Tool wear

​Flank wear

​Cause

Rapid wear causing poor surface finish or out of tolerance.

• Cutting speed too high
• Insufficient wear resistance
• Feed, f_z, too low

Solution

• Reduce cutting speed, v_c
• Select a more wear-resistant grade
• Increase feed, f_z

Cause

Excessive wear causing short tool life.

• Vibration
• Re-cutting of chips
• Burr formation on component
• Poor surface finish
• Heat generation
• Excessive noise

Solution

• Increase feed, f_z
• Down milling
• Evacuate chips effectively using compressed air
• Check recommended cutting data​

Cause

Uneven wear causing corner damage.

• Tool run-out
• Vibration
• Short tool life
• Bad surface finish
• High noise level
• Radial forces too high

Solution

• Reduce run-out below 0.02 mm
• Check chuck and collet
• Minimize tool protrusion
• Fewer teeth in cut
• Larger tool diameter
• For CoroMill Plura and CoroMill 316, select a higher helix geometry (g_p ≥45°)
• Split axial cutting depth, a_p, into more than one pass
• Reduce feed, f_z
• Reduce cutting speed, v_c
• HSM requires shallow passes
• Improve clamping of tool and workpiece

​Crater wear

Cause

Excessive wear causing a weakened edge. Cutting edge breakthrough on the trailing edge causes poor surface finish.

• Diffusion wear due to cutting temperatures that are too high on the rake face

Solution

• Select an Al₂0₃ coated grade
• Select a positive insert geometry
• First reduce the speed to obtain a lower temperature, and then reduce the feed​

Plastic deformation​

Cause

Plastic deformation of edge, depression or flank impression, leading to poor chip control, poor surface inish and insert breakage.

• Cutting temperature and pressure too high

Solution

• Select a more wear resistant (harder) grade
• Reduce cutting speed, v_c
• Reduce feed, f_z

Chipping​

​Cause

The part of the cutting edge not in cut is damaged by chip hammering. Both the top side and the support for the insert can be damaged, leading to poor surface texture and excessive flank wear.

• The chips are deflected against the cutting edge

Solution

• Select a tougher grade
• Select an insert with a stronger cutting edge
• Increase cutting speed, v_c
• Select a positive geometry
• Reduce the feed at the beginning of cut
• Improve stability

Cause

Small cutting edge fractures (frittering) causing poor surface finish and excessive flank wear.

• Grade too brittle
• Insert geometry too weak
• Built-up edge

Solution

• Select a tougher grade
• Select an insert with a stronger geometry
• Increase cutting speed, v_c, or select a positive geometry
• Reduce feed at the beginning of the cut​

Notch wear​

​Cause

Notch wear causing poor surface finish and risk of edge breakage.

• Work hardening materials
• Skin and scale

Solution

• Reduce cutting speed, v_c
• Select a tougher grade
• Increase cutting speed, v_c

Thermal cracks​

Cause

Small cracks perpendicular to the cutting edge causing frittering and poor surface finish.

Thermal cracks due to temperature variations caused by:

• Intermittent machining
• Varying cutting fluid supply

Solution

• Select a tougher grade with better resistance to thermal shocks
• Cutting fluid should be applied copiously or not at all​

Built-up edge (B.U.E)​

​Cause

Built-up edge causing poor surface finish and cutting edge frittering when the B.U.E. is torn away.

• Cutting zone temperature is too low.
• Very sticky material, such as low-carbon steel, stainless steels, and aluminium.

Solution

• Increase cutting speed
• Change to a more suitable insert geometry

Cause

Workpiece material is welded to the cutting edge due to:

• Low cutting speed, v_c
• Low feed, f_z
• Negative cutting geometry
• Poor surface finish

Solution

• Increase cutting speed, v_c
• Increase feed, f_z
• Select a positive geometry
• Use oil mist or cutting fluid