In order to penetrate a workpiece, a tungsten carbide drill bit is subject to a torque of 3.8 Nm and an axial force of 5 kN. Tungsten carbide is very strong (compressive strength 1400 MPa, tensile strength 340 MPa) but also brittle. Assuming the bit is a uniform cylinder with 4 mm diameter, what is the safety factor with respect to failure during this operation?
