basic workshop for mechanical engineering
- 1. FACULTY OF ENGINEERING & TECHNOLOGY BULE HORA UNIVERSITY DEPARTMENT OF INDUSTRIAL ENGINEERING Course: Basic work shop practice I
- 2. Course objective At the end of this course, the student will be able to: Explain the safety rule that perform in workshop Define the term related to manufacturing process Gives the basic knowledge for the production of various engineering products. Explains the construction function and the use of various working tools, measuring tools, equipment and machines as well as techniques of manufacturing a product from its raw material.
- 3. Chapter 1 Introduction The workshop practice gives the basic working knowledge for the production of various engineering products. It explains the construction function and the use of various working tools, measuring tools, equipment and machines as well as the technique of manufacturing a product from its raw material. To understand the subject and to develop the skill, one has to practice the workshop processes, starting from simple models to complicated products.
- 4. Manufacturing Process Considered as the general name given for the method of processing metal in order to obtain various shapes. Divided in to five groups. 1. Primary shaping process 2. Secondary shaping process 3. Joining process 4. Surface finishing process 5. Process changing to metal property
- 5. General safety Before doing anything in a workshop, You need to understand how to protect yourself and those around you . You need to know how to use each hand and machine tool in a safe manner.
- 6. Cont…. Safety in the workshop may be classified into four general categories. Personal safety Shop safety Machine and tool safety Operating machines
- 7. Chapter 2 Bench work and fitting Introduction The term bench work Relates to work performed by the mechanic at the machinist’s bench with hand tools rather than machine tools. Denotes the production of our article by hand on the bench. Operations that can be performed on bench are; Chipping, Filing and Scraping.
- 8. Measuring Tools in Workshop 1,Calipers Used for the measurement or comparison of linear dimension Precision of +/-0.05mm can be achieved. Two types Outside caliper (To measure external dimensions) Inside calipers( To measure internal dimensions) Diameter of hole Width of slot
- 10. Inside caliper
- 11. Transferring a dimension from one place to another Verinier Caliper
- 12. Precise tools capable of measuring External dimensions(1) Internal dimensions (2) Depth (3)
- 13. 2,Micrometer More precise measuring instrument than the Verinier Caliper. Types Outside micrometer Inside micrometer Depth micrometer
- 15. Marking out tools in workshop Marking is the preliminary work of providing guidance lines and centers before cutting and machining The work piece can then be cut or machined to the required shapes and sizes. 1. Scriber Used for scratching lines onto the workspace. Made of hardened steel.
- 16. 2,Engineer’s square Made of hardened tool steel For checking the straightness and the squareness of a workspace. Also used for marking perpendicular lines onto a workspiece.
- 17. 3,Spring dividers Made of hardened tool steels To scribing arcs or circles onto the a work piece 4,Punch
- 18. Cont…. • Two types – Center punch Has a point angle of 90° For making a large indent on a work piece for drilling. – Dot punch Has a point angle of 60° For marking small dotes on the reference line
- 19. 5,Surface plate Made of malleable cast iron Machined and scraped to a high degree of flatness The flat surface used as a datum surface for marking out and for measuring purposes.
- 20. 6,Aangle plate Used for supporting or setting up work vertically Are provided with holes and slots through which securing bolts can be located. Made of cast iron Ground to high degree of accuracy
- 21. 6,V block Made of cast iron or steel Generally used for holding circular work piece for marking out or machining.
- 22. Clamping Tools for Workshop Bench Vice Device for holding the work piece. The body of the vice is made of cast iron while the two clamping jaws are made of hardened tool steel. May have swivel base The vice height should be correct ergonomically. Clamps, made of copper are fitted over the vice jaws.
- 23. Vise cont..
