Manufacturing Machinery World - August 2022

AUTOMATION
production cell. One is the provision of
Okuma's turn-cut software in the proprietary
OSP machine control that allows, without the
need for special fixturing, turned features to
be produced that are not on the centreline of
a component. Three of the castings require
this technology to be used.
Features are machined by rotating a
turning tool in the VMC spindle, circular
interpolating the X and Y axes at the same
rotational speed and feeding the spindle
forward in Z. Had interpolation turning not
been available, it would not been possible to
produce all the parts in one hit. There is no
production efficiency penalty through the
use of relatively slow turn-cutting, as it is not
feasible to turn Inconel at high speed anyway
due to the material becoming difficult to
machine when hot.
To compensate for there being a lot of
variability in the shape of the castings,
another process improvement is the use of a
combination of Renishaw's Inspection Plus
and Productivity Plus probing software
packages running in the control coupled with
spindle probing of the workpiece. The
various elements of a casting can be
measured and manipulated by the
measurement cycles so that the workpiece
can be placed in a position where it can be
machined successfully; and if it cannot, the
part will be rejected.
Alternatively, if any given feature is
predicted to be out of tolerance, the customer
can be informed so a decision can be made as
to the feature's relevance and whether
machining should go ahead anyway. The
importance of harnessing all these
technologies can be gauged by the fact that
the raw castings are so expensive that
machining adds only 20 percent to the cost of
a finished component. For the same reason,
scrap is assiduously avoided, accounting for
only 0.015 percent of cell throughput.
Another feature of Okuma machines that
T&R Precision appreciates is the Thermo-
Friendly Concept design, involving both the
machine structure and the spindle. It allows
the aero engine parts to be machined to
within ± 25 microns, despite a significant
variation of temperature on the shop floor in
Foulridge.
Space for 30 machine pallets in the Cellro
store allows up to 30 hours' production
without operator attendance, so there is no
need for a manned night shift and full
advantage can be taken of lights-out
operation at the weekend. With an OEE
(overall equipment effectiveness) in excess of
80 percent, it adds up to a highly productive
facility in its present form, while the
flexibility to add a second VMC has the
potential to double output and extend
unattended running further.
The final word went to engineering
manager Graham Gilbert who said, “The
support provided by NCMT throughout the
project was fantastic. It was useful to be able
to visit Okuma's European headquarters in
Germany with them to prove out various
parts of the process.
“The engineer the agent deployed in our
factory for several weeks after installation
was knowledgeable and very patient with us
during the training period.
“This was important as, although we
operate a couple of dozen multi-axis CNC
machining platforms on a daily basis here in
Foulridge, the MU5000V was the first
machine we had bought from this source so
we were on a steep learning curve at the
outset.”
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