Thursday, 27 June 2019
Materials
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Fine Blanking material should have good cold deformation properties, i.e. higher strain hardening sensitivity. Further, fine blanking demands material with a low elastic limit / strength ratio of approximately 60% and high elongation.

For all practical purposes, there is no difficulty in fine blanking material with a carbon content of less than 0.35% and a tensile strength of 40-60 kg/mm2 if it has high elongation. If there is an increase in the percentage of carbon over 0.35% - special care should be taken about the microstructure of the material i.e. it should be fine grained, well-dispersed spheriodised cementite. Carbon steel with a carbon percentage of upto 1% and alloyed steels with a low carbon percentage can also be fine blanked after taking proper care of the material microstructure. If these steels are to be made suitable for fine blanking, the sorbite / pearlite content in the microstructure should be reduced to the minimum possible. Hot rolled strips can also be fine blanked if properly close annealed and acid pickled.

Influence of grain structure on fineblanking components (sample steel C45)
material_A1
A1 = ferrite-pearlite structure of a non-anmnealed hot-rolled strip

material_A2
A2 = cracking of the cut surface, after fineblanking

material_B1
B1 = annealed structure, ferrite and approx. 100% spheroidized cementite

material_B2

B2 = crack-free cut surface, after fineblanking (Feintool AG Lyss)


Last Updated ( Thursday, 06 June 2019 08:50 )