Infrared heating has enabled the paintshop to keep up with the demands of increased production meaning that these days you can watch paint dry in next to no time
Since its introduction in the 1950s, the application of infrared heating has increased in the automotive industry. It has been instrumental in eliminating production bottlenecks, speeding up production and saving costs. A good example of how a company can benefit from its application is found in the UK’s Federal Mogul, which has quadrupled throughput in the curing of powder coating on brake pads.
Federal Mogul brake pads have an anti-corrosion coating, which protects the brake pad against spray water damage in operation. After this black epoxy coating is applied on the production line, it must then be cured and this was originally carried out using conventional medium wave infrared emitters. However, increasing sales demands meant that this kind of drying could not keep pace with production requirements and the company had to eliminate the bottleneck to remain competitive.
There are various restrictions on the heating/curing process. For one, any heat applied should be effective only at the product surface and not within the material of the whole brake pad.
Medium-wave infrared radiation is ideal for melting and curing the epoxy coating and consequently an infrared system with fast-response medium wave emitters form Heraus Noblelight was chosen for the task. Fast-response, medium-wave emitters emit the effective medium-wave radiation, while at the same time delivering the power necessary to speed up the process. But more than this, fast medium-wave emitters have a response time of seconds, compared with the minutes required by conventional medium wave emitters to heat up and cool down. The reaction speed of modern fast-response emitters also means that they are easy to control. This means that it is possible to achieve temperature profiles inside the drying oven to suit a range of brake pads.
The new 162kW infrared oven is fitted with 30 fast-response emitters. It first brings the powder to melting point and then holds the coated products at the correct temperature to ensure curing. The installation of the modern infrared system has quadrupled the powder coating curing of a range of brake pads.
Today, every well-known carmaker has an infrared system installed somewhere. They are still used for bodywork. They are also used in pre-drying, drying of finishing lacquer, as well as in repair drying. Moreover, more and more components are processed with infrared. Petrol tanks, pumps, gears, oil sumps or the brake pads discussed earlier, everywhere there are coatings or protective lacquers that have to be cured or dried.
There are also the heating processes for the plastics used in motor vehicles. For example, injection moulded plastic parts can be deburred by heating, a step which improves quality if the plastic part is to be coated or lacquered later.
If necessary, power densities of up to 1000 kW/m² can be transferred. Such high power is needed for applications such as coil coating. For most applications, powers of around 100 kW/m² are sufficient. Usually, 20 to 30 kW/m² is sufficient to achieve a fast, economical drying of most coatings.
Modern infrared modules are so compact that they can easily be retrofitted into or complement existing ovens. An example is the infrared booster which can be located in front of a hot air oven for coated plastic bumpers. Pre-drying with infrared speeds up the process.
For complicated components, hot air heating and infrared can be combined to advantage. The infrared emitters provide the direct heat while the heat from the hot air oven seeks out all hidden nooks and angles.
Modern infrared emitters can be perfectly matched to product and process in terms of wavelength, power and emitter shape. In every case it is worthwhile to match the heating source exactly to the process and material, as this ensures that not only is the production speed increased but quality is also improved, reject rates are cut and costs are saved.