EMMS - Electrical Mechanical Machining Processes PDF

79 EMMS EMMS is an abbreviation for Electrical Mechanical Machine Shop. The preparation of specimen for testing, tools for machining, and cross section of wheels are done here. Operations such as grinding, turning, milling, and finishing are carried out. TOO...

79 EMMS EMMS is an abbreviation for Electrical Mechanical Machine Shop. The preparation of specimen for testing, tools for machining, and cross section of wheels are done here. Operations such as grinding, turning, milling, and finishing are carried out. TOOLS Single point cutting tool: A single point cutting tool is a simplest type consisting of a single effective cutting edge that removes the excess material from the work piece. Lathe tool (chamfering tool, parting tool, facing tool, etc.), shaper tools (tools used in shaping machine), planer tools, boring tools etc are the examples of single point cutting tool. Multipoint cutting tool: A multipoint cutting tool has more than one cutting edge and includes milling cutters, drill bit, reamers, broachers, grinding wheel etc.  80 Chip removal process: When the cutting tool is forced to move against the work piece, the tool exerts a compressive force on the work piece. The material of the work piece is stressed beyond its yield point causing it to deform plastically and shear off. The sheared portion of the metal begins to flow along the cutting tool face in the form of small pieces called chips. Three different types of chips are formed, they are  Continuous chips  Continuous chips with built up edge  Discontinuous chips TURNING (LATHE) Turning is a machining process used for the generation of external cylindrical and conical surfaces on a rotating work piece by means of a single point traversing cutting tool. The process is usually performed on a lathe, wherein a single point  81 cutting tool is fed against a rotating work piece. Both the work piece and the tool are held rigidly on the lathe.  Turret lathe is used for the preparation of cope and drag mould. MILLING Milling is a manufacturing process in which the excess material from the work piece is removed by a rotating multi point cutting tool called milling cutter. In milling, the cutter is held in the spindle of the machine and made to rotate at suitable speeds. The work piece, which is held rigidly by a suitable device is fed slowly against the rotating cutter. As the work piece advances against the rotating cutter, each tooth of the cutter removes metal from the surface of the work piece to produce the desired shape. Milling machines are preferred for small and medium sized jobs and are used for producing flat, angular or curved surfaces for cutting threads, toothed gears, keyways, slots and wide variety of operations.  82 GRINDING Grinding is a process of removing excess material from the work piece by the mechanical action of abrasive particles that are held together by an adhesive, generally in the form of solid wheel. The wheel known as grinding wheel is rotated at high speeds, and when the surface of the rotating wheel is brought in contact with the work piece, material is removed in the form of fine chips. The depth of cut is obtained by downward movement of the grinding wheel. The process removes very little material in the form of fine chips when compared to that of turning, milling or drilling, and this makes it to be called a finishing process. Grinding is employed to produce a work piece of high accuracy and surface finish.