Coining

In practice

In powder metal, coining or sizing re-presses a sintered part to tighten dimensions and raise surface density.

Where it comes up

• Metal stampingShort- to medium-run stampings: brackets, clips, shields, and plates cut and formed from sheet or coil in a press.
• Powdered metalNet-shape gears, bushings, and structural parts pressed from metal powder and sintered, with little or no machining.

Related terms

Tonnage

Tonnage is the force a press can apply, rated in tons, and the force a job requires. Stamping tonnage is estimated from cut length, material thickness, and shear strength. In molding and die casting, clamp tonnage must exceed cavity pressure times projected area to keep the tool closed.

Springback

Springback is the partial elastic return of formed metal toward its original shape after the forming load is removed. It means bends must be overformed to hit the final angle. Higher-strength steels, stainless, and aluminum spring back more than mild steel does.

Progressive die

A progressive die is a stamping die with a series of stations that pierce, form, and cut a part in sequence as a metal strip feeds through the press. One finished part drops with each stroke. It is the lowest piece-price option for high-volume small and medium stampings.