Two of the latest Citizen M32-V CNC sliding head turn-mill centres were installed at Triflow Concepts to reduce cycle times and increase quality of machined components.

Triflow Concepts designs and manufactures exclusive taps, water filtration systems, plus bathroom and kitchen accessories.

'Everything is manufactured in-house - including castings, full machining, finishing, plating and assembly,' said Keith Liversage, plant manager at the company's Wolverhampton site.

Two of the latest Citizen M32-V CNC sliding head mill-turn centres were installed mid-2008, which Liversage said were selected on merit.

'We have programmed 53 parts over six months and produced 98,000 components on one machine and 90,000 on the other,' said engineering manager, Ajit Singh.

'In achieving this, these two machines have replaced four, 3-axis mill-turn centres that could never come near the cycle time, level of quality, speed of resetting and changeover we are now obtaining.

'The average cycle time for all 53 parts has fallen from 2.33 minutes to just 0.66 minutes, giving an average saving of 1.67 minutes per part,' he added.

Liversage said that there were other important considerations in the decision to buy the Citizen machines.

'The brassware market is very competitive and we are fighting against a host of low-cost producers around the world keen to copy or provide a standard product,' he said.

'Having selected Triflow taps, customers normally want the installation completed quickly so we cannot afford stoppages in production.' He added that the company must reduce stockholding, work in progress and move towards a make-to-order initiative and this is where Citizen Machinery is helping achieve that goal.

Average changeovers take less than 45 minutes and these are predicted to reduce by half in the future.

Previously, the three-axis mill-turn centres took between two and four hours to reset.

'The flexibility of the M32 means we have taken away restrictions on our design team who can now push the barriers of new concepts to take our company further away from run-of-the-mill brassware producer,' said Liversage.

Commenting on quality achievement, Singh said that batch sizes are scheduled between 50 and 2,000 and each machine is always set to mid-limit.

Once the first-off is approved there has never been any requirement to adjust offsets and from the first to last part our records show there have been no deviations.

He added that abrasive band grinding has been eliminated and such is the level of surface finish achieved, even on spherical knobs, connectors and handles, that polishing is reduced to light mopping allowing the machined profiles to be maintained.

Both Citizen M32-V mill-turn centres were bought with identical specifications.

Programmable gantry unloading provides flexibility in scheduling machine loading and ensures identical floor-to-floor times without any concern of damage or marking of components.

Singh said that the level of flexibility through the 14-axis machines enables both front and back machining of a component using up to three tools simultaneously, which reduces cycle times.

This is achieved by independent programming of tools mounted in the turret, gang toolpost and the fixed toolpost.

Adding to the enhanced flexibility for production is the inclusion of two Y-axis movements on the 10-station turret and vertical gang toolpost able to carry up to five turning tools and four driven tools and the fixed toolpost is able to carry three tools.

The all-driven turret is able to accommodate up to 40 tools using multiple toolholders - the latest development by Citizen.

Programming is carried out via the Citizen Machinery CNC Wizard, enabling quick program creation with each machining process explained with a clear description and diagram.

Singh said this enabled him to create and optimise each machining cycle off-line to achieve high orders of cycle time reduction and then use the DNC link to transfer program data to the machine control.

Both machines are also set permanently with duplicated common tools to speed changeover.

Typical of the type of brass components produced is a wall connector - pot filler out of 32mm bar.

This part previously took 3.25 minutes on a three-axis turn-mill centre against, which has been reduced to 1.02 minutes by the Citizen M32-V.

The component is initially drilled through from solid with a 13.5mm drill then counterbored to 16mm diameter followed by the broaching of a 1/2in A/F hexagon.

It is then faced and the profile turned creating various grooves and radii.

Two opposed keyways are milled using the C- and Z-axis and the profile finish turned before being parted-off ready for the subspindle.

The part is then faced and chamfered on the back followed by a boring operation to create a thread, which is then screw cut to 1/2in NPT thread.

'The complete cycle is balanced and here the flexibility in programming and the ability to use a wide variety of tools means we can create a faster cycle time,' said Singh.

'We have been able to rethink our production methods with a clean sheet of paper to create new standards of quality right across our brass components,' added Liversage.

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