CENTERLESS GRINDING ALLOWANCES

Minimum allowance for removal of OD imperfections
Finished OD
Inches
0.125 and
Under
Over 0.125
to 0.180
Over 0.180
to 0.230
Over 0.230
to 0.360
Over 0.360
to 0.460
Over 0.460
to 0.580
Up to 3.000
0.012
0.014
0.016
0.020
0.022
Over 3.000 to 4.750
0.016
0.018
0.020
0.022
0.024
0.026
Over 4.750 to 6.000
0.018
0.020
0.022
0.024
0.026
0.028
Over 6.000 to 7.000
0.020
0.022
0.024
0.026
0.028
0.030
Over 7.000 to 8.000
0.024
0.026
0.027
0.028
0.031
Over 8.000 to 10.500
0.026
0.028
0.030
0.032
Over 10.500 to 12.500
0.028
0.030
0.032
0.034
Over 12.500 to 14.000
0.030
0.032
0.034
0.036
Over 14.000 to 15.000
0.033
0.035
0.036
0.037

NOTE: These allowances plus normal size tolerances must be considered in calculating the size to be ordered.


CENTERLESS GRINDINGS


Example #1:
Determine ordering size for tube to be centerless ground to 4.750”OD x .440” wall.
Step 1
Determine ID size:
4.750”
finished OD
Less 2 x wall thickness (.440”)
-.880”
3.870”
ID
Step 2
Apply centerless grinding allowances to OD:
Finished OD of 4.750” Takes .024” centerless grinding allowance from table1
4.750”
+ .024”
4.774”
Step 3
Add ID and OD tolerance and order:
4.774” OD + .013” – .000″ x 3.870″ ID +.000″ -.013