INTRODUCTION TO BASIC MANUFACTURING PROCESSES AND
WORKSHOP TECHNOLOGY
Rajender Singh
Professor, Deptt. of Mechanical Engineering
CRSCE, Murthal, Haryana
Publishing for one world, NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS, 2006
Table of Contents
1 . Introduction
2. Plant and Shop Layout
3. Industrial Safety
4. Ferrous Materials
5. Non-Ferrous Materials
6. Melting Furnaces
7. Properties and Testing of Metals
8. Heat Treatment
9. Carpentry
10. Pattern and Core Making
11.Foundry Tools and Equipments
12.Mold and Core Making
13. Casting
14. Forging
15. Hot Working of Metals
16.Cold Working
17.Welding
18.Sheet Metal Work
19. Fitting
20. Metal Cutting
21. Lathe Machine
22. Drilling Machine
23. Shaper, Planer and Slotter
24. Milling
25. Powder Metallurgy
26. Inspection and Quality Control
Manufacturing Processes - Important Points
1 . Introduction
Manufacturing is derived from the Latin word manufactus, means made by hand. In modern
context it involves making products from raw material by using various processes, by making
use of hand tools, machinery or even computers.
Advance manufacturing engineering involves the following concepts —
1. Process planning.
2. Process sheets.
3. Route sheets.
4. Tooling.
5. Cutting tools, machine tools (traditional, numerical control (NC), and computerized numerical control (CNC).
6. Jigs and Fixtures.
7. Dies and Moulds.
8. Manufacturing Information Generation.
9. CNC part programs.
10. Robot programmers.
11. Flexible Manufacturing Systems (FMS), Group Technology (GT) and Computer
integrated manufacturing (CIM).
Generally there are three basic types of production systems:
1. Job production
2. Batch production
3. Mass production
A fourth is now added. Lean Production
PROCESS PLANNING
Process planning consists of selection of means of production (machine-tools, cutting tools, presses, jigs, fixtures, measuring tools etc.), establishing the efficient sequence of operation, determination of changes in form, dimension or finish of the machine tools in addition to the specification of the actions of the operator. It includes the calculation of the machining time, as well as the required skill of the operator. It also establishes an efficient sequence of manufacturing steps for minimizing material handling which ensures that the work will be done at the minimum cost and at maximum productivity.
The basic process of process planning is generally explained in connection with with the machining only. But the process is valid and required for other processes such as casting, forging, sheet metal forming, assembling and heat treatment etc.
Important primary shaping processes are:
(1) Casting, (2) Powder metallurgy, (3) Plastic technology, (4) Gas cutting, (5) Bending and
(6) Forging.
Secondary or machining processes are —
(1) Turning, (2) Threading, (3) Knurling, (4) Milling, (5) Drilling, (6) Boring, (7) Planning,
(8) Shaping, (9) Slotting, (10) Sawing, (11) Broaching, (12) Hobbing, (13) Grinding, (14) Gear
cutting, (15) Thread cutting and (16) Unconventional machining processes namely machining
with Numerical Control (NC) machines tools or Computer Numerical Control (CNC) machines
tools using ECM, LBM, AJM, USM setups etc.
The process of putting the parts together to form the product, which performs the desired function, is called assembly An assemblage of parts may require some parts to be joined together using various joining processes.
The joining processes are carried out by fusing, pressing, rubbing, riveting, screwing
or any other means of assembling.
Some of the important and common joining processes are:
(1) Welding (plastic or fusion), (2) Brazing, (3) Soldering, (4) Riveting, (5) Screwing,
(6) Press fitting, (7) Sintering, (8) Adhesive bonding, (9) Shrink fitting, (10) Explosive welding,
(11) Diffusion welding, (12) Keys and cotters joints, (13) Coupling and (14) Nut and bolt joints.
Some of the commonly used surface finishing processes are:
(1) Honing, (2) Lapping, (3) Super finishing, (4) Belt grinding, (5) Polishing, (6) Tumbling,
(7) Organic finishes, (8) Sanding, (9) deburring, (10) Electroplating, (11) Buffing, (12) Metal
spraying, (13) Painting, (14) Inorganic coating, (15) Anodizing, (16) Sheradising, (17) Parkerizing,
(18) Galvanizing, (19) Plastic coating, (20) Metallic coating, (21) Anodizing and (22) Sand blasting.
