What should be paid attention to when setting mold exhaust for gear injection parts?

There are many ways to exhaust the mold cavity, but each method must ensure that the exhaust tank is designed to prevent the material from flowing into the tank when the exhaust is exhausted. Secondly, it is necessary to prevent blockage.

Therefore, the height of the exhaust slot with a length of more than 6-12mm shall be about 0.25-0.4mm measured from the surface of the die cavity to the outer edge of the die cavity. In addition, too many exhaust slots are harmful. Because if the mold locking pressure acting on the part of the mold cavity with no exhaust groove on the parting surface is very large, it is easy to cause cold flow or crack of the mold cavity material, which is very dangerous.

In addition to venting the mold cavity on the parting surface, the purpose of venting can also be achieved by setting an exhaust slot at the end of the material flow of the gating system and leaving a gap around the ejector rod. Due to the selection of the depth, width and position of the exhaust slot, if it is not appropriate, the flash and burr will affect the beauty and accuracy of the products. Therefore, the size of the above gap is limited to preventing flash around the ejector rod.

Special attention should be paid here: during exhaust, parts such as gears may not even have small flash. This kind of parts are vented in the following ways:

Remove the gas in the flow channel;

The matching surface of parting surface is shot peened with silicon carbide abrasive with particle size of 200#.

In addition, an exhaust slot is set at the end of the material flow of the gating system, which mainly refers to the exhaust slot at the end of the runner. Its width shall be equal to the width of the splitter, and the height varies depending on the material.