Where does the gas generated in the injection mold come from? What is the hazard?

2021-03-25 09:47:14 admin

Where does the gas generated in the injection mold come from? What is the hazard?

Injection mold is a technical task, and exhaust is also a more important issue, because hot air is easily generated during molding and pouring. If it is not discharged from the mold cavity in time, it will easily affect the quality of the mold. Therefore, the exhaust is also strict when the injection mold is made. A job.

1. The source of the gas

(1) There is air in the mold cavity itself;

(2) Some raw materials contain moisture that has not been removed by drying and evaporate into steam at high temperatures;

(3) Gas produced by the pyrolysis of some unstable plastics during the injection molding process;

(4) Volatile gases produced by certain additives in plastic materials or through mutual chemical reactions.

2. Harm of poor exhaust

If the injection molding tool does not exhaust the air in time during the exhaust, it will cause some damage to the quality of the object. Generally, there will be the following manifestations:

(1) During the injection molding process, 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, resulting in insufficient injection and unable to fill the cavity;

(2) Under a certain degree of compression, the removal of unobstructed gas will form high pressure in the cavity and penetrate into the plastic, resulting in quality defects such as pores, voids, tissue thinning, and cracking;

(3) Because the gas is highly compressed, so that the temperature in the cavity rises sharply, thereby causing the surrounding melting to decompose, burning plastic parts and partially burning carbonization. It is mainly found in two molten, grid flanges converge;

(4) Due to the poor gas discharge, the speed of the melt entering each cavity is different, which is easy to form flow marks and melt marks, which reduce the mechanical properties of plastic parts;

(5) Due to the obstruction of the gas in the cavity, the filling speed is reduced, the molding cycle is affected, and the tax collection efficiency is reduced.