When we make injection molding production we will meeting different problem, it will delay the production, now let us study some frequently asked questions:

Observation-1    Poor Knit Lines

Cause-1  Poor venting.  Solution:  Place vents at last place to fill and at converging flow fronts

Cause-2 Too cool a melt.  Solution:  Increase the melt and/or mold temperature.

Observation-2    Part Sticks During Ejection

Cause-1   Insufficient ejection force.  Solution:   1.Increase mold closed time. 2.Reduce mold temperature. 3.Reduce process temperature. 4.Reduce pack and hold pressure. 5.Sandblast "B" side. 6.Increase size of ejector pins. 7.Increase number of ejector pins. 8.Increase draft on part.9.Provide air assist.  

Observation-3    Bubbles

Cause-1  Gas entrapment.  Solution: 1.Relocate the gate or modify the flow path.  2.Add a pin in the area to eliminate the gas trap.

Observation-4    Part Sticks in "A" Half or Stationary Side of the Tool

Cause-1  Insufficient extraction force.  Solution:   1.Sandblast "A" side of tool. 2.Polish "B" side. 3.Run "A" side cooler. 4.Put keepers in "B" half of tool. 5.Increase draft on part in "A" half of tool.

Observation-5    Warped Parts

Cause-1  Anisotropic shrinkage.  Solution:   Relocate the gate so flow occurs in only one direction.

Cause-2  High molded-in stress.  Solution:   1.Increase the process temperature. 2.Reduce the pack pressure.Increase the mold temperature.

Observation-6   Surface Defects/Uneven shine/Beach marks

Cause-1  High molecular weight compound in highly polished mold.  Solution:   1.Change to a lower molecular weight compound. 2.Texture mold cavity surface (EDM, sandblast, etc.)

Observation-7    Silver streaking or splay marks

Cause-1  Contaminated material.  Solution:   1.Check for moisture (condensation) or dry the material. 2.Check regrind for contaminants or moisture. Dry if required  3.Reduce injection speed.

Observation-8  Part Flashes  

Cause-1  Too much injection pressure.  Solution:   Reduce injection pressure and time.

Cause-2  Too much material.  Solution:  Decrease shot size.

Cause-3  Material viscosity too low.  Solution:  Reduce injection speed.

Cause-4  Tool too loose  Solution:  Machine or dress the parting line.

Cause-5  Not enough clamp capacity.  Solution: 1.Use a higher viscosity compound. 2.Increase clamp tonnage.3.Reduce thickness of the vents. 4.Move to a larger machine.

For more information will be update…please kindly to contact us if you have any help during the injection molding production.

Contact: dkm@dakumar.com

Post by: Vivian