Influence of process parameters on the welding temperature of heat-treated Scots pine and the composition of welded strip under optimum parameters

In rotary friction welding experiments of wood, the influence of different process parameters on the welding temperature was investigated, followed by an analysis of how temperature affects the content of lignin, hemicellulose, and other components in the welded zone. Mass spectrometry was conducted under the optimal process parameters to accurately analyze the chemical composition within the welding zone. This study conducted rotary friction welding experiments using thermally modified Scots pine (a physically modified wood material treated at high temperatures to improve its properties) and untreated Scots pine. Experimental groups were designed based on tenon-to-hole diameter ratio, rotational speed, and feed rate. A series of single-factor experiments was carried out to investigate how each process parameter affects the temperature variation in both untreated and thermally modified wood. The results showed that the tenon-to-hole diameter ratio primarily influenced the peak temperature at the welding interface, while the feed rate mainly affected the rate at which this peak temperature was reached. In contrast, the rotational speed had a relatively minor effect on the welding interface temperature. Furthermore, mass spectrometry analysis under optimal welding conditions revealed the generation of various compounds, predominantly furfural, pinene, camphene, and borneol, in differing concentrations. Notably, differences were observed in the welded interfaces between treated and untreated Scots pine. Compared to the untreated wood, the welded zones of the thermally modified material were denser and more robust.