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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

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