An important turn-key project for special development marine valve blocks in 316
stainless - with a 3μm final bore tolerance and a complex network of intersecting
compound angle holes for oil feed - has been completed by Rodmatic Hytek
One-hit solution for valves
PRODUCTION manager Jonathan Imm explains: ‘We
were able to combine eight operations into one single
cycle on our Daewoo Puma MX 2000ST mill/turn
centre and produce burr free components straight from
the machine. Also as part of the turnkey we had to take
responsibility for heat treatment and arrange micro
finishing of the bore with a specialist contractor.’
The 70 by 70 by 100mm valve blocks were turned and
milled from 150 by 130mm long billets of 316 stainless
steel, having been solid modelled from a PDF drawing
using EdgeCAM Part Modeller, and programmed via
EdgeCAM Solid Machinist. There were numerous cut
outs to be milled in the 18mm high tolerance bore, a
host of compound oil feed holes that had to accurately
intersect in order to maintain maximum oil flow and
sharp edges had to be maintained on critical areas of
Oil exploration equipment specifies materials to perform
reliably under extreme conditions - and which consequently
are not the easiest to cut when producing components.
Snaps up large billets
SBD makes and repairs drilling equipment
for the demanding global oil and gas
industries. The company has been
established in Aberdeen for over twenty
years, a merger with Darron Oil Tools in
2000 (which created Schoeller-Bleckmann
Darron) enabling it to expand into additional
manufacturing and repair services. The
specialised products it handles include nonmagnetic
drill collars and flex collars, plus
an extensive range of downhole drilling
equipment and stabilising products.
These products are manufactured mainly
from specialised non-magnetic steel
produced by the SBD Oilfield Equipment
Group, and specified for its high strength
and corrosion resistance. When used in
directional drilling at depths of up to 5Km
the equipment has to work at temperatures
of 200 oC, with 3,000bar of pressure and 30G.
Machining and cutting the workpiece
material can pose problems, and so SBD
needed to enhance its manufacturing
january 2008
Compound oil feed
holes demand burrfree
accuracy to ensure
optimum flow in service
capabilities with new sawing machines to
reduce the often lengthy cutting times
associated with manufacturing large
components, typically from billet diameters
between 100 and 400mm.
The saw SBD had been using for many
years was no longer sufficiently productive,
so the company purchased an Alligator
4.2AWD band saw from Saws UK in 2006,
after observing its Dual Drive Technology at
work in a similar local environment.
Productivity gains are exemplified by a
reduction from 120 to under 40 minutes to
cut a 300mm diameter billet. Seen in the
context of a bandsaw making up to 20 cuts a
day and working six days a week this means
that productivity is up by at least 100% (200%
in some cases.)
The enabling technology is the dual drive
system that pulls as well as pushes the blade
through the workpiece, working in
conjunction with a CNC system that
automatically adjusts the torque and speed of
the component. The whole operation had to be
completely burr-free.
Once proven, each part required 1.1/2 hours
machining time to complete. However, because it came
from the mill/turn centre in one operation ready for
heat treatment and final bore finishing, the tolerances
and geometric relationships of the different features
were easily maintained. The lead time for the batch,
which was produced using mostly standard tooling, was
also far shorter than could be achieved with normal
multi-operational methods that would entail extensive
fixturing, work queues and inspection. Says Imm:
‘Some features would have had to be jig-bored to
achieve the relationship and geometrical positioning
and that would have been a very expensive and drawn
out process.’ www.rodmatic.com
energy sector
the blade. In addition, the saw uses the latest
design of tungsten carbide tipped and
conventional bi-metal blades, which also
contribute to these productivity
improvements.
Additional benefits include higher levels
of accuracy. ‘Blade wander’ on the old saw,
especially when blades were worn, would get
worse as the cut reached its end, with blade
deviation often more than 1 inch. Operators
thus had to compensate by allowing 1-2
inches extra on the cut billet length. This
was costly in terms of material wastage, and
also added time to the second operation in
the machine shop. The new saw is built upon
a polymer concrete machine base with a
frame that has two reinforced pillars for
extreme rigidity. This bestows a working
accuracy of 0.1mm, eradicating the
compensation issue and eliminating excess
waste on this operation. Surface finish is also
better.
www.sawsuk.com
MWP
35
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