Machining high performance cylinder heads, parts for watches that cost tens of thousands, and large components for the oil and gas industry, companies of all persuasions are benefiting from latest technology. Andrew Allcock reports
Motorsport enthusiast Ric Wood is the driving force behind two businesses in Stockport - Whitegates Garage, specialising in high quality vehicle repair and maintenance; and CNC Heads, combining state-of-the-art engineering technology with hands-on race experience to design, replicate and manufacture high performance, gas-flowed cylinder heads - "the very best cylinder head for your race or road car". To support its cylinder head endeavours, the company is using an XYZ Machine Tools Mini Mill 560.
According to CNC Heads' Alastair Heywood, the key to achieving optimum engine performance improvements for race, trackday and road cars is the accuracy to which the cylinder head is modified. He says that every cylinder head produced by CNC Heads for a particular make and model will be identical, with each of those cylinder heads guaranteed to perform to exactly the same standard. In fact, CNC Heads claims that "the performance and quality of our [fully gas flowed and fully balanced across all cylinders] cylinder heads cannot be beaten, and our prices are very much less than a fully developed hand-ported head".
Gas flowing and modifying a cylinder head can be a very time-consuming and expensive experience, but CNC Heads' investment in computer-based technology has resulted in significant reductions in production times and an extremely competitive pricing structure.
The manufacturing process begins with the scanning of a fully developed and flow tested cylinder head. This information is then used to generate machine code for all cylinders, ensuring that they are all identical. The code is then used to machine the valve throats, chambers and ports, via the recently installed XYZ Mini Mill 560 compact vertical machining centre, with the resulting machined finish described by CNC Heads as "superbly smooth, visually and to the touch".
Image: XYZ technology delivers a polished performance
IDENTICAL WITH CNC
"Each cylinder head type is optimised once and the digital data used to replicate the design exactly, with the more popular types machined in batches," says Alastair Heywood. "CNC technology means that, once you have machined the first optimised head, the next one will be machined in a much shorter time and will be identical to the original modified head."
The decision to install the XYZ Mini Mill 560 was prompted by a requirement to re-manufacture V12 cylinder heads for a historic race engine, which presented a problem when it came to machining the two end faces. "XYZ initially suggested inserting a riser block to provide the additional 150 mm daylight between table and spindle needed to be able to machine these faces," says Alastair Heywood. "However, XYZ then chose to redesign the machine's base casting, so the Mini Mill 560 installed in late 2008 does have an extended Z axis and came complete with bespoke, rather than modified, guarding."
With the machine installed and ready to run, Mr Heywood says the Siemens 810D ShopMill conversational control proved to be very user-friendly and the machine has since performed perfectly. XYZ's regional showroom in nearby Blackburn was the preferred venue for his initial training course as "it was just 20 minutes drive away, which enabled me to come back to work and put into practice what I had learned that day".
Moving to precision of a Swiss kind, and Kari Voutilainen is one of Switzerland's master watchmakers and his métier – his trade - is capturing time with 'movements' made of pinions, hairsprings, oscillators and escapements for those who can afford to buy ten thousand hours of passion and engineering genius and wear it on their wrists.
"This is a tourbillon watch," he says, holding up his hands, so I can get a better look. 'I made it before CADCAM and CNC were common in watchmaking, when everything was done the hard way, using techniques that hadn't changed for hundreds of years. It's a very difficult mechanism to make. It took time," he says, modestly. Mr Voutilainen made his tourbillon as an exemplar: a demonstration of his virtuosity and craftsmanship.
His company, Artisan d'Horologerie d'Art Voutilainen, is located in Môtiers, Val-de-Travers, at one end of what the Swiss tourist board calls Watch Valley, the arc of precision workshops that follows the line of the Jura mountains from Geneva to Basel and is home to most of Switzerland's watchmakers, including both the famous, as well as the less well-known.
"I first came here from my home in Finland to study at Wostep," he says, "an independent college nearby: a foundation of Swiss watchmakers. It's the best place in the world to learn the trade."
Mr Voutilainen also taught at the college between 1999 and 2002, but whether he was studying or teaching, his evenings and weekends were spent hunched at his bench, practising his painstaking craft.
"A watchmaker has to love tools almost as much as he loves watches," the artisan says. "My work is my passion and my hobby, so there's nothing I enjoy more than learning how to use a new tool to make parts for my watches."
And the latest addition to his already extensive toolbox is a Haas OM-1 Office Mill (01603 760539). It has taken pride-of-place in the company's largest workroom. I asked him what it enables him to do that he couldn't do before. After all, if you can make a tourbillon pocket watch without the help of CNC.
