Engineering sectors don’t come any more demanding than Formula One. Every component designed from scratch, often from exotic materials; extreme operating conditions, with heat, vibration, pollution and endurance to cope with; and a hard and fast deadline: races are every two weeks, and if you haven’t got the part to the grid by Sunday morning, then you might as well not have bothered.
It’s hardly surprising, therefore, that for the F1 teams, reliability and short cycle times are close to an obsession. For McLaren, this has led to a partnership with Japanese machine tool builder Yamazaki Mazak to kit out the machine shop at its gleaming Technology Centre (MTC) in Surrey.
When McLaren moved to the MTC in 2003, explained Simon Roberts, operations director for McLaren Racing, it was a chance for the team to reduce the amount of work it contracted out and bring production in-house, where it could control every aspect of design and manufacture. ‘For uprights, for example, when we contracted them out, we’d have an eight-week lead time. Since we brought the production in-house, we can machine an upright in 24 hours, with a five-week total lead time for the part.’
“Since we brought the production in-house, we can machine an upright in 24 hours”
Simon Roberts, McLaren Racing operations director
Roberts estimates that insourcing has increased by some 15-20 per cent since the move to the MTC. Some of this is for reasons of secrecy; the front wing and chassis have never been outsourced. The team also plans to bring the production of axles in-house, as it has now acquired the capability to machine them. Manufacture of rear wings will be outsourced next season — but they will be contracted out and made in several parts, to ensure secrecy.
The philosophy behind machine tools have change completely since the early days at the MTC, Roberts said. Originally, the shop operated with one man to one machine; today, the machines have multiplied, with at least two, and sometimes three, per person.
The machine shop now contains 25 Mazak machines, which work on aluminium and titanium components — magnesium cannot be machined at the MTC because of insurance constraints. The shop runs 24 hours per day with only half a day’s downtime per week, with three shifts operating.
This season’s car, the MP4-27, contains 3209 components which are machined in-house at the MTC; about half of the total number of components on the car, although this does not include any parts of the engine and the KERS, which both come from Mercedes. Senior production engineer Ian Greenfield said that McLaren prefers not to buy proprietary parts if at all possible. ‘We make the air valves for the wheels, although we used to buy them in; we had a failure so we make our own now, which is typical of us. Propietary parts either cost way too much or they’re susceptible to failure.’
Greenfield also explained how much time bringing production in-house can save McLaren. The car’s wheel nuts, for example, have a castellated profile which the pit team’s pneumatic guns grip onto to remove and tighten the nuts. ‘We used to contract the wheel nuts out, and it took about ten hours to put the castellations in each one,’ he said. ‘The part itself was 20 minutes milling, and the castellations were put in with spark erosion. We use it once and throw it away — not very cost effective. Using the Mazak machines, we’ve got production time down to two hours now.’
“Propietary parts either cost way too much or they’re susceptible to failure”
Ian Greenfield, senior production engineer
The rate of development on an F1 car is almost as ferocious as its speed in a straight: on average, a change is made to the McLaren car every 20 minutes, and only 6 per cent of a previous season’s car is carried forward to the current model. This means that the design offices and machine shops are working constantly, although one essential part of the design and testing process, the wind tunnel, is restricted to 60 hours operation per week because of its huge energy demand.
The smallest component made in-house is an anti-rotation stepped pin for the rear differential, which is just over 5mm long and about 3.5mm in diameter; this takes 45sec to machine in a single operation, and is made in batches of 100 each. The largest single part is the skeleton structure for the front wing, of which more later.
Weight reduction is clearly an important factor in component design and manufacture, but with the weight of an F1 car fixed at 600kg, it’s not a case of making sure that all the components are as light as possible. ‘Getting component weight down means that we can put the weight back exactly where we want it,’ Roberts said. ‘And that has advantages for the performance and particularly the handling of the car.’
The has knock-on effects throughout the car. For example, previous McLarens had a front wing made from carbon-fibre spars, with a more carbon fibre to form the outer skin. This tool a long time to build, however, so to reduce cycle times, the last few cars have had a front wing skeleton made from a single piece of aluminium, milled from a chunk of metal weighing 300kg on a Mazak Vortex five-axis vertical machining centre. The carbon fibre skins are the applied directly to this structure.
More often found in aerospace manufacturers machining wing spars, the Vortex is a high-speed machine with a tilting head that presents the cutting tool to the workpiece at the optimum angle. Its speed was the most important factor for McLaren when specifying the machine, according to Greenfield. ‘The roughing operation [on the Mazak] is so quick in comparison to our previous machine. We initially expected to cut cycle time by 50 percent; what we actually achieved was a 75 per cent reduction.’
Although the front wing structure is indeed skeletal, the central void is filled with tungsten, again making sure that weight is distributed in the best way possible for racing. ‘It seems strange to be filling components with tungsten sometimes,’ Greenfield said, ‘but that is the way that it works.’
The latest machines to arrive at the MTC are two Hyper Variaxis 5-axis machining centres, which it bought following a visit to the 2010 MACH show. The Variaxis machines are equipped with linear drives, have a large tool capacity and a fast spindle spindle speed for cutting aluminium, but enough power to machine titanium. ‘We bought a pair, because most of the things we make are a left and a right, so it allows us to make both at once,’ Greenfield said.
On average, a change is made to the McLaren car every 20 minutes, and only 6 per cent of a previous season’s car is carried forward to the current model
The first components to be machined on the Variaxis were the two parts of the rear crash structure insert, a component which bolts on to the rear of the carbon-fibre gearbox, which was previously contracted out. It’s also the largest component to be made on the machine, made from two 60kg billets of titanium, measuring 400x300x120mm, which are welded together halfway through the production process. The final component weighs less than 8kg and takes some 400 hours to machine.
‘This is something we’re getting into,’ Greenfield said. ‘With a part like this, there’s no way you could machine it in one piece because you couldn’t get the tool inside to make the interior. But if we can make it in two parts, beam-weld them together and machine the weld away, we save a lot of time.’
Like the other machines in the shop, the Variaxis is equipped with a swarf management system. With the components generally comprising only a very small fraction of the original metal billets, a great deal of swarf is generated; however, McLaren recycles the material by selling it back onto the metal market.
Partly because of this, Greenfield believes that techniques such as additive layer manufacuring are not currently suited to F1. ‘We made some structural parts, but we had problems with consistency,’ he said. ‘And really, the longest part of the manufacturing process is the finish machining and additive parts still need that. There’s no point spending 12 hours to grow something that still needs finish machining, when I can rough it out of a billet in two hours. But we are still persuing it.’
Having faster machines doesn’t ease the pressure on the machine shop, however. ‘Being able to machine faster just means we get less time to machine,’ Greenfield says. ‘But it does give the design department more time to get it spot-on, with more iterations in finite element analysis and so on. Meanwhile, these machines allow us to make better quality parts, which means we can make them thinner, which means we make them lighter.’