A346-347
02-05-24
14.27
GENERAL TURNING
Sida A 346
Practical tips
Problem:
Flank and notch wear
Crater wear
Plastic deformation
Built-up edge (B.U.E.)
a.
Rapid flank wear causing
poor surface finish or out
of tolerance.
b/c. Notch wear causing poor
surface finish and risk of
edge breakage.
Cause:
Remedy:
a.
Reduce the cutting speed.
Select a more wear resistant grade.
Cutting speed too high
or insufficient wear
resistance.
b/c. Oxidation
Select an Al2O3 coated grade.
For work hardening materials select
a smaller entering angle or a more
wear resistant grade.
b/c. Attrition
Reduce the cutting speed.
(When machining heat resistant
material with ceramics increase
cutting speed.)
c.
Select a cermet grade
Oxidation
Excessive crater wear causing
a weakened edge. Cutting
edge breakthrough on the
training edge causes poor
surface finish.
Diffusion wear due to too high
cutting temperatures on the
rake face.
Select an Al2O3 coated grade.
Plastic deformation
Edge depression or flank
impression
Leading to poor chip control
and poor surface finish.
Risk of excesive flank wear
leading to insert breakage
Cutting temperature too high
combined with a high
pressure.
Select a harder grade with better
resistance to plasic deformation.
Built-up edge causing poor
surface finish and cutting
edge frittering when the
B.U.E. is torn away.
Workpiece material is welded
to the insert due to:
Select a positive insert geometry.
First reduce the speed to obtain a
lower temperature, then reduce the
feed.
Edge depression
– Reduce speed
Flank impression
– Reduce feed
Low cutting speed.
Increase cutting speed.
Negative cutting geometry.
Select a positive geometry.
125
A346-347
02-05-24
14.28
Sida A 347
Practical tips
Problem:
Chip hammering
Frittering
GENERAL TURNING
Cause:
Remedy:
The part of the cutting edge
not in cut is damaged through
chip hammering. Both the top
side and the support for the
insert can be damaged.
The chips are deflected
against the cutting edge.
Change the feed.
Small cutting edge fractures
(frittering) causing poor
surface finish and excessive
flank wear.
Grade too brittle.
Select tougher grade.
Insert geometry too weak.
Select an insert with a stronger
geometry (bigger chamfer for
ceramic inserts).
Built-up edge
Increase cutting speed or select a
positive geometry.
Select an alternative insert
geometry.
Reduce feed at beginning of cut.
Thermal cracks
Insert breakage
Slice fracture – Ceramics
126
Small cracks perpendicular to
the cutting edge causing
frittering and poor surface
finish.
Insert breakage that damages
not only the insert but also the
shim and workpiece.
Thermal cracks due to
temperature variations caused
by:
- Intermittent machining.
Select a tougher grade with better
resistance to thermal shocks.
- Varying coolant supply.
Coolant should be applied copiously
or not at all.
Grade too brittle.
Select a tougher grade.
Excessive load on the insert.
Reduce the feed and/or the depth
of cut.
Insert geometry too weak.
Select a stronger geometry,
preferably a single sided insert.
Insert size too small.
Select a thicker/larger insert.
Too big tool pressure.
Reduce the feed.
Select a tougher grade.
Select an insert with smaller
chamfer.