Overmolding: From Magnet to Component
Dr. Martti Paju, Technical Director, Hangzhou Permanent Magnet Group
Incorporating a metallic magnet, especially a small magnet, to a magnetic system may sometimes be challenging. Magnets are fragile, which makes using of mechanical joints difficult. Surface active elements used in coating process may cause problems in glueing. Overmolding of sintered magnets with suitable polymer offers a unique and effective way to turn a magnet to a component, thus making final assembly easy and effective. In overmolding a magnet is placed in a normal injection molding tool and molded in plastic. The resulting component can be a sub-component, easy to assemble or the final component. Basically, design of the plastic part is only limited by the need to be able to utilize the magnetic field of the magnet in a proper way. Moreover, the magnet can be hermetically sealed in plastic and other parts, like shaft or bushing can be molded at the same time. In this presentation the overmolding process is presented and benefits discussed and illustrated with actual components.
Dr. Martti Paju is currently Technical Director of Hangzhou Permanent Magnet Group. He received his PhD in metallurgy in 1990 from Helsinki Technical University (Aalto University). After several years in steel industry, Dr. Paju started his career with magnets at Outokumpu Invest Oy, which in those days owned Swift Levick Magnets (UK), Outokumpu Magnets (now Neorem Magnets) and Sura Magnets AB in Sweden. After 12 years at Sura Magnets Dr. Paju moved 1995 back to Finland to start Prizztech Magnet Technology Centre in Pori. Since 2015 he has worked for HPMG.