Bosch has made its 10 billionth spark plug at its Bamberg plant in Germany, making the supplier the world’s most prolific manufacturer of the components, it claims.

Most (8bn) were made at Bamberg, which was established in 1939, while the rest were produced at other plants around the world. Laid end-to-end, the plugs would form a chain stretching for more than 560,000 kilometres, circling the equator approximately 14 times.

A century ago, Bosch produced just a few hundred spark plugs a year – today, it is over 300m.

Bamberg is the primary plant and sets standards for all other Bosch spark plug facilities. Factories in India, Brazil, China and Russia also produce plugs for their local markets.

Bosch unveiled its first spark plug combined with a high-voltage magneto over 00 years ago, and patented the innovative system on 7 January 1902. This reliable ignition system for engines with ever-increasing speeds finally solved what vehicle internal combustion engine pioneer Carl Benz described as the ‘problem of all problems’ in early automotive engineering.

Bosch believes the spark plug, in combination with industrial manufacturing techniques, opened the way for the surge in vehicle production experienced during the following decades. The result was affordable vehicles.

Constant developments of spark plugs as integral system components have made a significant contribution toward more economical, cleaner, and more efficient fuel combustion, as well as to more reliable engines and catalytic converters, Bosch said.

Despite the significant increases in performance, the service life for normal spark plugs now is around 20,000 (12,000 miles) to 30,000km (20,000 miles) – roughly 20 to 30 times higher than the spark plugs of 100 years ago.

Recent developments include the use of special metals such as platinum and iridium, or yttrium. By varying the number, design and structure of the electrodes, many adaptations are possible – there are currently 31 different electrode configurations in the company’s catalogue. Because many of the latest engines now have bespoke spark plugs, the range has grown to more than 1,250 variants and over 20,000 types have been developed in the last century.

OEM users of Bosch spark plugs include most major vehicle makers.