Reasons for the shrinkage of the surface of injection molded parts, how to solve the shrinkage of in

Shrinkage of plastic parts (surface concave and internal porosity) is caused by insufficient melt replenishment when the thicker parts are cooled. We often encounter any increase in pressure and increase the water inlet.

If you prolong the injection time, the shrinkage problem is a situation that cannot be solved. Among the commonly used raw materials, due to the fast cooling rate, PC modified plastics.

The shrinkage porosity problem is the most difficult to solve, and the shrinkage and shrinkage porosity of PP modified plastics are also relatively difficult to deal with.

Therefore, when encountering a serious shrinkage problem of thick and large pieces, it is necessary to adopt some unconventional injection molding techniques, otherwise it will be difficult to solve the problem. In the practice of production, we have explored a set of more effective skills to deal with this difficult problem of injection molding.

First of all, on the premise of ensuring that the injection molded parts are not deformed, the method of shortening the cooling time as much as possible is adopted to make the injection molded parts out of the mold early at high temperatures. At this time, the temperature of the outer layer of the injection molded part is still very high, and the skin is not too hardened, so the temperature difference between the inside and outside is relatively not very large, which is conducive to the overall shrinkage, thereby reducing the concentrated shrinkage inside the injection molded part. Since the overall shrinkage of the injection molded part is constant, the more the overall shrinkage, the smaller the concentrated shrinkage, and the degree of internal shrinkage and surface shrinkage can be reduced.

The problem of concave shrinkage is due to the heating of the mold surface, the cooling capacity decreases, the surface of the injection molded part that has just solidified is still soft, and the internal shrinkage porosity that has not been completely eliminated due to the formation of a vacuum, resulting in the surface of the injection molded part at atmospheric pressure.

The inward compression under the pressure, coupled with the effect of the contraction force, the problem of concave is born. Moreover, the slower the surface hardening speed, the easier it is to produce shrinkage, such as PP modified plastics, and vice versa, the easier it is to produce shrinkage holes.

Therefore, after the injection molded parts are molded early, they should be properly cooled to maintain a certain hardness on the surface of the injection molded parts, so that they are not easy to produce concaves. However, if the problem of shrinkage is more serious, moderate cooling will not be eliminated, and the method of freezing water quenching should be adopted to make the surface of the injection molded part harden quickly to prevent the shrinkage, but the internal shrinkage porosity will still exist. For a material with a soft surface such as PP, due to the effect of vacuum and shrinkage force, there is a possibility of concave in the injection molded part, but the degree of concave has been greatly reduced.

While taking the above measures, if the method of extending the injection time instead of the cooling time is adopted, the surface and even the internal porosity will be improved.

When solving the problem of shrinkage porosity, because the mold temperature is too low, the degree of shrinkage porosity will be aggravated, so it is best to use machine water to cool the mold, do not use frozen water, and if necessary, increase the mold temperature to 100 degrees, for example, when injection molding PC material, the mold temperature will be raised to 100 degrees, and the improvement effect of shrinkage porosity will be better. However, in order to solve the problem of concavation, the mold temperature cannot be increased, but needs to be lowered.

Finally, sometimes the above methods may not be able to completely solve the problem, but have been greatly improved, if the problem of surface concavity must be completely solved, the appropriate amount of anti-shrinkage agent is also a last resort.

The main reasons for shrinkage: 1. The injection volume is not enough.

2. The molten body temperature is too high.

3. The injection pressure and holding pressure are too small.

4. The injection time and pressure holding time are too small.

5. The injection speed is too large.

6. Improper mold temperature.

The main reasons for shrinkage porosity: 1. The injection volume is not enough.

2. The injection pressure is too low.

3. Improper injection speed.

4. The mold temperature is too low.

Summary. How to solve the shrinkage of injection molded products?

Hello dear, plastic products shrink:

The first is to adjust and increase the pressure and time of injection molding, and carry out replenishment.

The second is to adjust and increase the cooling water to appropriately reduce the mold temperature.

Mold temperature machine to solve the problem of shrinkage on the surface of plastic products method 1: the product does not need to be painted and other processing operations when processing, because the heat resistance of different materials after painting is different, so that the temperature control of the mold temperature machine is not accurate, resulting in the accuracy of product processing is not high, so before the product is processed by the mold temperature machine, try not to paint and other work.

