Injection Mold Design & Tooling Anatomy
Plain-English definitions of the terms you'll come across.
terms categories
Clamping Force
clamp tonnagetonnage
Clamping force is the force an injection molding machine applies to hold the two mold halves shut while molten plastic is injected under pressure.
Read moreWhat Is a Cold Runner?
A cold runner is an unheated channel system in an injection mold that carries molten plastic from the sprue to the gates, where the plastic cools and solidifies with the parts each shot and is then ejected as scrap or regrind.
Read moreWhat Is a Draft Angle? Definition & Guidelines
draft
A draft angle is the small taper added to the walls of a molded part, parallel to the direction the mold opens, so the part can release cleanly from the mold.
Read moreWhat Is an Ejector Pin?
An ejector pin is a steel pin in an injection mold that pushes the finished part off the mold core after the mold opens.
Read moreWhat Is a Gate in Injection Molding?
A gate is the small opening through which molten plastic flows from the runner into the mold cavity.
Read moreWhat Is a Parting Line? Definition & Placement
parting surfacewitness line
A parting line is the line on a molded part where the two halves of the mold — the cavity and the core — meet.
Read moreWhat Is Shot Size? Definition & Calculation
shot weight
Shot size is the amount of molten plastic an injection molding machine injects in one cycle: enough to fill every cavity plus the sprue and runners. It is measured by volume or weight and must suit the machine's barrel capacity; a shot that uses too little of the barrel leaves plastic in the heat long enough to degrade.
Read moreWhat Is a Sprue (Injection Molding)?
A sprue is the main channel that carries molten plastic from the injection molding machine's nozzle into the mold, feeding the runners and gates that fill the cavity.
Read moreWhat Is an Undercut?
An undercut is any feature on a molded part that prevents it from being pulled straight out of the mold in the direction the mold opens, such as a side hole, snap-fit hook, internal groove or thread.
Read moreWhat Is Wall Thickness?
Wall thickness is the distance between the opposite surfaces of a part's wall.
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