Andrew Allcock highlights how investment in top-of-the-range turning technology is paying handsomely for two companies. Lower cost alternatives simply would not deliver, he discovers
Allens Crankshafts will buy Mori Seiki machines only (0844 800 7650), following its NT4250 lathe experience.
The company's relationship with Mori Seiki started with an investment in a Mori Seiki MT for heavy duty milling and turning. As demand grew, the company needed extra capacity quickly and invested in a mill-turn centre from a different supplier, rather than wait for a Mori Seiki. But that machine proved to be unsuitable for crankshaft manufacture. "The machine we purchased was not solid enough for the production of cranks, so, after two years, we sold it and invested in a Mori Seiki NT4250 1500S. The difference is considerable: the NT4250 weighs 24 tonnes, compared with 11 tonnes for the machine we replaced, and it produces parts 33% faster," managing director Nash Sharma explains.
Mr Sharma bought Allen Crankshafts in 1981 and his big break came with a move to Wolverhampton 10 years ago, followed by a contract to produce crankshafts for Rolls-Royce Motor Cars and the Ministry of Defence. "For the six-year duration of the contract, we never had a crank set returned." Since then, the company has gone from strength to strength. It continues to work for the MOD, produces compressor cranks for companies like Gardner Denver and RAM Pumps, is the sole supplier of crankshafts to Engine Developments for their Judd engines and provides high performance cranks for motorsport applications, including the Honda K20 engine.
The NT4250 achieves metal removal rates of around 1,024 ml/min, which is equivalent to a conventional machining centre and far in excess of what is possible on competitors' mill-turn centres. Mr Sharma adds: "We have a 100-station tool changer on our NT and we use the best quality tools with through coolant operating at 70 bar. Tool life is now 100% better than we achieved on the old machine. It was all right for light work, but not sufficient for our needs."
Image: Mori Seiki's NT4250 's rigidity helps Allen Crankshafts to machine more effectively and produce hgih quality parts
Machining times can vary between 2 and 5 hours, depending on the design of the crankshaft – six cylinder cranks typically take 4.5 hours. By using the NT4250, Allens Crankshafts can produce a complete part in one operation, starting from a solid billet of EN40B. Journal diameters are left +0.5 mm before dynamic balancing, nitriding, finish grinding and final balancing. "The Mori Seki produces very consistent cranks, which are completely concentric and hardly need any balancing. If I produced a part now and then another a year later, they would both be exactly the same weight, giving us excellent repeatability," the managing director underlines.
"Mori Seiki produces the best machines. There are other, cheaper machines on the market, but they won't do the job. Mori Seiki's backup and response is second to none, with rapid on-site service. However, nothing goes wrong with their machines, so they don't break down in the first place! We will definitely only buy Mori Seiki from now on.
"There are three main crankshaft manufacturers in the UK and we are at least one year ahead of the competition in our technology. We are planning to invest in a further two NT machines, which will, without a doubt, make us number one in the UK."
At Vineham Engineering, a rapid response to it turnkey mill-turn needs was provided by Engineering Technology Group member and Nakamura Tome mill-turn technology agent Turning Technologies (01926 818 418).
In under a month, Turning Technologies delivered a Nakamura-Tome WT 250 II twin-spindle, twin-turret turning centre with powerful driven tooling, complete with all programs, tooling and production engineering that went straight into production at the Swindon-based firms works. The initial contract was a fast-response contract from a leading international manufacturer of tooling and metrology probes. This called for 700 components a week, delivered over a tight three-month period, to meet increasing customer demand. The component called for milling, drilling, tapping and counter-boring, with turning accounting for around 50% of the cycle time.
The Nakamura-Tome WT 250 II performed flawlessly throughout the three-month contract, allowing Vineham to win new business from the customer.
Image: The Nakamura-Tome WT 250 II twin-spindle, twin-turret turning centre allowed Vineham to deliver parts to quality, fast
Managing director Phil Vines says he did look at the possibility of other, lower cost, lower specification machines that were available, but would probably have had to buy two of them and they might still not have been able to make the parts complete in the time required. "So it would almost certainly have worked out more costly," he says.
And he adds: "We saw that the Nakamura WT 250 II was the ideal machine to produce these components complete in one set-up. And we also saw a great deal of potential for the machine, once the contract was completed. We are currently in the process of acquiring and integrating the operations of another subcontractor that has a fleet of smaller Nakamura and sliding-head machines. This machine will perfectly complement that capacity by extending their range to 65 mm bar and 10 inch chucking work."
Founded in 2003 as Pharma Tooling, as a specialist in tooling for pharmaceutical packaging, Vineham Engineering has a strong track record of expansion and diversification by acquisition.
Turning products and applications in brief
 Leeds-based Kingfisher (Lubrication) has broken into the US specialist aerospace sector winning, for the first time as a non-American company, a contract to supply non-standard grease nipples out of Monel material. With just eight weeks to deliver initial components, which were far from being a straightforward make and ship, the company purchased a new 20 mm capacity Citizen L20-VII turn-mill centre (01923 691500). And by milling the required hexagon form, material on a 6-month lead time could not hinder its success. Image: Citizen technology at Kingfisher supports the production of parts like this
 Okuma has launched the new, multi-function Multus B200 for turning components with up to 22 kW of main spindle power and, in the same set-up, performing 5-axis machining operations, using a milling spindle rated at up to 16 kW mounted on a swivelling B-axis offering 225° travel. The slant-bed lathe is capable of high accuracy machining in a normal shopfloor environment – tests have shown thermal deviation to be less than 10 microns over a 24-hour period, despite a variation in ambient temperature of 8 °C. This is a result of Okuma's patented Thermo Friendly Concept, applied to both the machine structure and the spindle, together with the use of 0.1 micron resolution linear scales in the orthogonal axes. (NCMT, 020 8398 4277.)  A totally new configuration has been applied to the latest 6-axis Miyano BNA-42 DHY compact, fixed-head turning centre that combines a main 42 mm bar capacity with a secondary spindle, an eight-station, all-driven, Y-axis turret capable of providing up to 16 tool positions and a totally independent six-station sub turret (01923 691500).
 The Puma 700XLM and Puma 700XLY lathes have been designed for high-accuracy and heavy-duty machining of large, heavy and long components up to 5 m in length, typically found and used in the oil/gas and power generation sectors. Both machines are able to support large chucks (up to 32") and have a bar working diameter (164-mm) capacity. They will support a workpiece up to 8.9 tons between chuck and tailstock. (Mills CNC, 01926 736736.)
 The NEW CMZ TX66 CNC turning centre combines three turrets and two spindles. All turrets are equipped with Y-axis and driven tools. (01788 562111.)
The Dugard ECO 65 is a 65 mm bar capacity, driven tool CNC lathe, which gives "amazing speed, power, precision and durability, all at a very affordable price". As a special introductory offer, it is available with parts catcher and bar feed system for £57,995. (01273 732286.)
First published in Machinery, March 2011