I want to shear 3mm diameter mild steel bar using a motor that converts rotational motion to linear motion. The motor is fitted with a triangular positive action cam with minimum dia 36mm and maximum dia 90mm. According to my calculations force required to shear 3mm bar = 3.14x1.5mmx1.5mmx 300mpa
= 2119.5 N.
Motor torque is 112.5Nm at the required rpm. The cam travels upto 33mm (radius)for the required stroke. Hence, t= f x r
Therefore, f= t/r
F= 112.5/0.033 = 3409N
However, in practical application, the wire is not getting cut. Is there something wrong with my calculations?