Sheet Metal Forming

Fig. 1.7
 
Different zones of a blanked part edge
Fig. 1.6
 
Punch geometries used in blanking. Adapted from 
Ref 1.3

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Chapter 1: Blanking / 5
The effect of tool wear on part edge quality is 
significant. Tool wear leads to the formation of 
burrs and increases burr length, as shown in Fig. 
1.10 in the work done by Husson et al. (Ref 
1.6), where the effect of tool wear was simu-
lated by assuming different punch corner radii 
in simulations. It has also been observed that 
the effect of tool wear is more pronounced at 
higher blanking clearances (Fig. 1.10).
effect of Material on Part edge Quality. 
The part edge quality also depends on the mate-
rial being blanked. Materials with large ductil-
ity, low yield strength, and homogeneity will 
have better blanked edge quality, dimensional 
tolerances, and longer tool life. Makich et al. 
performed blanking experiments on different 
materials and observed burr formation on each 
of them (Ref 1.5). The burr volume was calcu-
lated for each material. It can be observed from 
this study that the burr volume depends signifi
-
cantly on the type of material blanked (Fig. 
1.11).
Fig. 1.9
 
Increase in burr volume with increasing press strokes because of tool wear. Source: Ref 1.5
Fig. 1.8
 
Effect of punch-die clearance on part edge quality in blanking DP590 steel of 1.4 mm (0.06 in.) thickness. Source: Ref 
1.4 

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6 / Sheet Metal Forming—Processes and Applications
1.4 effects of Tooling and Presses
Punch Geometry
Punch geometry affects the punch stresses 
and temperatures as well as punch life. Figure 
1.5 shows the maximum forces while using dif-
ferent punch shapes when blanking a round