- 24. Hand tools for workshop • Hand tools are those tools which are hilled by hand to perform certain job or operation.) 1,File Hand cutting tool made of hardened high-carbon steel Series of teeth cut on body by parallel chisel cuts Used to remove surplus metal and to produce finished surfaces Manufactured in variety of types and shapes Each has specific purpose
- 25. filing • Filing is a method of removing metal. • which is the most widely used hand tool in the school workshop, is used for this cutting operation. • It is made of carbon tool steel containing about 1.3 per cent carbon. • Filing is a skill that is difficult to learn. It is not easy to explain how to use a file, but you should find the following basic principles of cross-filing helpful. 1. Hold the work firmly in the vice. 2. Allow a small part of the work to project from the vice and avoid vibration. 3. The work should normally be level with your elbow 4. Apply pressure in the forward stroke only. 5. Observe the correct methods for handling files, for heavy and light filing.
- 26. Cont….. Parts of a File 1. Tang 2. Heel 3. Edge 4. Face 5. Point 6. Length 4 3 2 1 5 6
- 27. Shapes of file Hand file Common file used for roughing and finishing Rectangular in section and parallel in width Has double cut teeth on two faces and single cut teeth on one edge and one save edge . Flat file Rectangular in section tapered slightly in width and thickness towards the tip Has double cut teeth on two faces and single cut teeth on two sides
- 28. Cont… Half round file The section is a chord of a circle with its taper towards the tip. Used for forming radii, grooves, etc Round File This is of round section tapering toward the end Used for enlarging holes, producing internal round corners Usually double cut in the larger sizes, and single cut for the smaller sizes.
- 29. Cont… Square File Square in section Tapered towards the tip Usually double cut on all four faces Used for filing rectangular slots or grooves. Three Square File Also known as triangular file A triangular in section Tapered towards the tip with double cut on both faces. Used for filing corners or angles less than 90°
- 30. Cont.. Needle files are a set of small files with their shapes made in a way similar to the large ones. Generally used for small and delicate(having fine strucures) works such as the repair of small instruments
- 31. 2,File card When filing the soft metals, the small pieces of metal will tend to clog the teeth. If the file is not cleaned, this small piece of metal will scratch on the surface of the work( pinning). File card is then used to remove pinning.
- 32. 3,Hacksaw • Used for cutting a metal into pieces. Solid frame hacksaw Adjustable frame hacksaw
- 33. Saw blades The cutting action is carried on the forward action only • Hacksaw teeth Should point towards the front end of the saw. Made of high-speed molybdenum or tungsten-alloy steel (hardened and tempered) Two types 1,Solid blade (all-hard) Hardened throughout and very brittle 2,Flexible blade. Teeth hardened, while back of blade soft and flexible
- 34. Tooth Pitch / blade pitch (Number of Teeth per Inch) Number of teeth per inch(1 in= 25.4mm ) Manufactured in various pitches 14, 18, 24, and 32 General use choice – 18 in. tooth blade Choose as coarse blade as possible Provides plenty of chip clearance and to cut through work as quickly as possible Should have at least two teeth in contact with work at all time Prevent work from jamming and stripping teeth 18,24,32 Teeth per Inch
- 35. 4,Hammer • Hammers are used to force objects together or apart. Ball Peen Hammer (Machinist’s Hammer) Most commonly used It has a flat striking face and a ball-shaped end
- 36. Drill and Drilling • Drilling is the process of cutting holes in metals by using a drilling machine. Made from High Speed Steel Carry Made from High Speed Steel Flutes used to carry away the chips of metal and the outside surface The outside surface is relieved to produce a cutting edge Twist Drill
- 37. Drilling machine and it’s tool Floor type drill press Bench drill press
- 38. Taps and Dies Flutes are grooves in the tap Flutes provide cutting edges, provide chip clearance and allow cutting fluid in Used to cut screw threads inside a hole Made of hardened High Carbon Steel or High Speed Steel. The ends of the shank are square to fit a wrench
- 39. Dies • Used to cut the external thread of the work. Mean that making of threads on round tubes and bars. • Made of hardened high carbon steel or high speed steel.
- 40. Chapter 3 Welding • Outline • Introduction • Applications • Types of welding • Arc welding • Safety • SMAW and its working principle • Equipment and accessories • Welding terminology • Welding positions • Types welds • Weld Joints
- 41. Introduction • Welding is a process of joining two similar or dissimilar metals by fusion, with or without the application of pressure and with or without the use of filler metal. • The fusion of metal takes place by means of heat • Used as an alternative method for casting and forging and as a replacement for bolted and riveted joints.
