Turning Process
In the turning process we have two things one is Generatrix, another one is a Directrix.
Generatrix: Rotary motion that generates the surface
Directrix: The direction in which the feed given
Single Point Cutting Tool
Two important phases of the tool are
Rake Face
Flank Face
Overview of Tool Geometry
Tool overview consists of
Tool Shank
Tool Angles
Faces/Surfaces
Edges
Axis (Reference Axis)
Cutting Edge Angles and Nose Radius
Cutting Edge Angles are solely determined by the nose radius of the tool
There are two cutting edge angles: Side Cutting Edge Angles and End Cutting Edge Angles
Nose Radius improves the: Tool life, Surface Finish and Conductivity
Types of Reference Systems
ASA System / American System
Orthogonal Rake System (ORS) / Continental System
Normal Rake System (NRS) / International System
Maximum Rake System (MRS)
Forces in Orthogonal Metal Cutting
Forces act in three locations
Shearing Zone (Fs, Fn )
Chip Tool Interface (F, N)
Forces on Cutting Tool by Workpiece (Fc, Ft )
Force Components in Metal Cutting
There are three force components in metal cutting:
Cutting Force (Fc ): Acts in tangential direction which is also called as a power component.
Thrust Force (Ft ): Acts in the direction of feed (Axial direction)
Radial Force (Fr ): Acts in the radical direction
Need for Force Relationships
To calculate co-efficient of friction
To calculate the normal stress
To calculate the shear stress
Ernst-Merchant Theory
Shearing action takes place in the direction in which the required shear energy is minimum. So, derivative of shearing energy along the shearing direction is zero.