Leaving the CNC lathe to run unattended between shifts and at night can provide a critical leap to improve production capacity, machine utilisation and reduce lead times without much additional cost.

Leaving the machine to run unattended between shifts and at night can provide a critical leap to improve production capacity, machine utilisation and reduce lead times with the advantage of little in the way of additional cost. While initially having doubts about this way of working, precision subcontractor Fisadco Engineering (1980) has become a staunch advocate since it installed a Colchester Tornado 220M 'Lights-out' turning package in the middle of 2004. For as well as enabling the Hull-based company to boost output, reduce machining costs, cut a swath through lead times and optimise set-up routines; the investment has helped managing director Daren Smith to win new business, lower tooling costs, reduce demands on inspection and cut reject and scrap rates.

Smith explains his early reticence: 'Our initial reservations about lights-out machining were mainly based on accuracy, safety and the efficiency of monitoring key dimensions'.

'However, Colchester assured us that the Tornado 'Lights-out' package was the way forward with its programmable bar feed, on-board scheduling software, broken tool detection, sister tooling and Renishaw probing'.

'It's quite simple they said, if there were any problems, the machine would just simply switch itself off.' Still with slight doubts, the machine was installed and the company found it got to grips with unmanned working much more quickly than it had originally expected.

And after just a few trial jobs, the three-axis mill/turn centre had demonstrated its capability for consistent cycles through the night by giving high quality components which even included milling of particular features using the lathe's driven tools.

But it has not stopped there, since June 2004, the 'Lights-out' Tornado package quickly made its mark on Fisadco's ability to quote for work which was previously considered uneconomic.

Making the most of the investment Smith found he could beat off competition by reducing hourly rates and lead times on certain projects having worked out that costs could be reduced by up to 40% against running a manned machine during the day.

As a result, his company has been able to put very competitive proposals to customers not only to win new business but to claw back an increasing number of jobs that had been lost to overseas producers in such countries as China and Poland.

As Smith added: 'While we still can't compete directly on cost with such low wage rate economies, our service and quality is far superior and consistent and we can now realistically offer half the lead time with the new Tornado - and this is really starting to pay dividends.' The decision to buy the 'Lights-out' package was not that difficult as the company already had two Tornado CNC lathes including a 200 and standard 220M three-axis model and all turning work was allocated to these machines.

It was just the scepticism of whether unmanned running was viable to them.

But now the company has established selection criteria to ensure the suitability of jobs to be run unmanned at night and these parts are first proven during normal manned working hours that the concept works.

In essence, lights-out components must be: easy to probe for key dimensions, of fairly simple profile and thus not requiring too many tools, of a material or process that does not generate ribbons of swarf and be required in suitable quantities say of a batch size over 100.

Fisadco has even put together different jobs which can be machined from the same bar size and utilise the machine's on-board scheduling software in the Fanuc control to stop the process, automatically initiate the next program and tools held in the 12 station turret and restart on the next batch.

Typically, the Tornado is set-up for unmanned working between 2 pm and 3 pm and then runs on its own from around 5.30 pm as the staff leave and the building is secured for the night.

But not only does Smith's setters run the machine unmanned during night, the Tornado is also run this way during the day which enables operators to get on with other tasks.

Here, the tool monitoring system has proven really effective, boosted confidence in the metal cutting process, and even enabled tooling to be optimised on the existing non-'Lights-out' Tornado 220M.

This earlier three-axis version is only run during the day with its tools changed at pre-set intervals on specific jobs as a safety measure, regardless of their actual condition.

However, the availability of tool monitoring on the latest machine has enabled the company to precisely measure tool wear'.

''In the past we tended to be over-cautious when it came to changing tools,' recalled Smith, 'But with the introduction of tool monitoring we now have very accurate life data and this has helped to fine-tune all our tooling'.

'You would not believe how cost-effective this has proved to be, it has allowed us to extend tool life by an average of 25%.' Established in the late 1920s and the subject of a management buyout in 1996, Fisadco is a producer of high precision machined components in quantities ranging from just one right up to 10,000 and an average batch size of around 1,000 parts.

Key customers for the 30-strong business are from printing equipment, valve industry, food machinery, and laser manufacturing sectors for which small bearing housings, gearbox parts, gears, special nuts, bolts and spindles are produced.

The company has a total of seven CNC machines, including the three Tornados installed in the 11,000ft2 factory in the centre of Hull.

The Tornado 200 CNC lathe was installed in 1997 while the first of the Tornado 220M three-axis machines arrived in 2002.

It was the success of the first three-axis Tornado 220M in terms of its performance, reliability and the new business it attracted, that convinced Smith to buy another.

This time, however, the totally inclusive specification of the latest 'Lights-out' 22kW spindle machine includes: bar capacity of 65mm diameter, a 12-station VDI 40 turret with six driven tool positions, full C-axis and a 3.7kW, 4,000 rev/min tool drive, a Colchester MBF 1000 bar feed, swarf conveyor and a Fanuc 21i-T CNC system.

One of the important advantages of the latest Tornado range which greatly helps the unmanned running capability is the total stability of the machine as a mill/turning platform.

This is helped by the Duo-stable construction which involves the use of an inert polymer concrete fill to the base with a reinforcement of a strategic network of ribs.

Mounted on this structure is the 60o cast iron bed that carries the carriage assembly and sources of generated heat, such as motors and transformers, which means running temperature is reached three times quicker, stability is 25% greater than a full cast iron bed and vibration is minimised.

One task that is a prime example of the 'Lights-out' Tornado success is the production of special train door spindles in batch sizes of 4,000.

The machining cycle involves basic shaft turning of several diameters and a small amount of milling on one end of the 20mm diameter by 60mm long EN1A steel components.

Compared with manned machining during the day, these parts are produced unmanned at night thus cutting in half the lead time to 2.5 days instead of one week.

Tool life has been increased by over 20% due to more accurate data and inspection time is greatly reduced as in-cycle probing of, say one part in three, means that only final inspection is required.

As a result, the cost to produce these particular spindles has been reduced by half.

Fisadco also produces acetyl spherical bearings for the automotive industry in batches of 2,000.

These 40mm diameter by 20mm long parts have a tight bore tolerance of 0.01mm and as a result of applying in-cycle probing of this and other key features, and the effective support of tool monitoring to ensure a high surface finish is maintained, these bearings are now produced more efficiently.

Here, Smith cites the unmanned machining routines have cut inspection times by 80%, reduced lead times by over 40% and saved a further 20% on rejects and reworking.

With its current selection criteria for unmanned working, the Tornado is run through two nights each week but this is changing fast as more suitable components are ordered by customers.

This has persuaded Smith to take on more complex work for the night shift now that the operators have really got familiar with the unmanned machining practices.

As Smith concluded: 'We are delighted with the performance of the new Tornado and it quickly proved that the concept of lights-out working is both a highly practical and a profitable proposition - especially when you consider the all inclusive price of the package.'