The temperature of injection molds has an impact on the 5 points of plastic parts and the 5 major conditions for mold injection molding

The temperature of injection molds has an impact on the 5 points of plastic parts and the 5 major conditions for mold injection molding

There are many reasons that affect the cooling of injection molds, such as the shape of the plastic part and the design of the parting surface, the type of cooling medium, temperature, flow rate, geometric parameters of the cooling pipeline, our spatial layout, mold material, melt temperature, and plastic part requirements, all of which have a certain impact on the temperature of the injection mold on the plastic part. Now let’s take a detailed look together.

1. A lower mold temperature can achieve a reduction in the shrinkage rate of plastic parts during molding.

The uniformity of mold temperature, short cooling time, and fast injection speed can reduce the warping deformation of plastic parts.

3. For crystalline polymers, increasing the mold temperature can stabilize the size of the plastic parts and avoid post crystallization phenomena, but it will lead to defects such as prolonged molding cycles and brittle plastic parts.

As the crystallinity of crystalline polymers increases, the stress cracking resistance of plastics decreases, so lowering the mold temperature is beneficial. However, for high viscosity amorphous polymers, their resistance to cracking is directly related to the internal stress of the plastic part. Therefore, increasing the mold temperature and filling speed, and reducing the replenishment time are beneficial.

If we increase the temperature of the mold, it can improve the surface quality of the plastic parts. The determination of mold temperature is a process in injection molding, and the temperature of the mold can directly affect plastic filling, shaping of plastic parts, molding cycle, and molding quality. That’s all for this video sharing. If you want to know more about injection mold content, please consult us in a timely manner!

The temperature of injection molds has an impact on the 5 points of plastic parts and the 5 major conditions for mold injection molding

1. The existence of injection molding pressure is to overcome the resistance of the melt during the flow process, or conversely, the resistance during the flow process needs to be offset by the injection molding machine pressure to ensure the smooth filling process. 2. The injection molding time is very short and has a relatively small impact on the molding cycle. However, adjusting the injection molding time plays a significant role in controlling the gate, runner, and cavity pressure. Reasonable injection molding time is helpful for ideal filling of the melt, and is of great significance for improving the surface quality of the product and reducing dimensional tolerances.

3. The injection temperature must be controlled within a certain range. The temperature is too low, resulting in poor plasticization of the molten material, which affects the quality of the formed parts and increases the difficulty of the process; If the temperature is too high, the raw materials are prone to decomposition. In the actual injection molding process, the injection temperature is often higher than the barrel temperature, and the higher value is related to the injection rate and material properties, up to 30 ℃.

4. At the end of the injection molding process, when the screw stops rotating and only advances forward, the injection molding enters the pressure holding stage. During the pressure holding process, the nozzle of the injection molding machine continuously replenishes material into the cavity to fill the empty volume caused by the shrinkage of the workpiece.

5. The use of high back pressure is beneficial for color dispersion and plastic melting, but it also prolongs the screw retraction time, reduces the length of plastic fibers, and increases the pressure of the injection molding machine. Therefore, the back pressure needs to be lower, generally not exceeding 20% of the injection molding pressure.

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