Chapter 6 Machining Center Carbide Insert Fundamentals 127
Insert Size
Insert size is determined by the largest inscribed circle (IC) that will
fit inside the insert or touch all edges of the insert, Figure 6-8. The most
common insert is a ¾″ square. As the size of the insert increases, the depth
of cut can increase as well. A rule to follow is to set the depth of cut to no
more than
2 /
3
the cutting edge length.
Nose Radius
The nose radius, Figure 6-9, will affect tool strength and surface finish.
The larger the nose radius, the stronger the insert and the better the finish.
However, if tooling and setup are not rigid, a large nose radius can cause
chatter. The chart in Figure 6-10 indicates the smoothness of surface finish
that should result from various combinations of nose radii and feed rates.
Insert Identification System
A standardized letter and number system developed by ANSI,
Figure 6-11, is used to identify and classify indexable carbide inserts. The
identification reference is a combination of nine letters and numbers. The
reference indicates the insert shape, clearance (relief angle), tolerance,
insert type, size, thickness, point (nose) radius or chamfer, cutting edge
condition, and (optional) manufacturer’s identifier.
Figure 6-8. The diameter of an inscribed circle determines
the size of the insert. In this installation, IC is the imaginary
inscribed circle, B represents the distance from a tangent
of the circle to the corner of the insert, and T is the
thickness of the insert. (Kennametal)
Nose radius
Figure 6-9. A large nose radius value results in a better finish, but can also
cause chatter if tooling and setup are not rigid. (Kennametal)