Page 51 - Best of STIL 2018 English

The wheel disk and rim are “married” on the wheel assembly line: they are welded together to create a wheel in just a matter of a few seconds
Königswinter is a town with a population of 41,000, located south-east of Bonn. The Maxion Wheels production facilities are located in the district of Niederdol-
lendorf, which nestles close to the Rhine. Here, the main road is a one-way street and the quickest way to get to the other side of the Rhine is by ferry. The former German government guest house, known as Petersberg, can be seen on the peak of the near- by Siebengebirge hill range.
It was in this idyllic setting that Johann, Franz and Simon Lemmerz established a factory for car wheels back in 1919. The two brothers invented the multi-piece wheel rim, which remains in com- mon use to this day. In 1997, the company changed its name from Lemmerz-Werk GmbH to Hayes Lemmerz International Inc. After acquisition by the Brazilian holding company Iochpe Maxion in 2012, the new company name of Maxion Wheels is now clearly displayed in the production halls. With an annual output of more than 58 million wheels (2017), the company is now the world's biggest manufacturer of wheels for cars, trucks, buses and forklift trucks as well as farming and cross-country vehicles.
How a coil is turned into steel wheels
In the production of steel wheels, the rim and disc are first manufactured separately and later welded together. By contrast, aluminum wheels are vir- tually always cast or forged from a single block. A steel wheel is produced by means of cold molding from hot-rolled steel with a high yield strength
(> 600 MPa).
Salzgitter Flachstahl is one of the suppliers for
the Königswinter plant. The coils from Salzgitter arrive by rail and truck, a crane heaves them into one of the two coil warehouses at the plant. At the start of the disc assembly line, the coils are broken down into slugs on the coiler and straightening machine. The cutting scrap goes to the scrap shears and is then passed on for recycling.
The round-cut steel slugs run through various forming stages in the transfer press until they finally emerge as finished discs. During pressing, each workpiece is flushed with a mixture of 90 % water and 10 % oil so as to cool and lubricate the tools. For the production of the rims, a materi-
al section is curved to form a cylindrical drum and them welded at the cutting edges. After this, machines press the profiling into the steel drum so that the disc can be welded on and later the tire is able to sit firmly on the wheel.
The disc and rim are then welded together: a robot lifts the disc into the rim, and a few meters further on the two are heaved up to the welding heads by a mechanical system before blue and white sparks start to fly. The welding process takes just 30 seconds – after which the disc and rim are inseparably joined.
The penultimate stage of the production process is the paint shop. The primer is burned in at a temperature of approx. 200 °C so as to protect
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