Rapid determination of the optimum frequency band and temperature profile using fully computerised VFM oven

Recent developments in variable frequency microwave (VFM) ovens in the market for both laboratory scale application and industrial use for materials processing has led to a new way of thinking for better determination of materials–microwave interactions. This paper reports the use of a VFM oven to determine rapidly and efficiently the optimum frequency band and temperature profile of some dielectric materials such as thermoplastic polymers. The objective was to accurately describe what is the best frequency band for processing these selected materials and the temperature profiles (time vs temperature) using a four-level cavity characterisation facilitated by a fully computerised VFM oven. A fibre optic sensor was used to determine the temperature profile when samples were heated in the oven. The results of the cavity characterisation and temperature profile were compared and analysed using suitable software. For each material, an optimum frequency which could successfully interact with the samples was found, thus allowing efficient use of microwaves in terms of time and energy. The time the microwave power takes to reach the expected processing temperature, at a certain frequency, was also investigated.