There are stains on the processing surface of the injection product
Aug 05, 2021
Some transparent plastic parts, white plastic parts or light-colored plastic parts are encountered during the processing of injection molds, and stains often appear during the injection molding production process. The stains on the surface of the plastic parts will affect the appearance quality of the product and cause waste during the production process. The specific reasons and improvement methods for problems such as high rate, high waste, and high cost mainly include the following aspects:
Stain problem is a difficult problem in injection molding. It needs to be controlled from nozzle material (runner aggregate) scraps, ingredients, feeding, environment, shutdown and every link in the production process to reduce black spots.
The direct cause of black spots on plastic parts is mixed with dirt or plastic melt degraded at high temperature, resulting in black spots on the surface of the product. The specific reasons and improvement methods are mainly as follows:
1. The overheated decomposition product of the raw material adheres to the inner wall of the barrel:
a. Thoroughly shoot the remaining glue. b. Thoroughly clean the material pipe. c. Reduce the temperature of the melt. d. Reduce the amount of residual material.
2. There are foreign objects (black spots) in the raw materials or the drying barrel is not cleaned up:
a. Check whether there are black spots in the raw materials. b. The drying barrel needs to be thoroughly cleaned.
3. The heat-sensitive plastic gate is too small and the injection speed is too fast:
a. Increase the gate size. b. Reduce the injection speed.
4. There is an included angle in the barrel that causes overheating and decomposition of the raw materials: check the nozzle, non-return ring and the barrel for wear/corrosion or the machine.
5. Dust falling into the air when the mold is opened: adjust the wind and direction of the fan in the machine position (turn off the fan) and cover the injection molding machine with a film.
6. Poor toner diffusion, causing condensation points: increase the diffusion agent or replace the high-quality toner.
7. Dust in the air enters the drying barrel: the air inlet of the drying barrel is equipped with a dust cover.
8. The nozzle is clogged or the nozzle hole is too small: remove the infusible material in the nozzle hole or enlarge the hole diameter.
9. The nozzle material is impure or polluted: control the nozzle material (use a dust-free workshop as far as possible).
10. The crusher/mixer is not cleaned up: clean the crusher/mixer thoroughly.
