Shearing of metals is a sheet metalworking process used to cut relatively thin sheets of metal less than 6mm thick. Sheet metal parts are commonly used in automobiles, appliances, furniture and other consumer and industrial products. Common sheet metal processes include cutting, bending, drawing, punching, blanking, perforating and others. Sheet metal operations require precision tools and dies to cut cleanly and maintain dimensional accuracy and surface finish of the cut parts. Process parameters like shear angle, clearance and forces must be properly controlled to achieve quality edges and avoid defects.

1. SHEARING OF METALS

16. Cutting

17. Clearance in Sheet Metal Cutting

18. Quality of sheared edges • Depends on process used • Edges can be rough, not square, and contain cracks, residual stresses, and a work-hardened layer • These are all detrimental to the ………………of the sheet • Quality can be improved by control of …………, tool and die design

19. Clearance in Sheet Metal Cutting

20. Clearance in Sheet Metal Cutting

21. Angular Clearance

22. Cutting Forces

23. Cutting Forces

26. Blanking Operations Figure 17-13 (Below) Typical die set having two alignment guideposts. ( Courtesy of Danly IEM, Cleveland, OH.)

27. Die Tooling

37. Sheet Metal Groups Allowances Metal group a 1100S and 5052S aluminum alloys, all tempers 0.045 2024ST and 6061ST aluminum alloys; brass, soft cold rolled steel, soft stainless steel 0.060 Cold rolled steel, half hard; stainless steel, half hard and full hard 0.075