- 42. Applications Construction Military vehicle and equipment's Ship building Off-highway equipments and machines Household furniture Railroad Construction
- 43. Cont.. Automobile & bus construction Piping and pipe lines Towers
- 44. Cont… Aircraft construction etc. Bridges construction Repair of broken & damaged parts Storage tanks
- 45. Types of welding Arc welding: • MIG (Metal Inert Gas) • TIG (Tungsten Inert Gas) • SAW (Submerged Arc Welding) • SMAW (Shielded Metal Arc Welding) Resistance welding Gas welding Soldering and brazing
- 46. Safety Precautions in Arc welding Shop • Mishaps/accident frequently occurs in welding operations. • Result in serious injury to the welder or other personnel working in the immediate area. • In most cases, mishaps occur because of carelessness, lack of knowledge, and the misuse of available equipment.
- 47. Safety rule in arc welding shop • Never look at arc with naked eyes • Always use a shield while welding • Always wear the safety hand glove, apron and leather shoes • Ensure proper insulation and check before opening • Apply eye drop after welding is over to relieve the strain on eyes.
- 48. Safety materials Eye protection devices Welders protective clothing
- 49. Shielded metal arc welding(SMAW) • Is performed by striking an arc between a coated- metal electrode and the base metal. • The molten metal from the electrode flows together with the molten metal from the base metal to forma sound joint. This process is known as fusion(the molten state of substance). • The coating from the electrode forms a covering, shielding it from contamination; therefore the process is called shielded metal arc welding.
- 50. Working Principles of SMAW • The electrode and the work are part of an electric circuit. Working Principles of SMAW
- 51. Cont…
- 52. Selecting the type of current • The welding current may be either alternating current or direct current depending on the electrode being used. • Direct current - is the most common current choice for stick welding. The current flows in one direction only and has many advantages over alternating current for the stick process. • These advantages include: fewer arc outages, less spatter, easier arc starting, less sticking, and better control in out-of-position welds.
- 53. Cont… DCEP or reverse polarity connection Best penetration and bead profile. For this reason. Most electrodes are made to weld with DCEP. DCEN or Straight Polarity Connection • Result in a narrow bead with little penetration. • works well when welding on sheet metal
- 54. Cont… • Alternating current (AC) is an electrical current that has both a positive and a negative half-cycle value (polarities) alternately. • Current flows in a specific direction for one half- cycle, stops at the "zero" line, then reverses direction of flow the next half-cycle at regular intervals. AC circuit
- 55. Equipment's and accessories Welding generator AC/DC Exhaust fan Eye Shield Hand gloves Apron Two cables- one for work and one for electrode Electrode holder Electrode Wire brush Chipping hammer
- 56. Welding terminology • Filler metals is a material used to fill the space between two pieces of metals when welding. Two types 1. Welding rods 2. Welding electrodes 1. Welding rod does not conduct an electric current during the welding process. Only supply filler metal to the joint. 2. Electrode conducts the current from the electrode holder to the metal being welded.
- 57. Electrodes are classified into two groups 1. Consumable Not only provide a path for the current but they also supply filler metal to the joint. An example is the electrode used in shielded metal-arc welding. 2. Non-consumable Only used as a conductor for the electrical current, such as in gas tungsten arc welding. The filler metal for gas tungsten arc welding is a hand fed consumable welding rod.
- 58. Welding positions Flat welding position Horizontal welding position
- 59. Cont… Vertical welding position Overhead welding position
- 60. Types of welds 1. Weld bead (bead) Is a weld deposit produced by a single pass with one of the welding processes. 2. Groove welds Welds made in the groove between two members to be joined.
- 61. Cont… 3. Fillet weld is used to join two surfaces that are at approximately right angles to each other in a lap, tee, or corner joint. 4. Surfacing is used to apply a hard, wear-resistant layer of metal to surfaces or edges of worn-out parts.