Heat treatments affect the physical properties and also make a marked change in the internal structure of the metal. Similarly the metal forming processes effect on the physical properties of work pieces Similarly shot peening process, imparts fatigue resistance to work pieces. A few such commonly used processes that change physical properties are given below:
(6) Tempering, (7) Shot peeing, (8) Grain refining and (9) Age hardening.
In addition, some allied manufacturing activities are also required to produce the finished
product such as measurement.
PRODUCT SIMPLIFICATION AND STANDARDISATION
Industrial engineering focuses on these tasks as staff support to all engineering departments.
The technique of simplification and standardization of product is closely inter-related that
leads to higher efficiency in production, better quality and reduced production cost.
Simplification is a process of determining limited number of grades, types and sizes of a components or products or parts in order to achieve better quality control, minimize waste, simplify production and, thus, reduce cost of production. By eliminating unnecessary varieties, sizes and designs, simplification leads to manufacture identical components or products for interchangeability and maintenance purposes of assembly of parts.
Standardization is the important step towards interchangeable manufacture, increased output and higher economy. The technique of standardization comprises of determining optimal manufacturing processes, identifying the best possible engineering material, and allied techniques for the manufacture of a product and adhering to them very strictly so long as the better standards for all these are not identified. Thus definite standards are set up for a specified product with respect to its quality, required equipment, machinery, labor, material, process of manufacture and the cost of production. The identified standard with time for a specified product should never be taken as final for ever because improvement is always possible. It must accommodate the outcome of all the new researches in the manufacturing areas in order to keep pace with increasing global competition. Improvements over the existing standards in all respects should always be welcomed. The different standards prevailing in different industries may be of the types of managerial, design, manufacturing and technical needs. Managerial standards are applicable to administrative functions within industry. These include the company policy, accounting procedures, personnel policies, performance evaluation, control of expenditures, safety aspects, security procedures and regulations, etc. where as design, manufacturing and technical standards are needed for manufacturing concepts of the industry. These include design and manufacturing techniques, practices, materials and parts, supplies, methods of testing, drafting method, abbreviations and symbols, specifications and nomenclature, etc.
The word ‘automation’ is derived from the Greek word automatos meaning self-acting. Automation can also be defined as the process of following a predetermined sequence of operations with little or no human intervention, using specialized equipment and devices that perform and control the manufacturing process.
The essential elements of automation comprise of mechanization, sensing, feedback,
and control devices. The reasons why one should go for automation are:
1. Increased productivity
2. Reduced cost of labor and dependence on labor shortages
3. Improved quality
4. Reduced in-process inventory
5. Reduced manufacturing time
6. Reduced dependence on operator skills
7. Increased safety or reduced risk of humans.
Automation can be classified into three categories, viz.
1. Fixed automation
2. Programmable automation
3. Flexible automation.
The computer aided manufacturing implies manufacturing itself, aided or controlled by
computers. In a wider sense, it denotes all the activities in the manufacturing environment
like use of computers in inventory control, project management, material requirement planning,
data acquisition, testing and quality control.
The integration of CAD and CAM systems is called Computer Integrated Manufacturing
(CIM) system.
MANUFACTURING SYSTEM: It is a chain of interrelated activities of production process and other support services activities of an manufacturing environment such as order processing, product design, design and manufacturing of tools, die, mould, jigs, fixtures and gauges, selection of material,
planning, managing and maintaining control of the processes, production, and reliable quality
of processed product in a systematic and sequential manner with proper coordination,
cooperation and integration of the whole manufacturing system that will lead to economical
production and effective marketing of proposed product in the minimum possible time.
PRODUCT DEVELOPMENT
A product development has to go through the following concepts of product engineering which
are given as under.
Product functions
1. Product specifications
2. Conceptual design
3. Ergonomics and aesthetics
4. Standards
5. Detailed design
6. Prototype development
7. Testing
8. Simulation
9. Design for manufacture
10. Design for assembly
11. Drafting.
Manufacturing activities controlled by computers.
