Chipbreaker Rates

Material to be drilled	Speed ft. / min.	Point Angle (n degrees)
Aluminum and Aluminum Alloys Brass Brass – leaded Bronze – ordinary Bronze – Hi-tensile	200-300 150-250 200-300 100-200 80-120	118 111 116 118 118
Cast Iron – soft Cast Iron – medium Cast Iron – hard Cast Iron – chilled Copper	100-150 70-100 50-70 25-35 100-200	90 118 118 135 Special
Magnesium and Alloys Malleable Iron Monel Steel – freecutting – leaded Steel up to 180 Brinell	Up to 500 70-80 40-50 100-200 80-110	118 118 118 118 118
Steel 180 / 285 Brinell Steel 285 / 375 Brinell Steel 375 and up Brinell Steel – Manganese (low) Steel – Stainless – freecutting	45-70 30-45 15-25 15-20 30-60	118 135 135 135 118
Steel – Stainless 304-316-320-32OW and tough grades Inconel, Hastelloy Inconel – X Titanium A-286	20-40 15-30 10-15 20-30 15-25	135 135 135 135 135

Always commence operations at the lower end of R.P.M.
Drill Diameter	Feed – Inches / rev.
1/4" to 5/16 " 3/8" to 7/16" 1/2" to 9/16" 5/8" to 11/16" 3/4" to 13/16" 7/8" to 1 1/8" 1 1/4" to 1 1/2" Over 1 1/2"	.006" to.010" .008" to.012" .010" to.014" .012" to.016" .013" to.018" .015" to .025" .020" to .040" .025" and up

Chipbreaker RPM’s for All-Purpose Drills
Drill Diameter	30	40	50	60	70	80	90	100
Drill Diameter	Revolutions Per Minute
1/64 1/32 3/64 1/16 5/64	7334 3667 2445 1833 1467	9779 4889 3259 2445 1956	12223 6112 4064 3056 2445	14668 7334 4889 3667 2934	17112 8556 5704 4278 3422	19557 9779 6519 4889 3911	22001 11001 7334 5500 4400	24443 12223 8149 5112 4889
3/32 1/8 5/32 3/16 7/32	1222 917 733 611 524	1630 1222 978 815 698	2037 1528 1222 1019 873	2445 1833 1467 1222 1048	2852 2139 1711 1426 1222	3260 2445 1956 1630 1397	3667 2750 2200 1833 1571	4074 3056 2445 2037 1746
1/4 5/16 3/8 7/16 1/2	458 367 306 262 229	611 489 407 349 306	764 611 509 437 382	917 733 611 524 458	1070 856 713 611 535	1222 978 815 698 611	1375 1100 917 786 688	1528 1222 1019 873 764
9/16 5/8 11/16 3/4 13/16	204 183 167 153 141	272 244 222 204 188	340 306 278 255 235	407 367 333 306 282	475 428 389 357 329	543 489 445 407 376	611 550 500 458 423	679 611 556 509 470
7/8 15/16 1 1 1/8 1 1/4	131 122 115 102 92	175 163 153 136 122	218 204 191 170 153	262 245 229 204 183	306 285 267 238 214	349 326 306 272 244	393 367 344 306 275	437 408 382 340 306
1 3/8 1 1/2 1 5/8 1 3/4 1 7/8	83 76 70 65 61	111 102 94 87 81	139 127 118 109 102	167 153 141 131 122	194 178 165 153 143	222 204 188 175 163	250 229 212 196 183	278 255 235 218 204
2 2 1/4 2 1/2 2 3/4 3	57 51 46 42 38	76 68 61 56 51	95 85 76 69 64	115 102 92 83 76	134 119 107 97 89	153 136 122 111 102	172 153 138 125 115	191 170 153 139 127