| Problem |
Caused by |
Solution |
| Warpage |
Orientation |
Increase the cooling time, the pressure and/or the compacting capability |
| Residual stresses |
Check the parallelism of the expulsion system |
| Temperature is uneven in the mold |
Use different temperatures in thick areas |
| mold design |
|
| Faulty expulsion |
|
| High temperature |
|
| Excessive shrinkage |
High de-molding temperature |
Increase in compaction capability, pressure, injection speed and injection pressure |
| |
Decrease the melting temperature of the mold |
| |
Increase the cooling time and compacting |
| |
Increase the temperature to improve compaction capability |
| |
Enlarge the injection point or rinsing. Place pieces in cold water |
| Dripping |
High fusion speed |
Reduce the injection initial speed |
| poorly located injection point |
Change the position of the injection point |
| |
Enlarge injection point |
| Burns |
Air loss |
Reduce injection speed |
| Degradation |
Increase the diameter of the injection point |
| |
Clean or enlarge the air exits |
| |
Use a material of greater fluidity |
| Short shot |
insufficient loads |
Increase the speed and injection pressure, melting temperature or material loading |
| High pressure fall |
Check the heating system |
| Low temperatures |
Check the fluency of the material in the chute |
| Faulty screw tip |
Revise the anti-return valve of the screw |
| |
Check the concentricity of the males part |
| |
Use the most fluent material |
| Weldlines |
Flow is not kept constant |
Increase the speed, temperature and pressure |
| Mold or extremely cold resin |
Increase mold temperature |
| I design inadequate of the mold |
Increase gas expels |
| |
Fix water leaks |
| |
Dry the material |
| |
Relocate the injection points and eliminate excessive differences of wall thickness |
| Flow lines |
Flow is not kept constant |
Increase the temperature of the barrel and of the nozzle |
| Cold mold |
Increase the temperature of the mold |
| Humid Material |
Polish cavities |
| Condensation |
Fix water leaks |
| |
Dry the material |
| Bubbles |
lack of material or compaction |
Increase the injection pressure and compactness |
| Humidity |
Increase the material load |
| Thick wall |
Increase the time of injection and compactness |
| High prosecution temperatures |
Decrease the melting and mold temperature |
| |
Dry the material |
| |
Redraw the thickness and/or the refrigeration circuit |
| Large dimensions |
Excessive compaction or cooling |
Decrease the cooling time |
| |
Decrease time and compacting pressure |
| |
Increase mold temperature |
| |
Use a material with more contraction |
| |
Check the dimensions of the mold and the shrink factor |
| Mold Flash |
Injection pressure (high) or closing (low) |
Decrease the injection pressure and compactness |
| High temperature |
Increase clamping pressure |
| Faulty mold |
Use a grade of lower fluency |
| |
Decrease the material load and mold and melting temperature |
| |
Check the parallelism of the press |
| |
Check the waste and the parallelism of the mold |
| Brittleness |
Degradation |
Lower melting temperature |
| Excess of Grinded |
Increase the diameter or the number of injection points |
| Polluted material |
Decrease the mold temperature |
| Poor plastic coverage |
Decrease the content of ground, dry the material and eliminate pollutants |
| Excessive orientation |
Use a material of greater impact resistance |
| |
Avoid excessive orientation by high pressure injection or low temperature |
| Sink Marks |
Lack of compaction |
Increase the speed and the pressure injection |
| Inadequate prosecution temperatures |
Increase the pressure and/or the time of compactness |
| |
Decrease the fusion and mold temperature |
| |
Increase the diameter of the injection point or place it in thick sections |
| Long production cycles |
High process temperatures |
Decrease the mold and melting temperatures |
| Low cooling capacity |
Increase the screw speed |
| Insufficient refrigeration in thick sections |
Optimize the journeys of the press and of expulsion |
| Extremely slow machine |
Check the refrigeration system capacity |
| |
Clean the refrigeration circuit |
| |
Post - cooling |
| Flashing |
Humidity |
Dry the material, reducer the content of grinded |
| Condensation |
Decrease the melting temperature |
| High temperature |
Reduce the injection speed |
| |
Enlarge the injection point |
| |
Use shorter nozzles |
| Black lines and/or particles |
Contamination and/or degradation |
Check the temperatures (cylinder and mold) |
| |
Purge and/or clean the screw and the barrel |
| |
Reduce the speeds of the screw |
| |
Center the screw |
| |
Open the water of the chute |
| |
Clean the cavities of the mold of grease residuals |
| Delaminating |
Low temperature |
Increase the pressure and the injection speed |
| Humidity |
Increase backpressure and the speed of the screw |
| Incompatible mixture |
Purge the cylinder and clean the mold |
| Degradation |
Increase the mold temperature and decrease it in the hot sifting system |
| |
Increase the temperature or the drying time |
| |
Check the compatibility of the mixture |
| Sticking in the mold |
Inadequate cooling |
Decrease the time of injection and/or compacting |
| Excessive Compaction |
Adjust the temperature of the mold (increase or Decrease as required) |
| Faulty mold |
Decrease the material load |
| |
Polish the cavities |
| |
Use an mold releasing agent |
| Fading |
Elevated fusion temperature |
Decrease the temperature |
| |
Decrease the counter pressure and/or screw rotation speed |
| |
Purge the cylinder |
| |
Use pigments of more thermal resistance |
| |
Use shorter injection chambers |
| Incomplete melt |
Low temperatures |
Increase melting temperature |
| Poor plastic coverage |
Increase pressure |
| |
Use a screw with a larger compression ratio |
