Today we are going to discuss the injection defects of burn marks.
1. Poor venting, the residual gas in the cavity generates high temperature due to adiabatic compression
2. The surface of the cavity is not smooth enough to easily adhere a small amount of plastic, which is easily scorched by high temperature, and then mixed into the melt
3. The melt temperature is too high
4. Injection pressure is too high
5. The injection speed is too fast
6. Plasticizing speed is too fast
7. Back pressure is too high
8. There is accumulation at the barrel and nozzle
9. The capacity of the injection molding machine is too large, or the geometry of the injection screw and the forming material
10. Too much recycled material is added, because the recycled material contains more impurities, it is easy to be coked
11. The melt index of the resin is too large
12. There is too much water and volatiles in the raw materials, and the large amount of gas produced cannot be discharged in time