How can back pressure porosity be prevented during casting?

Show Answers

Utilizing asbestos linerPositioning the sprue at a minimum of one-quarter inch from the casting ring's endAvoiding sudden heating of the investment in the burnout furnaceEmploying a sprue that is short and broad

Explanation

Back pressure porosity occurs when gases are trapped during casting. To avoid this, the sprue should be placed at least one-quarter inch away from the end of the casting ring, allowing proper gas escape and reducing porosity. Other methods like using asbestos liners, rapid heating, or sprue dimensions are less effective in preventing this issue.