Design Nomenclature / Physical Model Making
Vent
Also called riser vent, air vent, breather
This entry has not been translated yet and is shown in English.
A deliberate escape path for the air the incoming material has to displace. Trapped air stops a fill dead and leaves a smooth-walled void at the far end of the cavity — the corner that never fills. Vents are cut small enough that material chills and plugs them before it follows the air out.
Not to be confused with
- RiserA reservoir attached to a casting that stays molten longer than the part and feeds metal back in as the part shrinks while it freezes. Without one, the shrinkage forms a void inside the thickest section — invisible until the part is sectioned or fails in service. Risers feed. They are not vents.
- GateThe restricted opening where material finally enters the cavity, deliberately smaller than the sprue feeding it. The restriction speeds and directs flow, and gives a thin section to snap or trim. Gate placement decides where knit lines and trapped air end up, which makes it a design decision rather than plumbing.
- SprueThe main channel material travels down to reach the mould, and the solid stick of waste left standing in it afterwards. It is the trunk, not the door: it feeds gates, which feed the cavity. Cut it off and the mark it leaves on the part is the sprue scar.