- 发布时间：2021-05-06 20:32
- 发布时间：2021-05-06 20:32
1. The treatment method of the bubble phenomenon in the injection molding process of the plastic pallet
According to the cause of the bubbles, the countermeasures to deal with it have the following aspects:
1. When the wall thickness of the plastic pallet is large, the cooling rate of the surface surface is faster than that of the center part. Therefore, as the cooling stops, the plastic resin in the center part shrinks and expands outward, causing the center part to lack filling. This condition is called vacuum bubble. The main treatment methods are:
A. According to the wall thickness, the gate and runner size must be reasonable. The height of the ordinary gate should be 50% to 60% of the wall thickness of the product.
B. There is a certain amount of supplementary injection material left until the gate is sealed.
C. The injection time should be slightly longer than the gate sealing time.
D. Reduce the injection speed and increase the injection pressure.
E. Use materials with high melt viscosity grades.
2. Bubbles formed due to the generation of volatile gases, the main treatment methods are:
A. Enough to stop pre-boring.
B. Lower the resin temperature to prevent the generation of synthetic gas.
3. Bubbles formed by poor mobility can be treated by increasing the temperature of the resin and the mold, and increasing the injection speed.
2. Analysis of the reasons for the sticking of the main runner during injection molding of plastic pallets
The reason for the sticking of the main runner during injection molding and the cleaning method:
1. The cooling time is too short, and the main runner has not yet solidified.
2. The slope of the main runner is not enough, and its demoulding slope should be increased.
3. Improper matching size between the main runner bushing and the nozzle will cause leakage.
4. The main flow path is rough, and the main flow path has no cooling wells.
5. The nozzle temperature is too low, the temperature should be increased.
3. Analysis of the reasons for the slow consumption of plastic pallets during injection molding
The reasons and solutions for the slow consumption during injection molding are as follows:
1. The plastic temperature and mold temperature are high, and the cooling time is long.
2. The melting time is long, the back pressure should be reduced, the recycled materials should be used less to avoid overhead, and the feeding section should be sufficiently cooled.
3. The movement of the machine is slow, and it can be adjusted appropriately to speed it up from the oil and circuit adjustments.
4. The design of the mold should be easy to demould, and the design should be fully automatic operation as far as possible.
5. The manufacturing wall thickness is too large and the cooling time is too long.
6. The nozzle drools and hinders normal consumption. A self-locking nozzle should be used, or the temperature of the nozzle should be lowered.
7. The material barrel lacks heat, so you should switch to a machine with a large plasticizing capacity or increase the preheating of the material.
4. Analysis of the reasons why plastic pallets form dissatisfaction with injection molded products
The main reasons for the dissatisfaction of the injection molding products are the lack of material and the improper injection pressure and speed (including the excessive consumption of the pressure caused by the resistance). It may be caused by the following reasons:
1. The reason for the injection molding machine:
The plasticizing capacity or heating rate of the machine is uncertain, so a machine with a large plasticizing capacity and heating power should be selected;
The abrasion of the screw and the barrel or the number one over-rubber will result in material return and the actual filling modulus will be inadequate; the heating system faults such as thermocouples or heating coils will cause the barrel's actual temperature to pass too low; the sealing element of the injection cylinder wears and causes oil leakage Or backflow, but can not reach the required injection pressure; the nozzle inner hole is too small or the nozzle center is adjusted improperly, resulting in excessive resistance and pressure consumption.
2. The reason for the injection mold:
A. The temperature of the mold part or the whole is too low to cause difficulty in feeding, and the mold temperature should be increased appropriately;
B. The spread of the cavity of the mold is not balanced, and the wall thickness of the part is too thin, resulting in excessive pressure consumption and insufficient mold filling. The wall thickness of the entire part or part should be increased, or an auxiliary flow or gate treatment can be set near the filling defect.
C. If the flow channel of the mold is too small, the pressure loss will be caused; if it is too large, it will show weak injection; if it is too rough, it will cause dissatisfaction with the part. The size of the runner should be set appropriately, and the transition between the main runner and the branch runner, the transition between the gates or the turning point of itself should be applied with the appropriate arc transition.
D. Poor venting of the mold. The material entering the cavity is obstructed by the pressure of the gas that is too late to be discharged, resulting in a filling dissatisfaction. Exhaust from the gap of the screw or reduce the clamping force. Exhaust on the parting surface. If necessary, set up an exhaust channel or air hole.