Before the end of the Cold War, most of the world's supply of titanium was swallowed up by the defence industries. Raleigh Special Products, which manufactures the company's top range of racing bikes, started investigating the use of this extremely light, rigid, corrosion-resistant metal following an approach from a Russian titanium producer looking for a new market.
'Our product is mainly tubes. The titanium we were being offered was in tubes and so cheap we could use it to replace steel,' says Jim Bratby, technical manager.
But although titanium is one of the strongest and lightest metals, it is difficult to work with - welding it is a slow and labour-intensive process that must be carefully controlled to ensure consistent results. 'When titanium is heated it has similar handling properties to mercury,' says Mr Bratby.
At welding temperature, the metal becomes globular and sticky, contaminating the welding electrodes, which must be cleaned or changed frequently. To counteract this effect, titanium is worked in air-free chambers or cabinets. Air is excluded from the joints being welded by bathing them in inert gas.
'Hand welding in special chambers may be acceptable in the nuclear and defence industries but to capitalise on the fall in the price of titanium we had to create a production process,' says David Bednall, general manager of Raleigh Special Products.
The other difficulty is that hand welding is never 100 per cent consistent, posing potential safety and quality problems. The system developed by Raleigh is based on a machine produced by a robot welding company, WMA, based at Grantham, in Lincolnshire. A computer, from the industrial automation specialist, Allen- Bradley, runs multi-tasking software that controls simultaneously the manoeuvring of the bike into the correct positions, the movement of the welding torch and the titanium wire feed, as well as the actual welding process.
The joint still has to be shielded from the atmosphere with inert gas, but this is continuously 'poured on' like water and allowed to disperse. Using manual welding, a team of four could produce 25 titanium bike frames a week. Now the same team of four makes 150 frames per week, although some sub- assemblies are still welded by hand. Mr Bednall says that all manufacturers now use titanium for their top models.
Raleigh believes it is the first manufacturer to automate the welding process, giving it a significant competitive advantage and enlarging the market for titanium bikes. Most of the 20,000 competition bikes produced by the company each year are exported to the US.
The automated system has cut the cost of a mountain bike frame from around pounds 1,000 to little more than pounds 500. Typically, competition cyclists buy the frame and choose the other components separately, customising the bike to their own requirements. Raleigh has also started producing complete titanium-frame bikes.
Although its initial interest was sparked by the Russian approach, Raleigh now has titanium tubing manufactured to its own specification by the engineering company IMI, of Birmingham. Three years ago, all 20,000 competition bikes produced annually by Raleigh were made of special steels. Now 90 per cent are made of titanium.
(Photograph omitted)Reuse content