A control system for microwave processing of materials

This paper discusses a control system for microwave processing of materials . Microwave joining of ceramics and drying of timber are currently industry practices while microwave joining of engineering plastics and curing of ep oxy adhesives are still being researched. in this study, all materials are processed in rectangular sections of waveguide fed by a magnetron with a ma ximum output power 2 kW operating at 2.45 GHz. The most significant problem s encountered when processing these materials are: (i) maintaining proper t uning to ensure maximum power transfer, (ii) thermal runway, where the hear ing rate proceeds so rapidly that the material burns within a few seconds, and (iii) hot spot development, where localized regions heat up at a faster rate than adjacent regions. A computerized automated control system has be en developed to alleviate these processing problems and has been successful ly employed in joining a range of ceramics and engineering plastics, curing epoxy adhesives and drying wood Results of preliminary tests obtained usin g the developed prototype are presented.