The way in which the chips are generated and how the chips are disposed off differ according to the cutting edge geometry and the type of workpiece material that is being machined.
Conical spiral, long pitch, and zigzag type chips, all of which have a negative influence on drilling can be broken by changing the cutting conditions, by thinning the point angle or by using a peck feed.
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Types of chips
Conical spiral
Features:
The chips developed are curved by the flute. This type of chip is common when machining ductile materials at low feed rates. If the chip breaks after several turns, then the chip breaking properties are deemed satisfactory.
Workpiece:
Mild steel.
Segment
Features:
The chips generated are initially the same as above but due to the lack of workpiece ductility the chips can not curl easily. The chips are also broken by the wall of the hole being drilled. This type of chip is good for chip disposal.
Under high spindle speeds solid carbide drills may work loose.
Workpiece:
Carbon steel, alloy steel.
Long pitch
Features:
This type of chip is generally developed when machining malleable workpiece materials. Due to the malleablilty the chip extends and creates long pitch chips. These chips do not coil and can cause problems such as gathering around the drill
Workpiece:
Aluminium.
Buckling
Features:
This type of chip is formed in a zigzag type geometry (buckled). This is due to the characteristics of the workpiece material and the flute geometry. This type of chip can lead to chips packing in the flute.
Workpiece:
Stainless steel.
Needle
Features:
This type of chip is unique to brittle materials. The chip curl is very small and chip breaking performance is satisfactory, but this type of chip can easily cause chip packing.
Workpiece:
Cast iron.
Fan
Features:
This type of chip is broken by the flute and the wall of the drilled hole. It is generated when the feed rate is high.
Workpiece:
Free cutting steel.
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