Transport and Engineering. Production Technologies ________________________________________________________________________________________________________ 2013 / 35 93 Design of Internally Cooled Tools for Turning Artis Kromanis 1 , Guntis Pikurs 2 , Guntis Bunga 3 , Kalvis Kravalis 4 , Gatis Muiznieks 5 , Viktors Gutakovskis 6 , Riga Technical University, Institute of Mechanical Engineering Abstract – Nowadays more and more emphasis is put on the development of environmentally friendly technologies. It is well known that the use of cutting fluid or cooling liquid poses risks to environment and health. It can also increase the cost of manufacturing. This paper presents the latest developments in smart cutting tools having internal cooling. This paper unites the main researches that have been done in the field of internally cooled tools. Many proposed solutions are still at the conceptual level. This paper recognizes the concepts of internally cooled tools and gives directions for further research and discussions. Keywords – internally, cooled, smart, tool, turning. I. INTRODUCTION During the cutting, due to the friction and chip deformation, high cutting temperatures occur and a tool and a workpiece are subjected to increased thermal load causing significant tool wear. It causes wear and thermal damage of the cutting tool, shortening tool life and consequently, resulting in poor surface roughness and dimensional tolerance. To reduce the cutting temperature, cutting fluid is traditionally used to remove the heat generated, decrease cutting force, and improve tool life. Cutting fluid is also used to reduce formation of a built-up edge and increase the removal of chips from the cutting area. However, the use of cutting fluid has its disadvantages. Depending on the workpiece, the production process, and the production location, the costs related to the use of cooling lubricants range from 7 per cent to 17 per cent of the total costs of the manufactured workpiece [1]. Additionally, many cooling fluids contain harmful or damaging chemicals causing environment pollution and operator’s health hazards, so strict environmental policies and health regulations have been introduced in connection with the increasing awareness of the environment and human health [2, 3]. To cope with the mentioned hazards it is necessary to operate in dry cutting mode, where no cutting fluid is used. Therefore, components and/or products can be manufactured both ecologically and economically. Dry cutting could be a solution if other obstacles would not arise. In dry cutting as a result of absence of cutting fluid more friction and adhesion between the tool and workpiece will occur. Recently many research attempts have been initiated to investigate the possibility of avoiding the use of cutting fluid, such as using new tool materials and geometries, adding a heat pipe to the cutting tool, coating with solid lubricant, and applying internal cooling, etc. [3-7]. The most promising solution for dry cutting seems to be the use of internal cooling. Many researchers concentrate their research in this field, but still there is no concrete solution, which could be brought into industry. This paper analyses internal cooling techniques and introduces novel solutions or concepts, on which research could be carried on. II. DESIGN CONCEPTS OF INTERNALLY COOLED TOOLS In industry cooling of cutting tools as well as cutting area is provided still in the conventional way - cutting fluid is fed into the cutting area directly. In this cutting area certain part of the cutting fluid evaporates and the rest of cutting fluid mixes with chips. After certain time cutting fluid wears out and it cannot be used anymore. First designs of internally cooled tools proposed the following solution: a cavity in the tool holder was made; over this cavity a cutting insert was placed; cutting fluid was introduced through the channel in the tool holder; the cutting fluid flew to the said cavity under the cutting insert; heat from cutting insert was transferred to the given cutting fluid, which in turn was pushed away from the given cavity via an outlet channel made into the holder. This is a typical scheme of internally cooled tool in turning. Fig. 1 illustrates this typical scheme of internal cooling system [8]. Fig. 1. Scheme of the cooling system (a) and tool holder (b) [8] Another approach introduces a cutting tool having a cutting element such as an insert which is cooled indirectly by a micro-channel heat exchanger that is mounted against the rear face of the insert (see Fig. 2). The heat exchanger is formed