Fine blanking is an extremely precise process of deformation which is a mix between stamping and extrusion at room temperature. However the difference between them is very clear as much for the press being used as the specific machinery needed, as well as the product that is to be obtained.
The advantages of using the fine blanking process over other processes is, amongst others, the range of products that can be obtained, as the metal sheet to be punched can be up to 19mm. Even with such a thick material the results of the cut are excellent, with exceptional surface flatness and straight edges but without burrs. Additionally it is possible to get extremely small holes in comparison to the thickness of the sheet. Another very important factor is having the productive series repeated perfectly, ensuring that the piece will be the same regardless of when it was produced.
The clearance between the die and the punch must be very close, 0.5% or less, so the tolerances are within 0.001mm. Additionally the surface finishes must be excellent, with a roughness of less than Ra 0.5, to allow the punch to slide through the die and punch the sheet well, to avoid wear due to friction and increase its life span.
Due to the extremely close punch and die clearances and the pressures inherent in the fine blanking process, the punches must be produced within tolerances of 0.001mm in order for the clearance between punch and die to be 0.5% of material thickness – per side-, or even zero clearance. In addition high hardness in these tools is required to prevent wear out and surface finish must be Ra 0.5 or less.
_ MATERIALS:: CW 12% Co Fine grain 1.3 μm 10% Co Micrograin 0.7 μm
_ COATING: TIN / TIALN / AlCrN / Nanocrystalline diamond