Quantitative and qualitative analysis of strain near the cutting edge during highspeed machining of hardwood

A predicted increase of hardwoods in the Central Europe forests predetermines the transformation of industrial processes from softwood to hardwood cutting technologies. This study is part of the work systematically characterizing the high-speed linear and rotational cutting of hardwood by using of in-house device and conventional CNC machine. Based on the unique experimental data from Split-Hopkinson pressure and tensile bar the numerical models of hardwood linear and rotational cutting are built. In this study, the strain field near the cutting edge is analysed by digital image correlation. The images are acquired by high-speed cameras during the linear and rotational cutting of European beech ( Fagus sylvatica L.) at various moisture content (MC) levels and knife sharpness condition (Fig. 1). The analysis pointed out the differences compared to softwoods and specifics of hardwood cutting. The development of strain field during the chip formation is related to reaction forces pattern. The presented strain analysis may contribute to optimizing of high-speed cutting of hardwoods. The affected area near the cutting edge during the linear cutting of hardwood is larger compared to softwood; meanwhile, from the qualitative point of view the strain field was similar. There were recognized tension and compression normal strains. The findings about cutting conditions effects can be generalized for both hardwood and softwood similarly. The rotary cutting is specific compared to linear one from the quantitative point of view by an increasing magnitude of strains and increasing size of affected area during the chip formation, and from the qualitative point of view by almost no tension strain.

Automated summary

The predicted increase of hardwoods in the forests of Central Europe will lead to a transformation of industrial processes from softwood to hardwood cutting technologies. This study systematically characterizes the high-speed linear and rotational cutting of hardwood, and builds numerical models based on experimental data. The findings highlight the differences and specificities of hardwood cutting compared to softwoods, and provide insights for optimizing high-speed cutting of hardwoods.