Increasing efficiency of an industrial robot when machining timber beams – introduction of a parametric solving model to determine optimised stacks

ABSTRACT The aim of this study was to increase the economic efficiency of industrial robots (IR) when subtractive machining timber beams. The most compact possible stack configuration, consisting of three different workpiece geometries, was calculated and machined. When compared to machining individual workpieces, a reduction of the process time is strived for. The workspace of the IR should be fully utilised by an optimised spatial stack configuration (number, location and spacing of workpieces). The stacks were calculated using a parameterised evolutionary solver model in Rhinoceros, Grasshopper, Galapagos and Opossum software. Machining trials were performed to obtain process time data for the IR and as a reference for a benchmark joinery machine (JM). By applying the newly introduced optimisation model, the process time per workpiece, when machining stacks instead of individual specimens, was reduced by 16%. This result was primarily achieved by shifting the share of non-machining time to machining time. When compared to individual machining with a JM, the process time of the IR is still higher. This fact can be outweighed by advantages of IRs such as cost, availability and flexibility, showing that the overall economic efficiency of IRs does in fact hold potential for prefabrication in the timber construction sector.