There are many parameters to consider when choosing turning insert. Carefully select insert geometry, insert grade, insert shape (nose angle), insert size, nose radius and entering (lead) angle, to achieve good chip control and machining performance.
- Select insert geometry based on selected operation, for example finishing
- Select the largest possible nose angle on the insert for strength and economy
- Select the insert size depending on the depth of cut
- Select the largest possible nose radius for insert strength
- Select a smaller nose radius if there is a tendency for vibration
Turning insert geometry
Turning geometries can be divided into three basic styles that are optimized for finishing, medium and roughing operations. The diagram shows the working area for each geometry, based on acceptable chip breaking, in relation to feed and depth of cut.
Roughing
High depth of cut and feed rate combinations. Operations requiring the highest edge security.
Medium
Medium operations to light roughing. Wide range of depth of cut and feed rate combinations.
Finishing
Operations at light depths of cut and low feed rates. Operations requiring low cutting forces.
ap
inch mm
Above example illustrates the offer for steel, there are other options available for all material groups.
urning Wiper geometry
Use wiper inserts for improved surface finish with standard cutting data, or, maintained
surface finish 
at substantially higher feed rate.
The -WMX wiper geometry is first choice, and is a good starting point for most applications. When conditions change, there is always a productive alternative.
Choose a positive wiper geometry to lower forces and maintain productivity in case of vibration problems.
Choose wiper geometry as follows:
-WL:For improved chip control when moving to a lowerfn/ap.
-WF:Improves chip control at a lowerfn/ap. Also for lower cutting forces when vibrations occur.
-WMX:Always first choice within the wide chip application area. Provides maximum productivity, versatility and the best results.
-WR:When a stronger edge line is needed, for example, for interrupted cuts.
Turning insert grade
The insert grade is primarily selected according to:
- Component material (ISO P, M, K, N, S, H)
- Type of method (finishing, medium, roughing)
- Machining conditions (good, average, difficult)
The insert geometry and insert grade complement each other. For example, the toughness of a grade can compensate for lack of strength in an insert geometry.
Turning insert shape
The insert shape should be selected relative to the entering angle accessibility required of the tool. The largest possible nose angle should be selected to provide insert strength and reliability. However, this has to be balanced against the variation of cuts that need to be performed.
A large nose angle is strong, but requires more machine power and has a higher tendency for vibration.
A small nose angle is weaker and has a small cutting edge engagement, both of which can make it more sensitive to the effects of heat.
Turning insert size
Select insert size depending on the application demands and the space for the cutting tool in the application.
With a larger insert size, the stability is better. For heavy machining, the insert size is normally above IC 25 mm (1 inch).
When finishing, the size can in many cases be reduced.
How to choose insert size
- Determine the largest depth of cut,ap
- Determine the necessary cutting length, LE, while also considering the entering (lead) angle of the tool holder, the depth of cut,ap, and the machine specification
- Based on the necessary LE andap, the correct cutting edge length, L, and IC for the insert can be selected
Turning insert nose radius
The nose radius, RE, is a key factor in turning operations. Inserts are available in several sizes of nose radius. The selection depends on depth of cut and feed, and influences the surface finish, chip breaking and insert strength.
Entering angle for turning
The entering angle, KAPR (or lead angle, PISR), is the angle between the cutting edge and the feed direction. It is important to choose the correct entering/lead angle for a successful turning operation. The entering/lead angle influences:
- Chip formation
- Direction of cutting forces
- Cutting edge length in cut
