Shapes of inserts that can be used in machining

shapes of inserts that can be used in machining

1. Metal Cutting Technology 1.0 T 3.14
1
Selection of the insert shape
The influence of large and small insert shape
Large Insert Shape
Stronger cutting edge
Higher feed rates
Increase cutting forces
Increase vibration
Small Insert Shape
Increase accessibility
Decrease vibration
Decrease cutting forces
Weaker cutting edge
1.
2.
1.Cutting edge strength
2. Vibration tendency
R S C W T D V

2. Metal Cutting Technology 1.0 T 3.14
2
Selection of the insert shape
Number of cutting edges
Insert shape
ISO (first letter)R S C W T D V
Number of edges
Neagative inserts
8 4 6 6 4 4
Number of edges
Positive inserts
4 2 3 3 2 2

3. Metal Cutting Technology 1.0 T 3.14
3
Roughing strenght
Light roughing/semi finishing
(Number of edges)
Finishing
(Number of edges)
Longitudinal turning
(Feed direction)
Profiling accessessability
Facing
(Feed direction)
Operational versatility
Limited machine power
Vibration tendencies
Hard material
Intermittent machining
Large entering angle
Small entering angle
Selection of the insert shape
Factors affecting choice of insert shape
Most suitable Suitable

4. Metal Cutting Technology 1.0 T 3.14
4
Selection of the nose radius
Effect of small and large nose radius
Small nose radius
Ideal for small cutting depth
Reduces vibration
Weak cutting edge
Large nose radius
Heavy feed rates
Large depths of cut
Strong edge security
Increased radial pressures
Note: As a general rule of thumb, the depth of cut should be no less than 2/3 of the
nose radius.

5. Metal Cutting Technology 1.0 T 3.14
5
A small nose radius should be first choice
Choose a nose radius smaller than depth of cut
The relationship between nose radius and DOC ( Depth Of Cut) affects vibration
tendencies.
It is often an advantage to choose a nose radius which is smaller than the DOC.
DOC DOC DOC

6. Metal Cutting Technology 1.0 T 3.14
6
Effect of nose radius and DOC
Ratio on radial cutting forces

7. Metal Cutting Technology 1.0 T 3.14
7
High feed turning with wiper inserts
Wiper – General information
Why use wiper
–Increase feed and gain productivity
–Use normal feed rate and gain surface
quality
When to use wipers
–Use wipers as a first choice where it’s
possible
Limitations
–General limitation is vibrations
–Visual surface can look different even
though the measured surface is great

8. Metal Cutting Technology 1.0 T 3.14
8
High feed turning with wiper inserts
Wiper – Technical solution
Technical solution
–One edge is based on 3-9 radii
–Contact surface between insert and
component is longer with wipers
–Longer contact surface makes a better
surface finish
–Longer contact surface increases cutting
forces which makes a wipers more
sensitive to vibrations when machining
unstable components
A small conventional nose radius
and a larger Wiper nose radius

9. Metal Cutting Technology 1.0 T 3.14
9
High feed turning with wiper inserts
Wiper – Surface finish
Rule of thumb
–Two times feed with a wiper will generate
as good surface as conventional
geometries with normal feed
–The same feed with a wiper will generate
twice as good surface compared with
conventional geometries
Traditional inserts
Wiper insert
Half R
a, same feed
Wiper insert
Twice the feed, same R
a
(.008”) (.014”) (.020”) (.026”)
236
197
157
118
79
39
0
Ra
µinch µm
Metric
Achieved Ra surface
ISO inserts and wipers
0.00
1.00
2.00.
3.00
4.00
5.00
6.00
f
n = 0.20 mm 0.35 mm 0.50 mm 0.65 mm
Standard PM Wiper WM Wiper WMX

10. Metal Cutting Technology 1.0 T 3.14
10