Cutting Forces
In cutting operation, as the punch in its downward movement enters the material, it need not penetrate the thickness of the stock in order to Complete rupture of the part. The distance which the puch enters into the work material to cause rupture to take place is called ‘penetration’ and is usually given as the percentage of the stock thickness.
The per cent penetration depends on the material being cut and also on the stock thickness When a hard and strong material is being out, very little penetration of the punch is necessary to cause fracture. With softer materials, the penetration will be greater. For example, for soft aluminium, it is 60% of for carbon steel per cent carbon steel it is 38% of r and only 24% of r for 0.5 The percentage annealed. penetration also depends upon the stock thickness, being smaller for thicker sheets and greater for thinner sheets, as shown in Table 2.2