"The Haas Office Mill allows us to more easily produce parts which have elaborate shapes, other than just radii and straight lines," he says. "I used to make these sorts of parts using our Pointer machine, but, with the Haas, we can make them quicker and with less chance of a mistake."
Errors can be costly, especially when the materials being machined regularly include precious metals such as gold and titanium, as well as more mundane materials like steel and brass. Even the smallest dimensional error when machining features will have dire, knock-on consequences once the watch parts are finally assembled.
"We are very careful when setting the cutting tools to make sure that they turn perfectly,' says Mr Voutilainen. "There are so many opportunities to introduce errors when we are machining to tolerances of around 0.0025" [0.06 mm].
"We looked around for a suitable CNC machine and I was impressed by the OM-1's size and the fact that I could get it through my office door, without having to dismantle anything. I was also very impressed with its overall performance and with delivery. Like mainplates, pinions are time-consuming to make, so based on our experience with the OM-1, we're also planning to buy a Haas OL-1 Office Lathe," he says.
Image: Customers pay thousands for watches like this; a Haas Office Mill is playing its part
The company sends its watches to customers around the world, with most going to the Far East and the USA, to collectors. "These are people for whom quality and individuality is everything, and they are happy to pay for it: around $85,000 for a wrist watch - a lot more for a tourbillon." And all of Mr Voutilainen's watches are spoken for, up to 2012.
From one extreme to another, in terms of size, at least, and sub-contractor Express Engineering has recently installed a new, large capacity Doosan horizontal machining centre, supplied by Mills CNC .
The machine, a HM 1250, was installed at the company's Gateshead facility in June and is being used to manufacture large, complex parts predominantly for the oil and gas, power generation and aerospace sectors…and will help spearhead the company's drive to secure contracts from the renewable energy market. The machine is an integral element of a massive on-going three-year, £3.5 million expansion programme in plant, equipment and people.
The HM 1250 is a large, powerful machining centre, equipped with a BT 50, 37 kW, 6,000 rpm spindle (3- speed gearbox), and ultra-rigid, wrap-around box-ways, delivering high-accuracy, optimum metal removal rates and superior surface finishes. The machine is designed to handle big and heavy workpieces on each of its twin pallets – up to 3,000 kg in weight and 2,000 mm diameter.
Image: Large capacity HM 1250 horizontal machining centre
"We see our future growth and prosperity contingent on our ability to manufacture large complex parts and in developing and strengthening our position in specific sector supply chains - oil and gas, aerospace etc," says Nigel Davison, Express Engineering's managing director.
An integral part of the expansion programme was to increase the company's manufacturing capacity and capabilities, involving a strategic review of its machine tools and manufacturing processes and systems.
Explains Mr Davison: "The review identified the need to replace one of our existing horizontal machines, which was becoming unreliable, causing production bottlenecks to occur. We decided to replace it with a bigger capacity machine to allow us to manufacture larger and heavier components."
The machine needed to satisfy a number of criteria. "Because we work with hard and difficult-to-machine materials – alloy steels, duplex, titanium, stainless, Inconel-clad components etc, we needed a rigid machine with high-torque spindle capability to enable us to achieve fast stock removal and to meet our stringent geometric part accuracy and surface finish requirements – 25 micron accuracy or less on milled pockets, bores etc, and Ra 0.8µm surface finish or better," the managing director underlines.
To help the company improve productivity and increase flexibility, and to help it machine bigger and heavier workpieces, a machine with a twin-table configuration, and a machining envelope of 1.8 m cube to match its turning capability was required.
"Although the HM 1250 is a relatively new machine [in terms of its availability in the UK], we have invested heavily over recent years in Doosan machine tools - mainly large-capacity, Puma lathes. We know that Doosan machines deliver the goods, and that they represent excellent value for money," confirms Mr Davison.
The XYZ Mini Mill 560 has a 560, 400, 500 mm (650 option), X, Y, Z working envelope contained within a 2,000 mm wide by 2,060 mm deep footprint. A 15 hp (11 kW)/8000 rpm (12,000 option) BT 40 spindle is fitted and a 12-station toolchanger, holding tools up to 100 mm diameter, is standard.
The Office Mill OM-1A has X, Y and Z travels of 203, 203 and 305; an ISO 20, 3.7 kW, 30,000 rpm spindle; a 20-tool carousel toolchanger; and requires single phase electricity only and 30 amps.
First published in Machinery, October 2009