When sinking, the tool , the sinking punch, is pressed into the workpiece ; the workpiece is rarely pressed over the tool. The tool movement is straight, mostly perpendicular to the surface. There is no sliding over the surface. Compared to the related indentation , which also counts as indentation, the countersunk shapes are deep and the accuracies high.
- With free countersinking, the walls of the work piece are not supported at the side so that it can move away . Free countersinking is used when the countersunk cross-sectional area of the tool is small compared to the cross-section of the workpiece.
- If the walls of the workpiece are laterally supported by a clamping device , a flow of material occurs on the sides of the tool which is opposite to the tool movement. Because of the more favorable stress state , higher accuracies are possible.
The countersink punches are polished and partly also copper-plated to reduce friction . In addition, layers of phosphate can be used, which can be coated with lubricant . The materials of the tools depend on those of the workpieces as well as the exact process parameters.