It is possible to select the most suitable cutting edge geometry for different applications. If the most suitable cutting edge geometry is selected then higher machining efficiency and higher hole accuracy can be obtained. Note however that some geometries require special regrinding procedures and techniques.
Grinding name
Conical
Geometry
Features and effect
- The flank is conical and the clearance angle increases toward the centre of the drill.
Use
- For general use.
Flat
Geometry
Features and effect
- The flank is flat.
- Facilities cutting.
Use
- Mainly for small diameter drills.
Three rake angles
Geometry
Features and effect
- As there is no chisel edge, the results are high centripetal force and small hole oversize.
- Requires a special grinding machine.
- Surface grinding of three sides.
Use
- For drilling operations that require high hole accuracy and positioning accuracy.
Spiral point
Geometry
Features and effect
- To increase the clearance angle near the centre of the drill, conical grinding combined with irregular helix.
- S type chisel edge with high centripetal force and machining accuracy.
Use
- For drilling that requires high accuracy.
Radial lip
Geometry
Features and effect
- The cutting edge is ground radial with the aim of dispersing load.
- High machining accuracy and finished surface roughness.
- For through holes, small burrs on the base.
- Requires a special grinding machine.
Use
- For cast iron and light alloy
- For cast iron plates.
- Steel.
Centre point drill
Geometry
Features and effect
- This geometry has two-stage point angle for better concentricity and a reduction in shock when exiting the workpiece.
Use
- For thin sheet drilling.
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