How to Set the Mold Temperature in Injection Molding?

The setting of mold temperature in injection molding

The success rule of a factory is to do more work in a shorter time to maximize its benefits. In injection molding, mold temperature directly affects the production cycle of the product. The mold temperature request of each plastic is different. If the factory wants to improve product efficiency, it must focus on the control of mold temperature. Let us learn about the relationship between mold temperature and injection molding.

1. What should the mold temperature in injection molding be?

The setting of the mold temperature refers to the temperature of the mold inner wall that the melt plastic contacts. The mold temperature will affect the fluidity, crystallinity and condensation time of the melt plastic during filling cavity. And it directly affects the density, size, strength and shrinkage of the plastic product. When the set temperature drops to the point where the melt filled in the mold can be cooled and can be taken out.

(The lower temperature set, the more beneficial for the cycle time )

2. More about the mold temperature in injection molding

① The basics of mold temperature are:

  • The lower limitationis the temperature at which the material can be filled.
  • The upper limitationis the temperature below the thermal deformation of the material.

The temperature should be set within this range to ensure the quality and productivity of the molded product.

② Devices usually used by mold temperature control:

③ The heat distortion temperature varies according to the material.

To shorten the production cycle time, set the temperature lower to ensure quality. In this conditions, if it is difficult to ensure the product’s quality, the mold temperature should be increased a little, then try again.

The design of the mold should consider the uniform temperature of each part in the cavity, uniform product shrinkage, and uniform size. The thick wall and the gate should be strengthened to cool down to avoid heat accumulation. Then, reduce the temperature difference between the outgoing and incoming cooling water. So that it can avoid the shrinkage caused by the uneven mold temperature.

When the mold temperature between the fixed mold and the movable mold is different, it can control the direction of deformation and change the orientation stress for long-strip and thin-walled products.

Note: If the temperature difference is too large, the mold lock phenomenon will occur. The fixed mold temperature is too high to make the plastic product stick to the front mold wall.

⑦The lack of plastic in the products is affected by the flow speed of the melt plastic. The related factors are the temperature of the melt plastic and the mold temperature, as well as the clamping pressure to the gas exhaust hole. The unilateral setting effect is not good.

3. The importance of mold temperature control for the product quality

Mold temperature affects the product.

When the temperature is high, it can improve transferability, increase molding shrinkage, reduce residual deformation, etc. And it is also effective for shrinkage pits.

When the temperature is low, the melt fluidity is poor, and the surface of the plastic part will produce obvious flow lines and silver streaks.

When the temperature is inconsistent, the shrinkage rate is different. And that will cause the plastic product to warp and deform, and the shape and contour will change.

The large difference between the set temperature and the actual measured temperature will cause defects (defective release, deformation). So the final product of good quality is deciding the setting data, mark down the data setting as the correct one.

③ Affected by environmental factors, the mold opening and closing time should be shortened. The mold temperature between the mold opening and closing has changed. When measure the mold temperature, it shows 40 degrees Celsius, but the actual working temperature may have reached 50 degrees Celsius already. Finally, the mold temperature is set according to the requirements of the plastic product.

④ High mold temperature has a great influence on the performance of plastic parts. It can eliminate the residual stress in the plastic parts and improve the surface gloss of the plastic parts. When the mold temperature is set to 20%, 50%, 70%, 90%, their surface finish will be increased by 15%, 33%, 38%, and 40% respectively.

Through the above content, you must have understood the importance of mold temperature control. Of course, the injection mold temperature is not only a decisive factor for product design, mold design and manufacturing, but also has a great relationship with the setting of injection molding process conditions.

In short, the setting of injection mold temperature must complement and cooperate with many factors in order to achieve product quality and maximize production efficiency.

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