Discoloration issue in plastic injection molding

Discoloration means the surface color of a molded part is not consistent with the required color. Discoloration may be caused by a variety of reasons, which may cover the several aspects of injection molding machine, mold, process and raw materials, etc.

(1) Injection Molding Machine
① Equipment is not clean and needs to be cleansed. Dusts or powders are deposited in the barrel, which contaminates and discolors the materials;

② Temperature control failure caused by malfunction of thermal couple, temperature controller or the heating system;

③ Obstacles exist in the barrel, causing the plastic material to decompose; foreign metal objects are stuck in the barrel or the screw channel, which keep grinding, causing plastic material discoloration;

① Poor mold venting, causing plastic to be compressed in a heat-insulated environment, so the material tends to be burnt when reacting with oxygen under high-temperature and high pressure conditions;

② Mold gate is too small;

③ Too much lubricants/mold releasing agents exist in the barrel. Clean the material barrel, to remove the additives which possess poorer heat resistant properties than the plastic, such as antistatic agents;

④ Nozzle, sprue and runner sizes are too small;

(3)Injection Molding Process

① Screw speed/pre-molding back pressure is too high;

② Barrel/nozzle temperature is too high;

③ Injection pressure is too high/injection time is too long/injection speed is too fast, causing product discoloration.

(4) Raw Materials
① Material is contaminated;

② Too much moisture/VOC content contained in the material;

③ Coloring agents/additives are decomposed.

About JasonMould Industrial Company Limited

Jasonmould is a China mold maker of plastic molds- injection mold, die casting moulds, plastic blow molding, rotational molding, medical plastic injection molding, two shot plastic injection molding, insert molding, overmolding, metal injection molding, micro injection molding, powder injection molding, ceramic injection molding, liquid injection molding, husky injection molding, household mold, casting mold, die mold tool, custom molds, china moulds, rapid prototyping tooling, plastic prototyping tooling, punch press tooling, die and tooling for mobile/ cell phone parts, automotive parts, vacuum cleaners, rechargeable tools, telephones, copiers, computers, multimedia speakers, and many other electronic products and household appliances. And also a plastic product manufacturer- plastic parts, plastic water tank, plastic balls, plastic containers, plastic buckle, plastic anchor, plastic hanger, plastic spoon, plastic pipe fitting, plastic tumble, plastic tableware, plastic cups, plastic bottles, plastic tray, plastic cosmetic container, plastic case, plastic food container, plastic chairs, plastic caps, plastic cap closure, plastic tubes, plastic water pipes, plastic knobs, plastic tubing, plastic utility boxes, plastic racks and so on.

Person: James Yuan
Company: JasonMould Industrial Company Limited
Add:  LongGang Village,LongXi Town,BoLuo County,HuiZhou City,GuangDong Province, China
Tel: 86-752-6682869
Email: [email protected]

Site: https://www.jasonmolding.com/company/

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