- 62. Cont… 5. Tack weld Made to hold parts of an assembly in proper alignment temporarily until the final welds are made. 6. Plug and slot welds are welds made through holes or slots in one member of a lap joint. Types of joints 1. Butt joint
- 63. Cont… 2. Lap joint 3.Corner joint 4. T-joint 5.Edge joint
- 64. Brazing and soldering • Brazing Is the process of joining metal by heating the base metal to a temperature above 800°F and adding a nonferrous filler metal that melts below the base metal. • Advantages does not affect the heat treatment of the original metal. • Allows you to join dissimilar metals. • It needs source of heat, filler metals, and flux. • Heating Devices Furnace (mass production) Or Individual torches (oxyacetylene welding torch) • Filler Metals-
- 65. Cont… nonferrous metals or alloys are:- • Silver-base alloys • Aluminum-silicon alloys • Copper • Copper-zinc (brass) alloys • Copper-phosphorus alloys • Gold alloys • Nickel alloys • Magnesium alloys
- 66. Cont… Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal (solder) into the joint, the filler metal having a lower melting point than the work piece. • Used for extensively in electronics industry because of heat sensitive components • Jewelry components, machine tools and some refrigeration and plumbing(water pipe working) components are often assembled and repaired. etc.
- 67. Cont…
- 68. Oxyacetylene welding • Acetylene is a carbonaceous combustible gas. • When it is burnt in presence of oxygen gas in a controlled manner the combustion produces intense heat which is sufficient to melt a metal. • The flame is long, smoky and yellowish in color. • However when oxygen is also supplied, the size of the flame is reduces and it is not smoky (bluish in color) • Heat is produced due to following exothermic chemical reaction • 2C2H2 + 5O2 = 4CO2 +H2O + heat
- 69. Cont… Oxygen cylinder Acetylene cylinder Oxygen cylinders and houses Painted greenish or blush most of the time. Acetylene cylinders and houses Painted reddish in color .
- 71. Types of Flames 1. Neutral flame • Produced when the gas mixture has equal volumes of acetylene and oxygen. • Has two distinct zones Cone and an outer flame surrounding the cone. • Used for the welding of most of the materials like low carbon steels, cast steels, cast iron etc.
- 72. Con… 2. Oxidizing flame • Produced when the amount of oxygen is slightly more than the acetylene. • Very short in length and sharper in shape. • A hissing sound is produced at the tip of the torch. • Used for welding brasses, bronzes and cast iron.
- 73. Con… • Produced when the oxygen is kept slightly less than acetylene. • Has three distinct zones. • Advantageous for non-ferrous metals, silver soldering and hard facing. 3. Reducing or carburizing flame
- 74. Chapter 4 Sheet metal work Outline Introduction Safety Types of sheet metal Tools used in sheet metal Sheet metal Joints Sheet metal operations
- 75. Introduction Very important for every engineering concern. Deals with the working of metal sheets. Requires a through knowledge of projective geometry . The various operations performed cutting, shearing, bending etc. Safety 1. Be very careful from sharp tools. 2. Avoid putting or filling the cut portion by hand while cutting with snip. 3. Use hand leather gloves while handling heavy sheets. 4. Do not cut metal heavier than capacity of snip. 5. The safest and most efficient method of testing a soldering to the solder being to flow the correct temperature has been achieved. 6. Keep work area free from obstruction.
- 76. Types of sheet metal 1, Mild Steel sheets known as black iron sheet Exposed to rust and corrosion due to un coating. Mostly used ; For water tank Fabrication work Agricultural implements.
- 77. Con... 2, Stainless Steel sheets It is an alloy of high grade steel with chromium, nickel and traces of manganese, phosphorous, etc. It can be easily welded. Used in canneries, dairies, food processing plants. Very costly as compare to GI sheets.
- 78. Con... 3, Galvanized Iron sheets It is soft steel sheet coated with zinc. Have corrosion resistance due to zinc coating. Welding is not easy. Used for making AC duct Roof flashing Boxes Buckets Cooler etc.
