Clinching is a sheet metal joining process that has been used for decades ... Clinching is a clean process – it produces a button-like dimple at the joint but no burn marks, discoloration, or splatter ...

When dimple dies are used they are coining the sheetmetal, so the harder the applied pressure the more accurate the flare will be with less metal spring-back. Aluminum sheet is the easiest common ...

To prevent this, measure and mark where you want the hole and then use a center punch and hammer to create a small dimple ...