Solid Carbide Drills
General Application Instructions
(continued)
Wrong
Drilling and Chamfering
Correct
Drill into the solid fi rst, then chamfer.
chamfer tool
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Wrong
Correct
Drilling on Inclined or Rounded Surfaces
When drilling on inclined or curved surfaces, use a lower
feed than the standard value. The reduction of feed
required is dependent on the inclination angle of the
workpiece surface and the drill type (see table).
reduced feed
100% feed
>1°
reduced feed (% of standard value)
[
Wrong
0,025mm
3 x D 5 x D
Long <5 x D
1° 100% 80% premachine
2° 80–50% 80–50% premachine
3° 65% 50% premachine
4° 50% premachine premachine
6° 30% premachine premachine
premachine
Premachining is usually done with an end mill operation.
Drilling on Turning Machines Hole Depths Greater than 3 x D
When drilling on turning machines, the drill must be on
centre. The tolerance range of the centre position should
not exceed ±0.025mm. On bar-turning lathes, do not drill
into centre stub or bur. Cut-off tools must be mounted
precisely to eliminate centre stub or bur. Do not drill into
pre-existing holes. Hole depths that are deeper than three times the
drill diameter may require a speed reduction. A
15% lower speed is suggested.
[
widia.com
T145
no premachine
100% feed
inclination
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