• The shearing strain that each under formed layers of the material undergoes as it passes through the shear plane during the process of chip formation can be calculated with reference to figure.

• The shearing strain defined as ratio of the displacement of the layer EE’ to the thickness of the layer KF’ is related to shearing and rake angle as follows:

$\begin{aligned} \epsilon &=\frac{E E^{\prime}}{K F^{\prime}}=\frac{K E^{\prime}+K E}{K F^{\prime}} \\ \therefore & \epsilon=\cot \emptyset+\tan (\emptyset-\gamma) \end{aligned}$

Rate of strain in cutting:

$\epsilon^{*}=\frac{\varepsilon}{\Delta t}=\frac{E E^{\prime}}{K F^{\prime} \cdot \Delta t}=\frac{V_{s}}{K F^{\prime}}$

where $Vs$ = velocity of shear

$\triangle t$= Time elapsed for the metal to travel a distance EE’ along the shear plane.