High Energy Water Jet Cutting Equations for Wood

To evaluate the potential of cutting wood with high velocity water jets containing polymer additives it is necessary to develop general cutting equations that relate the cutting depth and specific energy to the jet parameters (nozzle size and pressure), the cutting speed and the wood properties. Wood has a complex structure and there are about 14 different properties based on standard physical tests. An experimental investigation is carried out to determine the dominant properties that effect the depth of cut for three typical wood types: maple, elm and poplar. The dominant properties are found to be the wood densities, (wet and dry) and a root mean square value of the compressive and tensile strengths normal and parallel to the grain. Linear and exponential non-dimensional equations are developed that relate the depth of cut to these wood properties and to the cutting speed and jet parameters. The exponential equation with a threshold jet velocity below which no cutting occurs gives the best agreement with experimental results. The equation is transformed to a nondimensional form from which the specific energy of cutting can be determined directly for wood with known physical properties.