Thursday, 27 June 2019
Fine Blanking
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menu_bulletFine Blanking, a precision mass production technique, is an unique development in the metal forming industry, occurring over the last eight decades.

menu_bulletIts conception, although innovated from traditional metal stamping techniques, employs an entirely different philosophy of machine movement, tooling and the plastic deformation of metal.

menu_bulletIts achievement is the geometrical accuracy and close tolerance of metal cutting operations; chip flowing like milling, grinding, shaving broaching etc; combined with the productivity of metal stamping operations.

menu_bulletThe fine blanking process presented for the first time in 1923 in Germany for production of parts for watch and clock industry has undergone massive change over the years.

menu_bulletThere have been several technological breakthroughs both in tool making and press manufacture, most revolutionary is the development of Electro Wire Erosion Machine and CNC Control Presses.

menu_bulletIn today's scenario, fine blanking technology has created exclusive positions in automobile industry for producing high precision parts for engine, door latch, window lifters, gearbox etc.

menu_bulletThe capability of the technology in producing 100% shear edge with extremely close tolerance has been recognized even by other industries like switchgear, compressors, motorcycles and scooters, aircraft and many others.

menu_bulletThe modern fine blanking deploys a triple action press and a short discussion of the process is as below :

 

a
A
B
C
s A
s_B
s_C
     
s_D
s_E
s_F
D
E
F
 
  • (A) Tool in open condition along with strip ready to be cut.

  • (B) Bottom moves up and tools closed. Ring groove?(Fr) and counter (Fg) forces activated.

  • (C) Blanking Force (Fr) activated and material being out to produce part. Ring Groove and Counter Force still remains active.

  • (D) Bottom moves down and tool in open condition.

  • (E) Ejector Force?(Fe) activated. Strip and slug ejected.

  • (F) Part Ejected.

The basic differences between fine blanked and conventionally stamped parts are as follows:

Fine Blanking
Conventional Blanking

Edges are 100% sheared and bright over the entire thickness.

Edges are sheared upto one-third of the thickness the rest remaining fractured.

No deformation occurs in blanking even upto a thickness of 14 mm, i.e. component remains flat.

Components get dished in blanking, especially with material above 1.5 mm thickness.

A wall thickness of 60% of the material thickness can be achieved in the blank.

Not possible.

Hole diameter of even 60% of the material thickness can be pierced to close tolerances.

Practically impossible, especially in the case of material thickness of over 1.5 mm.

Hardness of the sheared edges can be achieved upto 150-200% over the original hardness, due to work hardening. This gives better wear resistance and avoids heat-treatment in some cases.

Practically impossible.

Surface finish on sheared edges can be achieved upto 0.8 microns CLA.

Not possible.

Last Updated ( Thursday, 06 June 2019 08:47 )