Diamond drill bits

Diamond drilling is the most productive method of making a hole in friable, hard, nonmetallic materials. The most com monly used in industry are tubular drills consisting of a diamond rim crown, fixed in a cylindrical core (drill end). These tools take off material only on the rim surface. Usage of drills of this type helps to reduce axial load and to ease coolant supply to the cutting area. It provides high productivity and quality of processing and decreases diamond expenses.

Recommended rotational frequency index of drills for glass drilling
Drill diameter, mm  Rotational frequency, RPM Mechanical feeding, mm/min
1 — 3                   6 000 — 24 000                           20 — 50
3 — 6                  3 000 — 12 000                           30 — 60
6 — 15                2 600 — 6 000                           30 — 50
15 — 25              2 000 — 4 500                         25 — 40
25 — 50              1 200 — 2 500                         20 — 30
50 — 100              500 — 1 200                          10 — 20

In other cases of drilling, the coolant to the work area is supplied through an inside hollow of the tool. As a rule, for the hand drilling of furniture, mirror and automobile glass, industrial water is used.
The pressure of the coolant supplied is normally determined by the drill diameter:
Drill diameter, mm               Coolant pressure, MPa
1 — 5                                        0,3 — 0,5
6 — 10                                      0,2 — 0,4
11 — 20                                   0,15 — 0,25
21 — 40                                    0,05 — 0,15
41 — 100                                    0,2 — 0,1

Diamond drill bit