Welding with Natural Gas
Plastic components such as taillights, battery cases or fuel tanks used in automaking often exhibit a complex geometry and are assembled with the aid of welding machines. To date, these machines have used electric heating elements based on aluminum or aluminum-bronze alloys.
In cooperation with Bielomatik Leuze AG, Neuffen, the Gas Applications Competence Center of E.ON Ruhrgas AG, Essen, has developed hollow stainless steel heating elements with an integral tubular burner and an output of 7.5 kW. The tubular burner operates in either a pulsed or modulated mode. A large number of discharge openings directs the process heat to directly beneath the welding rib – exactly where it is needed.
The automotive supplier Valeo Beleuchtung Deutschland GmbH in Kronach was willing to test the new development under plant conditions for production of automobile taillights. The trials confirmed that the gas-fired heating elements function reliably and are ready to be marketed. The most important benefits include a highly uniform temperature, very good control characteristics, fast warm-up and short idle times due to rapid heating and cooling. The low radiant heat loss saves energy and improves the working conditions for operating personnel.
Energy consumption dropped by more than 20 %. At the same time, weld quality improved, resulting in fewer rejects. In addition, the hollow stainless steel heating elements have a longer service life than their counterparts of solid aluminum or aluminum-bronze alloy. They are also considerably lighter – this simplifies the design of hot-plate welding machines considerably. The natural gas technology can also be incorporated into the machine’s PLC-based controls without difficulty. Calculations show that even with moderate machine utilization, payback times for gas heating of under a year are possible.