Burr
the reason:
1.Insufficient clamping force.
2.The injection pressure is too high.
3.Injection speed is too fast.
4.The holding pressure switch is too late.
5.Insufficient mold support.
6.Defect of mold parting surface.
7.The melt temperature is too high.

8.Low viscosity.

Solution:
1.Reduce filling speed or holding pressure.
2.Improve the clamping force.
3. Change the position or method of holding pressure conversion or enter holding pressure early.
4.Reduce injection volume or material pad.
5.Reduce the material temperature.
6.Using multi-stage holding pressure.
7.Check if the injection molding machine board is balanced.