An important geometrical quantity in the cutting of metals which can be used as a criterion for machinability of metals is

Solution (By Examveda Team)

The correct answer is Option C: Shear angle.
Let's break down why:

Option A: Cutting speed
While cutting speed is important in machining, it's more of a process parameter than a fundamental material property that *defines* machinability.

Option B: Feed rate
Similar to cutting speed, feed rate is a process setting.

Option C: Shear angle
The shear angle is the angle between the shear plane (where the material is deformed and separated) and the cutting direction.
- A larger shear angle generally means less force is needed to cut the material.
- Less force usually translates to better machinability (easier to cut, smoother surface finish, less tool wear).
- Think of it this way: a bigger shear angle is like slicing something with a very sharp angle; it requires less effort.

Option D: Tool geometry
Tool geometry definitely affects how well a material can be machined, but it's an external factor. The shear angle is more related to the material's response to cutting.
In summary: The shear angle directly reflects how easily a material deforms and separates during cutting, making it a key indicator of its machinability.