Un-satisfactory surface finish

​Cause

• Excessive feed per revolution

Solution

• Set cutter axially or classify inserts. Check height with indicator
• Check spindle run-out and cutter mounting surfaces
• Decrease feed per rev to max. 70% of the width of the parallel land
• Use wiper inserts if possible (finishing operations)

Cause

• Vibration

Solution

• See section “Vibration”

Cause

• Built-up edge formation

Solution

• Increase cutting speed, v_c, to elevate machining temperature
• Turn off cutting fluid
• Use sharp cutting edge inserts, with smooth rake side
• Use positive insert geometry
• Try a cermet grade with higher cutting data

​Cause

• Back-cutting

Solution

• Check spindle tilt (Tilt spindle approx .004 inch/39.370 inch (0.10 mm/1000 mm))
• Axial run-out TIR of spindle should not exceed 7 microns during finishing
• Reduce the radial cutting forces (decrease the depth of cut, a_p)
• Select a smaller cutter diameter
• Check the parallelism on the parallel lands and on wiper insert used (should not be standing on ”heel or toe”)
• Make sure the cutter is not wobbling – adjust the mounting surfaces
• Make sure inserts are seated properly and pockets are clean

​Cause

• Workpiece frittering

Solution

• Decrease feed, f_z
• Select a close or extra-close pitch cutter
• Re-position the cutter to give a thinner chip at cutter exit
• Select a more suitable lead angle (45-degrees) and lighter cutting geometry
• Choose a sharp insert
• Monitor flank wear to avoid excessive wear