Analysis on Energy Efficient Switching of Machine Tool With Stochastic Arrivals and Buffer Information

Abstract

Energy saving in production plants is becoming more and more relevant due to the pressure from governments to contain the environmental impact of manufacturing, and from companies to reduce costs. One of the measures for saving energy is the implementation of control strategies that reduce energy consumption during the machine idle periods. This paper proposes a framework that integrates different control policies for switching the machine off when production is not critical, and on when the part flow has to be resumed. A general policy is formalized by modelling explicitly the energy consumed at each machine state. The policy parameters that minimize the requested machine expected energy are provided analytically for general distributions. Numerical results are based on data acquired with dedicated experimental measurements on a real machining centre, and a comparison with the most common practices in manufacturing is also reported.Note to Practitioners -The paper analyzes the control problem of switching off-on a machine tool for energy saving during the idle times. Different control policies are investigated pointing out the most significant factors. A mapping of the optimal control policy as a function of warm-up time and mean part arrival time is also provided. An algorithm is described for identifying the optimal control parameters. The results of this research will be useful for a practical implementation of a switching policy for energy saving. This implementation requires the fitting of the distribution modelling the part arrival times, the estimation of the warm-up time, and the estimation of the power adsorbed by the machine in four different states.

Design Model of Flow Lines to Include Switch-Off Policies Reducing Energy Consumption

“…To determine the best switch off control parameters, a full factorial design has been developed. According to Reference [23], the levels of buffer to switch off or switch on machines respect the following constraints (Equations (14)- (16)): Figure 5 reports on the experiment results for model 1. The design with the lowest inactive time has a value of 0, the design with the highest inactive time has a value of 1.…”

“…The decision of the switch on is crucial to maintain the productivity level of the production line. Some approaches have been proposed, by Frigerio and Matta [15,16], with a significant reduction in energy consumption in a flow lines context. The switch-off models proposed works on a flow line designed following classical objectives that solve the simple assembly line balancing problem [17,18].…”

“…Su et al [23] and Frigerio and Matta [16] studied upstream, downstream, and mixed policies in a single machine, and the extension to a production line, assuming stochastic arrivals, and constant warm-up under to stock control. These models did not consider how the control of the machines may reduce the production performance of the manufacturing system.…”

Peak Electricity Demand Control of Manufacturing Systems by Gale-Shapley Algorithm with Discussion on Open Innovation Engineering

“…These models control the switch-off of the machines when the upstream buffer is empty or the downstream buffer reaches a maximum level. These approaches need an adequate buffers' level to reduce the impact on throughput [6,7].…”

“…One field of the research concerns the reduction in energy consumption in manufacturing systems considering the switch-off of the machines [6][7][8]. The introduction of buffers is necessary to keep the throughput target of the system.…”