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B.E.

First Semester Examination, May-2010

Manufacturing Process (ME-103-E)

Q. 1. (a) What are various common safety precautions to be adopted while

working in workshops? Specify at least three safety precautions from each shop.

Ans. Adequate safety measures are needed while working in workshops:

(i) It is advisable to isolate the construction work from plant operation.

(ii) Necessary fire and safety precautions should be taken where hazardous operations like

welding, burning or cutting are carried out.

(iii) Adequate lighting should be provided in workshop.(iv) Students should not be allowed to work on slippery surfaces.

(v) All students should make to wear protective equipment.

(vi) All machinery should be properly inspected for safety before putting it to operation.(vii) Defective or broken tools and those fitted with loose handles should never be allowed to be

used.

Q. 2. (a) How cast iron differs from steel?

Ans. The cast iron produced consists of iron, carbon, silicon, sulphur phosphorus and manganesein varying proportions. In general use cast iron possess carbon from 3 to 4 percent. Otherconstituents present in cast iron are silicon 1 to 3 percent, sulphur 0.02 to 0.15%, phosphorus

upto 1.0% and manganese 0.5 to 1.0 percent. This metal is very brittle and has a low resistance to

tension but good in compression. It is available in different forms such as grey iron, white iron.

Whereas steel basically differs from cast iron in the amount of carbon content contained by it. Itis not only the quantity of carbon which makes the difference but also the form in which it is

present. In steel the amount of carbon present is upto 1.5%. It different form dead mild steel,

mild steel, medium carbon steels, high carbon steels.

Q. 1. (b) Differentiate among the primary, secondary, joining and surface

finishing operations in usual terms.

Ans. Surface Finishing Processes : These processes are used to provide a good surface finish to

the metal surface of the product. In this, either a negligible amount of metal is removed or a


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small amount of metal is added to the surface of the product. Various surface finishing processes

are :

(a) Sand blasting (b) Buffing (c) Lapping (d) Belt grinding (e) Polishing (f) Honing (g)Electroplating (h) Metal spraying (i) Anodizing (j) Phosphating (k) Super finishing (1) Tumbling

(m) Pickling (n).Hot dipping (o) Parkerizing (p) Galvanizing (q) Painting.

Joining Processes : These processes are used for joining two or more pieces of metal parts.Various joining processes are :(a) Welding (b) Soldering (c) Brazing (d) Riveting (e) Screwing (f) Adhesive joining (g)

Sintering (h) Pressing (i) Coupling (j) Keys and cotter joints (k) Nut and bolts joints.

Most of the metals used in the industry are obtained as ores. These ores are subjected to certainrefining processes. Which convert the metal into the molten form. The molten metals are poured

into moulds to obtain commercial castings known as ingots. All these ingots are further subjected

to one or more processes to obtain usable metal products of different shapes and sizes. These

processes are :1. Primary shaping processes 2. Secondary processes

3. Joining processes 4. Surface finishing processes.

1. Primary Processes : The ingots need to be remelted in cupola or some other foundaryfurnace. The molten metal is then poured into moulds to obtain castings or sometimes ingots are

converted to usable form by forging or any other primary shaping processes.

The primary shaping processes are :

(a) Casting (b) Forging(c) Rolling (d) Bending.

2. Secondary Processes: A fairly large no. of components need further processing after primary

processes. These components are subjected on various machine tools like drilling machines,

milling machines etc. to obtain complex shapes and dimensional accuracy. These machining

operation undergone to obtain desired shape is known as secondary processes.The secondary shaping processes are :

(a) Turning (b) Shaping

(c) Milling (d) Drilling(e) Grinding

Q. 2. (a) How are metals classified?

Ans. All metals used in engineering work can be classified into two categories : Ferrous andnon-ferrous. Ferrous metal are those in which the chief constituent is iron, although other

constituents like carbon, sulphur, manganese and phosphorous etc. also exist in varying

proportions. Iron, steel, and their alloys fall under this category. Non-ferrous metals are those


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which do not contain iron metals like lead, copper, zinc and tin, etc. & their alloys fall under this

category of metal classification.

Q. 2. (b) Using charts, describe the procedure for processing of cast iron andsteel for production of market form of supply.

Ans.

Q. 3. (a) Why are the following materials added to moulding sounds: (i) Dextrine

(ii) Wood floor (iii) Silica floor (iv) Mollasses (v) Pitch (vi) Corn floor.

Ans. Dextrine: Dextrine, wood floor, silica floor, mollasses, pitch, corn floor are additivesmaterials which are added to the moulding sand to improve upon some of its existing properties

or to impart certain new properties to it.

Dextrine and Mollasses : Their addition increases the dry-strength of the sand.

Wood Floor : It promotes mould wall movement, reduces expansion defects, increases

collapribility im-proves surface finish and thermal stability of mould.

Corn Floor : It promotes mould wall movement by being volatized by heat, reduces expansion


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defects, improves strength toughness and collapsibility of the sand.

Silica Floor : It increases hot strength decreases metal penetration into the mould, reduces

expansion defects and improves surface finish.

Pitch : It improves hot strength and surface finish on ferrous castings.

Q. 3. (b) Describe briefly the various defects and remedies associated with

soundness of casting.

Ans. Gas defects like blow holes and open blows, air inclusion and pin hole porosity. All these

defects are caused to a great extent by the lower gas passing tendency of the mould which may

be due to lower venting, lower permeability of the mould and/or improper design of the casting.

The remedies would be to choose the appropriate pouring temperature and improve gating

practices by reducing the turbulence.Shrinkage cavities caused by the liquid shrinkage occurring during the solidification of the

casting to compensate this proper feeding of liquid metal is required as also proper casting

design.

Moulding Material Defects are those defects which are caused because of the characteristics of

the moulding materials. The defects that can be put in this category are: cuts and washes, metal

penetration fusion, run out, rat tails and buckles, swell & drop.

These defects remedied by the proper choice of moulding sand and using appropriate moulding

method.

Q. 4. (a) Differentiated between hot working and cold working processes.

Ans.


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Q. 4. (b) Classify the various hot working and cold working processes using tree

structure approach.

Ans.


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Q. 5. (a) Differentiate between shaping and planning procedure.


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Ans.

Q. 5. (b) Describe briefly the (i) types of chips (ii) tool nomenclature.

Ans. (i) Types of Chips : When the machining is performed at a very low speed or the work

material is brittle, the shearing operation on the work material does not continue without causinga fracture. We shall now summarize the conditions for the various types of chips.

