Formed in 2008 by co-directors Yian Stavrou and George Dingley, specialist turn-mill sub-contractor Sub-CNC Precision has continued to buy the latest in manufacturing technology in order to stay one step ahead in the fiercely competitive market in which it operates.
Every aspect of the company is continually being improved by the use of advanced manufacturing routines and IT, as demonstrated by a trio of Citizen CNC sliding-head lathes and one fixed-head Miyano multi-axis turn-mill centre — all supplied by Citizen Machinery UK Ltd, Bushey (
www.citizenmachinery.co.uk). The latest addition to Dunstable-based Sub-CNC Precision’s machine portfolio is a seven-axis Citizen A32-VIIPL, which the manufacturer says is the world’s fastest 32mm CNC sliding-head machine.
Mr Stavrou says the machine was bought “primarily to give us the greatest flexibility and cost-effectiveness in machining a range of increasingly complex workpieces. The turn-mill sub-contracting of smaller parts is ultra-competitive, so you need the most suitable machines supported by the best manufacturing processes, not only to maintain existing contracts but also to bring in new work — especially work involving more-complex machining cycles that help to improve margins.”
Mr Stavrou says the company was recently — and very successfully — audited by a major customer that wanted to rationalise its machined-component supply base from 28 companies to just four. “A major factor in winning through and then being asked to quote for machining 500 different parts was our record of consistency — in particular, maintaining a 95% delivery and quality rating.
"Following this customer’s supply rationalisation, our volumes effectively doubled overnight from this source alone. To keep pace with such increased demands — and in this case increasingly more-complex components from bar up to 35mm in diameter — we had to invest in the latest, fastest and most cost-effective machining technology we could find; hence the new Citizen machine.”
Speed and precision
For Sub-CNC Precision, the Citizen A32-VIIPL provides unmatched speed and precision in the single set-up machining of parts that require a variety of turning, milling, cross-drilling and tapping operations. Mr Stavrou says: “Combined with its sub-spindle machining capability, which eliminates secondary operations, plus a C axis, driven-tool stations on the rear turret and high-pressure coolant at 2,000psi, the machine is key to our ability to provide complex parts at highly competitive rates.
"Compared with the L-series CNC sliding-head machine it replaced, the latest Citizen offers cycle times that are some 40% shorter — and it can complete even the most complex part in a single setting.”
The 23-tool machine features six tools for turning, four rotary tools for cross-machining, nine tools for back-end machining and five for front-end operations. Its main 7.5kW spindle is complemented by a 3.7kW sub-spindle drive and a 1kW 5,000rev/min drive for the rotary tooling.
The machine accommodates bar up to 35mm (with the increased-capacity option), has a maximum cutting length of 320mm in a single chucking (components up to 600 mm long can be machined with the optional long workpiece unit) and features a rapid-traverse rate of 45m/min.
Mr Stavrou also mentions the speed and ease of use of the machine’s CNC Wizard off-line programming, which Sub-CNC Precision can ‘replicate’ using Cloud-based storage on every PC and mobile phone within the business. The machine sits alongside a pair of Citizen A20-VII CNC sliding head turning centres and a fixed-head Miyano BNA-42MSY turn-mill centre; this accommodates bar up to 42mm in diameter and billets up to 130mm in diameter.
Material variety
Sub-CNC Precision is currently processing 150 different parts for the newly expanded contract, which includes a variety of valves and connectors for oil and gas applications in materials such as Monel, S80 stainless steel and nickel-alloy bronzes. Tolerances are generally in the order of 0.025mm and batch sizes range from 25 to 2,000 parts.
The Citizen-supplied machines are currently undertaking a wide range of contracts — in materials that include Inconel, titanium, mild steel, aluminium alloys, brass, copper, bronze, nylon, PEEK and Delrin — for companies in the telecommunications, aerospace, motor-sport, automotive, medical, defence, marine and agricultural sectors.
All the machines feature bar feeders, which are fully utilised for unmanned overnight working, and they are linked to the directors’ mobile phones, for call alerts relating to ‘out of hours’ problems such as tool breakage; they are also monitored by CCTV so that production can be assessed remotely.
Mr Dingley says: “We’ve grown up around Citizen machine tools and have been using them since we were teenagers, so we had no hesitation in investing in this technology when we started our own company; and while we ensure that we are always aware of the potential offered by alternative brands, so far we’ve not found anything that can improve upon what we’ve got.”
One-stop supply
The two directors maintain that having the appropriate machines and using them round-the-clock, while also providing the necessary inspection/quality control measures, is only part of the answer for successful 21st-century sub-contracting.
Mr Stavrou says: “Customers are demanding a worry-free one-stop supply of machined components that consistently meet their quality, delivery and cost requirements. This includes pre-production approval, initial sample inspection reports, material certificates, certificates of conformity and certificates of compliance — all as part of the service.”
Accredited to ISO 9001, Sub-CNC Precision uses manufacturing resource planning software and tool-vending systems. The company also has a purpose-built bonded stores and a new fully automatic component-cleaning system, as well as dedicated areas for inspection, tool-room work and despatch. It also offers a variety of metal-finishing processes, including anodising, bead blasting, barrel zinc plating, alo-chroming and laser engraving.
Sub-CNC Precision also has an eye on energy savings and has installed an ‘intelligent’ energy-efficient compressor system that automatically adjusts to air demand and runs to the loads required. This has proved to be particularly useful during unmanned ‘lights out’ production.
Now with seven employees (including two apprentices), Sub-CNC Precision has grown year on year and recorded a 30% increase in turnover in 2014 (compared with 2013). Moreover, the company sees its apprentices as a key resource, as Mr Stavrou explains: “The opportunity is here for them to work at every level within the company.
"Such is the success of these youngsters — we currently have one in his second year and another completing his final year — that we are planning to take on another apprentice this year. It is the continual progression of such workforce skills, coupled with the use of ‘smart’ manufacturing technologies, that is giving us an edge and allowing us to say ‘yes’ to even the most complex workpieces.”