Induction heaters have been used in vehicle repair workshops for a number of years, mainly to heat up seized nuts and bolts and warm up mild steel chassis.
Now, with the introduction of smaller units, repairers can use induction heaters for a variety of applications, including glass removal, moulding removal and the removal of stone chips and sealers.
Induction heating is the process by which heat is generated with the use of an electrical current. It operates on the basic principle of using an applied form of electromagnetic induction.
This was first discovered by Michael Faraday in 1831, who found that when an alternating current is passed through a preformed coil and a steel rod is placed within the middle of the coil an electric current will be induced.
These principles have been developed and applied to manufacturing since the 1920s.
Heat induction systems have been used for a number of years in the production of vehicles on assembly lines. The process maximises productivity with virtually instantaneous start-up, giving the required temperature without a warm-up cycle. The systems have the capability to measure the temperature of each individual component, maintaining a constant required temperature. This eliminates the inconsistencies and quality issues associated with other heating methods.
Because the heat is generated through electromagnetic induction, the workpiece never comes into direct contact with the heat source.
This allows painted parts to be warmed up without damage to the paint surface. It is used to reduce drying times of adhesive and sealer applications in the fitment of glazing and body panels.
Induction heating is a relatively low cost process compared to other forms of heating such as electric and gas ovens.
Induction heaters have been available and used in vehicle repair workshops for a number of years and a variety of machines exist ranging in size and power outputs. Traditionally they have been used for heating up seized nuts and bolts and warming up mild steel chassis to accommodate repair and straightening. The process is also used in fabrication, giving the operator a quick clean source of heat which can be safely used to bend and shape ferrous materials by applying heat locally to a joint which is to be brazed or soldered.
Heat induction systems have recently come to the forefront of body repair shops with the introduction of small units powered from a 240 volts AC supply. This means the units can be run from most 13 amp supplies.
These give the repairer an energy efficient process converting up to 90 per cent of expended energy into useful heat. These devices are available with a selection of hand-held tools for a variety of applications.
In addition to these, attachments have been developed for the following procedures:
Glass removal
This is achieved by the operator applying heat directly above the adhesive through the glass. The electromagnetic current picks up the metal frame to which the glass is bonded. Once the adhesive becomes soft, the glass can be pressed out with the use of wedges between the glass and the frame.
Moulding removal
Side mouldings and impact strips which have been fitted to vehicles with adhesive tape can now be removed with the use of heat induction. The process warms the adhesive by passing the heat source over the moulding allowing the panel behind to become warm which in turn releases the adhesion of the tape or adhesive. Again with the use of a plastic scraper/wedge the moulding can be removed. Once the old adhesive has been cleaned off the moulding, new clear logo tape can be applied to it and the moulding can be reused.
This can benefit those involved in the repair process: the work provider due to the reduction in costs of expensive mouldings; the repairer who no longer needs to order and wait for a new moulding and who can complete the job on time; and the owner who can now have his/her vehicle returned to them.
Removal of stone chip and sealer
Vehicle manufacturers protect areas of the vehicle which are susceptible to stone chipping and water ingress. These need to be removed from the panels to accommodate panel repairs and replacement. Traditionally heat produced from hot air blow guns and naked flames have been used in the removal of these materials.
Heat induction warms up the panel the material is applied to softening the material and allowing it to be scraped off with a plastic scraper. This saves time and reduces the amount of smoke and harmful fumes.
Heat induction units provide an environmentally friendly and efficient source of heat. They can be used for many applications and can virtually replace the traditional naked flame eliminating in most cases the need for oxygen/acetylene equipment and the associated costs rental consumables and insurance cover.
Manufacturers and repairers can make considerable savings using this process providing their employees with a very controllable source of heat and an improved working environment by reducing toxic fumes smoke noxious emissions noise and wasted heat. In cases where the correct processes are used to remove components cost savings to insurers can be achieved as the number of waste components is reduced with a cost saving on their disposal.
Source: Thatcham Research News issue 5/10.