In a perfect world, impeders and induction welding coils would not require cooling. Unfortunately nothing is quite that perfect! Copper is an excellent electrical conductor but at the frequencies and power levels used for induction heating, it still has sufficient resistance to require cooling by water or mill coolant. Impeders also require cooling because they operate in close proximity to molten metal and the ferrite that they contain absorbs energy in changing its magnetic polarization, this is dissipated as heat.Impeder and work coil cooling is particularly critical in producing small diameter tubing.
It takes approximately the same amount of power to weld 1/2 inch (13 mm) OD and 4 inch (100 mm) OD tubing of similar gauge, although obviously the impeders and coils for 1/2 inch (13 mm) tubing are much smaller and coolant flow is much less. Most tube mill central coolant systems do not provide sufficient pressure to properly cool these small components, causing them to lose efficiency due to their higher operating temperatures. Return flow impeders and any impeders used with ID scarfing systems benefit particularly from use of a suitable coolant filtration and booster pump system.EHE manufactures a range of impeder and coil coolant systems which provide a steady flow of filtered coolant at optimum temperature for efficient operation.
This increases welding efficiency and greatly reduces the downtime and cost of frequent impeder and coil replacements. These coolant systems use single or dual washable stainless steel mesh filters and regenerative turbine pumps to boost coolant pressure as high as 20 bar (300 PSI) to ensure proper cooling of even the smallest impeders and coils.
All coolant systems can be supplied with flow switches, pressure switches and filter condition indicators for local or remote operation and integration into most existing mill control systems. Dual filter units have isolation valves which allow one filter to remain in line and operating while the other is removed for cleaning. To further increase impeder life, easy to clean magnetic filtration cannisters can be added to both CS-1 and CS-2 models to magnetically remove metallic particles from mill coolant.