Fine boring


Chip breaking​

 

 

Cause

a) Too short, hard

b) Too long

Solution

a) Increase cutting speed
    Decrease feed
    Change geometry to a more open chip breaker (L-K, L-WK)

b) Increase feed
    Decrease cutting speed
    Change geometry to a more closed chip breaker (L-F, PF)

Tool vibrations

 

Cause

a) Cutting force too high
b) Tool length/coupling size ratio too high
c) Unstable conditions
d) Feed too high
e) Speed too high
f) Friction instead of clean cutting action

Solution

a) Choose a light-cutting insert (L-K)
    Use smaller nose radius
    Choose sharp cutting edges with thin coating or uncoated
    Wiper or L-F inserts are not recommended for long overhangs or unstable 
    conditions
    Choose a smaller nose radius
     Decrease depth of cut

b) Use largest possible coupling size
    Shorten the assembly if possible
    Use damped boring tools (Silent Tools)

c) Ensure rigid clamping with face contact to spindle
    Check workpiece clamping
    Check that all units in the tool assembly are assembled correctly with 
    correct torque
    Check machine spindle, clamping, wear etc

d) Decrease feed

e) Decrease cutting speed

f) Increase depth of cut

 

Surface finish​

 

Cause

a) Vibration

b) Feed marks

c) Worn insert

d) Surface damage from chips

Solution

a) Reduce speed. See above for additional solutions

b) Use L-WK or L-F geometry (not for 391.37 A / B, long overhangs or
    unstable conditions)
    Use larger nose radius
    Decrease feed

c) Change cutting edge. For how to avoid specific wear patterns, see General 
    turning

d) Improve chip breaking