The theory of operation for an induced current fixture includes several different rationalizations. The induced current fixture can find indications traditionally found with a direct current shot. Processing a round part with direct current requires a minimum of two orientations and can subject sensitive parts to pressures and heat that many designers try to avoid. The advantage of the induced current fixture is a noncontact method, and if running bearing races, or fine gears, contact surface can be a significant issue. Also, the full part can be processed in one step, saving time.
So what makes an induced current fixture different from a normal coil? The answer is simple: the laminated core. Laminated, soft iron works best as a core material.