(i) Continuous chips without BUE

(a) Ductile material (b) Small uncut thickness(c) High cutting speed (d) Large rake angle

(e) Suitable cutting fluid.

(ii) Continuous chips with BUE(a) Stronger adhesion between chips and tool face.

(b) Low rake angle (c) Large uncut thickness

, (iii) Discontinuous Chips :

(a) Low cutting speed (b) Brittle work material (c) Small rake angle (d) Large uncut

thicknessIt is obvious that continuous chips without BUE are most desirable and the machining is steady.

(ii) Tool Nomenclature means systematic naming of the various parts and angles of a cuttingtool. The surfaces on the point of a tool bear define relationship to each other that are defined by

angles. The principles underlying cutting-tool angles are the same whether the tool is a single

point too, a multipoint tool, or a grinding wheel. Since a single point tool is the easiest to

understand. The complete nomenclature of the various parts of a single-point tool is shown.


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These are shank, face, flank, heel, nose, back rake, side rake, side clearance, end cutting edge,

wide cutting edge and lip angle. These elements define the shape of a tool.

Q. 6. (a) Classify the welding processes using tree structural approach.

Ans. Classification of welding processes using tree structure-approach.


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Q. 6. (b) Differentiate among welding, brazing and soldering.


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Ans. Welding may be defined as the process of joining similar metals by the application of heat,

with or without the application of pressure 3nd filler metal, in such a way that the result is a

continuity of homogeneous material. The welded component results in continuity of ahomogeneous material having the same composition and characteristics of the two parts to be

joined together.

Advantages of Welding:(i) It produces a permanent joint.(ii) The overall cost of welding of equipment is generally low.

(iii) Many portable welding instruments are available.

(iv) A large number of metals can be welded.(v) . A good weld is as strong as the base metal.

Disadvantages:

(i) It creates residual stresses and distortion in work pieces.

(ii) Edge preparation is generally required before welding.

Soldering : Soldering is a metal joining process with the help of a low melting point metal by the

use of heat and filler material. Soldering is of vital use not only in some machine tools but all

types of modern technologies most of the electronic marvels are joined by soldering. Soldering isadvantageous as similar and dissimilar materials can be joined by this process.

In soldering, the melting point of the filler metal is less than 427C. Although soldering is done

below 427C, generally the solders used have a melting point between 180 to 270C.

Brazing : Brazing may be defined as the technique of joining two similar or dissimilar materialsby addition of special filler metal. Brazing gives a much stronger joint than soldering but

requires greater heat which cannot be obtained from a copper bit in soft-soldering.

The filler metal used in brazing is known as a shelter. In brazing, metallic parts are joined by anonferrous metal or alloy. The melting temperature of a shelter should be above 427C and

brazing is carried out above this temperature.

Q. 7. (a) Compare process layout with a product layout.

Ans. Comparison:

Product Layout Process Layout

1. Investment

Needs high investment in Comparatively low investmentm/c equipment. needed.

2. Duration of ProductionNeeds less manufacturing Production time cannot

time as the economy be economized due toin time can be planned frequent movement

in the beginning of men and material.

3. Immobilization due to Breakdown


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Breakdown of any Breakdown of any

unit/component immobilizes machine does not

The whole system. Immobilize the whole system.

4. Adjustability to ChangesInflexible as each Flexible as different

machine can perform sections can adjust

pre-designed operation the operations accordingonly to changes in operations.

5. Floor SpaceRequires less space. Require more space.

6. Men/Equipment Utilization Product layoutnot to full Comparatively better

capacity. utilization.7. Control and Inspection

Specialized and Comparatively betterexpertise. efforts.

Q. 7. (b) What factors govern the preparation of a shop layout?

Ans. Factors govern the preparation of a shop layout are as follows:

1. Availability of space.2. Availability of power.3. Availability of water.4. Safe working conditions.5. Provision of stores within the shop i.e., for tools, instruments finished parts and consumable

materials etc.

6. Lighting and ventilation.7. Inter-dependability of one shop over the other.8. Proper supervision and control.9. The material have to move a minimum distance.10.The layout provides adequate safety and satisfaction to the shop workers/student.

Q. 8. Write short notes on any three of the following:

(a) First Aid Box

(b) Properties of Engineering Materials

(c) Wire Drawing

(d) Uses of Coolants

(e) Soldering.


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Ans. (a) First Aid Box : Whenever one speaks of an industry it automatically involves a largenumber of machines and other equipment which carry a still larger number of moving part and

dangerous projections which may cause hazardous accidents and fatal injuries, so safe-guarding

against them to providing first aid box which contain all medicines, cotton, Dettol and other firstaid requirement which when provided, to ensure adequate safety for men at work place.

(b) Properties of Engineering Materials : Those characteristics of the engineering materials

which describe their behavior called mechanical properties.

Like strength : It can be described as the measure of ability of a material to withstand external

forces.

Elasticity : It is a type of tensile property of a material due to which it resists permanentdeformation under applied loads.

Stiffness : It that property of a material due to which it is capable of resisting deflection.

Plasticity : It is the property of a material due to which it can undergo permanent deformationwithout failure.

Thermal Properties: They determine the behavior of materials under varying temperature

conditions in order to evaluate their suit abilities.

Electrical Properties : They determine the ability of a material to allow or resist the flow of

electricity through it.

Magnetic Properties : It is important to know the response of different materials to an applied

magnetic field in order to assess their suit abilities.Chemical Properties : These properties indicate the reactions of materials when they come in

contact with other substances like water.

1. Wire Drawing : This process consists of extruding a rod through a die, thereby causingreduction in cross-sectional area of rod. Generally the wire is drawn by pulling the rod

through several dies of decreasing diameter in order to obtain very thin wire. Raw

material used for wire drawing is generally a rolled bar obtained by hot rolling process.The rods as obtained from hot rolling are first cleaned in acid baths to remove scale and

rust and then coated with some lubricants in order to avoid corrosion and oxidation and to

facilitate the operation of drawing through the die. Soaps are used as lubricants and are

picked up by passing the undrawn wire through a container. Dies for wire drawing aregenerally made of chilled cast iron, hardened alloy steel, cemented tungsten carbide and

various other carbide materials for small size,! Wires, the diamond dies are used.

