British engineers teach old Cadbury candy factory new tricks

Automation, 1980s style, has caught up with one of the world's oldest and most famous chocolate factories. Engineers at the Cadbury Chocolate Plant in Birmingham, England, are transforming operations at the factory with a (STR)100 million ($144 million) program in new technologies.

The project will bring to the 105-year-old factory process control techniques similar to those found in the chemical or steelmaking industries. It will sweep away half the plant's manufacturing work force and enable chocolate to be made to tight scientific standards.

Each week the factory turns out some 1,500 tons of chocolate - about 1.6 million chocolate bars of various kinds plus some 50 million individual chocolate sweets. Cadbury is part of the multinational group Cadbury Schweppes, which has a significant presence in the American candy and soft-drinks market.

As a result of the modernization process, which started in 1980 and should be finished next year, the number of individual production lines in the factory will drop from 37 to about a dozen.

Each will be controlled by a battery of computers and will operate 24 hours a day. Just 20 people will be needed to operate a manufacturing unit that both makes and wraps some 1,500 chocolate bars a minute. Three or four times that number are required for conventional chocolatemaking procedures.

In each of the new production lines, tubs of raw chocolate - a mixture of cocoa beans, sugar, and milk - are taken to the start of the line by forklift truck.

In a conventional chocolate plant, a series of operations, each supervised by a worker at an individual control point, turns this material into a finished bar or sweet.

There are three operations: Raw chocolate is emptied into a series of molds to produce shallow ''trays'' of chocolate. The filling, which could be some kind of cream or another batch of chocolate treated in a certain way, is then squirted into these trays. In the final step, another layer of chocolate seals the filled tray, finishing the sweet or bar. It then goes to another part of the line for wrapping and packing.

Control of temperature and of the amount of mixture added at specific points is absolutely crucial, explains Geoff Loosemore, the engineering manager at Cadbury. If the temperature is incorrect, fat globules in the chocolate will crystallize at the wrong time, making the finished product too hard or too soft. Alternatively, the final sweet could have unsightly streaks on the chocolate or be too ''crispy,'' which would spoil the taste.

Monitoring the volumes of chocolate poured into each tray is important. If too much chocolate is added, Cadbury wastes material and produces an uneven product that is difficult to wrap and pack.

Engineers control these factors with a series of microprocessors distributed around each production line. In the line that makes Cadbury's new ''Wispa'' bar, microprocessors monitor conditions at 1,000 points. These feed instructions to central computers that deal with 250,000 separate instructions at any one time.

One person can supervise the whole operation from a central control room with computer terminals and TV screens. Another result of the program is that many of the chocolate products can now be packed into boxes automatically by small robot arms. In the old process the individual sweets were made to less accurate dimensions. So the packing had to be left to teams of human workers, who could spot any imperfections.

The modernization program has had a staggering effect on the numbers employed at Birmingham. Total work force is some 4,700, compared with 6,000 four years ago. There are about 3,000 men and women on the factory floor, roughly half the figure in 1977.

But output has stayed roughly the same, meaning the productivity gains from the new hardware have been significant and have ''satisfied Cadbury's investment criteria for installing the new machinery,'' Mr. Loosemore says.