On-screen control of the whack factor: Golf-club heads can now be designed by computer program instead of laboriously by hand, reports Clive Davidson

GOLFERS tend to be traditionalists, at least when it comes to choosing their favourite mashie niblick. Although the wooden shafts and iron heads of yesteryear have been replaced by steel and aluminium, the clubs used by the players in last week's Open, for example, were designed and produced in a way that has remained fundamentally unchanged for years.

But for ordinary golfers' clubs, computer technology may soon oust the laborious process of hand-crafting prototypes which are then mass-manufactured. Golf-club heads are now mostly manufactured in Asia. For a British- based club maker such as Dunlop Slazenger International this poses problems of how to retain control over design and an edge on competitors.

Dunlop Slazenger's golf division in Normanton, West Yorkshire, has found a solution in a computer-aided design (CAD) system that keeps design and testing in Britain but allows the company to take advantage of the economics of manufacturing in the Far East. The system is improving the speed and accuracy with which the company can create a co-ordinated set of clubs.

Golfers are notoriously fussy about the feel of their clubs. In a recent international tournament Gary Player went back to using a putter he had owned for more than 25 years to correct his play. Since the weight of club heads is more or less standardised, differences are determined largely by the design.

It is in the 'irons' - the clubs used between driving off from the tee and putting on the green - that most variation in design is found. By increasing the 'loft' - effectively the angle between the club face and the ground - the ball will lift higher into the air when hit. Changing the 'lie' - the angle between the club head and the shaft - affects the swing. Power and precision are controlled by the distribution of weight in the head.

Dunlop Slazenger's new range of clubs, called Synergy, is the first to be designed with the company's CAD system. To begin with, a wireframe model of a generic club head is created on the screen of a graphics work station. Then a designer working with a programmer uses a mouse input device to move the lines of the wireframe to the desired shape.

'Having developed the shape we can get the computer to calculate the volume,' says Mike Shaw, works director of Dunlop Slazenger International's golf division. 'We can then calculate the weight and check if it is satisfactory. If not, we repeat the process, or use the computer to make adjustments.'

Once the shape is acceptable the computer examines the 'sweet spot' - the hitting area of the club head. The sweet spot is dependent on the the point of balance around which the head can be rotated. Concentrating the weight of the head behind it decreases its area but increases the club's power. On the other hand a larger sweet spot makes for a more forgiving club but lessens its whack factor.

Weight is distributed about the head by creating a cavity behind the club face. By altering the shape of the cavity metal can be taken from the centre to the periphery. The more metal at the edges the less the club will be inclined to rotate if the ball is struck off the centre of the sweet spot.

'CAD allows us to make weight changes and assess the impact in terms of how they affect the moment of inertia without actually having to make a club,' says Mr Shaw.

The CAD system has other advantages. 'We can use it to assess things such as strength,' says Mr Shaw. 'We can design to strength thresholds so we don't over-engineer clubs.'

The system also handles the aesthetics of the design. The software does surface modelling - the wireframe can be covered with textured and highlighted surfaces so the designer can play with the look of the clubs.

'Finished cosmetics have an influence on the end user,' says Mr Shaw. 'The clubs have to look attractive as well as play well.'

The CAD system not only produces the design but also generates the tool settings for the machine rooms where the clubs are manufactured. It is not necessary to send drawings to the Far East; the tool-setting data can be sent via a modem link direct to the factory machines.

Dunlop Slazenger claims to be at the forefront of computer-assisted golf- club design. But other manufacturers are following suit. One United States golf-club maker, Karsten Manufacturing Corporation, recently discovered a different benefit of CAD - combatting copycat designs.

The company has patents covering the design of its Ping golf clubs, but its legal department suspected that a new club marketed by one of its competitors infringed Karsten's patents. Superficially, the rival's club looked very different, so convincing a jury of non-experts of their similarity might have been a problem.

To uphold its contention that the two designs were similar, Karsten created a three-dimensional computer model of its rival's club. When the rival company's lawyers saw this superimposed on an existing 3D model of the Ping club, they agreed to a settlement.

Although Dunlop Slazenger started with a commercial CAD package called Duct from the company Delcam, it is adapting this to its own requirements. Chief of these is ease of use.

'Traditional designers are hands-on people,' says Mr Shaw. 'They take a block of steel and by hand and eye they conjure up a head. The problem is how to convert that man to someone who works with images.'

Mr Shaw hopes that by making the computer interface as intuitive as possible, within two years the designer will be able to operate the system without the aid of a programmer.

The software runs on a 4D/25 Personal Iris high- performance graphics work station from Silicon Graphics. Mr Shaw says Dunlop Slazenger is planning to build up a library of computer-generated head shapes that could be used as the starting point for other designs. He and his colleagues are still exploring the ways in which the system can assist the design process.

'There is no reason why having designed an iron you couldn't have the computer fill out the spec for the rest of the set,' says Mr Shaw.

However, this kind of automation is a long way off, and clubs produced by this system have yet to win the endorsement of professional players. But for the meantime, says Mr Shaw, Dunlop Slazenger is freed from having to 'shop out of our supplier's basket, where the choices don't give us the product differentiation or performance we are looking for'.

(Photograph omitted)