Blanking and Piercing
Due to its higher shear strength, more power is required along with greater tool wear when working with stainless steel. This can be minimised by using angular shear on the punch and die or by punch staggering during multi hole operations.
With regard to the die material, these should be both hard and tough, for intricate jobs shock resistant tools must be used. These materials include D2, D4 and carbide (HRC 60-65) and S1 or S5 (HRC 57-60) for the latter. Clearance between punch and die has always been a contentious issue when blanking thin materials. Some manufacturers recommend clearances below 0.025mm per side, others prefer more generous clearances. However, for cutting plate the general rule appears to be 10 to 15% of material thickness per side. The choice of clearance is always a trade off between degree of burring, risk of "shear break" and tool life.
A cut edge, especially a sheared edge is usually rough or burred, and the material is in the work hardened condition. The resulting burrs are not only dangerous for the operators, but can lead to damage and excessive wear to form tools. In addition the notch effect and the work hardened edge can reduce the materials ability to be formed in subsequent operation. Burrs can be removed by manual grinding or filing or by various automatic deburring equipment.
Usually blanking and piercing are done without lubrication. However, to prolong tool life or to minimise burr or shear break lubrication may be used. Sulphurised or chlorinated oils are usually used. However, care must be taken to ensure their removal especially if the parts are to be welded or heat treated.
Cold Forming - Blanking and Piercing | Press Breaking and Roll Forming | Spinning and Flow Forming | Coining and Embossing | Press Forming | Deep Drawing
Cutting - Sawing | Hand Hacksawing | Shearing | Abrasive Cutting | Thermal Cutting
Hot Rolling - Hot Rolling Process | Hot Rolling Application | Types of Hot Rolling Mill | Hot Rolled Steel Tube | History
Cold Rolling - Physical metallurgy | Degree of cold work | Cold Rolling Stainless Steel | Manufacturing Process
Foil rolling | Rolling Mill | Steel Mill | Production methods | Recycling of Steel | Modern Steelmaking | Contemporary Steel
|
