Car manufacturing made easy

How all the parts come together to make a car

Cartoon films portray car factories with lumps of raw iron going in one end and gleaming automobiles purring away at the other. It is of course a false image. Cars are not made all in one place. But the reality is scarcely less remarkable, for the process can involve factories all over the world in the making of just one car.

At Saragossa, Spain, where the American company General Motors has a huge assembly line, the steel for the body may come from Spain, the engine from Britain, the suspension units, gearbox and fuel-injection system from Germany, the tyres from France or Italy, the radio from Holland or Japan, with contributions even from Australia and Korea.

Once things were a lot simpler. At the beginning of the century, the first cars were produced much the same way as horse-drawn coaches – with workers wandering around, slowly and expensively hammering metal panels individually onto wooden frames. Although the elements of mass production had long been established for products such as ship’s pulleys and guns, it took an organisational genius to apply this to the motor industry Henry Ford.

The first assembly line

In 1903, Ford started to make cars in Detroit. Within three years, he was the largest car producer in the USA. Within five years, he was concentrating on a single model – the Model T – in order to make the best use of his standardised parts.

Then in 1913 he introduced the concept that was to revolutionise car production – the assembly line. This reversed the relationship between worker and product, for now the product rolled past a line of stationary workers, each one of whom did one specific task. When first applied to the making of magnetos, the new process cut assembly time from 20 minutes to five.

Fired by this success, Ford extended the principle to chassis construction. A rope pulled a line of chassis along a track, at which stood 50 workers, each fixing their own allotted part to each chassis as it moved by. Assembly time for a chassis dropped from 12 to one and a half hours.

Commercially, the results were astounding. In less than ten years, the price of a Model T dropped from $850 to $250. Ford sold 1.8 million of them. Profits and wages boomed. Ford Motors led the way again in 1951 by using automatic equipment to produce engine blocks. In 500 distinct operations, 40 machines transformed a rough metal casting into a finished block, reducing production time per engine from several hours to 15 minutes.

The world of robots

The urge to save labour has continued to inspire new developments, with robots

Manual assembly In 1913, Henry Ford introduced assembly lines at his Detroit car factory. Moving belts carried the parts past flywheel mechanics, and the engines to Assembly workers. By 1915 a ready 2 drive Model T Ford was rolling off the lines very one and a half minutes.

replacing workers, cutting out tedious tasks and guaranteeing greater accuracy. On the Fiat Uno, just 30 of the 2700 welds are done by hand. Only specialised crafts, such as electrical wiring, now remain in human hands. In a typical car-assembly plant of the 1980s – such as the Fiat Uno works at Mirafiori or Rivalta, Italy, which produce a total of 3000 cars a day – the first stage involves sheet steel arriving at the press shop. Here, in areas as large as three football stadiums, robot cranes supply rolled sheets of steel to giant stamping machines which cut the pieces of metal to make up the car body.

Next, robots build the underbody or floorpan, making numerous welds and creating a complex shape with spaces for wheel arches, boot wells and spare wheels.

At the next stage, large jigs position the body sides and roof to be welded into place automatically. Meanwhile, the doors have been made on nearby assembly lines in a process that involves several different pressings to create an outer skin clinched over an inner frame.

Finally, on advanced assembly lines, lasers check every car body for the smallest distortion or irregularity.

The final touches

Painting a car is a major process protecting against corrosion as well as providing an attractive glossy look. The car, now largely assembled, is cleaned in a degreasing tank, rinsed and coated with phosphate to make it more receptive to the paint. After further rinses, base primer coat is applied, in several layers. These primer coats are sprayed on electrostatically, using an electric field to attract the paint.

The last layers – usually three – are of glossy acrylic paint. The paintwork on most mass-produced cars is 0.1mm thick. A Rolls-Royce has 22 layers of paint, giving a thickness of 0.2mm.

Special wax to protect against water, snow, grit and salt is then injected into hollow sections such as pillars and sills.

The next stage, the trim, fits out the interior. The car acquires its ‘nerves’ – the electrical system. Robots fit underfelt, carpets, seats and other fittings. Many factories use robot carriers to move components about, reducing possible damage as well as the need for human labour.

Windscreens and some other windows are often glued to the car, to make a better fit and reduce wind resistance and noise.

Robots apply the glue to the edge of the glass and then put it in place on the car with sucker grips.

In the final assembly, the car receives its heart. It is raised on a hoist, and a jacking system brings the engine, complete with clutch and gearbox, into position. The fuel tank is mounted at the rear end of the car. Next come suspension, steering, radiator and battery, and then the wheels and tyres.

With the addition of water, antifreeze, oil and petrol, the car is in full running order. Inspectors at the gate examine it, before it undergoes final tests – in particular a ‘rolling road’ test that assesses performance. When the car is given its final bill of health, it is ready for the dealer.