Field and laboratory studies on natural stones leading to empirical performance prediction of chain saw machines

Abstract

Quarries using chain saw machines have been visited to collect natural stone samples and recording performance and operational conditions of these chain saw machines. After defining the physical and mechanical properties, the samples were tested with a linear cutting test rig using chisel type cutting tools having different sideways angles to determine the cuttability of the stones; this included the maximum tool forces and relationships between cutting performance of chisel tools and the mechanical properties of the stones. Two empirical models for prediction of the areal net cutting rate of the chain saw machines were developed, which is very important for decision makers at the feasibility stage of a quarrying operation. One of the models is based on the chain saw penetration index, and uses the uniaxial compressive strength of the stone, weight of the chain saw machine and useful cutting depth of the arm as predictor parameters. The other model is based on the results of linear cutting experiments performed in the unrelieved cutting mode with a standard chisel tool and uses specific energy as the predictor parameter. Experimental studies indicate that laboratory cutting performance and optimum cutting conditions for chisel tools can be reliably predicted by using uniaxial compressive strength and Brazilian tensile strength of the stone. Variation in maximum tool forces, which is very important and required by machine manufacturers to design the tool, tool holder, and chain and evaluate machine vibrations, is found for different sideways angles of the cutting tools. It is statistically proved that the model based on chain saw penetration index and linear cutting experiments are valid and reliable for predicting the areal net cutting rate of chain saw machines.