Makino V55, Maintenance Manual, Page: 212 / 568

6 - 10
6.4.1.2 Balanced Tool Holders
Tooling manufacturers can supply holders that are either balanced or bal-
anceable. Balanced and balanceable holders cost more, but the benefit in
surface quality alone will offset this cost in reduced time on the finishing
bench.
When ordering holders:
• Order tooling with a G2.5 or lower grade specification at the machine’s
maximum rpm.
• Ensure the holder will operate safely and successfully at the required
rpm.
Tooling you currently own can be sent to a service for balancing. Depend-
ing on cost and delivery of balancing individual tools and the number of
tools balanced per year, the purchase of a tool balancer machine may be
justified.
Operation of a tool balancer machine is not difficult, but requires training
and machinery to properly remove or add material to obtain balance.
6.4.2 Concentricity
Concentricity is important in all machining applications, but it is imperative
for effective HSM. It is particularly important when using tools with more
than one cutting edge.
If the tool’s cutting edges do not swing
through the same arc they are said to be
eccentric or “runout” as shown in
Figure 6-4
.
On an eccentric tool, the outside edge wears
more quickly resulting in a wider “wear land”
which shortens the edge’s life. A wider “wear
land” on one edge places unequal side pres-
sure on the tool, which adversely affects bal-
ance, deflection, radial load, and surface
finish.
Sources of runout are extensions, bushings,
and adapters. Do not use extensions, espe-
cially at higher spindle speeds. Use bushings
and adapters only when absolutely neces-
sary.
F
IGURE
6-4
RUNOUT OR
ECCENTRICITY