1. Computer Aided Design (CAD)
2. Computer Aided Engineering (CAE)
3. Computer Aided Design And Drafting (CADD)
4. Computer Aided Process Planning (CAPP)
5. Computer Aided Tool Design (CATD)
6. Computer Aided Manufacturing (CAM)
7. Computer Aided Numerical Control (NC) Part Programming
8. Computer Aided Scheduling
9. Computer Aided Material Requirement Planning, etc.
10. Flexible Manufacturing System (FMS)
11. Group Technology (GT)
12. Computer aided Testing (CAT).
2. Plant and Shop Layout
3. Industrial Safety
4. Ferrous Materials
Sometimes, it is possible to use more than one material and manufacturing processes. The best possible material and process must be utilized in manufacture of product. It is therefore important to know what materials are available in the universe with its usual cost, their properties and their amenability to fabrication methods.
A product designer, tool designer and design engineer should always be familiar with various kinds of engineering materials, their properties and applications to meet the functional requirements of the product. Industrial engineers whose job is to reduce cost of products and processes by using alternative materials, design rules and production and service processes also need to have the same familiarity.
Ferrous metals are those which have the iron as their main constituent, such as pig iron, cast iron, wrought iron and steels.
The ferrous metals commonly used in engineering practice are cast iron, wrought iron, steel and
alloy steels. The basic principal raw material for all ferrous metals is pig iron which is obtained by smelting iron ore, coke and limestone, in the blast furnace.
Main Types of Ferrous Materials used in Engineering Products
1. Pig iron
2. Cast iron (A) White cast iron (B) Gray cast iron (C) Malleable cast iron (D) Ductile cast iron
(E) Meehanite cast iron (F) Alloy cast iron
3. Wrought iron
4. Steel
(A) Plain carbon steels 1. Dead Carbon steels 2. Low Carbon steels 3. Medium Carbon steels 4. High Carbon steels
(B) Alloy steels 1. High speed steel 2. Stainless steel
The carbon content in cast iron varies from 1.7% to 6.67%. Cast iron has low cost, good casting characteristics, high compressive strength, high wear resistance and excellent machinability. The compressive strength of cast iron is much greater than the tensile strength. Hence the cast iron is used for components that are subjected more to compressive loads.
Applications ; The grey iron castings are mainly used for machine tool bodies, automotive cylinder
blocks, pipes and pipe fittings and agricultural implements. The other applications involved are:
(i) Machine tool structures such as bed, frames, column etc. (ii) Household appliances etc.
(iii) Gas or water pipes for under ground purposes. (iv) Man holes covers. (v) Piston rings.
(vi) Rolling mill and general machinery parts. (vii) Cylinder blocks and heads for I.C. engines.
(viii) Frames of electric motor. (ix) Ingot mould (x) General machinery parts. (xi) Sanitary wares.
(xii) Tunnel segment.
Wrought iron is the assumed approximately as purest iron which possesses at least 99.5%. It is said as a mechanical mixture of very pure iron and a silicate slag. The wrought iron can be easily shaped by hammering, pressing, forging, etc. It is never cast and it can be easily bent when cold. It is tough and it has high ductility and plasticity with which it can be forged and welded easily. Its ultimate strength can be increased considerably by cold working followed by a period of aging. It possesses a high resistance towards corrosion. It can accommodate sudden and excessive shocks loads without permanent injury.
It is used for making chains, crane hooks, railway couplings, and water and steam pipes.
Steel is an alloy of iron and carbon with carbon content maximum up to 1.7%.
Types of Steels
1 . Dead carbon steel — up to 0.15% carbon
Steel wire, sheets, rivets, screws, pipe, nail and chain are made from this steel. This steel is used for making camshafts, sheets and strips for fan blades, welded tubing, forgings, chains, stamping, rivets, nails, pipes, automobile body etc.
2.Low carbon or mild steel — 0.15% to 0.45% carbon
It is tough, malleable, ductile and more elastic than wrought iron. It can be easily forged and welded. It can absorb shocks. It rusts easily. It is used for making angle, channels, case hardening steel, rods, tubes, valves, gears, crankshafts, connecting rods, railway axles, fish plates, small forgings, free cutting steel shaft and forged components etc.
