Issue 4: Unacceptable Roundness or Position
Excessive Boring Tool Imbalance • Change to auto-balance or balanceable head • Balance tool assembly • Reduce speed Excessive Cutting Forces • Check stock allowance and feed rate Insufficient Workpiece Clamping • Check for uniform workpiece clamping Original Bore Off Position • Semi-finish with twin insert boring head
Workpiece Non-Symmetrical • Reduce cutting forces; change to ground insert • Increase cutting speed, reduce feed
PRO TIP Make sure your hole is in-spec before moving on to finishing. If your holes are out-of-round after roughing, a finish pass won’t fix the problem. Fine boring heads aren’t supported by inserts on both sides like rough boring heads, and they’re designed to remove only a small amount of material.
Issue 5: Poor Surface Finish
Issue 6: Taper
Wrong Insert Radius • Use larger insert radius Excessive Feed Rate • Reduce feed; maximum 25% of insert radius Poor Chip Evacuation • Increase bore-to-boring bar clearances • Apply through-tool coolant; adjust nozzles • Change insert to higher rake angle • Check depth of cut PRO TIP Surface finish improves as you decrease the feed rate (keeping speed the same) and increase the size of the nose radius. But be careful not to decrease the feed rate too much, as the reduced axial depth of the cut can cause chatter.
Premature Insert Wear • Change to higher wear- resistant insert grade • Increase insert radius • Change from ground to pressed geometry insert • Increase coolant flow PRO TIP Quality, high-pressure coolant with extra lubricity matters in deep-hole boring and/or with hard-to-machine materials. This can help you get better results and save tool life.
STILL HAVING FINE BORING ISSUES? CALL IN THE EXPERTS. 888.866.5776 • bigdaishowa@us.bigdaishowa.com • bigdaishowa.com
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