Burn Marks

Discolored, often burnt areas on or in the past part of the cavity to fill, occasionally
as a surface bubble or blister after moulding has been ejected.

Some possible causes:
Air is trapped in the cavity. Being compressed by the melt, the air temperature
rises and get so hot that it oxidises the surrounding plastics.

Remedies, to check:
a. Mould vents - could be blocked.
b. Injection speed - may be too high.
c. Mould clamping force - may be too high.
d. Mould temperature - may be too high.
e. Melt temperature - may be too high.


                                        Burn marks



                                     Burn marks