Twist drill drilling force situation is more complicated, mainly the deformation resistance of the material of the workpiece, the friction between the twist drill hole wall and chip. Each cutting edge of the drill will be Fx, Fy, Fz of three component effect.

In the ideal case, as shown in Figure 2, the force of cutting edge substantially balance each other. The rest of the force of the axial force and circumferential force, the circumferential force constitutes torque processing major power consumption. Twist drill cutting forces transverse bending, buckling and torsional deformation, the torsional deformation is most significant. Torque is mainly generated by the main cutting edge of the cutting force. The finite element analysis shows that 80% of the total torque on the the ordinary drill tip cutting edge torque, chisel generated torque of about 10%. The axial force is mainly produced by a transverse blade, the axial force generated on the common drilling sharp chisel edge is about 50% to 60%, about 40% of the axial force on the main cutting edge.cutting wheel
Changing the thickness of the core drilling diameter D = 20mm twist drills, cutting disc,for example, in the case of other parameters constant, from which the stiffness variation curve (Figure 3) can be seen, with the increase in the diameter d of the drill core, stiffness Do increases, deformation reduce the amount. Thus, the thickness increases significantly increases the axial force in the twist drill when working drill core, directly affect tool machinability, and the size of the tool stiffness also affect the accuracy of machining geometry.