Question

In the injection moulding process, venting at the runner side can reduce the air pressure.

(a) True

(b) False

This question was posed to me in an interview.

I want to ask this question from Venting of Moulds topic in section Mold and Mold Making of Casting-Forming-Welding I

Answer 1

The correct answer is (a) True

To elaborate: Venting at the runner side can decrease the air pressure because the air inside the sprue is ejected instead of compressing it into the mould cavity. Bernoulli’s principle states that an increase in velocity of fluid occurs simultaneously with a decrease in pressure. According to this law, the velocity of air flowing through the runner results in air suction from the mould cavity to the runner.