2. Uses of Coolants : The use of coolants is indispensable in all metal working operationsin the workshops, particularly, in metal machining these coolants play a very

signiilcantrole. As we are aware, a lot of heat energy is generated during the machining


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processes which is either wasted unnecessarily or proves harmful to the tool or work or

both. These fluids help in minimizing these adverse effects and thus help to increase the

tool life and surface finish on the job not only this, but when two or more metal surfacesare in contact and either slide or run with respect to one another a lot of wear takes place

the common functions are :

1. To minimize the friction between mating surfaces; thus prevent rise in temperature.2. To provide lubrication at high pressures.3. To provide a cushioning effect between the job surface and the tool to prevent adhesion

of the two.

4. To drive away the chips, scale and dirt.5. To protect the finished surface from corrosion.

(e) Soldering: Soldering is a method of joining similar or dissimilar metals by means of a filler

metal whose liquids temperature is below 450C. Though soldering obtains a good. Joint

between the two plates, the strength of the joint is limited by the strength of the filler metal used.

Soldering is normally used for obtaining a neat leak roof joint or a low resistance electrical joint.The soldered joints are not suitable for high temperatures service because of the low melting

temperatures of the filler metals used.The joint design used for soldering is similar to that of brazing since the filler metal enters the

soldered joint by capillary action. Further, since the soldered joint is weaker compared to that of

the brazed joint, mechanical fastening of other means is used in addition to soldering to provide

the necessary joint strength.The soldering joints also need to be cleaned meticulously to provide chemically clean surfaces to

obtain a proper bond. Solvent cleaning, acid pickling and even mechanical cleaning are applied

before soldering.

Q. 1. What do you understand by the following terms :

(a) Simplification (b) Automation (c) Mechanization (d) Standardization (e)

Interchangeability

Ans. (a) Simplification : It is a process through which a limited number of grades, types and

sizes of a product arc determined in order to have better control, minimise waste, simplifyproduction and thus reduce price. By eliminating unnecessary varieties, sizes and design it leads

towards interchangeable of products.


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1. Automation : It involves adoption of automatic controls for the operations of differentmachines. This automatic control may be adopted for only a few operationos or all the

operations of a machine and accordingly the machine will be known as semi-automatic orfully automatic. Also it may be adopted only for a single machine out of the whole lot or

a series or group of such machines depending upon the operation required for the

product.2. Mechanization : It is a term which implies an endeavour or trend towards minimising thehuman efforts, to the extent. It is possible, by adopting mechanical. Means or methods for

different processes. Such a trend may be in material handling, loading and unloading of

components, actual operations done on the job or transportation etc. But no feedback isprovided by the process, operation or machinery.

3. Standardization : It is the second step towards interchangeable manufacture increasedoutput and higher economy. The process of standardisation involves determining the best

material, manufacturing processes and allied techniques for the manufacture of a productand adhering to them very strictly so long as the better standards for all these are not

known.

Two types of standards prevailing in various industries : (i) Managerial standards (ii) Technical

standards.

(e) Interchangeability : It is a principle applied to the mass production of identical components

suchthat any one of the components, selected at random, will suit the assembly conditions to meet the

requirements

ot operation. For this the components are allowed a predetermined amount of variation in theirfinished

dimensions, the two extremities of which are called limits.

All the components of which the finished dimensions lie within these limits are acceptable

components.

Q. 2. (a) How cast iron differs from steel?

Ans. The cast iron produced consists of iron, carbon, silicon, sulphur phosphorus and manganesein varying proportions. In general use cast iron possess carbon from 3 to 4 percent. Other

constituents present in cast iron are silicon 1 to 3 percent, sulphur 0.02 to 0.15%, phosphorus

upto 1.0% and manganese 0.5 to 1.0 percent. This metal is very brittle and has a low resistance totension but good in compression. It is available in different forms such as grey iron, white iron.Whereas steel basically differs from cast iron in the amount of carbon content contained by it. It

is not only the quantity of carbon which makes the difference but also the form in which it is

present. In steel the amount of carbon present is upto 1.5%. It different form dead mild steel,mild steel, medium carbon steels, high carbon steels.


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Q. 2. (b) Differentiate among mild-carbon steel, medium-carbon steel, high-

carbon steel and high-speed steel in terms of chemical composition, properties

structure, application and limitations.

Ans. Mild Carbon Steel : It is having carbon content below 0.15% used in forgings, stamping,tubes, castings.

Medium Carbon Steel : It is having carbon from 0.3% to 0.8% used in drop forgings, boilerdrums, marine shafts, axles, rotors.

High Carbon Steel: It is having carbon from 0.8% to 1.5%, used in springs, shear blades, wood

chisels, cold sets, hammers.

Q. 3. (a) Make a layout of a casting shop, showing all possible tools and

equipments available there.

Listed of tools and equipments used in casting shop :

shown at(i) Foundary cupola of required casting Nos - 7

(ii) Blower of proper capacity for cupola Nos - 6

(iii) Pit furnances Nos - 9 & 10(iv) Oil fired fitting furnance Nos - 8

(v) Drying oven Nos - 5(vi) Bench for bench moulding Nos - 2


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(vii) Space for floor moulding Nos - 1

(viii) Space for care making Nos-4

(ix) Coke store Nos- 13

Q. 3. (b) Discuss the step-by-step full casting process in detail.

Ans. Casting Process :(a) PatternMaking: In casting process first step is to making of pattern. A pattern may be

defined as amodel or replica of the object to be cast. Except for various allowances and core prints, apattern

exactlyresembles the casting to be made during making of pattern design considerations are :

(i) Careful selection of parting line is necessary for easy removal of the pattern from sand.

(ii) As far as possible employ full core instead of joined half cores.

(iii) Proper allowances should be provided.(iv) All sharp corners should be suitable provided with fillets.

o Moulding Sand Preparation : Proper conditioning and preparation of sand isneeded to get good castings sand preparation is also known as sand tempering and

quality of moulding sand depends upon the manner in which it is prepared. Sandpreparation means mixing the moulding sand ingredients such as sand, binder,

clay, water and other additions. Sand conditioning means preparation of moulding

sand, so that it becomes suitable for moulding purposes.

o Moulding: It is a cavity in a moulding box, formed by a pattern. It is similar inshape and size so that of the actual casting plus some allowance.

oPouring of molten metal in a cavity.

Q. 4. (a) Describe briefly the various characteristics of hot working and

cold working processes.

Ans. Those processes, working above the recrystallisation temperature are termed as hotworking processes where those below are termed as cold working processes.

Characteristics of Hot Working Processes :(i) As the material is above the recrystallisation temperature, any amount of working canbe imparted since there is no strain hardening taking place.

(li) At high temperature, the material would, have higher amount of ductility and

therefore therse is no limit on the amount of hot working that can be done on a materialeven brittle materials can be hot worked.

