Development of a CNC machine energy consumption model and energy analyzer software: towards energy-efficient CNC machining

Abstract

This thesis proposes energy-saving strategies for CNC machining to address high energy consumption challenges encountered by manufacturing sectors. A novel energy consumption model for three axis CNC milling machines is presented in this thesis. This energy model computes energy consumption of any three axis CNC machine based on any given numeric code. The model categorizes energy consumption in CNC machining into seven divisions. Each of the seven energy divisions has its own corresponding power state which can be analyzed individually in controlled experiments. An energy analyzer software was developed to compute energy consumption in CNC machining, based on numeric codes. This software utilizes the energy model developed in this thesis to compute energy consumed by CNC machines. The software then selects the most energy efficient tool pathway strategy. By conducting some machining trials, the energy model and software were validated. The greatest percentage deviation of the software predictions from the measured energy consumption was -1.9%. Nine tool pathway strategies were studied in this thesis using energy analyzer software. The energy consumption of the nine tool pathway strategies was studied on two geometries, the rectangular pocket and the circular pocket. Results from the software revealed the pocket-in and the pocket-out tool pathway strategies were the most energy efficient tool pathways for both the rectangular pocket and the circular pocket. Spiral-in tool pathway had the highest energy demand in rectangular pockets while zig-y tool pathway strategy had the highest energy demand in circular pockets. Results from the software also revealed that, energy efficiency of different tool pathway strategies vary with respect to the geometry being machined. Energy savings were up to 67% for rectangular pockets and up to 33% for circular pockets.