注塑成型：故障排除

Poor Knit Lines

Poor venting.

• Place vents at last place to fill and at converging flow fronts.
• Increase size of the vents.

Too cool a melt.

• Increase the melt and/or mold temperature.
• Increase injection speed.

Part Shorts
and has burn marks

Gas trapping/ poor venting.

• Improve venting and/or relocate to burned area.

Part Shorts
No burn marks

Not enough material.

• Increase shot size, if possible. If not, move to a larger machine.

Blockage in flow at the feed-throat.

• Reduce rpm and back pressure.
• Decrease the barrel temperature in the rear.

Not enough injection pressure.

• Increase injection pressure.

Material too high in viscosity.

• Increase injection rate.
• Increase process temperature.
• Use a lower viscosity TPE.
• Increase gate and runner size.

Part Flashes

Too much injection pressure.

• Reduce injection pressure and time.

Too much material.

• Decrease shot size.

Material viscosity too low.

• Reduce injection speed.
• Reduce process temperature.

Tool too loose

• Machine or dress the parting line.

Not enough clamp capacity.

• Use a higher viscosity TPE.
• Increase clamp tonnage.
• Reduce thickness of the vents.
• Move to a larger machine.

Voids or Sinks
Voids occur inside the part. Sinks pull away from the mold wall.

Material shrinkage & insufficient supply of molten material.

• Decrease wall thickness.

Not enough pack pressure during material solidification.

• Increase the pack pressure and time.
• Increase the gate size.
• Relocate the gate to the thickest section.
• Increase the runner size.

Bubbles
Part surface bulges above a bubble.

Gas entrapment.

• Relocate the gate or modify the flow path.
• Add a pin in the area to eliminate the gas trap.

Flow Marks
Back fills

Filling from thin to thick sections.

• Reposition the gate to a thick section.

Flow Marks
Shadowing

Surface irregularity.

• Radius dimples.

Flow Marks

Folds

Uneven filling of section.

• Relocate gate to balance the flow or reduce the runner diameter.

Jetting

High viscosity flow.

• Increase process temperature.
• Increase injection speed.
• Decrease gate size.
• Change type of gate.
• Relocate gate to impinge.

翘曲的零件

Anisotropic shrinkage.

• Relocate the gate so flow occurs in only one direction.

High molded-in stress.

• Increase the process temperature.
• Reduce the pack pressure.
• Increase the mold temperature.

Surface Defects
Uneven shine
Beach marks

High molecular weight TPE in highly polished mold.

• Change to a lower molecular weight TPE.
• Texture mold cavity surface (EDM, sandblast, etc.)

Surface Defects
Silver streaking or splay marks

Contaminated material.

• Check for moisture (condensation) or dry the material.
• Check regrind for contaminants or moisture. Dry if required
• Reduce injection speed.

High shear in the material.

• Increase the process temperature.
• Increase the gate size.

Ejector Pin Marks

Parts soft during ejection.

• Increase mold close time.
• Reduce mold temperature.
• Reduce process temperature.
• Texture mold surface for better release.
• Increase size of pins.
• Increase draft on part.
• Reduce wall section.
• Use a TPE with mold release.
• Use a harder TPE.

Burnt Smell
Parts have a yellow cast

Degraded material.

• Purge machine and observe whether problem reoccurs.
• Reduce process temperature. (Particularly in rear of machine).
• Reduce regrind level.
• Reduce residence time.
• Purge machine after shutdown.
• Move to a smaller machine.
• Reduce hot runner system temperatures.
• Minimize dead spots in hot runner manifold.

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

Insufficient extraction force.

• Sandblast "A" side of tool.
• Polish "B" side.
• Run "A" side cooler.
• Put keepers in "B" half of tool.
• Increase draft on part in "A" half of tool.

Part Sticks During Ejection

Insufficient ejection force.

• Increase mold closed time.
• Reduce mold temperature.
• Reduce process temperature.
• Reduce pack and hold pressure.
• Sandblast "B" side.
• Increase size of ejector pins.
• Increase number of ejector pins.
• Increase draft on part.
• Provide air assist.

颜色不均匀

Poor dispersion.

• Increase back pressure and/or screw rpm.
• Change the color concentrate carrier to a material with a lower melt temperature.

Contamination.

• Check for clean regrind.

Shorts

Inadequate shot size.

• Material blockage at throat - lower feed zone temperature.

Vents blocked.

• Clean vents.

Flashing

Too much material.

• Check shot size.

Clamp pressure low.

• Check for dirt on the mold parting line of low hydraulic pressure.

Injection pressure too high.
Injection speed too fast.

• Check injection pressure and speed.

Burns

Dieseling in the mold.

• Clean vents.

颜色不均匀

Poor concentrate mixing or dispersion.

• Check barrel temperatures.
• Check back pressure and screw rpm, increase if necessary.

Off-Color Part or Odor

Contamination.

• Check for contamination.

Material degradation.

• Reduce the level of regrind.
• Reduce the rear zone temperature.
• Reduce the residence time.
• Add delay to screw recovery.

Dimensions Out of Specification

Loss of control of shrinkage.

• Check hold pressures.
• Check melt and mold temperatures.
• Check that cushion was maintained.

Surface Defects (Streaks)

Moisture in part.

• Dry material.
• Check for contamination.

Possible mold sweating.

• Raise mold temperature.

Voids or Sinks

Inadequate amount of material.

• Make sure there is a cushion maintained.
• Increase shot size.
• Increase pack and hold pressures.
• Increase hold time.