(iii) Hot working requires much less force to achieve the necessary deformation.

(iv) Better mechanical properties achieved.


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Characteristics of Cold Working Processes :(i) Cold working increases the strength and hardness of the material due to the strain

hardening which would be beneficial in some situations. There is no possibility ofdecarburisation of the surface.

(ii) No oxide would form on the surface and consequently good surface finish is obtained.

(iii) Better dimensional accuracy is achieved.(iv) It is far easier to handle cold ports and it is also economical for smaller sizes.

Q. 4. (b) Differentiate among Forging, Rolling and Extrusion, using principle,

set-up, process, products, advantages and applications.

Ans. Rolling is a process where the metal is compressed between two rotating rolls for reducing

its cross-sectional area.

This is one of the most widely used of all the metal working processes because of its higher

productivity and low cost. Rolling would be able to produce components having constant cross-section throughout its length. Many shapes such as 1, T, L and channel sections are possible. It is

also possible to produce special sections such as railway wagon wheels by rolling individualpieces. Rolling is normally a hot working process unless specifically mentioned as cold rolling.

Forging is the operation where the metal is heated and then a force is applied to manipulate themetal. In such a way that the required final shape is obtained. This is the oldest of the metal

working processes known to mankind since the copper age forging is generally a hot working

operation though cold forging is used sometimes.Extrusion is the process of confining the metal in a closed cavity and then allowing it to flow

from only one opening so that the metal will take the shape of the opening.

The operation is identical to the squeezing of tooth paste but of the tooth paste tube. By the

extrusion process it is possible to make components which have a constant cross-section over

any length as can be had by the rolling process. The complexity of parts that can be obtained byextrusion is more than that of rolling because the die required being very simple and easier to

make. Also extrusion is a single pass process unlike rolling.

Q. 5. (a) Using figures, show the relative motions between work-piece and cutting

tools in case of operations on lathe, shaper, planer, milling, drilling and slotter.


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Ans. Relative motion of


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Q. 5. (b) How do you specify a lathe machine?

Ans. In order to specify a lathe, the following specifications should be included :

(i) (a) Height of centres (b) Type of bed i.e. straight, semi-gap or gap type (c) Centre distance.

(ii) (a) Swing over bed (b) Swing over cross slide (c) Swing ingap (d) Gap in front of face plate (e) Width

of bed.

(iii) (a) Spindle speech range (b) Spindle nose (c) Spindle bore (d) Taper in nose.(iv) (a) Metric thread pitches (b) Lead screw pitch (c) Longitudinal feeds (d) Cross feeds.

(v) (a) Cross slide travel (b) Top slide travel (c) Tool section.

(vi) (a) Tail stock sleeve travel (b) Taper in sleeve bore.

(vii) Motor horse power and RPM.

(viii) Shipping dimensions : Length x width x height x weight.

Q. 6. Differentiate among gas welding, arc welding and resistance welding, using

(a) principle (b) process-set-up (c) types (d) applications (e) advantages (f) tools

used

Ans. Gas Welding

: Gas welding also called as oxy-fuel gas welding (OFW), derives the heat from the combustion

of a fuel gas such as acetylene in combination with oxygen. The process is a fusion welding


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process wherein the joint is completely melted to obtain the fusion. The heat produced by the

combustion of gas is sufficient to melt any metal and as such is universally applicable. The fuel

gas generally used is acetylene because of the high temperature generated in the flame.

Gas welding contains the supply units for oxygen and acetylene with associated regulators and

the torch, which mixes the two gases before they are ignited. The oxygen is normally stored in

strong cylinders at a pressure ranging from 13.8 MPa to 18.2 MPa. Acetylene is normally madeavailable in the following two forms; acetylene storage cylinder and acetylene generator.

The principal advantage of an oxy acetylene welding set up is the versatility of the equipment.

The same equipment with a range of torches would be used for oxygen cutting as well as for

brazing and braze welding.

Arc Welding : In welding generation of heat by an electric arc is one of the most efficientmethod. Approximately 50% of the energy is liberated in the form of heat. The electric arc

welding process makes use of the heat produced by the electric arc to fusion weld metallic

pieces. This is one of the most widely used welding process, mainly because of the ease of useand high prduction rates that can be achieved economically. An arc is generated between twoconductors of electricity, cathode and anode (DC). When they are touched to establish the flow

of current and then separated by a small distance. An arc is a sustained electric discharge through

the ionised gas column plasma between the two electrodes.

The main requirement in an arc welding setup is the source of electric power. They areessentially of two types :

(a) AC machines : (i) Transformer (ii) Motor

(b) DC machines : (i) Transformer with DC rectifier (ii) Motor or engine driven generator.

Resistance Welding : It is a function welding process where both heat and pressure are applied

on the joint but no filler metal or flux is added. The heat necessary for the melting of the joint isobtained by the heating effect of the electrical resistance of the joint and hence name resistancewelding.

In resistance

(RW), a low voltage (typically 1 V) and very high current (typically 15,000 A) is passed through

the joint for a very short time (typically 0.255). This high amperage heats the joint due to the

contact resistance at the joint and melts it. The pressure on the joint is continuously maintained


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and the metal fuses together under this pressure. The heat generated in resistance welding can be

expressed asH = kl2 Rt

The maim requirement of the process is the low voltage and high current power supply. This is

obtained by means of a step down transformer with a provision to have different tappings on theprimary side, as required for different materials.

Resistance welding are very well suited for mass production, as they give a high production rate.

There are no consumables used in this process except for the electrical power and a relatively

smaller electrode wear. As a result it is very economical process. It is possible to weld dissimilarmetals as well as metal plates of different thicknesses.

Q. 7. Differentiate among types of plant layouts in detail.

Ans. Plant layout is defined as it is such a systematic and effective functional arrangement of

different departments machines, equipment and services of an organisation that will facilitate the

processing of the proposed or undertaken product in the most efficient and economical manner in

the minimum time.Different types of layout:

1. Fixed Position Layout: In this type of layout the major part of an assembly or materialremains at a fixed position and all its accessories, auxilliary material, machinery and

equipment needed, tools required and the labour are brought to it to work at site. Thus the

location of the major component or material is not disturbed till the product is ready fordespatch. This type of layout is mostly adopted for extremely large items manufactured in

very small numbers e.g. ship, aeroplanes etc.

2. Process or Functional Layout: In this type of layout similar, machines or operations aregouped together, so that all the operations of same type are performed at the same placealways, for example all the lathes may be grouped together to do turning and threading

etc. all drilling machines in one area to do drilling work, all buffing and polishing

machines at one place to do surface finishing work and so on.

