Manufacturing gluing-in-rods under low temperatures and with shorter process times using induction and resistive heating

Abstract

This paper summarizes joint research efforts of the University of Kassel and Fraunhofer IFAM, focusing on resistive and inductive heating as techniques to achieve fast curing in the particular context of tests on glued-in rods, as performed in the last 2 years. In different series of experiments, conducted on metallic bars glued into timber, the difficulties practitioners face with regard to temperature control are described. In a further set of experiments, induction is combined with a pre-applicable structural adhesive (PASA); it is shown how an innovative combination of PASA with induction heating leads to a process of gluing G-FRP rods into timber that substantially gains in terms of process quality and time. In the final series, in which a 1 K epoxy is mixed with metallic particles that exhibit a Curie temperature adapted to the curing temperature of the adhesive, we show how the induction process can be run without any outside control, leading to a technical solution adapted to practitioners.