Blanking and piercing

Blanking and piercing are shearing processes in which a punch and die are used to produce parts from coil or sheet stock.

The selection criteria of all process parameters are governed by the sheet thickness and by the strength of the work-piece material being pierced.

The punch/die clearance is a crucial parameter, which determines the load at the cutting edge of the tool, commonly known as point pressure.

Material specific design guidelines are developed by companies in order to define the minimum acceptable values of hole diameters, bridge sizes, slot dimensions.

[1] There are various types of blanking and piercing: lancing, perforating, notching, nibbling, shaving, cutoff, and dinking.

[citation needed] Lancing can be used to make partial contours and free up material for other operations further down the production line.

The dies and punches are needed to be made of tool steel to withstand the repetitious nature of the procedure.

[2] Perforating is a piercing tooling that involves punching a large number of closely spaced holes.

For added accuracy and smoothness, most shapes created by nibbling undergo filing or grinding processes after completion.

[4] The shaving process is a finishing operation where a small amount of metal is sheared away from an already blanked part.

Materials that can be fine blanked include aluminium, brass, copper, and carbon, alloy, and stainless steels.

[7] Because the material is so tightly held and controlled in this setup, part flatness remains very true, distortion is nearly eliminated, and edge burr is minimal.

[9] Tolerances between ±0.0003–0.002 in (0.0076–0.0508 mm) are possible, depending on the base material thickness and tensile strength, and part layout.

[10] With standard compound fine blanking processes, multiple parts can often be completed in a single operation.