What are the injection molding processes that affect the strength of injection molded parts?

Injection molding machine (abbreviated as injection molding machine or injection molding machine) is the main molding equipment that uses plastic molds to make various shapes of plastic products from thermoplastic or thermosetting materials. Injection molding is achieved through injection molding machines and molds.
So, here are some injection molding processes that affect the strength of injection molded parts:
1. Increasing injection pressure can improve the tensile strength of PP injection molded parts
PP material has greater elasticity compared to other hard rubber materials, so the density of injection molded parts increases with the increase of pressure, which is relatively obvious. When the density of plastic parts increases, their tensile strength naturally increases, and vice versa, it decreases.
However, when the density increases to the maximum value that PP itself can achieve, increasing the pressure will not continue to enhance the tensile strength, but will instead increase the residual internal stress of the injection molded part, making it brittle. Therefore, it should be stopped appropriately.
There are similar situations with other materials, but the apparent degree may vary.
2. Mold heating oil injection molding can improve the strength of steel and nylon parts
Nylon and POM materials are both crystalline plastics. Using a hot oil machine to transport hot oil for injection molding can slow down the cooling speed of the injection molded parts and improve the crystallinity of the plastic. At the same time, due to the slowing down of the cooling rate, the residual internal stress of the injection molded parts is also reduced. Therefore, the impact resistance and tensile strength of nylon and POM parts injected with hot oil using a hot oil machine will be correspondingly improved.
It should be noted that nylon and POM parts injected with hot oil using a hot oil machine may have different sizes compared to injection molded parts injected with water, and nylon parts may also be slightly larger.
3. Melting speed too fast
Normally, PVC 90 degree material is injected at 180 ℃, and the temperature is sufficient, so there is generally no problem with raw rubber. However, it is often due to reasons that do not attract the operator's attention, or intentional acceleration of the glue melting speed in order to accelerate production, which causes the screw to retreat quite quickly. For example, in only two to three seconds, the screw retreats to a position where the maximum glue melting amount is more than half, and the PVC material is heated and stirred for a serious lack of time, resulting in the problem of uneven glue melting temperature and mixing of raw rubber, The strength and toughness of injection molded parts will become quite poor.
Therefore, when injecting PVC materials, it is important to be careful not to arbitrarily adjust the melt speed to over 100 rpm. If it is necessary to adjust it quite quickly, it is important to remember to increase the material temperature by 5 to 10 ℃, or increase the back pressure of the melt adhesive appropriately to cooperate. At the same time, it is also important to regularly check for any problems with raw adhesive, otherwise it is highly likely to cause significant losses.