- 79. Con… 4, Tin plate Steel or iron coated with tin. Used for making food container Dairy equipment Furnace fittings.
- 80. Tools used in sheet metal 1, Bench Vice: For gripping different tools. Measuring and marking Tools Steel rule, Scriber Steel square (engineer’s square) Divider Pliers: used for holding small articles which are difficult to be held by hand.
- 81. Con... 2, Punches 2.1 Prick punch Used for marking indentation marks for locating the center position or dividers, having included angle of 300 2.2 Centre punch Used for marking the location of the point and the center of holes to be drilled. Its tapered point is grounded to 900 included angle.
- 82. Cutting Tools 1. Straight Snip For cutting along straight lines Blades are straight. 2. Bent snip Blades are curved back from the cutting edge which allows the metal to slide over top blades.
- 83. Con... 3. Hollow punch: Used when circular holes are to be cut in the sheet . 4. Chisel For cutting sheets, rivet and bolts.
- 84. Striking Tools Hammer: Used for; Striking work Bending of sheets Smoothing of sheets, Locking of joints, etc. For those operations the following hammer are generally used. Setting hammer Raising hammer Riveting hammer Ball peen hammer Mallet
- 85. Supporting Tools • Stakes: Stakes are used to support sheets in bending, seaming, forming, riveting, punching etc. Some common stakes are; A , Hand stake Used for pressing the inner sides of straight joint. B,Half round stake Used for pressing round seam joint on inner side.
- 86. Con… C,Anvil: It is made of cast steel mounted on CI stand or provided with a handle. The top working or cutting face is made of tough steel. Square and round holes are provided for bending operation. D,Taper stake Used for rounding of tapering jobs such as conical jobs. E,Grooving stake Used to make grooves of different sizes. Grooves are made to impart strength.
- 87. Sheet Metal Joints 1. Lap joint 2. Seam joint 3. Locked seam joint 4. Hem joint 5. Wired edge joint 6. Cup or circular joint 7. Flanged joint 8. Angular joint 9. Cap joint
- 88. Sheet Metal Operations 1,Measuring and Marking The required size from the standard size is to be cut. A little allowance for cutting is to be added to the required overall sizes so that the cut pieces are not under size. 2,Laying out Laying out means the operation of scribbling the development of the surface of component on the sheet or sheet blank, together with the added allowance for overlapping, bending, hammering, etc. Which when cut out of the blank and folded and joined will give the required components.
- 89. Cont…. 3,Hand cutting and Shearing The sheet metal is cut by chisel and hammer manually. The term shearing is stand for cutting the sheet metal by two parallel cutting edges moving in opposite direction. This can be done either manually by using hand shear or snips or by means of machine called shears. The operation is known as machine shearing or mechanical shearing. 4,Hand forming The term metal forming stands for shaping and/or bending of sheet metal in three dimensions in order to give it desire shape and size of the final product. For these, the metal is either is required to be starched or shrunk in all direction or may need a combination of both.
- 90. Cont… 5,Nibbling Nibbling is a process of continuous cutting along a contour, which may be a straight line or irregular profile. The machine used known as nibblers, which are portable size shearing machine. 6,Circle cutting It is the operation of cutting circular blank or curved contour with the help of a circle cutting machine. It is also a continuous cutting operation.
- 91. Cont… 7,Piercing and Blanking: Piercing is basically a hole punching operation while blanking is an operation of cutting out a blank.
- 92. Cont… 8,Edge forming and Wiring The edges of sheet metal product are form to ensure safety of hands, retain shape during handling i.e., will not get buckled by simple hand or finger pressure during handling. 9,Joint making For joining large size parts, screwed fasteners can be used. Also be joined by riveting, welding, brazing and adhesives. 10,Bending It may be done over stakes, blocks of wood or edge of a bench top.
- 93. Cont… 11,Drawing The walled hollow shapes are produced. Operation is carried out with the help of die and a punch on a suitable press. If the drawn length of the component is less than its width or diameter it is called shallow drawing. When the drawn length is more than the width, the operation is known as deep drawing.
