Page 465 - Hartner

Point geometries

acc. to Works Standard acc. to DIN 1412 (extract, edition 03/01)

Relieved cone Web-thinned chisel edge Web-thinned chisel edge
standard point design according to DIN 1412 A with modified lip
Application: For all routine drilling Application: For all routine drilling opera- according to DIN 1412 B
operations in steel, non-ferrous metals and tions Application: For high-strength steels,
plastics. The point angle depends on the with thick-webbed drills, and for drilling manganese steels containing more than
machinability of the materials. into solid material with large diameter drills. 10% Mn, hard spring steels and enlarging
Advantages: Strong lips, resistant to Advantages: Good centering for spot existing holes.
impact drilling due to reduction of chisel edge to Advantages: Resistant to impact, one
and lateral forces. Regrinding is simple and 1/10 of drill diameter and reduction in feed sided-loading and lateral forces. No
may be carried out by hand. pressure. snatching on thin-walled workpieces.
Disadvantages: Wide chisel edge requires Disadvantages: Greater outlay for regrin- Disadvantages: High feed pressure, tendency
high feed pressure. ding. to more off-centre; greater outlay for regrinding

Split point Double-angle point for grey
according to DIN 1412 C cast iron acc. to DIN 1412 D
Application: For drills with very thick webs Application: For drilling workpieces made
destined for very tough, hard materials and from grey and malleable cast iron, and
for deep-hole drills. forgings.
Advantages: Good centering, low feed. Advantages: Protects outer corners due to
Improved chip removal by means of chip increased lip length, resistant to impact,
breaker. good heat conduction properties and thus
Disadvantages: Correct regrinding only increased tool life.
possible by machine. Disadvantages: Greater outlay for regrin-
ding.

Centre point
according to DIN 1412 E
Application: For drilling sheet metal and
soft materials, for flat-bottomed blind
holes.
Advantages: Good centering, reduced
burrs
on through holes, precise drilling in thin
sheet and pipes, no snatching. Available
over 2.5 Ø.
Disadvantages: Sensitive to impact and
one-sided loading. Correct regrinding only
possible by machine.

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