This type of layout is usually preferred for the industries involved in job order type of production

and manufacturing and/or maintenance activities of non-repetitive type as shown in figure.


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o Line Production or Product: In this type of layout all the machines are arrangedin a line according to the sequence of operation i.e. each following machine or

section is arranged to perform the next operation to that performed by itspreceding machine or section. It is an ideal form of layout in which the handling

time is minimum.o Combination Layout (or Group Layout): Because of the inherent advantages

and disadvantages associated with both the process layout as well as product

layout the best results can be obtained by combining the advantageous features of

both these layouts into a single one and this is what is known as a combination

layout. In this type of layout a set of machinery or equipment is grouped togetherin a section and so on, so that each set of machines or equipment is used to

perform similar operations to produce a family of components.o

Q. 8. Write short notes on any three :

(a) Tree structure classification of Manufacturing processes

(b) Cupola furnace

(c) Tool wear

(d) TIG welding

(e) Shearing operations

Ans. (a) Tree Structure Classification of Manufacturing Process :

(b) Cupola Furnace : For melting of cast iron in foundary the cupola furnace is used. It has a


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construction in the form of a hollow vertical cylinder made of strong mild steel plates and

riverted or welded at the seams. Welded joints' are more common in modern practice. In large

cupolas the lower portion is made of comparatively thicker plates so as to make it strong enoughto hold the upper structure and fire brick lining. Thus the stress in the whole structure is

distributed uniformly. Also such cupolas are further strengthened by providing the brick

retaining rings at suitable heights. The bottom door of the shell can be in one piece hinged to asupporting leg or in two pieces, each piece hinged separately to the two opposite legs. When thecupola is in operation, the bottom door is supported by a prop so that it may not collapse due to

the large weight of the charge and coke etc. it carries when we do not need the cupola for further

operation, the charge feeding is stopped, air supply cut off and the prop removed. As soon as theprop is removed the door, drops down providing a clear space for the coke fire, residue of the

molten metal with slag and the sand bed to fall down and thus, the fire inside ceases gradually.

(c) Too) Wear : It is not very difficult to realize that the success of a machining process dependson the

sharpness of the tool. Even common sense tells us that the use of a blunt tool results in a largepower

consumption and deteriorated surface finish when a cutting tool is unable to cut consuming

reasonable energy

and cannot produce an acceptable finish it is considered to have failed.The failure of a cuttingtool may be due

to one or a combination of the following models :

(i) Plastic deformation of the tool due to high temperature and large stress.(ii) Mechanical breakage of the tool due to large force and insufficient strength and toughness.(iii) Blunting of the cutting edge of the tool through a process of gradual wear.

It is clear that the wearing action takes place on those surfaces along which there is a relative

sliding with other surfaces. Thus, the wear takes place on the rake surface where the chip flowsover the tool and on the flank surface where rubbing between the work and the tool occurs.

These wears are called the crater and the flank wears.

1. TIG Welding : Tungsten Inert Gas (TIG) welding is an inert gas shielded arc weldingprocess using non-consumable electrode. The electrodes may also contain 1 to 2% Thoria

mixed along with 0.15 to 0.40% Zirconia. The pure tungsten electrodes are less expensive

but will carry less current. The thoriated tungsten electrodes carry high currents are more

desirable because they can strike and maintain a stable arc with relative ease. TheZirconia added tungsten electrodes are better than pure tungsten electrodes are better than

pure tungsten but inferier to thoriated tungsten electrodes. The TIG welding process can

be used, for the joining of a number of materials though the most common ones arealuminium magnesium and stainless steel.


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2. Shearing Operation : The metal is brought to the plastic stage by pressing the sheetbetween two shearing blades so that fracture is initiated at the cutting points. The

fractures on either side of the sheet further progressing downwards with the movement of

the upper shear,

Finally result in the separation of the slug from the parent strip. The metal under the upper shear

is subjected to both compressive and tensile stresses. In an ideal shearing operation, the uppershear pushes the metal to a depth equal to about one third of its thickness. Because of pushing of

the material into the lower shear; the area of cross-section of the metal between the cutting edge

of the shears decreases and causes the initiation of the fracture.This portion of the metal which is forced into the lower shear is highly burnished and would

appear as a bright band around the blank lower portion. The fractures which are initiated at both

the cutting points would progress further with the movement of the upper shear and if the

clearance is sufficient, would meet. Thus completing the shear action.

Q.l. (a) How will you classify manufacturing processes? Differentiate between

any two of them.

Ans. There are a large number of processes available for manufacture to the engineer. These

processes can be broadly classified into four categories.

(i) Casting processes, (ii) Forming processes,(iii) Fabrication processes, (iv) Material removal processes.

Casting processes : These are the only processes where liquid metal is used. Casting is also the

oldest known manufacturing process. It requires preparation of a cavity usually in a refractorymaterial to resemble closely the final object to be made. Molten metal is poured into this

refractory mould cavity and is allowed to solidify. The object after solidification is removed

from the mould. Casting processes are universally used to manufacture a wide variety of

products. The principal process among these is sand casting where sand is used as the refractorymaterial. The process is equally suitable for the production of a small batch as well as on a large

scale.

Some of the other casting processes for specialized needs are :

(i) Shell mould casting, (ii) Precision investment casting,

(iii) Plaster mould casting, (iv) Permanent mould casting,(v) Die casting, (vi) Centrifugal casting.


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Forming processes: These are solid state manufacturing processes involving minimum amount

of material wastage and faster production in a farming process, metal may be heated to atemperature which is slightly below the solidus temperature and then large force is applied such

that the material flows and takes the desired shape. The desired shape is controlled by means of a

set of tools called dies which may be completely closed or partially closed during manufacture.These processes are normally used for large scale production rates. These are generallyeconomical and in many casses improve the mechanical properties too. Some of the metal

forming processes are :

(i) Rolling, (ii) Drop forging,

(iii) Upset forging, (iv) Extrusion,(v) Wire drawing, (vi) Sheet metal operation.

(vii) Press forging.

Q. 1. (b) Describe various methods of safety.

Ans. In order to control the accident, the following methods must be taken by safety organization.

(A) Supervisory safety performance:

(i) Job safety analysis.

(ii) Proper job placement.

(iii) Development of safe working conditions.

(iv) Enforcement of safety rules.

(v) Promotion of employee participation in safety.

(B) Mental condition of person:

(i) Adequate induction and job training.

