Page 1038 - Tungaloy Catalog

Technical Reference
Drilling Tools
Cutting edge failure of drilling tools

Chipping
Flaking (Small or minute fracture
(Shell-like spalling) of cutting edge)
Breakage
Irregular wear (Relatively large fracture)
(Irregular flank wear)

Flank wear Crater wear
(Wear of cutting edge) (Groove-like wear on rake face)

Corner wear
Feed mark (Wear of peripheral corner)
(Wear stripes in periphery)
Fracture
(Catastrophic breakage
of drill body)
Note: If these failures are not excessive,
the tool is in a normal condition.

Change of chip shapes in drilling

d Change of chip shapes relating to cutting conditions
Photographs below show the change of chip shapes relating to change of the feed and the cutting speed. These chip shapes are
all well controlled in a proper condition range.
When the speed and feed are low, the chip shows whitish color and the tail of the chip tends to lengthen gradually. In contrast, as
the speed or the feed increases, the chip tends to increase in brightness and becomes a compact shape with a short tail. These
changes in the shape depend on the cutting temperature. As the temperature increases, chips tend to be broken.

Technical Reference High Feed Low

14

Tail

High Cutting speed Low

14–20