Exhaust facilities must be installed during the injection mold process

2021-03-23 11:37:02 admin

Exhaust facilities must be installed during the injection mold process

In the process of injection moulding, it is easy to generate hot gas due to heat. Once gas is generated and not discharged, it is easy to cause problems in the mold, especially in the rapid prototyping process, once there is excess gas, it will cause the mold to bulge, so Exhaust is a very important job.

1. The source of the gas in the injection mold.

1. The presence of air in the casting system and mold cavity.

2. The raw materials of some companies mainly contain a moisture that can be removed without being dried, which vaporizes into water vapor at high temperatures.

3. As the injection molding temperature is too high, the gas generated by the decomposition of some unstable plastics passing through occurs.

2. Harm of poor exhaust

Poor venting of injection molds will bring a series of hazards to the quality of plastic parts. The main results are as follows:

1. In the process of injection molding, the melt will replace the gas in the cavity. If the gas is not discharged in time, it will be difficult to fill the melt, which will result in insufficient injection to be unable to fill the cavity.

2. Compressed to a certain extent, the pores, voids, loose tissues, cracks, etc. formed in the high pressure difference gas cavity will be eliminated and penetrate into the plastic, quality defects.

4. Eliminate the difference of gas into the melt, make the speed in each different cavity, so that it is easy to form flow marks and fusion lines, and reduce the mechanical properties of the plastic parts.

Third, the distribution of bubbles in plastic parts

1. The bubbles in the cavity are usually located on the opposite side of the gate.

2. The chemical reaction in the decomposition of plastic materials or bubbles is distributed along the thickness of the plastic part.

3. The air bubbles generated by the residual water vaporization technology in the plastic raw materials are irregularly distributed on the entire plastic part.