(ii) Safety training, safety awareness, safety promotion.(iii) Regular safety contacts by supervisor.(iv) Involvement.

(vi) Adequate communication concerning the employee.

(C) Physical condition of person :

(i) Pre-employment medical examination. (ii) Periodical medical check-up. (iii) Adequate

medical facilities.(D) Safe work place layout and improvement of working conditions.

(E) Safety devices in machines.(F) Persona] protective devices.

Q. 2. Describe briefly the composition, properties and applications of


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(a) -High speed steel

Malleable cast iron

Medium carbon steel.

Ans. (a)

High Speed Steel: High speed steel contains very fine tungsten carbide after tempering and the

tool made out of this steel retains its strength at elevated temperatures it continues to machine,

even when it gets red hot i Cutting speeds can be more than ten times higher for the high speed

steel as compared to a carbon steel.

Malleable cast Iron : In malleable cast iron in which free carbon is present the form of nodules in the

matrix of cementite and ferrite. This is achieved by first chilling the casting so that all white cast iron is

formed followed by a controlled heat treatment process so that some of the cementite is transformed

to ferrite and nodules of free carbon. This material is more ductile than grey cast iron. This form is

suitable only for components with very small section thicknesses. Since all white cast iron is to form the

starting point for malleable iron.

Medium carbon steel : These are less ductile but harder and have greater tensile strength than low

carbon steels. They also have better machining qualities and are more responsive to heat treatment.

These are wider used in industry used for making shafts, connecting rods, spindles, rails, axles,

gears, turbine bucket wheels storing arms and other machine parts requiring medium strengthand wear resisting surfaces. It comprises 0.30 to 0.60% of carbon.

Q. 3. (a) What is pattern ? Classify its types.

Ans. A pattern is a replica of the object to be made by the casting process. There are various types of

patterns depending upon the complexity ofthe job, the number of castings required and the moulding

procedure adopted.(i) Single piece pattern : These are inexpensive and the simplest types of patterns as the same indicates,

they are made of a single pieces. This type of pattern is used only in castes where the job is very simple

and does not create any vvithdrawl problems.

(ii) Split pattern : This is the most widely used type of pattern for intricate castings.

(iii) Gated pattern : This is an improvement over the simple pattern where the gating and runner system

are integral with the pattern. This would eliminate the hand cutting of the runners and gates.


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(iv) Cope and drag pattern : These arc similar to split patterns. In addition to splitting the pattern the

cope and drag halves of the pattern along with the gating and risering systems are attached separately

to the metals.

(v) Sherton pattern : A Sherton of the pattern made is strips of wood is used for building the final

pattern by packing sand around the shereton.

(vi) Sweep pattern : It is used to sweep the complete casting by means of a plane sweep used for

generating large shapes.

Q. 3. (b) Describe briefly the functions of core, risers, runner and gates.

Ans.

Functions of core : Cores are the materials used for making cavities and hollow projections

which

cannot normally be produced by the pattern alone. Any complicated contour or cavity can bemade by means

of cares so that really intricate shapes can be easily obtained. These are generally made of sand

and are even

used in permanent moulds.

Functions of risers : Most of the foundry alloys shrink during solidification the volumetric

shrinkages. As a result of this volumetric shrinkage during solidification, voids are likely to formin the castings. Unless additional molten metals is fed into these places which are termed as hotspots since they remain hot till the end.

Hence a reservoir of molten metal is to be maintained from which the metal can flow readily into

the casting when the need arises these reservoirs called risers.

Function of runner: It is generally located in the horizontal plane which connects the sprue to

its ingates, thus letting the metal enter the moulds cavity. The runners are normally made

trapezoidal in cross section. It is a general practice for ferrous metals to cut the runners in the

cope and the ingates in the drag. The runner would always be full and thus slag trapping wouldtake place.

Functions of gates : These are the openings through which the molten metal enters the mould

cavity. The shape and the cross-section of the ingate should be such that it can readily be broken

off after casting solidification and also allow the metal to enter quietly into the mould cavity.

Q. 3. (c) Explain with the help of neat sketches the following casting defects:

(i) Shrinkage (ii) Hot tears

(iii) Blow-holes (iv) Misrun

(v) Pinholes (vi) Fins


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Ans. (i) Shrinkage : The main reason for these defects are :

1. Volumetric contraction both in liquid and solid state.2. Low strength at high temperature cracks often being at the shrinkage cavities and work

their way. Outward as the casting is stressed in service. The shrinkage problem isparticularly secure in junctions.

(ii) Hot tears : Since metal has low strength at higher temperatures any unwanted cooling stress

may cause the rupture of the casting. In the example shown in fig, the horizontal members beingthinner cool fast and try to bring the thick vertical members closer which is resisted by the core.

This resistance would cause the tearing of metal to take place at the joint with the th icker rib.

(iii) Blow-holes: These are the spherical, flattened or elongated cavities present inside the castingor on the surface as shown in fig. On the surface

they are called open blow inside they are called blow holes. These are caused by the moisture leftin the mould and the core. Because of the heat in the molten metal, the moisture is converted into


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steam, part of which when entrapped in the casting ends up as blow hole and reaches the surface.

(iv) Misrun : Misrun is caused when the metal is unable to fill the mould cavity completely and

thus leaves unfilled cavities. These defects are caused by the lower fluidity of the molten metal.(v) Pin holes : This is caused by hydrogen in the molten metal. This could have been picked up

in the furnace or by the dissociation of water inside the mould cavity. As the molten metal gets

solidified, it loses the temperature which decreased the solubility of gases and thereby expellingthe dissolved gases.

(vi) Fins : Under the influence of the metallostatic forces, the mould walls may move casting

fins in the dimensions of the casting.

Q.4. (a) What do you understand by sheet metal work ? What are its various

operations ? Make a component which can reflect these various operations.

Ans. The sheet metal work is generally considered to be a plate with thickness less than about 5

mm. Oneof the principal concern in a sheet metal work is the spring back of the metal. When the metal isdeformed and

then plastically when the applied load is removed, the plastic component of the deformation

remains permanently,but the elastic part springs back to its original shape.

Various operations of sheet metal work are shearing, blanking, piercing, trimming shaving,

notching, nibbling, stretch forming, canning, sizing, ironing, hobbing, drawing, spinning,bending, forming and embossing.

Shearing operations : The metal is brought to the plastic stage by pressing the sheet betweentwo shearing blades so that fracture is initiated at the cutting points. The fractures on either side

of the sheet further progressing downwards with the movement of the upper shear. Finally resultin the separation of the- slug from the parent stip.

