TURN AROUND TO CITIZEN CNC SLIDING HEAD BY PRECISION PRODUCTS

Brian Owen, Managing Director of Precision Products, had a good chance to win a single source supply contract worth over £150,000 a year if NC Engineering could obtain a top of the range 13-axis Citizen M32 CNC sliding head mill/turn centre and install, commission and train setters at his Rustington factory near Littlehampton, West Sussex, within a time frame that could not exceed three weeks.

“ It was tight but an opportunity we could not afford to miss in producing this complicated stainless steel component that we had to machine in a single cycle to be viable,” said Mr Owen. And he reflects: “At the time, the Citizen M32 was in great demand around the world but NC Engineering was able to juggle the supply of a machine through other distributors in Europe to help us out and we won the business.”

Since the M32 installation, a further Citizen has been installed, this time to help secure a contract for a brewing industry component. Initial trials on the part could not guarantee the level of secure process that, in Mr Owen’s mind, would maintain a consistent hole size of 0.75 mm diameter and strict positioning requirements of five holes equi-spaced on a pitch circle diameter. However, with the installation of the Citizen K16, this enabled batches of 10,000 a month of the stainless steel part to be produced in a single operation, with total confidence over the levels of quality achievable.

Precision Products, which has two production units on the South Coast, one in Rustington and the other in Hollingbury, Brighton, employs 43 people and has some 60 machines installed. This ‘one stop’ subcontractor supplies precision turned and mill/turn parts between 0.5 mm and 51 mm diameter to the automotive, telecoms, jewellery, domestic, medical, appliance, utility and brewing industry in part quantities that range from small batch to continuous production.

Indeed, with nine multi-spindle autos and 23 coil-fed autos, nine Citizen and nine other CNC machines, more than one million parts a month leave the South Coast with around 10 per cent of production exported to areas such as Singapore and Puerto Rico. “This demand for export has been through us having to switch delivery of components to overseas as a result of customers setting up their production off-shore, but most important to us, to ensure a continued quality supply of key parts, our customers have maintained order contracts with us.” he says.

Precision Products has become a specialist in machining stainless steel parts while also producing parts from brass, mild steel and aluminium. From long experience, the company rarely finds stainless a challenge. He maintains: “With CNC we have the flexibility to fine tune the operation to achieve surface finish, which tends to be just as important as size to our customers, especially as a lot of sealing diameters and faces are involved.” Then he adds: “Tolerances and especially the maintenance of geometrical relationships of features on a component is a factor of the design and build quality of the machine, a reason we have nine Citizens on our plant list.”

The decision to opt for the Citizen M32 came about when the customer offered single source supply on a part that was produced on multi-autos at Precision Products in a dual source contract with another company. The parts were then despatched to the customer where further operations were performed on special purpose machines. There were eight different types of part, some requiring the drilling of up to 20 radial holes of 2 mm diameter plus others with variations of milled slots, so Mr Owen contacted NC Engineering to discuss how these could be made in a single cycle and combine up to four separate operations into one. “Such were the savings that the Citizen M32 was able to generate, that the contract was won to supply complete and the machine engaged to run around the clock.

Because of the flexibility and tooling capacity of the Citizen M32, which can carry up to 72 tools, common tooling can be left as set on the machine to reduce setting time. But an important element in the cycle was that the radial holes could be drilled two at a time, one from the turret and one from the gang slide using the C-axis spindle to index each position. Also, by specifying CoolBlaster 2,000 psi high pressure coolant system, swarf was easily controlled on the process as well as providing greater security of the tooling on the stainless steel component. To further enhance the operational security, each drill is flagged to check for breakage.

Precision Products’ association with Citizen began with the purchase of a secondhand B12-V with subspindle in early 1999. Mr Owen approached NC Engineering to check the machine out, install and train his setters and despite the fact he never sourced the machine from the Watford based company. He maintains: “They could not have been more supportive.” Indeed, it was this level of help that was well remembered when the company started looking for further installations of another B12, a C16-IX, two L20-VIIs, the top of the range Citizen M32-III and the latest purchase of the K16. As the M32 proved to be so successful, Precision Products installed a second machine six months later – followed by a third M32-III.

This level of support was even carried over to the recent Citizen K16 installation where NC Engineering application engineers worked with Mr Owen’s setters to develop the process for the brewing pump component. “The part is very difficult,” he says, “the five 0.75 mm holes must be perfectly cylindrical and square to the two faces. We cannot even deburr the edges because this will influence the flow pattern, could cause frothing and lengthen the time to pull a pint,” he said.

He follows on to maintain that despite the support of NC Engineering in the past he went to other suppliers for quotations but the K-series delivered the quickest cycle largely due to the streamline control technology that significantly reduced any idle times. “The design of the machine also ensured zero backlash for positioning when drilling the pitch-circle holes,” he says. Since the machine was installed it is now also producing high tolerance connector pins and is to be used on further components.

Indeed, over the last four years, well over £1.5 million has been spent by the company on new machines. Adds Mr Owen: “We reckon we can replace one mechanical machine with a CNC machine, although it may not match the cycle time, it’s a bit like the hare and the tortoise, CNC is more consistent and reliable, we have less stoppages and it can be easily tuned to optimise the process and cycle time. We are also confident to run the machines minimally manned and unmanned at weekends,” he maintains.

Precision Products was set up by Mr Owen and his father in 1974 with a line of capstan lathes, pillar drills and a new cam driven sliding head auto. By 1983, the company outgrew its premises and moved to a new site in Brighton and built-up the factory to contain 35 machines. Another company was acquired and expansion continued until over 90 people were employed to generate a turnover approaching £3.5 million.

With changing markets, the company decided to move further into CNC technology. In 2002, Precision Products slimmed down from three to two sites and with the lower overheads and the advantage of ‘one-hit’ machining techniques, has rejuvenated the business with improved machine utilisation and eliminated manual processes. The company still operates a 100 hour week with weekends unmanned when needed. All setting and maintenance on the CNC machines is carried out during the day with patrolling overseers at night keeping a watchful eye on quality. Most CNC machines are Wi-Fi linked for program downloads and up to four people are engaged to program off-line.

Over the last few years, due to the build up of relationships with customers, new work tends to be based on ‘partnership sourcing’ and here, Eric Mole, production engineer, maintains it is the flexibility of the Citizen machines that has enabled them to progressively develop the process to build up efficiency and profitability.

Not having to worry about second operations has made a big difference to profitability and delivery lead time and has been a subject of comment from customers on the consistency of quality supplied. Says Mr Owen: “We can now work far more easily to delivery dates, we almost have no concern over any possibility of handling damage due to the advantage of a single operation strategy and are finding we are very competitive. This is now generating a higher yield for our business and our customers,” he said.