TOOLING 3D-PRINTED CUTTING INNOVATIONS
manufactured version, while still meeting
accuracy, roundness and surface nish
requirements for aluminum motor body
boring.
“The main bore, that houses
the stator of an electric motor
measures approximately 250
mm in diameter and
approximately 400 mm in length,
with a smaller bearing bore at
the bottom,” explains Harald
Bruetting, manager, program
engineering. “When
manufactured using conventional
means, a reamer for this type of application
would weigh more than 25 kg, far too heavy
for the existing machine tool or for an
operator working with the tool.”
Bruetting and Kennametal’s Solution
Engineering Group turned to the company’s
in-house additive manufacturing capabilities
to 3D-print a strong but lightweight indexable
tool, equipped with proven Kennametal
technologies, including ne adjustable RIQ
reaming inserts for high precision nishing
and a KM4X adaptor for maximum rigidity.
The tool also features internal 3D-printed
cooling channels that help maximise
productivity and tool life.
“By using metal powder-bed 3D-printing,
together with nite element analysis software,
we were able to design and build a tool that
brought the moment of inertia very close to
the spindle face, increasing its rigidity while
meeting the customer’s weight restrictions,”
said Werner Penkert, manager, future
solutions. “It is an excellent example of how
Kennametal is using advanced manufacturing
technology to help meet our customer’s
unique challenges.”
Two versions of the tool were built, one
with a carbon- bre tube, the other using a
3D-printed metal tube. The tool with the
3D-printed tube weighed in at 10.7 kg and
the carbon bre version at 9.5 kg, less than
half of their conventional counterparts.
Also at EMO, Ceratizit (https://is.gd/
tovaso) demonstrated an effective tool
programme for every machining task
encountered in the production of electric
motors, unveiling two newly developed ne
boring tools for the high volume production of
electric motor housings. Closely concurring
with Kennametal on the dimensions of motor
housings, it adds that IT6 tolerances and
Ceratizit’s 3D-printed stator boring tool, above and inset (at the end of the
production process). Below, the plastic modular design tool
roundness values of 2/100 mm
must be maintained while
machining parts in volumes of
100,000+.
Solid steel tools are too heavy for most
machine spindles, so lightweight bodies that
reduce tool weight to somewhere below
20 kg are required for use with standard CNC
machining centres. With four cutting edges
per step and up to ve steps per tool, even
challenging boring tasks can be completed at
high feed rates in a single operation. Using
additive manufacturing, Ceratizit has
developed a special tool for stator bores that
satis es all the stipulated requirements and
leaves nothing to be desired, in terms of
machining speed and precision.
TWO DEVELOPMENTS
Despite its large diameter (in excess of 200
mm) and considerable length, weight is below
17 kg and the tool designed to accommodate
the tilting moment of machining centres. The
tool body is produced via additive
manufacturing, as are the cartridges into
which PCD cutting edges are soldered. This
eliminates any heat input into the base
body and prevents the
associated deformation.
Once the loaded
cartridges have been
tted into the
designated xtures in the
base body, the tool is precisely
ground to the required size.
Coolant holes in both the base
body and the cartridges make sure
that every cutting edge receives
exactly the amount of coolant it
needs while at the same time
ushing chips out of the bore.
Scratched surfaces are avoided,
which contributes greatly to
increased process security and a
reduction in waste.
In a similar development, Ceratizit has
developed another ne boring tool for electric
motor housing machining. A somewhat
simpler design, it’s no less innovative and is
more affordable and of a modular design that
makes it easier to manufacture.
The plastic step boring bar consists of a
tubular lightweight base body that is made
via conventional cutting processes. The
diameters of the stator bore are fashioned
using additively manufactured plastic steps
containing cartridges equipped with PCD or
indexable inserts (a special plastic developed
by Ceratizit is employed). This special plastic
is also vibration-damped, while the
3D-printing method allows the coolant holes
to be con gured as required. The toolholders
for each step that hold PCD cutting edges or
indexable inserts are of a design that
prevents the tightening torque of the
indexable insert from acting on the plastic.
The cartridge also has an electronic
component that enables ne adjustments to
be carried out digitally on the indexable
insert. A display can be docked via a digital
interface and cutter adjustments then
performed to micron-level precision.
The modular design
featuring base body and steps
allows the lightweight
counterboring tool to be
con gured as a multi-step tool
to a customer’s requirements in
support of complete stator bore
machining in a single operation. Further
enhancements to allow for the holding
of an additional tool on the front, e.g.
for the rotor shaft bearing, are under
consideration.
And even though everything’s made
to measure, Ceratizit holds the base
body in stock as a semi- nished
product, in either Komet ABS or HSK
interface, while the plastic steps are
produced quickly on a 3D printer.
16 www.machinery.co.uk @MachineryTweets December 2019
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