Shearing oper ion shown in fig.

Blanking : It is a process in which the punch removes a portion of natural. From the stock which

is a strip of sheet metal of the necessary thickness and width. The removed portion is called ablank and is usually further processed to be same use.

Piercing : Also sometimes called punching the piercing is making holes in a sheet. It is identical

to blanking except of the fact that the punched out portion coming out through the die in piercingis scrap. Normally, blanking operation will generally follow a piercing operation.

Trimming : In operation such as drop forging and die casting, a small amount extra metal gets

spread, out near of parting plane, which is termed as flash. The flash is to be trimmed before the


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casting or forging is to be used.

Shaving : Inblanking or piercing operations the edge of the blank or the hole is not perfectly

clean because of the burr generated in the shearing process which is equal to the clearance on thedie for close tolerance work, the blanking or piercing process is followed by shaving which

removes the burr left on the poroduct.

Nibbling : Nibbling is removing the metal in small increments when a specific contour is to becut in a sheet metal, a small punch is used to punch repeatedly along the necessary contour,generating the required profile. Nibbling is resorted to when the contour is long and a separate

punch is impractical and uneconomical.

Notching : Notching is a method to cut a specified small portion of metal towards the edge of thestock.

Typical shearing processes Drawing: It is the process of making cups, shells, similar articlesfrom metal blanks.

Q. 4. (b) Give the various tools and equipment's required in forging operation.

Name the various forging operations also.

Ans. The various tools and equipments required in forging operation are as follows :

(i) Anvil (ii) Top fuller

(iii) Bottom fuller (iv) Sledgehammer

(v) Hot punch (vi) Chisel

(vii) Tongs (viii) Machine hammer

(ix) Board hammer (x) Air-lift hammer

(xi) Hydraulic forging press


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The various forging operations are:

(i) Drawing down or swaging (ii) Upsetting

(iii) Punching (iv) Setting down

(v) Bending (vi) Fullering

(vii) Blocking

Q.5. (a) Differentiate between shaper and planer.

Ans. Shaper: The shaper makes use of a single point tool that traverse the work and feeds over at the

end of each stroke it is used principally to machine flat or plane surfaces in horizontal vertical and

angular planes. The cutting tools is mounted on the shaper head to the ram. The ram imparts a

reciprocating motion to the tool which operates over the shaper table. It is generally not used as

production machine; however, widely used in machine shops and tool rooms. Since it is easy to set upand operate. Also the cutters used are low in cost and are easily sharpened. A big advantage of it is that

since the amount of metal removed at one time is relatively small in area. Therefore little pressure is

imparted upon the work and the elaborate holding fixtures are not needed. The worker is usually held in

a shaper vise, but same time it may be desirable to bolt it directly on to the table,

In comparision to planer it occupies less space, consumes less power, less costs, occupies lessflour area. Shaper is easier to operate and about three times quicker in action.

Planer : In case of planer the work reciprocates and tool is given the feed. Planer are used to

machine plane surfaces that may be horizontal, vertical or at an angle. Angular surfaces are often

easier to machine on a planer. Planing is also the most effecive method of machining partshaving complex shapes and requiring machining of long and narrow surfaces.

In case of planer, the setting time is of the order of 5 to 6 times that for shaper.

Also the operation of a planer requries a high degree of mental effort and mechanical skill.

Planer is generally used for machining large workpieces which cannot be held in a shaper.

Q. 5. (b) Describe briefly the mechanism as of chip formation. How many types

of chips are evolved in metal cutting? Specify the various conditions for

generation of various types of chips.

Ans. Metal cutting process is a very complex process.


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Fig. shows the basic material removal operation schematically. The metal in front of the toolrake face gets immediately compressed. First elastically and then plastically. This zone is

traditionally called shear zone in view of the fact that the material in the final form would beremoved by shear from the parent metal. The actual separation of the metal starts as a yielding or

fracture, depending upon the cutting conditions, starting from the cutting tool tip. Then the

deformed metal (called chip) flows over the tool (rake) face. If the friction between the tool rakeface and the underside of the chip (deformed material) is considerable then the chip gets further

deformed, which is termed as secondary deformation. The chip after sliding over the tool rake

face is lifted away from the tool, and the resultant curvature of the chip is termed as chip curl.Chip formation in metal cutting could be broadly categorised into three types :

(i) Discontinuous chip

(ii) Continuous chip

(iii) Continuous chip with BUE

Discontinuous chip : When brittle materials like cast iron are cut, the deformed material gets

fractured very easily and thus the chip produced is in the form of discontinuous segments. Higher

depths of cut (large chip thickness), low cutting speeds and small rake angles are likely to

produce discontinous chips.Continuous chip: Continuous chips are normally produced when machining steel or ductile

metals at high cutting speeds. The continuous chip which is like a ribbon flows along the rake

face.Some ideal conditions that promote continuous chips in metal cutting are sharp cutting edge,

small chip thickness, large rake angle, high cutting speed, ductile work materials and less friction

between the chip tool interface through efficient lubrication.

Continuous chip with BUE : When the friction between tool and chip is high while machining

ductile materials, some particles of chip adhere to the tool rake face near the tool tip. When such

sizeable materials piles upon the rake face, it acts as a cutting edge in place of the actual cutting

edge this is termed as built up edge (BUE).

Q. 6. (a) Differentiate among gas welding, resistance welding and arc welding

techniques.

Ans. Gas welding : In gas welding heat is supplied by burning a mixture ofoxygen and acetylene. The


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gases are mixed in a torch or blow pipe which controls the welding flame. The flame draws theoxygen from the atmospheric air and thus results in a reducing flame. Then the acetylene value is

opened to get the required flow of acetylene. The oxygen value is then slowly opened till theintermediate flame feather of the reducing flame recedes into the inner while-cone.

The torch tip should be positioned above the metal plate so that the while cane is at a distance of

1.5 to 3.0 mm from the plate. The torch should be held at an angle of 30 to 45 degrees from thehorizontal pane. The torch movmeent along the joint should be either oscillating or circular.

Resistance Welding : In resistance welding coalescence is produced by the heat obtained from

the resitance offered by the flow of electric current in a circuit of which the work is a part and by

the application of pressure. The duration of the application must be short to limit the zone ofmelting in order to obtain quality weilds. Electrodes are copper alloyed with metal like tungsten.

Resistance at the surfaces of contact between the work and the electrical must be kept low.

Arc welding : It may be done with carbon or metal elecrtode. It may be shielded or unshielded.

