September AMP_Digital

FEATURE A D V A N C E D M A T E R I A L S & P R O C E S S E S | S E P T E M B E R 2 0 1 8 4 6 *Member of ASM International INDUCTION HEATING: EVERYTHING YOU WANTED TO KNOW, BUT WERE AFRAID TO ASK As a regular contributor to the HTPro eNewsletter, Professor Induction answers a wide variety of questions regarding induction heating and heat treating. Included here are three recent challenges and solutions. Valery Rudnev, FASM,* IFHTSE Fellow Inductoheat Inc., Madison Heights, Mich. I nduction heating is a multifaceted phenomenon com- posed of complex interactions involving electromagnet- ics, heat transfer, materials science, metallurgy, and cir- cuit analysis—with applications across multiple industries. Figure 1 shows a small portion of a virtually endless variety of workpieces where electromagnetic induction heating is used to develop an attractive blend of microstructures and properties at a competitive cost. We use an induction process where we need to include physical barriers and/or a safetywarning for peoplewithmed- ical devices suchasmetallic implants and cardiac pacemakers to stay a certain distance away. What is the required distance for people with such devices to stay away from induction heat- ing coils? Thank you for any help you can provide on stand-off distances. Answer: Many studies have been conducted to eval- uate the direct and indirect effects of electromagnetic field (EMF) exposure on health, passive and active medical im- plants, and hypersensitivity. Several national and interna- tional organizations including the Institute of Electrical and Electronic Engineers (IEEE), International Radio Protection Association (IRPA), World Health Organization (WHO), Occu- pational Safety & Health Administration (OSHA), and others have developed awareness programs regarding non-ioniz- ing radiation and evaluation of the health risks associated with external field exposurewhen using any electromagnetic device (such as cell phones, household electrical applianc- es, computer monitors, transmitting antennas, microwave ovens, induction coils, and others). A large body of scientif- ic research exists and a number of international standards, guidelines, and regulations have been put into effect. For example, in the U.S. these include the following standards: • IEEE: C95.6 Safety levels with respect to human expo- sure to electromagnetic fields, 0 to 3 kHz. • IEEE: C95.1 Safety levels with respect to human expo- sure to electromagnetic fields, 3 kHz to 300 GHz. All manufacturers of electromagnetic devices (in- cluding induction heating manufacturers) are supposed to comply with international/national standards and reg- ulations related to controlling external exposure to EMF in the workplace. Fig. 1 — Induction heating applications across a variety of industries. 14