Determining the cutting speed and the speed
Version 1.0.2 - 2020-07-06
44
Translation of original operating manual
GB
D
rilling
_
VC_GB.fm
6.3
Examples to calculatory determine the required speed for your drilling machine
The necessary speed is depending on the diameter of the drill bit, on the material which is
being machined as well as on the cutting material of the drill bit.
Material which needs to be drilled: St37
Cutting material (drill bit): HSS spiral bit
Set point of the cutting speed [
v
c
] according to the table: 40 meters per minute
Diameter [d] of your drill bit: 30 mm = 0,03 m [meters]
Selected infeed [f] according to the table: about 0.35 mm/rev
Speed
Set a speed on your drilling machine which is less than the determined speed.
INFORMATION
In order to facilitate the production of larger drill holes they need to be pre-drilled. This way, you
reduce the cutting forces and improve the guiding of the drill bit.
The pre-drilling diameter is depending on the length of the
chisel edge. The chisel edge does not cut, but it squeezes
the material. The chisel edge is positioned at an angle of
55° to the major cutting edge.
As a general rule of thumb it applies: The pre-drilling
diameter is depending on the length of the chisel edge.
Recommended working steps for a drilling diameter of 30 mm
Example:
1st working step: Pre-drilling with Ø 5 mm.
2nd working step: Pre-drilling with Ø 15 mm.
3rd working step: Drilling with Ø 30 mm.
Drill bit
Ø
in mm
Speed
n
in rpm
39,0
33
49
65
82
98
122
147
163
204
245
286
327
408
490
653
817
40,0
32
48
64
80
96
119
143
159
199
239
279
318
398
478
637
796
41,0
31
47
62
78
93
117
140
155
194
233
272
311
388
466
621
777
42,0
30
45
61
76
91
114
136
152
190
227
265
303
379
455
607
758
43,0
30
44
59
74
89
111
133
148
185
222
259
296
370
444
593
741
44,0
29
43
58
72
87
109
130
145
181
217
253
290
362
434
579
724
45,0
28
42
57
71
85
106
127
142
177
212
248
283
354
425
566
708
46,0
28
42
55
69
83
104
125
138
173
208
242
277
346
415
554
692
47,0
27
41
54
68
81
102
122
136
169
203
237
271
339
407
542
678
48,0
27
40
53
66
80
100
119
133
166
199
232
265
332
398
531
663
49,0
26
39
52
65
78
97
117
130
162
195
227
260
325
390
520
650
50,0
25
38
51
64
76
96
115
127
159
191
223
255
318
382
510
637
n
c
d
------------
40
m
min
3 14
0 03m
---------------------------------------------------
425 rpm
=
=
=
Chisel edge length 10% of the
drill bit - Ø
