Two-in-one tool production

Citation

(2005), "Two-in-one tool production", Aircraft Engineering and Aerospace Technology, Vol. 77 No. 4. https://doi.org/10.1108/aeat.2005.12777dab.007

Two-in-one tool production

Two-in-one tool production

Keywords: Machine tools

The development of the new Quattro- Cut single blade reamer has reportedly set Bencere Elliott apart from its competitors and given the company a global lead in the production of holes to 2 μm tolerances. Not only is the reamer assembled by adhesive rather than being brazed, but it is also produced with inserts that have four cutting faces rather than the conventional two – and it utilises an innovative method of insert location that allows inserts to be quickly, easily and accurately set to within 1 μm – every time.

“Combined with the use of four cutting edges, the novel location feature – which is based on a highly accurately machined serrated location – means we’ve effective:/ de-skilled toolsetting from an operation that consistently produces high quality holes”, says managing director Gerry Minshall.

Launched in late 2003, it was expected that Quattro-Cut would generate increased business values of around 15 per cent in its first 12 months but, reflects Gerry, “in the event, we took orders to that value within four months!”

Quattro-Cut is the latest enhancement to Bencere Elliott’s impressive global reputation for producing bespoke high-quality drilling, boring, grooving, reaming, spot facing, chamfering and debarring tooling for aerospace, automotive and hydraulics companies, in particular – indeed, 62 per cent of output is exported. And it will not be the last, says Gerry, who adds that the overwhelming success of the new product and especially the innovative serrated location, is already spurring the development of other, equally impressive new generation tooling.

For a company that started life in 1967 as a tool importer and sales outlet (as Bencere, based in Hook Norton, Oxon, UK) and now occupies an impressive 14,000 ft2 site in nearby Chipping Norton, UK, (the site formerly occupied by the Tom Walkingshaw Racing team), it is not only ground breaking products that are enabling Bencere Elliott to enjoy year- on-year growth – 20 per cent last year – since Gerry and two co-directors took over in the 1990s.

Of course, clever design thinking is crucial, but so too is the application of “intelligent” and Lean manufacturing – and that includes the use of adhesive instead of braze for Quattro-Cut – as well as the appropriate machining technology to produce components and products in the most cost-effective and efficient way.

A prime example of the company’s “smart” approach to manufacturing concerns a Walter Helitronic Power & Diamond five-axis tool grinder. Bencere Elliot! actually uses the machine rather than a cylindrical grinder to generate features on the tool body as well as its more conventional application on tool cutting faces/edges.

As Gerry explains, there was never any doubt about the company’s future. “With an impressive client list that included Rolls-Royce, GM and Ford, I had a few ideas of how I wanted the company to grow and how the products should develop”, he says. “I had a clear sight of the goal: the manufacture of special-purpose, high-precision single blade reamers for the aerospace, hydraulics and automotive markets”.

Using profit gained from tool sales, Bencere soon began investing in machines, employees and its own tool designs, and a blossoming relationship with Elliott Tool Technologies of America (which included a licence deal) saw Bencere designing more product and outsourcing higher volumes of machining work.

Business grew, and with the Quattro- Cut project foremost, the two companies entered into an agreement whereby Elliott funded the new tool’s development in return for the product’s US sales rights.

“After 18 months or so the product was ready, and the market immediately took off. The original idea was that Elliott would also produce Quattro-Cut in the US, but in the event we were asked to concentrate on manufacture – in fact, we then agreed to become Elliott’s manufacturing centre, operating as a wholly owned subsidiary”.

Wary that UK costs might make Bencere Elliott’s tools too expensive for a global market, Lean manufacturing principles and “smart” working practices have been steadfastly applied as the company progressively moved into “serious” production.

Gerry never forgot the time he spent in Sweden with Volvo. After having bought “a very expensive” round of drinks in a bar, he jokingly asked the Volvo engineers how they actually managed to make cars that were price- competitive. “Their response was you have to work smarter; you have to be intelligent in manufacture”.

“People needn’t be the major cost factor; rather, you have to adopt good processes and systems, and invest in the best machines and use them in the most productive ways, if you wish to be competitive”.

The Lean philosophy at Bencere Elliott begins with the design process. Four numbers are simply entered onto an Excel spreadsheet before a 3D image of the “special” is automatically generated, giving all turning, milling and grinding instructions. The result is that a drawing can be ready for production within 15 min, compared with perhaps a day by conventional methods.

