Printed from Kezuriba (kezuriba.net/en/troubles/ream-undersize/)

Hole becomes undersized (reaming)

Reaming Reaming

Check first

Reaming allowance is small
Reamer wear (wear on the periphery)
Elastic recovery of a thin-walled workpiece, or distortion from holding

Try first

Use a narrower margin and larger lead angle and back taper
To limit peripheral wear, reduce the cutting speed and improve lubrication
Change the pilot drill to increase the reaming allowance

?Likely causes

Reaming allowance is smallAgreed by 2+ makers^[1][2]
Reamer wear (wear on the periphery)Agreed by 2+ makers^[1][3]
Cutting speed or feed is lowOne maker^[1]
Elastic recovery of a thin-walled workpiece, or distortion from holdingAgreed by 2+ makers^[1][2]
Burnishing action is too great (wide margin, small lead angle)Agreed by 2+ makers^[2][3]

✓Fixes

Cutting conditions

To limit peripheral wear, reduce the cutting speed and improve lubricationOne maker^[3]

Tool

Use a narrower margin and larger lead angle and back taperAgreed by 2+ makers^[2][3]

Setup

Change the pilot drill to increase the reaming allowanceOne maker^[2]
Change the workpiece holding methodOne maker^[2]

↔Related problems

Hole becomes oversized (reaming)Poor hole surface or chatter (reaming)Hole is not round, bends, or tapers (reaming)Reamer breaks or seizes

📚Sources

Causes and fixes are summarized in our own words from cutting-tool makers’ troubleshooting guides and technical data. “Agreed by 2+ makers” means two or more makers say the same thing.

Sandvik Coromant — Troubleshooting for reaming sandvik.coromant.com
OSG — Series No.35 Reamers, Table 6.1 Troubleshooting, pp. 30-31 osg.co.jp
Tungaloy tungaloy.com