###### Abstract  
When a comparison is made between production methods, it will be seen that a significant amount of energy is consumed in machining processes and a large part of this energy is lost as waste heat. This is an important risk factor for both energy efficiency and environmental protection. During metalworking, a very high level of heat is generated at the cutting tool-workpiece interface. We have conducted a comprehensive literature study on this subject, but so far, no study has been found on the recovery of the heat generated in machining processes. Therefore, the aim and motivation of this study is to recover this waste heat to a certain extent. For this purpose, a comprehensive coolant temperature control and heat recovery system has been developed. This system, which was produced as a prototype, can be easily integrated into the machine tool and automatically adjust the coolant temperature to a certain constant temperature level and maintain this temperature value throughout the process. More importantly, it recovers the heat energy taken from the coolant and makes it useful. On the other hand, although it is not the subject of this study, cutting performance increases, coolant consumption decreases and tool life is extended with the cooling of the coolant. Thus, environmental risks are also reduced. Also, the efficiency and economic feasibility of the developed system were also examined. For this purpose, the energy amount consumed by the developed system and the machine tool were measured separately, and the total energy consumed was determined. Then, the consumed and recovered energy amounts were compared, and it was seen that the amount of energy recovered was more than the total amount of energy consumed. When the decrease in coolant and cutting-tool consumption is also taken into account compared to the classical cooling system, it is understood that the amortization period of the developed system is quite low. On the other hand, optimum conditions were investigated in order to provide maximum energy recovery. For this purpose, experiments were carried out by drilling 2592 holes on 27 samples, 96 holes in each sample, by taking the coolant solution ratio, cutting speed, and feed rate as variable parameters. The experimental results were evaluated using the Taguchi method. It has been observed that the system can be easily adapted to other machining processes, such as turning and milling, and that it has a high potential to increase energy efficiency and prevent environmental risks in this area. colant temperature; energy recovery; coolant--water source heat pump; energy efficiency; sustainable manufacturing +
Footnote †: journal: Applied sciences  
amount of heat energy is generated at the interface of the cutting tool and the workpiece during cutting. Unfortunately, this energy is released into the environment as waste heat and is lost [5; 6]. Machining processes generate high temperatures at the tool-workpiece interface, which, if used effectively, can significantly increase energy efficiency and reduce operating costs. Therefore, waste heat recovery in machining has enormous untapped potential. Energy consumption in machining processes results in significant heat generation at the tool-workpiece interface due to friction and plastic deformation [7; 8]. Historically, very comprehensive studies have been conducted in the field of machining. These studies generally focused on areas such as tool wear, cutting forces, energy consumption, and different cooling methods. However, no study has been found on the recovery of the waste heat generated [9; 10]. While industries such as steel and glass manufacturing have long adopted heat recovery technologies, sectors such as machining have been slower to integrate similar solutions due to the complexity of heat transfer mechanisms in metal cutting. During the metal-cutting process, heat is dissipated between the chip, tool, and workpiece, complicating efforts to recover this energy [11].