Waxing lyrical about radiant heating in automotive anti-corrosion process

Victory Lighting recently helped a major global automotive manufacturer reduce their energy bill and improve their line throughput by developing a radiant heating system for their anti-corrosion wax coating process.

Front Car Pano1

Currently the process requires painted body shells to spend up to 20 minutes travelling through an 80m long oven which takes the injected wax through it’s “jellification” state and allows it to run through the under-body chassis to fully coat the internal sub-frame structure.  While the process is well controlled there is a lot of wasted energy (i.e. the whole body is heated, not just the areas of wax coating) and the oven is open ended as the line passes through, hence heat escapes at either end.  Additionally, there needs to be a tilt stage to ensure the wax flows into the “nooks and crannies” of the interior multi-layer sub-frame structure, difficult to perform in a continuous line and inside an oven.  Lastly in the rare case of a line-stop, bodies in the oven may experience excessive heating (certainly unnecessary heating) as the oven must remain on at all times to maintain the process temperatures required.

Using a half-sectioned painted body in our R&D laboratory in Hemel Hempstead, Victory were able to develop a radiant heating system that could achieve the required internal cavity (sub-frame) temperatures to covert the wax from semi-solid to liquid, within 60 seconds.  The system heats only the sub-frame and only applies the heat for the 60 seconds required by the process.  In a second station the heat is applied a second time for 30s to ensure heat lost in station-transfer is regained, then the vehicle is tilted to ensure internal multi-cavity parts are coated.  The process is performed in an open line, no oven structure is required and the heat is applied instantly-on and removed; instantly-off.  Heat is only applied to the sub-frame areas where wax is injected, hence no other parts of the body are heated, so there is no wasted heat in the process itself. Likewise, in the rare case of a line-stop all heat can be instantly removed, meaning nothing gets excessively heated and no energy is wasted.

The end result is a reduction in this process cycle time from 20 minutes to 2 minutes per vehicle and a line length reduction from 80m to approximately 10m.  Other savings will be in the energy bill reduction.

The system was developed with automotive line access and up-time concerns in mind too.  For example every heating element is identical, so carrying spares is simple and low cost.  Being in an open environment access to both the vehicle and processing system itself is straight-forward should it be required (access in an 80m oven is difficult to say the least).

There is an additional environmental saving too, above and beyond the energy saving the new system offers.  The collection of the wax which inevitably flows out of the sub-frame was attempted in the 80m oven, but proved difficult over such a large system.  Utilising two near identical short-length process cells, wax collection and re-use is relatively easy and saves both material and further cost saving to the vehicle maker.

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