The minimum length should be sufficient to exceed the distance from weld point to the front of the work coil Cooling - Ferrites will have a decreasing ability to concentrate flux as the operating temperature rises. At temperature exceeding the Curie temperature, all practically useful magnetic properties would be lost. These changes are completely reversible and it follows that maximum cooling will give the best performance. Ferrite Geometry - Geometry should be such as to give maximum ferrite packing consistent with good coolant flow through the impeder. MMG fluted rods with wide open flutes in tightly fitting tubes give this best compromise in the smaller sizes and form the basis for our standard small impeders.
Larger sizes are generally less critical and utilize bunched ferrite rods for improved water flow.
Frequency mills require impeders of greater length than standard, or in dimensions other than shown. Customers are encouraged to inquire about non-standard sizes as a large variety of sizes can be manufactured. Standard Return Flow Impeders Standard H.F. Welding Return Flow Impeders have a coolant inlet and outlet at the same end to prevent coolant flooding down the welding tube. Through Impeders are available with brass components designed to protect the impeder housing and prolong its life. I ntegral Impeders are designed for easy attachment to the hollow 'tie-bar' for scarfing and bead rolling applications.