LABORATORY MANUAL J E C GROUP OF COLLEGES PREFACE This laboratory is aimed at providing an introduction to the Know-how of common processes used in industries for manufacturing parts by removal of material in a controlled manner. Auxiliary methods for machining to desired accuracy and quality will also be covered. The emphasis throughout the laboratory course will be on understanding the basic features of the processes rather than details of constructions of machine, or common practices in manufacturing or acquiring skill in the operation of machines. Evidently, acquaintance with the machine is desirable and the laboratory sessions will provide adequate opportunity for this. - HEAD OF DEPARTMENT DEPARTMENT OF MECHANICAL ENGINEERING LABORATORY MANUAL J E C GROUP OF COLLEGES INDEX S. No. List of Experiments Page No. 1. To study of single point cutting tool geometry and to grind the tool asp er given 1-4 tool geometry. 2. T o study the milling machine, milling cutters, indexing head sand i n d e x i n g 5-14 methods and to prepare a gear on milling machine. 3. T o machine a hexagonal / octagonal nut using indexing head on milling 15-18 machine. 4. To cut BSW/Metric internal threads on lathe machine. 19-22 5. T o cut multi-start Square/Metric threads on lathe machine. 23-26 6. Boring using a boring bar in a centre lathe. 27-28 7. Study of capstan lathe and its tooling and prepare a tool layout & jobas per 29-34 given drawing. 8. Demonstration on milling machine for generation of plane surfaces anduse of 35-38 end milling cutters. 9. Grinding of milling cutters and drills. 39-42 10. Cylindrical grinding using grinding attachment in a centre lathe. 43-48 11. To determine the coefficient of permeability of a soil using constant head 49-54 method. 12. To study lathe machine construction and various parts including 55-64 attachments,lathe tools cutting speed, feed and depth of cut. DEPARTMENT OF MECHANICAL ENGINEERING LABORATORY MANUAL J E C GROUP OF COLLEGES Experiment No. 1 Object Study of single point cutting tool geometry and grind the tool as per given tool geometry. Apparatus Mild Steel Job Piece, Grinding machine etc. Theory Both material and geometry of the cutting tools play very important roles on their performances in achieving effectiveness, efficiency and overall economy of machining. Tool Surfaces and Elements The design components of the cutting tool are defined as follows: Rake face is the surface over which the chip, formed in the cutting process,slides. Flank face is the surface(s) over which the surface, produced on the workpiece, passes Cutting edge is a theoretical line of intersection of the rake and the flank surfaces Cutting wedge is the tool body enclosed between the rake and the flank faces Shank is the part of the tool by which it is held Cutting tools may be classified according to the number of major cutting edges (points) involved as follows: Single point: e.g., turning tools, shaping, planning and slotting tools and boring tools Double (two) point: e.g., drills Multipoint (more than two): e.g., milling cutters, broaching tools, hobs, gear shaping cutters etc. Fig. 1.1 DEPARTMENT OF MECHANICAL ENGINEERING 01 LABORATORY MANUAL J E C GROUP OF COLLEGES The terminology used to designate the surfaces, angles and radii of single-point tools is shown below. The tool shown in Figure (a) and (b) is a single-point cutting tool, but the same definitions apply to index able tools as well. Fig. 1.2 Figure.1.2 (A)Three views of a typical HSS (High Speed Steel tool) showing the various angles and their values with abbreviations. (b) Designations and symbols for the right-hand cutting tool with the tool signature Terminology Face The flat surface of a single-point tool into which the workpiece rotates during a turning operation. On a typical turning set-up, the tool face is positioned upwards. Feed The rate at which the cutting tool and the workpiece move in relation to each other. For turning, “feed” is the DEPARTMENT OF MECHANICAL ENGINEERING 02 LABORATORY MANUAL J E C GROUP OF COLLEGES rate that the single-point tool is passed along the outer surface of the rotating workpiece. Flank A flat surface of a single-point tool that is adjacent to the face of the tool. The side flank faces the direction that the tool is fed into the workpiece, and the end flank passes over the newly machined surface. Lead angle A common name for the side cutting edge angle. If a tool holder is built with dimensions that shift the angle of an insert, the lead angle takes this change into consideration. Nose radius The rounded tip on the cutting edge of a single-point tool. The greater the nose radius, the greater is the degree of roundness at the tip. A zero degree nose radius creates a sharp point. Rake angle (γ): Angle of