Section 13. qxd

swing
(diameter) and the 
distance between centers
when the tailstock
Fig. 13.4.11
Standard nomenclature for single-point cutting tools.
Section_13.qxd 10/05/06 10:32 Page 13-56

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TURNING
13-57
Table 13.4.3
Recommend Tool Geometry for Turning, deg
High-speed steel and cast-alloy tools
Carbide tools (inserts)
Back
Side
End
Side
Back
Side
End
Side
Material
rake
rake
relief
relief
rake
rake
relief
relief
Aluminum alloys
20
15
12
10
5
0
5
5
5
15
Magnesium alloys
20
15
12
10
5
0
5
5
5
15
Copper alloys
5
10
8
8
5
0
5
5
5
15
Steels
10
12
5
5
15
5
5
5
5
15
Stainless steels, ferritic
5
8
5
5
15
0
5
5
5
15
Stainless steels, austenitic
0
10
5
5
15
0
5
5
5
15
Stainless steels, martensitic
0
10
5
5
15
5
5
5
5
15
High-temperature alloys
0
10
5
5
15
5
0
5
5
45
Refractory alloys
0
20
5
5
5
0
0
5
5
15
Titanium alloys
0
5
5
5
15
5
5
5
5
5
Cast irons
5
10
5
5
15
5
5
5
5
15
Thermoplastics
0
0
20
30
15
20
10
0
0
20
30
15
20
10
Thermosetting plastics
0
0
20
30
15
20
10
0
15
5
5
15
S
OURCE
: “Matchining Data Handbook,” published by the Machinability Data Center, Metcut Research Associates, Inc.
Side and
end cutting
edge
Side and
end cutting
edge
Positive 
rake angles
improve the cutting operation with regard to
forces and deflection; however, a high positive rake angle may result in
early failure of the cutting edge. Positive rake angles are generally used
in lower-strength materials. For higher-strength materials, negative rake
angles may be used. 
Back rake
usually controls the direction of chip
flow and is of less importance than the 
side rake.
The purpose of 
relief
angles
is to avoid interference and rubbing between the workpiece and
tool flank surfaces. In general, they should be small for high-strength
materials and larger for softer materials. Excessive relief angles may
weaken the tool. The 
side cutting-edge angle
influences the length of chip
contact and the true feed. This angle is often limited by the workpiece
geometry, e.g., the shoulder contour. Large angles are apt to cause tool
chatter. Small 
end cutting-edge angles
may create excessive force normal
to the workpiece, and large angles may weaken the tool point. The pur-
pose of the 
nose radius
is to give a smooth surface finish and to obtain
longer tool life by increasing the strength of the cutting edge. The nose
radius should be tangent to the cutting-edge angles. A large nose radius
gives a stronger tool and may be used for roughing cuts; however, large
radii may lead to tool chatter. A small nose radius reduces forces and is
therefore preferred on thin or slender workpieces.