- 94. Chapter 5 Woodworking Outline Introduction Application Timber Classification of wood Characteristics of good timber Woodworking tools Wood working procedures Wood joints Joinery materials Woodworking machines
- 95. Introduction Described as the technological process of making wooden components. It starts from a marketable form of wood and ends with a formation of useful value added finished product. Applications Building work Furniture Cabinet-manufacturing Interior decoration Toy manufacturing and others.
- 96. Timber Is the name given to the wood obtained from well grown trees. Grain refers to the appearance or pattern of the wood on the cut surfaces. The grain of the wood is a fibrous structure and to make it strong, the timber must be so cut, that the grains run parallel to the length. Timber is sold in the market in various standard shapes and sizes.
- 97. Classification of Wood Generally classified into two broad categories: Soft woods and hard woods. Hard wood is generally obtained from a tree with deciduous or broad leaves whereas the soft wood from trees having middle shaped conifers. Characteristics of Good Timber (a) Have minimum moisture content, well seasoned. (b)Have straight and long grains. (c)Retain its straightness after seasoning. (d)Produce a characteristic sound (nearly metallic) on hammering.
- 98. Cont… (e)Be free from defects. (f) Have uniform color throughout. (g)Respond well to the finishing and polishing operations. (h) Not split easily during driving the nails and screws. • Woodworking tools Marking and Measuring Tools Steel Rule & steel tap Marking Gauge Used to mark lines parallel to the edge of a wooden piece. Mortise Gauge; consists of two pins to draw two parallel lines on the stock.
- 99. Cont… Try-square Compass and dividers Scriber or marking knife Bevel/Blade; used for laying-out and checking angles. Tap rule Mortise Gauge Marking Gauge Bevel/Blade
- 100. Holding Tools Carpenter's vice. C-clamp; used to holding small works. Bar Clamp; Is made of steel bar of T-section, with malleable iron fitting and a steel screw. It is used for holding wide works such as frames or tops.
- 101. Planning tools Planning is the operation carried out on wood to produce flat surfaces. A plane is a hand tool used for this purpose. Different types of planes used for different purposes. Cutting Tools Saws Chisels Drilling, Boring and other miscellaneous tools.
- 102. Wood working procedures a) Selection and Laying Out b) Marking d) Chiseling e) Drilling or Boring Holes C, Planning
- 103. Wood Joints There are several kinds of joints used to join wood stock. Each joint has a definite use and requires laying-out, cutting and putting them together. Strength of the joint depends upon the amount of contact area, and the reinforcement with nails, screws or dowels, etc.
- 104. 1,Lap Joints In lap joints, equal amounts of wood are removed from both the pieces to be joined. Lap joints are easy to layout, using a try square and a marking gauge. This type of joint is used for small boxes to large pieces of furniture.
- 105. 2,Mortise and Tenon Joint It is supposed as strong joint and requires considerable skill to make. It is commonly used in the construction of quality furniture.
- 106. 3, Bridle Joint Considered as the reverse of mortise and tenon joint in form. Therefore, the marking and layout of the joint is the same as for mortise and tenon joint. This joint is used where the members are of square or near square section and suitable for mortise and tenon joint.
- 107. Joinery Materials The joinery materials are used to join the processed/finished wooden pieces or wooden pieces with other materials. The common joinery materials used in practice are: (a) Adhesives (b) Nails (c) Screws (d) Bolts and Nuts (e) Dowels
- 109. Woodworking machines Woodworking machines are made to do a wide variety of jobs. For any one job there are usually a number of makes, sizes, and styles of machines from which to choose. Woodworking machines may be divided into three broad classes based on function Sawmill Planning mill and Industrial plant machinery
- 110. Cont... The function of sawmill machinery is to cut the log into rough, green lumber. The planning mill takes the rough lumber (usually dry), and prepares it for general construction uses, such as flooring, siding, shiplap, or framing. The industrial plant machinery cuts up lumber and makes it into doors, furniture, boxes, or other fabricated products.