With complementary Y (Vertical) and Z (Ram) axis traverses of 4,000 mm and 1,000 mm, respectively, plus a 700 mm W axis (Spindle) stroke, coupled with twin 40 and 24 station toolchangers and axis feed rates and rapids of 5 - 15,000 mm/min and 15 m/min, respectively, the machine can accommodate workpiece weights of up to 70,000 Kgs on a traversing and rotating CNC table, so clearly has the capacity to satisfy every machining situation likely to come its way.
But Craig Bill also emphasizes the machine's ability to quickly and easily utilize and change between different machining modes as the factor that, he says, "Effectively transforms what is on paper a six-axis milling and boring machine into an unrivalled and highly productive 11-Axis machining centre".
Also supplied with the machine by ‘Ward CNC’ is the automatic accessory changer that comprises:
- A linear motor ‘Cytec’ gyroscopic 2-Axis milling head with built-in high-speed electro spindle and served by its own dedicated toolchanger;
- D'Andrea ‘UT5 800S’ CNC facing and profiling head with 1,000 mm facing capacity.
The machine specification is further enhanced with the integration of the 70 tonnes loading capacity ‘Eimeldingen’ heavy-duty rotary and traversing CNC table, extensive floor plates and zoned guarding allowing the machine to be efficiently set up for pendulum or three zone machining.
Craig Bill emphasizes that such has been the impact of the machine specification and the flexibility offered by the accessory changer system, combined with the inherent power and productivity of the Union machine that, as a result, "we are able to finish machine component features in a single set-up that would have been very difficult, perhaps even impossible, to achieve any other way".
One example of this concerns the production of a hydro power industry 3,200 mm by 3,400 mm by 3,000 main inlet valve (weighing 73 tonnes in finished state) and its accompanying 2,500 mm diameter by 350 mm thick main service seal (reverse engineered and machined from stainless steel). A number of holes are drilled, tapped, counter bored and thread milled in the bore 'outwards'. "Without the flexibility of using a variety of heads, we would find it very, very hard to produce these features," he confirms.
"When we decided to replace the two old boring machines, we looked at other boring and milling machines and their suppliers," continues Craig Bill, "but the Union PCR and ‘Ward CNC’ won the contract based on a combination of machine capability, capacity and price as well as on ‘Ward CNC's’ ability to provide the level of support we needed.
Of heavily ribbed design with three-way, backlash-free, heavy-duty compact roller guide system for highly-accurate guidance of the cross slide, the sturdy machine bed is complemented by a similarly constructed box-type column. The column saddle also features compact roller guides as well as ballscrew drive for transverse movement.
The vertically traveling headstock with axially traversing ram (Z-Axis) accommodates the high-precision main spindle system featuring preloaded spindle bearings with lifetime lubrication. Speed range changes are catered for by a two-step gearbox having hardened and ground helical gears, and a hydrostatic guiding system of the ram with droop compensation in relation to longitudinal displacement, together with an additional mechanical compensation system, ensures high and accurate cutting data.
For example:
- X, Y, Z and W Axes positioning of +/- 0.005 mm (up to 800 mm), +/- 0.008 mm (to 5,000 mm) and +/- 0.012 mm (to 10,000 mm); and
- Repeatability of +/- 0.003 mm.
The Union was installed as part of the ‘RWE N-Power’ company's £3.5 million CNC machine tool investment programme last year as the platform for the company's strategic move into the wider arena of sub contract machining, based around a quick-response machining service for customers in industries such as oil and gas and automotive.
These sectors have been identified by Craig Bill and the TSG Ferrybridge team as ideal to complement and build on the company's core (and established) skills applied since 1974 in the refurbishment of power station equipment, including rotors, valves, pumps and gearboxes and, in particular, turbines and turbine blades.
RWE Power International, TSG Ferrybridge was established as one of three sites to perform such work for power stations within the RWE group, as well as third party sites (basically, the company has worked on equipment at every coal, gas and hydro/wind power station in the UK).
"We were spending a lot of money on turbine blades," continues Craig Bill, "and basically reckoned we could save a lot of cash, and produce the blades quicker, if we did it ourselves." In some cases a single, large turbine blade could cost £36,000. That's not surprising when it is realized that the leading blade on a large 5 m diameter rotor, revolving at 3,500 revs/min, is actually moving at twice the speed of sound - so the blade has to be right!
Since then, the operation has progressed to a £52 million turnover concern, and involves up to 350 people. Aside from its high-tech turbine blade high-speed machining production facilities - including the development of an innovative and patented 'blade cropping' process – the company has an impressive range of machine tools throughout its three large workshops alongside the Ferrybridge C power station in West Yorkshire.
In conjunction with a general fitting and assembly area - housing press, welding, heat treatment, grit blasting, NDT, grit blasting and 120-tonne gas turbine rotor de-stacking - the light and heavy machine shops accommodate a wide array of CNC machines. These extend from milling, turning and machining centre capacity through to 25-tonnes vertical borers and large capacity lathes, including a Safop 100-tonnes capacity machine able to handle 17 m between centers.
In addition, the company also offers an on-site machining service, which utilizes a battery of 'mobile machine tools' to enable customers' fixed plant and equipment to be re-machined, refurbished, repaired or modified in situ. While the large capacity Safop is currently being targeted to 'partner' the Union PCR to further extend the machines' capabilities by linking the two via existing Unigraphics/Vericut CAD/CAM facility, Craig Bill and the team have other plans for Union, to further reduce lead times and so magnify the enormous savings already being made.
The idea is to use additional floorplates to enable component set-up to be performed offline, then to lift the complete fixture, with component, into position and ready to machine.
Commenting that the Union has lived up to everything - and more – that ‘Ward CNC’ said it would, Craig Bill also reflects that the level of service and support provided around the machine has been exemplary.
One measure of this, he concludes, is the fact that when RWE Power International wanted to move a pair of horizontal table borers and replace these with a horizontal machining centre, he had no hesitation in selecting another machine from ‘Ward CNC’: a Toshiba twin-pallet model from the Sheffield machine tool specialist's extensive stock of highquality used machines.
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