3.Medium carbon steel — 0.45% to 0.8% carbon
It can be easily hardened and it possesses good balance of strength and ductility. It is generally used for making railway coach axles, bolts, connecting rods, key stock, wires and rods, shift and break levers, spring clips, gear shafts, small and medium forgings, railway coach axles, crank pins on heavy machines, spline shafts, crankshafts, forging dies, set screws, die blocks, self tapping screws, clutch discs, valve springs, plate punches, thrust washers etc.
4.High carbon steel— 0.8% to 1.5% carbon
Because of their high hardness,these are suitable for wear resistant parts. Hence they were used and are still used in the manufacture of cutting tools. But they operated at low cutting speeds in the case of machine tools. These steels are easy to forge and simple to harden.
High carbon steels containing 0.7 to 0.8% carbon possesses hardness of 450-500 BHN. It has application for making cold chisels, drill bits, wrenches, wheels for railway service, jaws for vises,
structural wires, shear blades, automatic clutch discs, hacksaws etc.
HC Steel containing 0.8 to 0.9% C possesses hardness of 500 to 600 BHN. This steel is used for making rock drills, punches, dies, railway rails clutch discs, circular saws, leaf springs, machine chisels, music wires.
HC Steel containing 0.90 to 1.00% carbon is also known as high carbon tool steel and it possesses hardness of 550-600 BHN. Such steel is used for making punches, dies, springs keys and shear blades.
Steel containing 1.0 to 1.1 % C is used for making railway springs, mandrels, taps, balls, pins, tools, thread metal dies.
Steel containing 1.1 to 1.2% C is used for making taps, twist drills, thread dies, knives.
Steel containing 1.2 to 1.3% carbon is used for making files, reamers Files, dies for wire drawing, broaches, saws for cutting steel, tools for turning chilled iron.
Alloy Steels
The chief alloying elements used in steel are nickel, chromium, molybdenum, cobalt, vanadium, manganese, silicon and tungsten.
An alloy containing 25% nickel possesses maximum toughness and offers the greatest resistance to rusting, corrosion and burning at high temperature. It has proved beneficial in the manufacture of
boiler tubes, valves for use with superheated steam, valves for I.C. engines and sparking plugs for petrol engines. A nickel steel alloy containing 36% of nickel is known as invar. It has nearly zero coefficient of expansion. Therefore, it is in great demand for making measuring instruments for everyday use.
Chromium improves corrosion resistance (about 12 to 18% addition). It increases tensile strength, hardness, wear resistance and heat resistance. It provides stainless property in steel. It is used in steels as an alloying element to combine hardness with high strength and high elastic limit. Alloy steel containing 23-30% chromium with less than 0.35% C are are particularly suitable for working at high temperatures and are thus stable at high temperatures. The furnace parts and annealing boxes are generally made by this steel.
Spring steels are used for the making springs. Various types of these steel and their uses are:
(i) Carbon-manganese spring steels. These steels are quenched and tempered up to 350 BHN. They are widely used for laminated springs for railway and general purposes.
(ii) Hyper-eutectoid spring steels. These steels are oil quenched and tempered at low temperature. This type of steel is used for volute and helical springs.
(iii) Silicon-manganese spring steels. These steels are hardened and tempered. This type of steel is used for the manufacturing of railway and road springs generally.
Tungsten increases hardness, wear resistance, shocks resistance and magnetic reluctance. It increases ability to retain hardness and toughness at high temperature. It prohibits grain growth and increases wear resistance, shock resistance, toughness, and the depth of hardening of quenched steel. The principal uses of tungsten steels are for cutting tools, dies, valves, taps and permanent magnets.
Vanadium. It improves tensile strength, elastic limit, ductility, fatigue resistance, shock resistance and response to heat treatment. These steels are frequently used for parts such as springs, shafts, gears, pins and many drop forged parts.
Applications of free cutting steel
These steels are used for manufacturing axles, bolts, screws, nuts, special duty shafts, connecting rods, small and medium forgings, cold upset wires and rods, solid turbine rotors, rotor and gear shaft, armature, key stock, forks and anchor bolts screw stock, spring clips, tubing, pipes, light weight rails, concrete reinforcing etc. This property is due to higher sulphur and phosphorus. Sulphur exists in the form of manganese sulphide (MnS) which forms inclusions in steel.
