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Bad molding and treatment
Author:admin  From:Letian Plastics   Hits:2128  Update:2008-12-9
Bad phenomenon
cause www.2013338.com
Treatment
Insufficient filling up

1、Short of Injection pressure

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 葡京在线
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 www.29977.com
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 葡京投注
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
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