 Hello, I am Mr. D. J. Doshi, working as assistant professor, Department of Mechanical Engineering, Walsh University of Technology, Seoul. Today's learning outcomes are at the end of this session, students will be able to classify the different machine tools, discuss the construction of lathe machine. And in this video are introduction to machine tools, classification of machine tools, principle and construction of lathe machine. So, in introduction of machine tools, we will introduce what are machine tools, what work the machine tools carry out. And the classification of machine tool, we will discuss how the machine tools are classified depending upon the type of operation, type of material removal and type of work done on it. And third part is principle and construction of lathe machine, in which we will discuss about the principle of working of lathe machine and construction of lathe machine. First one, introduction of machine tools. These are the machines used for carrying out metal cutting processes and surface finishing processes. So, the machines which are used for cutting the metal are called machine tools. Each machine can carry out one or more than one type of processes. So, under each under this it will be turning, facing, shaping or forming or giving any shape which we will discuss under this machine. These are order machines used for making the component of desired shape, size, accuracy and surface finish by removing the material on it. These machines are different types of cutting tools, remove the material. So, machine tools are broadly classified under metal cutting machine tools and surface finishing machine tools. Under metal cutting machine tools, these machines remove major part of the material which will give the shape and size, whereas the surface finishing machine tools are removing very little part of the material and give it finish or desired accuracy or design fitting required. Under metal cutting machine tools, first one is lathe machine in which the job is hold in the spindle or jug and the material can be removed parallel to the axis and perpendicular to the axis. When we remove the material parallel to the axis, it is cylindrical turning or turning operation which will generate different size of the shafts. Whereas, if you remove the tool perpendicular to the axis, it will generate the flat surfaces. Second one is drilling machine. It generates the aperture of any size depending upon the tool in the work piece or in the component. So, drilling of machine in this drilling machine, the job is hold on the plate or on the table and the tool will move vertically up and down and around it one axis. So, it will generate the aperture in the component. Milling machines can remove the material parallel as well as perpendicular to the table moment and it will generate the flat surfaces as well as if the cutter has a convex or concave surface. Accordingly, it will generate the concave or convex surface of the desired radius on the component. Shipping machines here the job is hold in the bench wise or in the picture and the tool will reciprocating on it. So, it will generate the required surface on the face or side of the face. Now, second classification is surface finishing machine tools. As I told, these are to remove very little material, minute material and this will give only the finished surface of desired size. So, first one is grinding machine where the grinding tools are used to make the surface finish or the cylindrical surface finish or the flat surface finish with the help of grinding tools or grinding wheel what is called as. If it has a particular shape then that type of surface finish can be operated on the job or component. Now, the grinding machine these machines are generating the cylindrical hole as a finished surface. So, usually these are used for cylindrical blocks or cylinders of the component or wherever in inner surface of the component is to be finished as well as accuracy size. Lapping machines these are almost remove very minute material and this will give you super finish by using the lapping tool or polish papers of different size. Polishing machine these are used to carry out surface finishing on the surface which is machined which will give you the polished finish. Pause the video and answer this question. What is the main difference between metal cutting machine tools and surface finishing machine tools? I hope you have written the answer of this question. The answer for the question is metal cutting machine tools remove major stock of material to give desired shape and size whereas, surface finishing machine tools remove minor stock of material to improve surface finish. Firstly, we will study about lathe machines. So, what is lathe machine what are principles of it and what is the construction of the lathe machine. In the lathe machine the work piece to be machined is held firmly and rotated about it axis. So, here the spindle of the machine rotates on which a fixture is mounted which will hold the work piece and it when we start the machine the spindle starts rotating which will make the job to rotate along its own axis and the job is hold firmly in the fixture. So, it will be rotated the job component will be rotating along its own axis or along the axis of the lathe. Whereas, the cutting tool is moved relative to the work piece that is parallel to the axis perpendicular to the axis and or angular to the axis. In this case as I told you the work piece is rotating along its own axis or along the axis of the lathe whereas, the tool will either move parallel to the axis of the lathe perpendicular to the axis of the lathe or if the angular surface is required the tool will be moved angular to the axis of the lathe. The cutting tool is made of harder material than the work piece. So, the cutting tool which we are using is made up of either HSS, carbide or diamond. So, these tools are harder than the material to be removed so that we can remove the material on the component on the work piece. The cutting tool removes undesired material from the work piece in the form of chips to give desired shape and size. So, when the cutting tool moves either perpendicular, parallel or angular to the axis of the lathe it will go on removing the undesired material the material which is not required will be removed with the help of tool step by step. So, we cannot remove the material at a time but it will be step by step which is called as depth of cut. So, when I apply certain depth of cut it will remove only that much material. Suppose 1 mm is the depth of cut then it will go on removing 1 mm on the surface if it is perpendicular to the axis or 1 mm along the radius when it is parallel to the axis. So, here the diameter will be reduced by 2 mm. So, we will go on removing the material step by step and we will give the desired shape and desired size. When we make the tool to travel either perpendicular to the parallel of the axis it will remove the material in the form of chips or in the form of scrap. So, it will give you the desired shape and size. Now principle and construction of lathe machine if you observe here the job is hold in a work piece holding device which is usually called as a chuck which is shown in the figure. And the work piece is hold in the chuck which will rotate along its own axis it may be supported from the front side. So, that there will not be any movement of the work piece perpendicular to the axis. Now in first case the tool is moving parallel to the axis. So, the cutting tool when moves parallel to the axis as I told it will go on generating the cylindrical surface. And the material removed along the radius will be the depth of cut where the diameter will be reduced double the depth of cut. Now second one is perpendicular axis the tool movement perpendicular to the axis. In this case again job is hold in the work piece holding devices the work piece will rotate along its own axis and the tool will move perpendicular to the axis. It will reduce the length of the component or length of the work piece the depth of cut will be the chip removed and the depth of cut will reduce the length. So, it will be equal to the depth of cut the reduction in the length will be equal to depth of cut. In third case again the job is hold in the work holding device and the tool will made to move angular to the axis. Now the angle calculations are different part that we will study or discuss during next lecture or next video. But the tool will move angular to the axis it should not move parallel to the axis. So, it will go on reducing the material or removing the material angular to the axis and it will generate the surface which is taper surface and give the desired diameter at the end of the taper surface as well as at the starting of the surface. In this case also it needs to support the work piece from front side which is usually called at length. Now reference is used RBL single a textbook of basic mechanical engineering TechMax publication. Thank you.