dark and poor gloss near the gate. It should reduce the injection speed properly and increase the section area of gate.
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