The principal alloying elements in structural steels are chromium, nickel and manganese. These steels have various applications as structural members of bridges, buildings, rail road, cars etc. They are also used for manufacturing components subjected to static and dynamic loads. These components include valves, pins, studs, gears, clutches, bushes, shafts etc.
Stainless steel contains chromium together with nickel as alloy and rest is iron. It has been defined as that steel which when correctly heat treated and finished, resists oxidation and corrosive attack from most corrosive media.
It is used for making heat exchangers, conveyors chains, furnaces, spokes, brewery, dairy and chemical industrial components, cutlery parts, surgical and dental instruments, household appliances such as kitchen utensils, sinks and saucepans. These are also used in making components in power stations, especially in nuclear power stations, steam pipes, boiler tubes, radiator and super heater tubes.
High Speed Steels (HSS) have been given this name due to the fact that these steels may be operated as cutting tools at much higher speeds that are possible with plain high carbon tool steel. High speed steels cutting tools operate at cutting speed 2 to 3 times higher than for High carbon steels. High speed steel (18:4:1) contains 18% tungsten, 4% chromium and 1 % vanadium, 0.8 carbon and remaining iron.
5. Non-Ferrous Materials
Aluminium - Applications
It is mainly used in aircraft and automobile parts where saving of weight is an advantage.The high resistance to corrosion and its non-toxicity make it a useful metal for cooking utensils under ordinary conditions. It is a cheap and very important non ferrous metal used for making cooking utensils.
Aluminium metal of high purity has got high reflecting power in the form of sheets and is, therefore, widely used for reflectors, mirrors and telescopes. It is used in making furniture, doors and window components, rail road, trolley cars, automobile bodies and pistons, electrical cables, rivets, kitchen utensils and collapsible tubes for pastes.Aluminium foil is used as silver paper for food packing etc. In a finely divided flake form, aluminium is employed as a pigment in paint.
Various aluminium alloys are:
1. Duralumin,
2. Y-alloy,
3. Magnalium and
4. Hindalium
Copper - Applications
Copper is mainly used in making electric cables and wires for electric machinery, motor winding, electric conducting appliances, and electroplating etc. It can be easily forged, casted, rolled and drawn into wires. Copper in the form of tubes is used widely in heat transfer work. It is used for household utensils. It is also used in production of boilers, condensers, roofing etc. It is used for making useful alloys with tin, zinc, nickel and aluminium.
Brasses
Red brass - Applications: Red brass is mainly utilized for making, heat exchanger tubes, condenser, radiator cores, plumbing pipes, sockets, hardware, etc.
Yellow brass - Applications: Yellow brass or muntz metal is suitable for hot working by rolling, extrusion and stamping. It is utilized for making small various components of machine and electrical equipment such as bolts, rods, tubes, valves and fuses. This metal is utilized for making for pump parts, valves,taps, condenser tubes, sheet form for ship sheathing (because of excellent corrosion resistance).
Cartridge Brass - Applications: It is utilized for making for making tubes, automotive radiator cores, hardware fasteners, rivets, springs, plumber accessories and in tube manufacture.
Admiralty brass is highly resistant to corrosion. It is highly resistant to impingement attack of sea water. It can be cold worked.
Applications: Admiralty brass is utilized for making condenser tubes in marine and other installations.
It is used for making plates used for ship building. It is utilized also for making bolts, nuts, washers, condenser plant and ship fittings parts, etc.
Naval brass is similar to muntz metal. 1% zinc in muntz is replaced by 1% tin. Corrosion resistance to sea water is significantly improved. Applications: Navel brass is commonly utilized for making marine hardware casting, piston rods,
propeller shafts, welding rods etc.
Manganese brass possesses sufficient toughness and good corrosion resistance. It is very active in reducing the oxides of other metals. Applications: Manganese brass is utilized for making hydraulic rams, valves and cylinders, tubes, pump rods, propellers, bolts, nuts etc.
Iron brass or delta metal is hard, strong, tough, and having good corrosion resistance. It can be casted easily. Applications: If corrosion is to be resisted in mild steel, then some amount of iron brass or delta metal is added in mild steel.
Gilding brass is a very cheap metal for making jewellery, decorative and ornamental products. Applications: Because of better appearance this metal is commonly used for jewellery, decorative and ornamental work.
