Do you know how to avoid the gas burning during the injection molding?

Gas burning refers to the burning phenomenon on the molded plastic part surface during molding.
When the resin fills the mold cavity, the existing air will be vented from the vent, and the gas generated by the resin is in the same way. However, the gas cannot be vented if the mold vent is blocked or there is no vent at the flow end. Therefore, the high temperature is formed after being compressed, causing the resin to burn.
(2-1) When the injection speed is too fast, as the resin is filled, the air in the mold cavity and the gas contained in the resin will be vented from the vent. However, if the injection speed is too fast, the gas will not be able to be vented from the vent in time. Therefore, the high temperature will be formed due to the insulation compression, which will cause gas burning. When the VP switching is too slow, gas burning is also likely to occur due to the same reason.
(2-2) Poor venting
Similar to the above situation, when the exhaust capacity of the vent is low, gas burning will also occur. There are two reasons: one is that the vent thickness is originally thin, and the other is that the vent is blocked by mold scale during use. Therefore, when the resin contains too much gas, gas burning will also be aggravated.

(2-3) Higher mold or resin temperature
When the mold temperature or resin temperature is too high, gas burning also tends to worsen.

(3-1) Slow down the injection speed
Gas burning is caused by the rapid compression of gas and the formation of high temperature. Therefore, slowing down the injection speed can reduce gas burning. When the shape of the molded product is restricted, please adjust the VP switching position or use multi-section injection. If the problem cannot be solved anyway, the exhaust condition should be improved by strengthening the venting port and other measures.

(3-2) Improve the venting condition
Please check the following items to know the venting:
1. Is it blocked by mold scale?
Please clean it if blocked. Poor performance venting ports are prone to block.
2. Enhance the venting capacity
Increase the number and thickness of venting.
3. Is it located in the appropriate position?
If the venting is not at the end of the flow, it is meaningless. Therefore, please effectively configure the venting at the location where the burning occurs.

※Attention
After making these measures, other failures sometimes occur. Therefore, please be careful to change the settings.