More stringent safety requirements and the trend for more equipment to be included as standard has increased the weight of cars, but Ford has succeeded in making the Focus up to 2% lighter than the Escort, depending on the model. The interior space has increased, while body stiffness, important in reducing noise, has increased 100% to 827kNm/radian.
A key factor in this was Ford’s multi-functional optimisation (MFO) software, developed with a US university. Graham Curle, body engineering manager, says: ‘MFO helps to answer questions like if you downgauge a panel what is the effect elsewhere? or where is the best place to put in weight? ‘
For example, in designing the cross member under the front seats, which forms an important part of the car’s safety cage, the most effective solution was found to be to add weight, fabricate the member in one piece, and delete weight elsewhere, says Curle.
The body is between 10% 15% high-strength steel and uses laser-welded blanks for two components: the internal reinforcement of the B-pillar, and the rear side rail. The side rail is formed in three sections using different gauges of steel for different functions: the rear part is designed to collapse progressively in an impact; the centre section is stiff and secure; the rear suspension pick-up points and the front use a thinner gauge steel, because their task is mainly to transmit forces into the rest of the bodyshell.