Free cutting brass is highly machinable and it does not allow bending. Applications: Free cutting brass is used for making cast, forged or stamped blanks to be used for
further machining such as high speed turning and screwing.
Lead brass is also known as cloak brass. Applications:Lead brass or cloak brass is used in making small gears and pinions for clock work.
Bronzes
Bronze is a common alloy of copper and tin.
Properties: Bronze has higher strength, better corrosion resistance than brasses. It is comparatively
hard and resists surface wear and can be shaped or rolled into wire, rods and sheets very
easily. It has antifriction or bearing properties. Bronze is costlier than brass.
Phosphor Bronze
Properties: Tensile strength, ductility, elasticity, soundness of castings, good wearing quality and resistance to fatigue of phosphor bronze increases with increase of phosphorus in bronze. This material possesses good corrosion resistance especially for sea water, so that it is much used for propeller blades. Phosphor bronze of proper composition can be easily casted, forged, drawn, and cold rolled.
Applications: Phosphorus bronze is used making for bolts, electric contact springs, bearings, bushes,
gears, ship sheathing, valve parts, propeller blades, worm wheels, gears, nuts for machine lead screws, pump parts, linings and for many other purposes. It is also suitable for making springs and corrosion resistance mine cables.
Silicon bronze has good general corrosion resistance of copper combined with higher strength. It can be cast, rolled, stamped, forged and pressed either hot or cold and it can be welded by all the usual methods.
Applications:Silicon bronze is widely used for making boilers, tanks, stoves or where high strength and good corrosion resistance is required. It is used also for making screws, tubing’s, pumps etc.
Beryllium bronze possesses higher tensile strength than other bronzes. It possesses excellent corrosion resistance. It is having high yield point and high fatigue limit. It is having good hot and cold resistance. This can be heat treated by precipitation hardening. It possesses excellent formability in soft condition, and high fatigue and creep resistance in hardened condition. However it involves high cost.
Applications: Beryllium bronze is particularly suitable material for making springs, tubes, diaphragms and electrical contacts, heavy duty electrical switches, cams and bushings. This is used for springs, heavy duty electrical switches, cams and bushings. Having non-sparking characteristics,
it is used for making chisels and hammers using for such conditions where spark might cause
explosion. It has a film forming and a soft lubricating property, which makes it more suitable
as a bearing metal. Since the wear resistance of beryllium copper is five times that of
phosphorous bronze, therefore it is used as a bearing metal in place of phosphor bronze.
Manganese bronze is highly resistant to corrosion. It is stronger and harder than phosphor bronze. Applications: Manganese bronze is mainly used for bushes, plungers, feed pumps, rods etc. Worm
gears are frequently made from this bronze.
The aluminium bronze with 8% aluminium possesses very good cold working properties. When iron is added to this metal, its mechanical properties are greatly improved by refining the grain size and improving the ductility. This material possesses good resistance to corrosion and it is somewhat difficult to cast due to oxidation problem.
Applications:Aluminium bronze is generally used for making fluid connection fittings, gears, propellers, air pumps, bushings, tubes, slide and valves etc. Cams and rollers are commonly produced
using this alloy.
Bell metal is very strong. It possesses resistance to corrosion water and atmosphere. It is used to make bells.
Constantan has high specific resistance and it is unaffected by temperature variation. Applications: Constantan is used for accurate resistors like thermo-couples, Wheet-stone bridge, Low temperature heaters and Resistances
NICKEL AND ITS ALLOYS
LEAD
ZINC
TIN
BEARING OR ANTIFRICTION ALLOYS
CUTTING TOOL MATERIAL
6. Melting Furnaces
7. Properties and Testing of Metals
8. Heat Treatment
9. Carpentry
10. Pattern and Core Making
11.Foundry Tools and Equipment
12.Mold and Core Making
13. Casting
14. Forging
15. Hot Working of Metals
16.Cold Working
17.Welding
18.Sheet Metal Work
19. Fitting
20. Metal Cutting
21. Lathe Machine
22. Drilling Machine
23. Shaper, Planer and Slotter
24. Milling
25. Powder Metallurgy
26. Inspection and Quality Control
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