Productivity bonus

Advanced CNC technology is helping to cut costs and move the UK metalworking industry into areas that are less sensitive to threats from low-cost overseas competition. Mark Venables reports.

Various strategies are employed by the UK’s metalworking sub-contractors to remain competitive in the face of the challenge from low-cost manufacturing countries. These include concentrating on high-value niches, training and retaining high-quality engineers – but the approach that is universally accepted as essential is investing in hi-tech CNC machines. Middlesborough-based Burdon, for example, is enjoying a period of considerable growth and is on target to double its current business levels over the next three years through investment in five-axis mill/turn machine tools. ‘We could see a market opportunity from OEMs for larger, more complex components in reasonable volumes,’ said managing director Barry Hindson. ‘By investing in five-axis mill-turn technology from DMG we are responding to this demand, although it also offers much more besides. For instance, the technology differentiates us in the marketplace, reduces our machining costs and moves us into areas that are less sensitive to threats from low-cost overseas competition.’ Installed last year, the first machine to arrive at Burdon was a DMC 160 FD duoBLOCK, which can accomplish milling and turning operations on a single machine – the first of its type sold in the UK. The machine was immediately set to work on a contract for the oil and gas sector, although it soon provided Burdon with the opportunity to manufacture ring components for body scanners in the medical industry. Today the machine operates round the clock across three shifts, manufacturing small repeat batches (up to 20-off) of large, complex parts featuring tight tolerances and over a range of materials including stainless steel, aluminium and exotics. Another success story from a UK sub-contractor also features a high-tolerance medical component. Every year in Europe, around 700,000 people suffer a hip fracture, which is frequently linked to osteoporosis. The medical facilities currently available mean that rapid surgical intervention can be conducted to reduce the fracture by applying plates and retaining screws – allowing patients to quickly regain mobility. The hip screws used are highly complex parts that require numerous machining operations involving swarf evacuation. The highly-resistant materials used in these implants, including stainless steels and titanium, often require several rough-working, finishing and deburring operations. the best solution, in terms of productivity and feasibility, is to proceed with the complete machining of the parts in a single chucking operation using one machining unit. Thanks to the A-line products from Tornos (the Tornos Deco 20a in this case) it is now possible to machine specific parts in minutes. The Tornos Deco sliding head lathe is fully adapted to this family of parts. It drastically simplifies allocation of the various machining operations from the bar (main spindle) and for back operations (counter-spindle). The kinematics – 12 numerically-controlled axes all with simultaneous interpolation – allows up to four tools to be used simultaneously, and execution of back operations is 100 per cent in hidden time. The procedure to manufacture hip screws involves turning, centring/drilling/reaming, high-pressure drilling to 120 bar, tapping, hexagon broaching/swaging, external hexagon milling, external thread whirling in back-operation mode, deburring, part support and over 20 tools to conduct the numerous operations. The machine lends itself particularly well to hip screws, due to its dimensional geometry, chucking facility, re-chucking for back-operation and facility to change between main operations and back operations. Helping Rodford Engineering to fly high in the aviation world is a Miyano BNJ-42SY twin-turret, twin-spindle turning centre. The machine has helped the Wimborne, Dorset, sub-contractor to improve its productivity by an average of 30 per cent and up to 50 per cent on many components. The second-tier aerospace company manufactures components for Westland Helicopters, Airbus UK and Flight Refuelling of Wimborne. ‘We have invested heavily in new equipment in the last three years – buying three mill/turn centres and also replacing older machining centres,’ said Rod Dallyn, Rodford’s managing director. ‘Despite only purchasing the Miyano in September, the BNJ-42SY is likely to have the largest impact of all our machines on the bottom line of the business.’ The company’s 13 staff operate scheduled batch runs with over 100 permanent component types being supplied on a Just in Time (JIT) contract basis. Operating a JIT system in the aerospace industry adds considerable pressure, as Dallyn explained. ‘We are under ever-increasing cost-down pressure from our suppliers and all the while we are expected to absorb the rising material prices. To combat this, investment in technology is a must. ‘We recently purchased three mill/turn centres that successfully produce our components to the high standard required. However, the machines do not have a barfeed and they do not have twin turrets like the Miyano BNJ-42SY. The barfeed facility allows us to run the machine unmanned leaving the machinist to attend to other tasks, while the twin turret has improved productivity beyond belief. ‘The turning centre’s ability to machine the back of a part with the back spindle and turret while the front of the next part is machined on the main spindle has slashed cycle times by 50 per cent on many parts.’ An example of this productivity can be seen with Rodford’s manufacture of trunnions and threaded bushes. the company previously made significant quantities of both products by using up to four alternate set-ups or machines. The parts are now manufactured in one hit with a cycle time reduction of over 50 per cent. Looking ahead, Dallyn said: ‘We are always looking to become more productive, and I see twin spindle and twin turret turning centres playing a large part in our future. ‘Another option for us would be to introduce tool monitoring equipment to enable the machine to run throughout the night unmanned. Innovation is always the key in this industry and we will be looking for further innovative products in 2006.’