Andrew Allcock reviews three installations involving latest technology turning equipment. Although the capacities differ, combining operations in a single machine is a recurring theme
Manufacture of mill-turned components has become much more profitable at Staffordshire Precision Engineering (SPE), Newcastle-under-Lyme, since the sub-contractor invested in a Star SR-20J sliding-head CNC lathe (01332 864455) in February 2009.
Image: Precision Engineering's Star sliding-head investment
Joint managing directors Phil and Gary Smith say it is the result of reducing cycle times on existing components and bringing work in-house that was previously sub-contracted. Most importantly, however, the Star lathe gives them the opportunity of attracting new business that they would not otherwise have won.
In the past four years, SPE has spent £500,000 on new CNC plant, including the Star multi-axis lathe, which has made a considerable impact on the sub-contractor's shopfloor. For example, there has been a 35 per cent saving in the time taken to turn a family of titanium aerospace components. Manufactured by SPE for a global aerospace customer, the components were previously machined in a longer cycle on a fixed-head CNC lathe. In addition, subsequent operations were needed on a centre lathe to de-pip the reverse end after part-off, or to deburr inside diameter edges. Comments Mr Smith: "The savings on this family of parts alone are substantial, as we can produce them in one hit on the Star and achieve a better lead-time."
There were several factors that convinced SPE to invest in sliding-head technology. The most significant was that the company was often 30 per cent too expensive when quoting to produce some volume turned parts, especially those of a smaller diameter.
The company had considered investing in sliding-head technology in the past, but held reservations about set-up times. "We knew of the process, but had been put off, due to fears about how long it would take to set up jobs," recalls Mr Smith. "People said it could take five hours to change over a CNC slider to make a new part and then, with batch runs becoming smaller these days, the machine would run for only a day or so.
"On the contrary, we find the Star quick to set up. Programming a new part at the Fanuc control is straightforward, particularly if it is a variant within an existing family of components, and we are back into production rapidly."
HOBBING ON SLIDING-HEADS
Gibbs Gears Precision Engineers produces more than 600,000 gears a year at its Stoke Mandeville sub-contract and development machine shop. Of these, some 200,000 are produced on a top-of-the-range Citizen (01923 691500) M32-V CNC sliding-head turn-mill centre in single-cycle operations involving turning and gear hobbing, with certain gears also requiring the additional milling of drive hexagons.
Image: Gibbs Gears Precision Engineers hobs on its Citizen sliding-head machine
Such was the significance of the Citizen installation to the £3.75 million turnover company that it became a key element to help ride out the growing effects of the recession, which, at the time (September 2008), were beginning to bite. On the back of the Citizen installation, Gibbs Gears was able to secure a competitively priced contract that resulted in the retention of gear production in the UK and reversed plans by the long-served customer to source these volume parts offshore and, as a result, close its UK gear machining facility.
Says managing director Reece Garrod: "We took a flyer on buying the machine and came up trumps. When we originally found out the customer was possibly closing its UK operation for gear machining, we made an approach and, with the help of Citizen Machinery UK, quoted against its targeted overseas suppliers for the range of 30 fine pitch spur gears between 5 mm dia by 0.3 module and 18 mm by 0.8 module."
As Gibbs Gears was working on the premise of using the latest single-cycle machining technology, with the ability to run unmanned at night, it found it was very competitive in meeting the proposed offshore pricing strategy of the customer. "We could easily ensure the level of quality and we gave the customer confidence that we could meet the tough demands on delivery to line," Mr Garrett adds.
During the negotiations, technical director David Worthington approached the suppliers of sliding-head machines and had sample components produced. Due to the locality of Citizen Machinery UK at nearby Watford, coupled with the service and support given that helped to win the contract, he ordered the Citizen M32-V.
"Although the machine was over capacity with its 32 mm bar size for our immediate needs, when the largest gear we were quoting for was being produced from 18 mm material, the machine guaranteed the additional rigidity for heavier and greater consistency for hobbing teeth without vibration. It also gave us the added flexibility to produce further sub-contract components when needed," says Mr Worthington.
To which Mr Garrod adds: "In the event, installing the Citizen was a life saver. Had it not been for winning this contract, over the coming few months our business could have been slashed by half, due to market conditions. However, our fortunes changed. Two competitors went out of business, which helped to raise the order book and, by the New Year, we had benefited from a considerable increase in new business. Such was the effect that we had to increase our workforce by taking on a few employees from the gear customer that ceased production, which raised our head count to 40." In fact, he qualifies the change in circumstance by indicating how the last financial year, closing in August 2009, saw sales of £3.75 million achieved, equal to the previous year.
CAM AUTOS REPLACED
St Helens, Lancs-based sub-contractor Wealdpark installed sliding-head machines to replace its 50 mm diameter capacity cam autos. However, with a diameter less than 50 mm, the company also installed a Miyano BNE-51SY5 (01384 489500).
Image: Wealdpark's 51 mm diameter bar capacity Miyano complements its 32 mm capacity sliding-head machines
The 51 mm diameter Miyano turning centre, purchased in 2008, freed up work from many of the cam autos working outside the 32 mm diameter capacity of the sliding-head machines. The 8-axis Miyano turning centre, with two opposing main spindles plus lower and upper turrets and Y-axis slides, enabled Wealdpark to produce parts in one-hit, as opposed to multiple set-ups that were the norm with the cam autos.
The Miyano soon replaced four cam autos by eliminating second ops and improving cycle times, while creating space on the shopfloor. Phil Smith, company director, says: "The Miyano has blown the cam auto cycle times out of the water. The difference is that the Miyano can run for 16 hours a day without intervention, while the cam autos need regular operator intervention. This allows us to run the machines for 160-plus hours a week, despite only working a 37-hour week.
"During the downturn, all businesses look at the bottom line, and pay more attention to costs and how it may be possible to cut back. With the Miyano, we have naturally made significant savings that we were unaware of. For instance, 10 cam autos require constant operator attention.
"In the last 12 months, we have been able to relocate employees, while any people that have left the company have not been replaced, so the Miyano has contributed to reducing our wage bill. At one point, we had 53 staff, a major commitment in terms of paying salaries; we now have 17 employees. This is not a direct result of the downturn, but efficiency savings created by our technology investments."
First published in Machinery, March 2010