Multi-Magnetrons and Phenolic Moulds—A New Concept in Flexible Foam Moulding

Abstract

This article reviews the previous history of difficulties with the original mould con struction based on epoxy fiber glass construc tion with a filled lossy layer. It will then trace the investigation work for a material with a suitable permittivity and loss angle, preferably obtainable in composite form, it should be economical, simple to form and manipulate and should permit to a large de gree transparency to micro-wave energy. This resulted in a mould material, known as a felt, manufactured from phenolic resin and asbestos, which is manufactured in pre-im pregnated sheets. The techniques of manu facture of moulds will be discussed, together with the necessary safeguards in obtaining a mould with long life which is reasonably in expensive.