The total number of common molding defects is 9. The three molding defect we discuss the last article and some are molding defect is discussed here. They are following

  • Sort shots
  • Burn mask
  • Flash

Common plastic injection molding defects

What causes a short shot?

Short shots occur because the mold is not completely full before the plastic solidifies resulting in a partially molded part. Another reason for short shot is trapped air or gas in the mold cavity, the molten plastic cannot occupy the same space as the gas, therefore in a short shot mold.

Short shots and their preventative measures

Key preventative measures

  • Ensure the gates size large enough to fill the mold cavity
  • assure the tool has capable gas/air vents to grant the gas raises up to avoid the cavity
  • advance the climate of the mold and plastic equality injected this will balm enough the mold and plastic being injected this will balm enough the mold quick
  • Make sure there is enough material injected into the mold per shot
  • Increase the injection pressure

Burn marks and their preventative measures

What causes burn masks?

Burn marks show up on the finished part as changed are dark discoloration which is caused by trapped gas overheating in the mold, it can also be an effect of plastic degradation due to excessive heat or by the injection speed being too fast.

Burn marks and their preventative measures

Key preventative measures

  • Ensure the tool has capable gas/air vents to grant the gas figure up to breakout the cavity
  • Reduce the injection speed
  • Reduce the pressure
  • Reduce the temperature of the plastic during injection
  • cause clear the part layout does not have any plume brink as this can boost the occasion of burn marks

Flash and their preventative measures

What causes a flash?

The Flame is a crack where molten plastic has liberated the cavity, commonly at tool parting lines or vent range or even declining ejector pins.

Flash and their preventative measures

Key preventative measures

  • assure the clamping stress is being controlled during the injection treat
  • Increase clamp pressure (this could mean changing machines to a large clamp force capability)
  • Make sure the surface of the mold is clean and not damaged before it is loaded into the machine
  • Reduce the injection pressure
  • lower the climate of the mold and plastic presence injected
  • analysis the width of the ejector pins and the pin gap strength, if the strength is too wide this could grant molten plastic to move down between the pin and hole appear
  • Make sure the venting is not too large