The ceramic heating plate

Electrolux and AEG, both manufacturers of ceramic heating plates, have more or less introduced me to a firm called Schott. This firm 

After the glass plates have been cut to size, their edges are polished and provided with a decoration. This part of the process is not included in the figure. The decoration process involves ceramic dye which is applied under pressure and subsequently burned into the glass. After that the glass is ceramized, i.e. the crystal growth in the glass 

Finally the plate is tested on heat expansion coefficient, temperature shock resistance, temperature stress (6,000 hours at 650°C), density, E-modulus (92 x 103 N/mm2), flexural strength, impact resistance, Knoop hardness, acid and base resistance. The heating element is insulated with a compressed mixture of powder and fibre which contains aluminium oxide and silicon oxide. In the middle the element contains a so-called Stabausdehnungsbegrenzer (= expansion limiter), which automatically switches the element off in case the temperature exceeds a certain pre-set value. 

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