Sawing frozen wood differs significantly from sawing unfrozen wood. Temperatures below zero degrees result in an increasing hardness of wood, rising cutting forces and a progression of tool wear. Currently, the adaption of process parameters due to different wood temperatures is based on operator experience, leading to overloaded saw blades, hence causing considerable economic damage by increasing production downtime. This paper presents the development of a measuring and control unit featuring an integrated database of processing values enabling operators to use most suitable process parameters, thus extending the service life of circular saw blades and increasing the performance of sawmills.
Wood as a renewable material plays an important role in transforming society towards sustainability and climate neutrality. However, wood is a difficult material to saw due to its anisotropic and inhomogeneous properties. Currently, the adaption of process parameters due to varying wood temperature and moisture content are solely based on operator experience. This frequently results in unfavorable settings of process parameters leading to a drastic increase in energy consumption and poor surface quality of the sawn wood. This paper investigates the cutting force when sawing frozen spruce wood with a two tooth research saw blade and the surface quality of the resulting wood samples under varying influencing factors. The material properties temperature between 20 ℃ and −40 ℃ and moisture content as well as the kinematic factor cutting direction were observed. The results show that the cutting force of moist and wet wood increase with decreasing temperature and remain constant for dry wood. Additionally, the surface quality of wet and dry wood samples is improved when sawing wood with lower temperature values. Using these results, the operator can be supported by a data driven approach for the adaption of machining parameters, hence improving the energy- and resource-efficiency of the process.
The processing of wood as a renewable and sustainable material is steadily gaining in importance. However, sawing processes in sawmills are characterized by high electrical energy consumption. Improving the geometry of the saw teeth is an option to make sawing processes more energy efficient and sustainable. Since the industrial sawing processes in sawmills are rather inflexible, the development of new saw tooth geometries takes place in smaller experimental setups. However, the inhomogeneous and anisotropic properties of wood make it difficult to compare different material samples and saw teeth on the basis of measured values. This leads to untapped potentials regarding energy efficiency and sustainability in industrial sawing processes. This paper discusses material properties of spruce wood samples, depending on their place of extraction from the tree trunk. The measured variables considered are the wood moisture content, strength properties and the cutting force occurring during the sawing process. The results show that the measured values vary to different degrees within a tree trunk and between different tree trunks. Based on the results the validity of comparison measurements in the tool development process can be improved and thus increase the efficiency and sustainability of industrial sawing processes.
Often, carbon fiber reinforced plastic (CFRP) manufacturing represents an expensive, time-consuming, small-scale production due to products and components characterized by complex geometric properties. In the field of orthopedic products individual molds, usually made of metal alloys or plaster, are necessary to shape the contour of the components. The presented case study focuses on individually manufactured masks for post-operative treatment of uncomplicated midfacial fractures that are frequent and typical injuries in popular contact sports like football or handball. To improve the costly process of CFRP production of individually manufactured masks, this paper describes the advantages of the combination of optical metrology (i.e. 3D-scanning) and additive manufacturing (i.e. 3D-printing). Therefore, the conventional process chain consisting of the main process steps molding (master pattern), casting (mold), CFRP laminating, curing, cutting and final assembly is replaced by 3D-scanning (instead of master pattern), followed by the revision of the CAD-model (to prevent cutting efforts), 3D-printing (mold), CFRP laminating, curing and final assembly. Summarizing, this case study on manufacturing of carbon fiber reinforced plastic orthopedics shows that the combination of innovative manufacturing technologies opens up new possibilities to increase efficiency in craft based manufacturing.
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