“Grinding was another problem area for us. Because everything has to be ground to two a micron tolerance, hand finishing on manual machines was the traditional route and it was clear that we had to reduce grind times, ideally via lights out running and by de-skilling the process. Our reamers have six grinding features and while we looked at CMC cylindrical grinding, we then saw a Walter Helitronic tool grinder in action. It occurred to me that the machine could actually move to all of the required positions, to actually also grind the tool body features and thus obviate cylindrical grinding”.

“Walter GB of Redditch probably thought I was crazy, but the trials were a great success – for example, a product that had a grinding cycle of six hours fell to 1.5 hours. My only concern was that the programming time for our usual one-/two-offs would be four times longer than machining times”. He wanted the machine programming process to mirror the ease and speed with which tools were designed.

The result was that Walter developed bespoke software which is based on just two questions being answered on the screen – tool size and geometry. The machine then automatically probes the part, determines the required features and generates the program.

“It might take ten minutes to probe, but the process is unmanned and it allows us to use semi-skilled people to load/unload the machine”.

Because Quattro-Cut features PCD pads – which were taking between two/ three days to grind manually – the conversation between Walter GB and Gerry focused on the “two-in-one” Helitronic Power+Diamond, a five- axis tool grinder that combines CMC erosion with “conventional” CMC tool grinding for the fast, accurate and cost-efficient machining of both PCD and carbide and HSS tools (Plates 3 and 4).

Knowing that the machine’s erosion functionality would automatically take care of the PCD pads in-cycle and, with an eye to the future expansion of the product range, Gerry knew this was the machine he needed.

Plate 3 The “two-in-one” Walter Helitronic Power+Diamond tool grinder has reduced grind times by a factor of six and improved quality levels at Bencere Elliott

Plate 4 The “two-in-one” Walter Helitronic Power+Diamond is proving critical to the success of Bencere Elliott’s innovative Quattro-Cut single blade reamer

Using rotational erosion technology to produce radii down to 0.1 mm and generate surface finishes that can eliminate the need for finish-grinding, the Helitronic Power+Diamond can “revert” to being a Helitronic Power in only a few minutes – due to the use of the twin-head electrode/grinding wheel spindle, unit and a dielectric that has been especially developed for this application. The dielectric is used as the machine’s cutting fluid as well as the erosion dielectric, and can operate at up to 158ºC.

In Helitronic Power mode – with 24 kW spindle drive and digital drives that ensure rapid traverse rates of 15 m/ min in all linear axes and 120º/s on the rotational axes – the machine can accommodate tools 370 mm long (300 mm for face grinding) and 320 mm diameter.

It can work on the basic body of a PCD tool – producing flutes and front geometries, for example – then quickly “switch” to erosion mode without operator intervention. The range of PCD tools which can be machined includes circular milling cutters, milling tools, drills, core drills, combination tools as well as hogger saw blades. It is also possible to produce continuous peripheral clearance angles on tool profiles.

For erosion, a fully automatic measuring program determines all necessary parameters such as angle between axes, angular pitch and tool orthogonal rake, cutting edge position convex/concave and length of cutting edge. The electrode dressing device allows users to create the appropriate contours on electrode diameters down to 6 mm.

The machine uses Walter’s proven HMC 500 control technology – the CMC used across the complete Walter range – and the multi-tasking Windows NT operating system allows for parallel data entry during the erosion/grinding process. An integrated editor allows the user to easily generate profiles and to transfer and change existing profile DXF data directly on the machine or via a PC workstation.

“The machine has reduced grind times by a factor of six and improved quality levels”, adds Gerry “Also, features that were not previously ground are now processed on the machine and, in terms of the highly-accurate serrated location plate, we simply couldn’t produce these without the Walter. Its erosion functionality has added another dimension to our operation, not only in respect of future potential but also in that we can now erode diamond in the same amount of time it used to take us to manually grind carbide. And the machine does it all automatically, and often at night”.

Processing a wide range of tools in mainly one- to three-offs from 6 mm to 200 mm diameter and from 230 mm to 1 m long, with perhaps five cutting blades, or PCD or carbide pads, Gerry points out that the only way the company can operate so successfully in such a high variety, make-to-order environment is by having a very tight production scheduling process and an able and flexible workforce that utilises the appropriate production equipment.

“We have a team of first-class employees who can move between machining disciplines and are empowered to re-arrange their own working hours to suit the workload”, he concludes. “In addition, the flexibility and capability of the Walter Helitronic Power+Diamond certainly means we have the best of both worlds in terms of tool production”.

Details available from: Walter GB Limited. Tel: +44 (0) 1527 60281, web site: www.walter-ag.de