The second method of the mold temperature machine to solve the problem of surface shrinkage of plastic products: strengthen the setting of the alarm device, so that the mold temperature machine can have accurate alarm settings for high temperature steam, cold water, air, temperature, and pressure, so that we can process and operate more strictly in accordance with the data in our processing, so as to improve the processing accuracy of the product.

The mold temperature machine solves the problem of shrinkage on the surface of plastic products: the output data of the mold temperature machine is accurately controlled, the input and output temperature is accurately detected, the actual temperature of the mold is fed back PLC, and the color map is displayed in a digital color map, so that we can prepare to grasp the temperature change and accuracy, so as to reduce the shrinkage of the surface of plastic products.

How to solve the shrinkage of injection molded products?

How to solve the shrinkage of injection molded products? Hello dear, shrinkage of plastic products: one is to adjust and increase the pressure and time of injection molding, and make up for shrinkage.

The second is to adjust and increase the cooling water to appropriately reduce the mold temperature. Mold temperature machine to solve the problem of shrinkage on the surface of plastic products method 1: the product does not need to be painted and other processing operations when processing, because the heat resistance of different materials after painting is different, so that the temperature control of the mold temperature machine is not accurate, resulting in the accuracy of product processing is not high, so before the product is processed by the mold temperature machine, try not to paint and other work.

The second method of the mold temperature machine to solve the problem of surface shrinkage of plastic products: strengthen the setting of the alarm device, so that the mold temperature machine can have accurate alarm settings for high temperature steam, cold water, air, temperature, and pressure, so that we can process and operate more strictly in accordance with the data in our processing, so as to improve the processing accuracy of the product. Mold temperature machine solves the problem of shrinkage on the surface of plastic products

The output data of the mold temperature machine is accurately controlled, the input and output temperature is accurately detected, the actual temperature of the mold is fed back PLC, and the color map change is displayed, so that we can prepare to grasp the temperature change and accuracy, so as to reduce the shrinkage of the surface of plastic products. Hope it helps.

How to adjust PP shrinkage?

How to adjust PP shrinkage? Hello dear, the PP material shrinks seriously, the injection speed can be appropriately accelerated, and then the holding pressure can be increased a little, and the holding time can be extended a little. Hope it helps.

What should I do if I still can't adjust it?

If you still can't adjust it, what should you do, then it is recommended that you go to a professional maintenance point for maintenance.

Kiss! Hello, happy to answer your <>

The fundamental reasons for the shrinkage of plastic parts are as follows: the shrinkage phenomenon of plastic is mainly due to the shrinkage of the volume, the surface raw material at the wall thickness is pulled in, and there are dent traces on the surface of the finished product when it is transformed.

Shrinkage is the most undesirable phenomenon on the surface of the finished product, most of which occur at the wall thickness, and generally if the pressure drops, the shrinkage probability will be greater. 1。Plastic Injection Molding:

Increase the injection pressure and hold the pressure on the mold after the injection. and give enough cooldown time; 2。In terms of plastic molds:

The design of the cooling channel of the mold is unreasonable, and the mold needs to be modified; 3。Product structure: due to the uneven thickness of the product, it is difficult to cool the thick part of the product (the outer surface is cooled, but the inside may still be molten), so it is necessary to change the structural design of the product.

Hope mine can help you <>

Do you have any other questions?

Answer: Dear repentance! I have found out for you how to adjust the shrinkage of injection molding products?

Shrinkage of injection molded products is caused by the shrinkage of cooling and changes in the molecular structure of plastics during the injection molding process. In order to adjust the shrinkage of injection molded products, you can start from the following aspects:1

Adjust the parameters of the injection molding machine: The flow resistance and cooling process of the plastic can be controlled by adjusting the injection speed, injection pressure, holding time and other parameters of the injection molding machine, so as to affect the shrinkage rate of the product. 2.

Adjust the temperature of the mold: The temperature of the mold has a great impact on the shrinkage rate of the product. The cooling rate and shrinkage rate of the product can be controlled by adjusting the temperature of the mold.

3.Adjust the formula of plastic materials: Different plastic Chang Sui materials have different shrinkage rates, and the shrinkage rate of products can be controlled by adjusting the formula of plastic materials.

4.Adjust the structural design of the product: The structural design of the product will also affect the shrinkage rate of the product.

The shrinkage rate of the product can be controlled by adjusting the structural design of the product. It is important to note that adjusting the shrinkage rate of the product needs to be adjusted on a case-by-case basis, and needs to be tested and adjusted to achieve the best results. Kiss!

I hope my answer helps! <>