Injection molding is a method of making industrial products, usually using rubber injection molding and plastic injection molding. Injection molding can also be divided into injection molding and die-casting method.
Injection molding machine (referred to as the injection molding machine or injection molding machine) is a thermoplastic or thermosetting plastic molding materials made of various shapes of plastic products, the main molding equipment, injection molding through injection molding machines and molds to achieve.
Well, here know the impact of injection molding strength of several injection molding process:
1) Increasing the injection pressure can improve the tensile strength of PP injection molded parts
PP material is relatively more elastic than other hard materials, so the density of injection molded parts will increase with increasing pressure, which is relatively obvious.When the density of plastic parts increases, its tensile strength will naturally follow Increase, and vice versa will be reduced.
However, when the density increases to reach the maximum value of PP itself, then increase the pressure, the tensile strength will not continue to increase, but will increase the residual stress of the injection molded parts, make the injection molded parts become brittle, so should be enough.
Other materials have a similar situation, but the obvious degree will be different.
2) Mold Hot Oil Injection can improve the strength of race steel and nylon parts
Nylon and POM materials, all belong to the crystalline plastic mold hot oil machine hot oil injection, can make the cooling rate of injection-molded parts slowed down, the crystallinity of the plastic is improved.At the same time as the cooling rate is slow, the remnants of the injection-molded parts Therefore, the internal stress is also reduced, so the impact resistance and tensile strength of nylon and POM injection molded by hot oil machine are correspondingly improved.
It should be noted that the use of hot oil machine hot oil injection of nylon and POM relative water injection molding parts will be somewhat different size, nylon pieces may be larger.
3) too fast melt rate Even 180 ℃ plastic injection will be raw
Under normal circumstances, pvc90 degree material with 180 ℃ injection, the temperature is sufficient, the general does not appear raw rubber problem, but often not caused by the operator's attention to the reason, or in order to speed up the production and deliberately speed up the melt speed, making the screw back The speed is quite fast, for example, only took two or three seconds, the screw back to the maximum amount of more than half of the location of the melt, PVC material was heated and stirred a serious shortage of time, resulting in melt temperature and uneven mixing The raw rubber problem, making the strength and toughness of injection molded parts will become quite poor.
Therefore, in the injection of PVC material, be careful not to arbitrarily adjust the melt speed to 100 rev / min or more.If you have to be quite fast, we must remember that the material temperature increased by 5 to 10 ℃, or Increase the appropriate melt back pressure to cooperate, but also pay attention to always check whether there is a problem of raw glue, otherwise it is very likely to cause significant losses.
On this issue, because most people will not be too concerned, so here is particularly reminded to pay attention to production, and remember to do a good job checking.
The opposite should also be noted that if the melt speed is too slow, even if the 180 degree injection of PVC90 degree of material will result in the problem of burning plastic, especially transparent PVC, injection molded parts will have many dark spots and striae produce.