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One of the leading F1 race car teams in the 2012 season is now pounding the race circuits of the world having components on board machined on a Citizen CNC sliding head turn-mill centre by a ‘fledgling’ subcontract precision machinist that set up just under three years ago in a converted cowshed just outside Luton. 

Sub-CNC partner directors Yian Stavrou (managing) and George Dingley (technical) have progressed from working day and night, weekends and holidays with a single used Citizen L20 CNC sliding head turn-mill centre to enter 2012 with the reward of more than doubling sales and profitability from the previous year. 

Following setting up in April 2009, Sub-CNC installed a fixed head, 44 mm capacity, two-axis chucking lathe which was followed by a second, larger capacity Citizen L32 in the same year to meet the fast growing order book.  But with customer demand continuing through 2010 to expand the order book plus a growing level of ‘word-of-mouth’ recommendations also adding new business, spindle capacity was running out fast.  So the decision was made to purchase the company’s first new machine. This time a Citizen A20-Vll, was installed and in the same month the two partners had no option but to move to a new machine shop in nearby Dunstable as they had totally outgrown their original premises.

While demand for under 20 mm component size had rocketed, such as the breaking into the F1 industry with a new contract, the two engineers felt the Citizen A20 purchase and factory move meant there was a breathing space to re-align the business for the future.  Said Mr Dingley: “Existing customers were not only adding to our order book but were beginning to make it very clear that they wanted Sub-CNC to supply larger diameter bar components as complete packages rather than have to deal with ‘cherry-pickers’ who could or were only willing to perform certain tasks.”

Not wishing to miss opportunities or risk customers looking elsewhere, the partners decided at the close of the year to order the machine that had really impressed them at the recent Citizen Machinery UK open house. This time it wasn’t a sliding head but the newly released Miyano BNA-42MSY, a six-axis fixed-head turning centre with the ability to be set for chucking work as well.

Not only was 2011 the time for investment in new machine tools, Sub-CNC also went through a series of other major changes.  The company appointed a general manager, Nick Walker to cover sales, customer interface and purchasing.   An accounts manager, Karen Condon,  joined in April and a machine  operator was also taken on.  In June 2011 an apprentice James Collins was employed direct from school to learn CNC machining and spend one day a week at college. Said Mr Stavrou: “We know how we want the business to be run and it is difficult to get people with the skill and in particular the interest and willingness to work in our particular way.  So we decided to offer an apprenticeship as a longer term solution.”

Further investments made last year to move the business forward and help to improve margins and productivity include a non-contact measuring machine, an ultrasonic component cleaning system and the capability to offer in-house anodizing and surface treatment as part of the service.  And, ticking-off the boxes of tasks to be completed, one of the most important achievements for which they were very proud was when Mr Walker obtained ISO 9001 at the first attempt in November without a single recommendation for change or improvement listed.

Said Mr Dingley: “Both Yian and I have been so focused on tooling up for new work that we could have never paid sufficient attention to developing systems. But through last year we have been able to set up a fully functional quality, production control/scheduling system and provide to customers a stock holding service with next day delivery.  We also have full traceability records. 

Mr Walker’s background in sales helps to develop key accounts which led to the F1 contract and far from being simple work, the two electronic enclosure components which are assembled by the race car customer, have six micron tolerances on bores and outside diameters.  However, because they have to be anodized, initial prototyping involved some experimentation on the Citizen A20 to obtain a pre-plating process size. 

Said Mr Dingley: “Here, the level of accuracy and repeatability we obtained from the Citizen A20 gave us total confidence once we were able to establish the process size and then work effectively between the tolerance levels we had determined.”

An initial 20 sample parts were followed by an in-depth supplier analysis by the race car customer which resulted in a contract for 800 of each part to be delivered in 200 component batches.

The progressive build up of Sub CNC’s customer base to 25 current active companies has created a good spread of sectors covering aerospace, defence, electronics, marine, medical, metrology, hobbies, fittings and motorsport.  While around half of the order book is repeat business in batches that range from prototype and development with customers, part quantities tend to range between 20 or 50 parts to a recent 70,000/month contract. The average batch size tends to be around 1,000 parts with materials varying from non-ferrous and plastics to difficult to machine grades of stainless steel. 

The other 50 per cent of orders still keep the two partners busy on setting and prove-out of new work.  Said Mr Stavrou: “Our machine selection has been really important in our growth.  For instance, the Citizen A20-VII with its Streamline technology control/software has made such a difference.  It is very quick and easy to set which is so important to us due to the need to be continuously setting new and often challenging work.   From our records it certainly generated an immediate payback.” 

He follows on to describe one of the first jobs to be set on the machine. “When we moved into the new building we had an urgent 10,000 part order.  We set it on Friday, had the confidence to partially run it unmanned over the weekend but by Monday the order was complete.” 

The five-axis Citizen A20 Vll has a heavy duty rigid cast iron base, a 3.7 kW main and 1.5 kW secondary spindle each with a top speed of 8,000 revs/min.  In Vll specification, as at Sub-CNC, the machine has an additional X2-axis to the secondary spindle that provides a distinct advantage of allowing simultaneous front and back machining and hence lower cycle times.  It can carry up to 21 tools including five turning tools, four 6,000 revs/min driven tools for cross machining, four tools for front drilling and eight for back drilling.

Both Mr Stavrou and Mr Dingley each had some 15 years experience of setting Citizen sliding head machines before branching out into their own business.  Said Mr Stavrou: “We find this gives customers a lot of confidence, especially as we have continued to buy machines from Citizen and have very good levels of understanding of how to get the best from them.  What has also been very important to us and to the benefit of customers is the help available when we need to discuss an application or special features on a component with the Citizen team at Watford.”

Mr Dingley maintains the decision to buy the Miyano BNA-42DHY was one of the most important steps in the development of the company.  He said: “While we needed the larger 42 mm bar capacity we also needed a machine that gives us the maximum productivity and flexibility for the investment.”

The Miyano has a main 7.5 kW and secondary 5.5 kW spindles with an eight station +/-35 mm Y-axis, and an all-driven turret that can be tooled to give up to 16 tool positions.  As an option Sub-CNC has also ordered a Quad turning holder for the turret which puts up to four turning tools on a single station.

The BNA machine was the first model from Miyano to take on-board the Citizen Streamline control and software which in addition to speed, will provide a consistency of programming familiarity to Sub-CNC.  A one metre bar feed will be fitted, mist extraction and a 5 inch chuck for billet work.  The pick-up size of the secondary spindle is increased to 40 mm in place of the standard 32 mm and an engraving package incorporated, which can be applied to all Sub-CNC’s Citizen machines.  As part of the machine specification a comprehensive set of turning and milling tooling is being included.