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John Cable, managing director of precision turned-parts specialist C and M Precision, has paid tribute to the role Citizen CNC machines play in his business.

The company now owns four Citizen top of the range M-Series sliding head turn-mill centres, two larger capacity twin-turret turn-mill centres and a pair of two-axis lathes.

Cable recounted how C and M progressed from separate operations, at the company’s conception in 1992, into single-cycle turn-milling, which has enabled it to achieve high levels of precision on complicated components.

‘It is viable if you select very carefully the right machinery, tooling and have people with the attitude and willingness to make it work.

‘We treat the machining of a simple washer in batches of several thousand with the same dedication as a small batch of high pressure, quick-release hydraulic connectors that require a multitude of driven tool positions,’ Cable said.

The company developed a gang tool method of holding air-driven spindles on its first two-axis lathe to produce 75,000 parts a month for a metering customer.

This eventually led C and M into sliding-head technology.

‘We persuaded a service manager from the lathe supplier to alter the control and create a subroutine.

‘We immediately slashed the overall floor-to-floor times for producing the parts by 75 per cent by being able to switch from a series of dedicated operations on manual drills and milling machines to just two operations,’ Cable added.

With an expanding order book for small turned parts and an export contract for 200,000 components, Cable decided sliding-head technology and single-cycle machining was the way forward.

Unfortunately, the quality of build of the first three machines installed and growing problems with reliability led him to consider Citizen Machinery.

Very quickly the three original sliding heads were disposed of and replaced with a Citizen M12 quickly followed by an M16 and later two of the top-of-the-range, 14-axis M32-Vs being installed at the 4,100ft2 machine shop in Maldon.

‘It was a breath of fresh air with the level of support for these machines coupled with greater reliability and higher productivity.

‘As a result, the two Citizens gave the same output as three of the previous machines,’ continued Cable.

Each of the Citizen’s M32-Vs has IEMCA bar feed; special swarf extraction capable of handling chips and stringy swarf; and Citizen’s fully programmable automated gantry-based unloading system for component removal from the subspindle and conveyoring from the working zone.

Each machine features a 2,000lb/in2 high-pressure Coolblaster coolant system as well as a high-quality fume-extraction system.

Cable believes the high-pressure Coolblaster is essential and rewarding for the continuous rate of production his machines run at.

‘We often have to produce deep holes and the programmable coolant feed ensures the cycles are consistent, tools perform at their optimum and swarf is well controlled.

‘For instance, on one regular brass component 145mm long, we have to drill a 14mm hole from solid on the M32-V.

‘Due to Coolblaster, we can hit this with just one peck in eight seconds and we have the confidence to do this operation completely unmanned,’ he said.

C and M Precision has six machinists to look after the eight machines over two shifts: 6am to 2pm and 2pm to midnight, with 2pm to 5pm overlapping.

The rest of the time these machines are run unmanned, which confirms the level of confidence in the processes.

By incorporating the gantry unload, this reduces coolant loss from ‘drag-over’ swarf contamination of components and eliminates any potential damage.

Cable added: ‘Unloading costs us nothing as it is overlapped with the main and subspindle operations so we make further gains on output.

‘If quality drops and you have problems with parts, margins are squeezed and your production planning goes out of the window.

‘You then start to let other people and yourself down,’ he insists.

C and M Precision’s customers span the connector industry from simple plug connectors to high-level electro-mechanical fittings used in the mining industry.

Exquisite brassware components are produced for bathrooms.

Custom car components are made from phosphor bronze, mild steel and 303 stainless steel, which have to be blemish-free.

For the aerospace industry, Cable’s company has produced parts in 316 stainless steel measuring 8mm diameter by 8.5mm in length.

C and M has had a long-serving customer of more than eight years taking special manifolds for use by scuba divers.

The contract for the award-winning Minibreather was won on the back of the original Citizen M12, to which Cable then added the Citizen M16 but with an 18mm oversize bar capacity.

These were then followed with the two M32-V machines.

‘The M32-Vs with two Y-axis crossfeeds give such outstanding flexibility for optimising a cycle time by overlapping tools and cutting with three tools simultaneously,’ Cable said.

He then described how in the early days of the contract he cut cycle times in half by milling two large flats simultaneously with each Y-axis and combining drilling or turning.

So successful was the Minibreather for its inventor that it also reflected back to C and M Precision, creating new business opportunities.

The developer was approached by a long-distance truck driver who had bad experiences from delays and a fire in European tunnels.

The result was a compact, portable 200 bar compressed-air supply device that could be kept in the cab of the truck and used simultaneously by two people should there ever be a problem.

Production of the complex valve and control device, as with Minibreather, was scheduled for the Citizen machines of C and M Precision and the product is currently being evaluated for short-term respiratory protection to people having to gain access into dusty or smoke-filled environments.

At the other end of the scale, the Citizen sliding-head turn-mill centres have provided a miniature service for the 2mm Scale Association, producing thick model train wheels in batches of up to 4,000 and measuring 9mm diameter by 1.3mm thick, with axles just 1mm diameter.

Cable is also using his own skills and in-house capacity to develop, produce and sell a range of hand-held electric-powered herb and spice grinders.

Here, he maintains, the multi-axis interpolation capabilities of the Citizen M-Series machines enable the different configurations of mating fine-cutting edges that chop and pulverise the different herbs to be precisely milled in-cycle to totally finished dimensions.

Citizen Machinery

Citizen is the world leader in CNC sliding head ‘one-hit’ turn-milling technology. It has a range of machines having a maximum bar capacity between 4 mm on the compact micro-machining capable Citizen R04 to 32 mm on the top of the range Citizen M32-VII which has the added capability of two Y-axis cross-feeds.   

The M32 can carry up to 80 tools, of which 20 can be driven, and can cut with three tools simultaneously giving low cycle times and high levels of productivity.  Also, fully automated unmanned cycles can be utilised through an integrated gantry option and conveyor system that helps ensure damage free parts during uninterrupted batch production.  A high pressure 2,000 psi CoolBlaster coolant system is a further option to optimise swarf control, tool life and machining difficult materials.

Following the acquisition in Japan in 2008 of 65 per cent shares in Miyano, the fixed head turning centre specialist, the two companies are maintaining their separate high profile brand names utilising a single sales operation.  However, turn-milling solutions from bar up to 64 mm diameter can now be provided.  In addition, with the Miyano range of turning and turn-milling machines for chucking operations, cell-type applications can now be accommodated with a wide range of automation options.   

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