For con-rod splitting to work properly the fracture must be fully brittle, and is achieved by a YAG laser cutting a stress-raising groove on each side of the bore.

Albon makes around 350,000 connecting rods a month for a worldwide customer base that includes Caterpillar, Cummings Diesel, Detroit Diesel, Daimler Benz, SAAB Cars and MG Rover. These are mostly for diesel engines, with the majority destined for seven to sixteen-litre truck engines, and Trumpf YAG lasers play a vital role in their manufacture. The large end of the connecting rod is in two halves so that it can be bolted around the crankshaft, and as the parts are machined from forgings this means that the forging has to be split during manufacture.

The conventional way to do this was to allow extra material so that the forging could be cut in two, the faces machined, and the parts bolted back together.

But as Albon's Technical Director, Ralph Howard, explains, 'When you machine two halves of a con rod you have to have a location to fit them back together again - maybe a serration or a machined hole with a fitted bolt - and it never goes back together quite how it was.

What's more, all that machining around the joint face is quite an on cost.' To reduce these costs, Albon has developed a process where the con rods are fractured rather than cut.

This means that when the parts are reassembled the fracture surfaces mate to give a perfect location with no machining.

For the process to work properly the fracture must be fully brittle, and this is achieved by creating a stress-raising groove on each side of the bore to initiate the fracture.

This groove used to be produced using a V-shaped broach, but the broaches quickly lost their edge, which meant that the quality of the groove - and hence the fracture - began to deteriorate.

Albon's solution was to use Trumpf HL 62P YAG lasers to produce a consistent and closely controlled scribe mark.

Not only does the laser never lose its edge, but the heat input from the laser beam hardens the metal and creates an even better stress raiser.

'We did a lot of development work on the laser settings and the groove profile,' says Howard.

'The key factors to control are the number of pulses and the profile of the groove.

We aim to produce a groove that is about 0.1mm wide and 0.3mm deep that is wider at the bottom of the groove than the top.

And when you look at the bottom of the groove after fracture you should see a neat sawtooth profile.

Once you get the parameters right you get an excellent fracture.

The other thing we have to consider is the cycle time.