inclination of rake surface from reference plane Clearance angle (α): Angle of inclination of clearance or flank surface from the finished surface . Positive rake – helps reduce cutting force and thus cutting power requirement. Negative rake – to increase edge-strength and life of the tool Zero rake – to simplify design and manufacture of the form tools. Clearance angle is essentially provided to avoid rubbing of the tool (flank) with the machined surface which causes loss of energy and damages of both the tool and the job surface. Hence, clearance angle is a must and must be positive (3 ~ 15 degree) depending upon tool-work materials and type of the machining operations like turning, drilling, boring etc.) Procedure 1. Job is fixed in hand for proper alignment. 2. Start the grinding machine and grind the job as per given specification. 3. A rough cut is used to grind the outer periphery. 4. Final grinding operation is completed in sequence. 5. The compound slide is set at the angle as per calculation and grinding operation is completed Precautions · Work piece should be firmly gripped in the hand. · Coolant is to be used. · Hand gloves and apron must be used while working. · Proper rpm should be selected before the operation Result Thus we successfully study the geometry of single point cutting tool and grind the single point cutting tool on the grinding tool according to the tool geometry. Viva- Voce 1. What is single point and multi point cutting tool? 2. Explain tool geometry? 3. What is tool face and tool rake? 4. What is negative and positive rake? DEPARTMENT OF MECHANICAL ENGINEERING 03 LABORATORY MANUAL J E C GROUP OF COLLEGES 5. What is grinding and drilling? DEPARTMENT OF MECHANICAL ENGINEERING 04 LABORATORY MANUAL J E C GROUP OF COLLEGES Experiment No. 2 Object Study the milling machine, milling cutters, indexing heads and indexing methods. Milling machine Introduction The milling machine removes metal with a revolving cutting tool called a milling cutter. With various attachments, milling machines can be used for boring, slotting, circular milling dividing, and drilling. This machine can also be used for cutting keyways, racks and gears and for fluting taps and reamers. Types of Milling Machines Milling machines are basically classified as being horizontal or vertical to indicate the axis of the milling machine spindle. Milling operation is broadly classified as peripheral milling and face milling. Peripheral Milling This operation is also called plain milling operation. In this operation axis of rotating tool is always kept parallel to the surface being machined. This operation is done by the cutting edges on outside periphery of the milling cutter. Different type of peripheral milling operations are possible as described below. Slab Milling In this milling operation the cutter width extends beyond the workpiece on both sides. Slotting It is also a type of milling operation, also called as slot milling operation. In this case width of the cutter is less than the width of workpiece. It is used to make slot in the workpiece. Thin slots can be made by using very thin milling cutters. The workpiece can be cut into two pieces by making a very thin slot throughout the depth of workpiece. Cutting the workpiece this way be slot milling is called saw milling. Side Milling The cutter is used for milling of sides of a workpiece. Straddle Milling It is just like side milling with difference that cutting (milling operation) takes place simultaneously on both the sides of workpiece. Face Milling In the operation of face milling, axis of the milling cutter remains perpendicular to the surface being milled. In this case cutting action is done by cutting edges of both sides (end and outside) periphery of the milling cutter. Depending upon the relative geometry of workpiece and milling cutter face milling is different types as described below. DEPARTMENT OF MECHANICAL ENGINEERING 05 LABORATORY MANUAL J E C GROUP OF COLLEGES Conventional Face Milling In this case diameter of milling cutter is greater than the width of workpiece. The milling cutter remains over hanging on both sides of workpiece. Partial Face Milling In this case the milling cutter overhangs on the workpiece on one side only. End Milling In case of end milling thin (low diameter) cutter are used as compared to workpiece width. It is used to make slot in the workpiece. Knee-type Milling Machines Knee-type milling machines are characterized by a vertical adjustable worktable resting on a saddle supported by a knee. The knee is a massive casting that rides vertically on the milling machine column and can be clamped rigidly to the column in a position where the milling head and the milling machine spindle are properly adjusted vertically for operation.