Mounting benefits for Dunlop Aviation from Hainbuch collet system

Citation

(2002), "Mounting benefits for Dunlop Aviation from Hainbuch collet system", Aircraft Engineering and Aerospace Technology, Vol. 74 No. 1. https://doi.org/10.1108/aeat.2002.12774aab.008

Mounting benefits for Dunlop Aviation from Hainbuch collet system

Keywords: Braking systems, Efficiency

It is reported that Dunlop Aviation Braking Systems has dramatically reduced its set-up times and improved production efficiency and output by equipping a CNC millturning lathe with the quick-change Hainbuch colletstyle workholding system from Leader Chuck Systems. To change a Hainbuch collet on the Rotary Parts Cell lathe is said to take literally seconds compared to minutes for a standard collet, and this is stated to be a major contributor to the 30 per cent reduction in set-up times achieved by the cell following its investment in the new turning machine. At the same time, quality benefits are reportedly gained from the superior clamping accuracy of the Hainbuch system (Plate 3).

Dunlop, has also always been acknowledged as an innovator in the development of wheels and brakes for the aviation industry. Today, it is a major supplier of hydro-mechanical and electronic systems in brake control and anti-skid technologies. These are manufactured at the Holbrook Lane site in Coventry by Dunlop Aviation Braking -Systems, one of the four business divisions that make up Dunlop Aviation.

Because these braking systems work under the most stringent and safety-critical conditions, component quality is vital. It is also a globally competitive business with costs and on-time delivery being other important ingredients to success. Dunlop has met these pressures by organising its manufacturing operations on a cellular basis, in which team working and capital investment combine to ensure continuous improvements in terms of quality, on-time delivery, lead times and stock turns.

The new lathe fitted with the Hainbuch system and how the cell team members run them is considered an example of the benefits to Dunlop Aviation of cellular manufacture. The team has been able to exploit the Hainbuch system to not only reduce set-ups and improve quality but also to speed throughput and improve working methods.

The potential of the HAinbuch system had been recognised by the cell members for some time, as team leader John Snell, explains: "While we saw the advantages of the system for the small diameter precision jobs that predominate in the cell (5 to 35mm diameter bar sizes), we could not exploit the benefits and justify the investment on the older machines in use. Then when we received authorisation for investment in new lathes, we immediately specified Hainbuch."

Dunlop purchased two lathes, one with the Hainbuch system for small work down to 3mm clamping diameter and the other with a standard three-jaw chuck for larger diameter work. However, the Hainbuch system can be used on either machine if necessary.

While the smallest bore Hainbuch collet is 4mm, John Snell and his team have designed a method to clamp 3mm diameter material – a 3mm SC collet is bolted to a Hainbuch collet that has been bored out to accept the spigot of the 5C collet, thus retaining the accuracy and fast changing capabilities of the Hainbuch. It has also reduced costs for Dunlop by utilising the large number of 5C collets held in stock, and expanded the Hainbuch system beyond the 45 soft and 10 hard serrated jaw collets originally purchased.

The first benefit claimed of the Hainbuch collet was to speed up changeovers between sizes, which is particularly valuable in the Small Parts Area.

John Snell comments: "Our batch sizes are small so we are regularly changing part numbers, with as many as four or five set-ups being needed in each shift. A conventional collet takes four to five minutes to change while we can change a Hainbuch collet in seconds. That is a major saving that adds up over a shift to a significant increase in productivity.

"Also, the Hainbuch system is far more accurate with a repeatability of 5 to 8 microns compared to the 12 to 25 microns of a conventional collet. This is an important asset for machining rotary parts for hydraulic valves, electromechanical assemblies and other precision components."

He continues: "An average set-up time for a new job used to be more than three hours. Now it is down to just 11/2 hours with the average reduction being at least 30 per cent, thanks also to probing and VDI tooling."

The savings are said not stop there – Because of the fast changeover, first and second operations are now done consecutively so a part is completed ready for assembly and does not have to wait between operations. Before – when minutes were needed to change collets – this part-by-part method would have been hugely time consuming. Instead, operations were done on a batch- by- batch basis with part-machined work being stacked between operations. The part- by-part method reportedly made possible by Dunlop has cut set-up times and improved output by using the Hainbuch collet-style chuck the Hainbuch system gives a shorter lead time, reduces work-in- progress and improves housekeeping.

Team member Gary Hackleton, who is responsible for the new lathe, highlights another benefit of the fast change feature: "Because there is no time loss in removing a collet, I regularly clean out the collet and holder even between parts in a batch. This helps to keep the system in good condition and maintains accuracy. Before, that would have -taken too long and cleaning would only be done between batch changeovers."

Plate 3 Dunlop has cut set-up times and improved output by using the Hainbuch collet-style chuck

Another benefit that only a skilled and vigilant operator recognises is said to be the "axis fix" method of clamping that the Hainbuch system bestows. According to Leader, unlike a conventional collet, there is not a micron of axial movement when the Hainbuch collet is activated to clamp the part. so, when the workpiece is placed in the collet it stays "where it is put, and this is believed to be another time saver for Gary Hackleton.

"I used to get fed up with the old style chuck by continually having to mic, up the part length to ensure it had not changed. I don't have to do that now; I am totally confident it will not move."

In the past 12 months, output from the cell has encompassed more than 200 different part numbers. Some were "regulars" repeated often on a monthly basis and some only occurred once.

John Snell explains: "As well as current production we also receive requests for spares needed on aircraft that may go back several decades. We don't know what is coming up next, but now with the quick change Hainbuch collet system we can quickly set-up any job so that it is neither a worry nor a problem – and it is always accurate."

Details available from: Leader Chuck Systems Ltd, Tel: +44 (0) 121 771 4843; Freephone 08000 LEADER (08000 532337), Fax: +44 (0) 121 771 0966;E-mail: information@leaderchuck.co.uk;Web site: www.leaderchuck.com