|
Bad phenomenon |
cause |
Treatment | |
|
Insufficient filling up |
|
1、Increase Injection pressure | |
| 2、Charging speed is slow | 2、Increase injection speed | ||
| 3、temperature of resin is low | 3、Increase temperature of charging barrel | ||
| 4、air exhaustion is not well | 4、Set air vent at un-filling section(2-4mm long and 0.015-0.02 deep | ||
| 5、pouring head is too small | 5、Increase the size of pouring head or shorten the distance between pouring port and flow path | ||
| 6、the space between the reflux valve and charging barrel | 6、Decrease the space between the reflux valve and charging barrel | ||
| 7、shortage of feeding | 7、Increase the amount of feeding | ||
| 8、temperature of mould is too low | 8、Elevate temperature of mould | ||
|
Indentation and void |
1、density of product is not enough | 1、Increase batching and Injection pressure or prolong the injection time | |
| 2、gas generated is too much | 2、Thoroughly dry treatment of raw materials (120-150 ℃ , 5-3hr) | ||
| 3、wall is too thick | 3、Maximum thickness is 7-10mm( except for special grade resin of thick wall) | ||
| 4、shrinkage is too large | 4、Decrease temperature of charging barrel or mould | ||
|
Bad condition of surface or without brightness |
1、density of product is not enough | 1、Increase batching or Injection pressure | |
| 2、Charging speed is slow | 2、Increase injection speed | ||
| 3、temperature of charging barrel is slightly low | 3、Increase temperature of charging barrel | ||
| 4、temperature of mould is slightly low. | 4、Properly elevate temperature of mould | ||
| 5、air exhaust is not in good condition | 5、Air exhaust sufficiently | ||
|
Internal crack |
1、the cooling of product is too fast. |
1、elevate temperature of mould or prolong the cooling time | |
| 2、residual stress in product | 2、Decrease the Injection pressure, increase mould temperature and reduce injection speed | ||
| 3、non-uniform in wall thickness | 3、Change the design for uniform wall thickness | ||
| 4、the wall is too thick | 4、Use special grade resin of thick wall | ||
|
Distortion and deformation |
1、non-homogenous cooling of product | 1、Adjust the temperature balance of mould | |
| 2、non-uniform wall thickness of product | 2、Make the wall thickness uniform | ||
| 3、excessively charging | 3、decrease batching and Injection pressure | ||
| 4、injection speed is too fast | 4、reduce injection speed | ||
| 5、unbalance of push-out | 5、Repair tooling | ||
| 6、the cooling time is too short | 6、Prolong the cooling time | ||
| 7、the mould temperature is too high | 7、Decrease the mould temperature |
|
Bad phenomenon |
cause |
Treatment |
|
Strength of adjoiner is low |
1、Pressure in moulding chamber is not enough | 1、Increase Injection pressure and charging |
| 2、Air detention in moulding chamber | 2、Set air vent and overflow section for resin, increase backing pressure and decrease injection speed | |
| 3、unsuitable position of pouring head or without cold slug well | 3、Change the position of pouring head avoiding the loaded place introduced by seamline, or install cold slug well | |
| 4、the temperature of charging barrel or mould is too low | 4、Increase the temperature of charging barrel or mould | |
|
burned |
1、air detention | 1、Add air vent |
| 2、the temperature of resin is too high | 2、Decrease the temperature of charging barrel | |
| 3、injection speed is too fast | 3、Reduce the injection speed | |
|
Poor dimensional stability and short of stiffness at high usage temperature |
1、The crystallization is not adequate | 1、elevated the mould temperature(140-170℃) |
| 2、anneal treatment on product(200-230℃, 4-6 hours) | ||
|
Difficult to demould or bad push-out |
1、Draft angle is not enough | 1、Increase the draft angle |
| 2、poor smoothness of mould | 2、Improve the smoothness of mould or use demould agent(zinc stearate, PTFE, silicon demould agent ) | |
| 3、bad position of pin-lift or too small of pin-lift diameter | 3、Repair tooling and improve the system of push-out | |
| 4、inadequate cooling of product | 4、Increase the molding period and prolong the cooling time | |
| 5、the temperature of charging barrel or mould is too high | 5、decrease the temperature of charging barrel or mould | |
|
Difficult pull-out of flow path |
1、the bushing of pouring head is not smooth | 1、Improve the smoothness of running channel |
| 2、The taper of flow path is not adequate | 2、Increase the taper of flow path | |
| 3、the R of flow path and nozzle is not suitable | 3、Modify the R of flow path and nozzle | |
| 4、bad design of mould | 4、Improve the design of mould | |
|
Too much overfall at injecting nozzle |
1、too much moisture in resin | 1、Thoroughly dry treatment of raw resin(120-150℃, 5-3 hours) |
| 2、too much air generated in resin | 1、decrease the temperature of nozzle and machine barrel | |
| 2、use overflow valve | ||
|
Ink dot in product surface |
1、cool resin contained in product | 1、extend the cold slug well |
| 2、increase the nozzle temperature | ||
| 2、impurity mixed in raw resin | 2、Remove the impurity in raw resin |