Arc is maintained between the electrode and the work. In some cases direct current is used and insome alternating current. In D.C. arc the greater portion of the heat is liberated at the positive

terminal. The polarity of the electrode influences the penetration and amount of heat imparted to

the work. Arc welding machines may be motor generator sets, rectifier sets, transformers orgenerators driven by other prime movers.

Q. 6. (b) Describe briefly the brazing process. State its advantages, disadvantages

and applications.

Ans. Brazing is the coalescence of a joint with the help of a filter metal whose liquidus temperataure is

above 450C and below the solidus temperature of the base metal. The filler metals is drawn into the

joint by means of capillary action (entering of fluid into tightly filled surfaces). In brazing, joints need to

be extremely clean. Any grease or oil present in the joint prevent the flow of filter metal. Hence the joint

should be throughly cleaned using proper solvents, oxides and scales present are removed by acid

pickling.

Advantages : Dissimilar metals, such as stainless steel to cast-iron can be joined by brazing. Almost all

metals can be joined by brazing except aluminium and magnesium because of the lower temperatures

used there is less distortion in brazed joint.

Also, in many cases the original heat treatment of the plates being joined, is not affected by the brazing

heat.

Because of the simplicity of the process it offers an economical joining method with reasonable joint

strength.

Disadvantage : The brazed joint is generally not useful for high temperatures because of the low melting

temperature of the filler metal. The colour of the filler metal in the brazed joint also, may not match

with that of the base metal.

Application : For joining Aluminium and alloys, Ferrous and non-Ferrous copper and copper alloys.

Q.7. (a) Define plant layout. What are its various objectives ?


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Ans. A plant layout is an arrangement of facilities and services in the plant. It outlines

relationship between production centres and departments.Plant layout can be defined as an optimum arrangements of industrial facilities, including

personal, equipments, storatge space, material handling, equipment and all other supporting

services, in an existing or proposed plants. Plant layout can also be defined as,A technique of locating machines, processes and plant services within factory in orderto securethe greatest possible output of high quality at the lowest possible total cost of production.

Various objectives of plant layout as follows :

(i) Integrate the production centres. A good layout integrates the production centres (men,materials

and machines) into a logical balanced and effective production unit, (ii) Reduce materialhandling. (iii) Effective utilization of available space. (iv) Worker convenience and job

satisfaction. (v) Flexibility. (vi) Removal of bottlenecks. (vii) Quick disposal of work. (viii)

Avoids industrial accidents.

(ix) Eliminates physical efforts required of operative workers. (x) Maintenance of decencyand orderliness inside the plant area.

Q. 7. (b) In which conditions various types of plants layout are preferred?

Ans. Condition in which various tyeps of plants layout are preferred.

(i) When starting a new plant: When starting a new plant it is necessary to determine.

1. The arrangement of the production and service departments, their proximity to each otherin plant.

2.

The arrangement of the production facilities within these departments.

(ii) Changes in the product design : The products manufactured by the industries are subjected

to periodical changes in design because of marketing demands. This may result in a revised

sequence of operations or a new set of operations.(iii) Necessity of introducing a new product: Sometimes new items are added to the company's

line in place of the existing items of productions or a new product may be introduced to balance

the production line to utilize the idle capacity of the plant.

(iv) Changes in the volume of production : An increased demand for a products may necessitateexpansion or revision of present plant layout or planning a completely new layout.

(v) Poor working conditions.

(vi) When production in job and batch and non repetitive type of work then process layout isprefered.

(vii) Continous production product layout preferred.

(viii) When work piece is very big or too heavy to move then static layout used.

Q. 8. What short notes on any four:

1. Industrial safety


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2. Properties of engineering materials3. Pattern allowances4. Wire drawing5. Tool wear6. Welding defects.

Ans. (a) Industiral safety : It has been observed that a lot of accidents occur because of lack

of safety

awareness. Man fall from ladders, operate their machines without a guard, drop objects on

their toes, or cut their hands because of misuse of tools. These are the results of unsafe acts.

The reason for these being that there had not been complete instructions on safe practices.

Further accident also occur due to unsafe condition of operation. The superviser have to

understand that safety is a practice of good management, the safety efforts help in

improving production cost and quality. To prevent accidents, safety rules have to be

enforced, safe working conditions developed, workers trained to do the job safely.

Ans. (b) Properties of engineering materials: Manufacturing of a component is normallyinfluenced by the mechanical and thermal properties of the work material also, The

mechanical properties are affected by the

manufacturing process employed. Some of the properties of engineering materials which

are influential in or influenced by the manufacturing processes line.

Strength : The resistance offered by a material on application of external force called

strength.

Hardness, ductility, toughness : The mechanical properties of engineering material

determine its usefulness for a particular job.

Ans. (c) Pattern allowances : The dimensions of the pattern are different from the finaldimensions of casting required because liquid shrinkage refers to the reduction in volume

when the metal changes from liquid to solid state. Solid shrinkage is the reduction in

volume caused, when metal loses temperature in solid state.

Thus, the shrinkage allowance is always added to the linear dimensions even in case of

internal dimension at the time of withdrawing the pattern from the sand mould, the

vertical faces of the pattern are in continuous contact with the sand, which may damage the

mould cavity to reduce the chances of this happening, the vertical faces of the pattern are

always tapered from the parting line. This provision is called draft allowance.

Shake allowance used to enlarge the mould cavity slightly which facilitates its removal.

Ans. (d) Wire drawing: This process consists of extruding a rod, through a die thereby

causing reduction in cross sectional area of rod. Generally the wire is drawn by pulling the

rod through several dies of decreasing diameter in order to obtain very thin wire. Raw

material used for wire drawing is generally a rolled bar obtained by hot rolling process.

For wire drawing, two types of processes are commonly used viz single draft and continuos

drawing.

Ans. (e) Tool wear: Tool get worn out due to long term usage. Type of wear found in

cutting tools is shown in fig.

Two major types of wear found in tools they are :


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Crater wear: The crater is on the rake face and is more or less circular. The crater does not

always extend to the tool tip, but may end at a distance form the tool tip.

Flank wear : Flank wear or wear land is on the clearance surface of the tool. The wear land

can be characterized by the length of wear land.

Ans. (f) Welding defects: In view of the severe thermal regime through which the welding

process proceeds, the weldments are likely to be affected and if proper care, is not taken,

likely to end up with certain defects. The defects likely.

Incomplete function : Main causes for this defect are improper penetration of the joint

wrong design.

Under cut: Due to improper welding technique or excessive welding current.

Porosity : Caused by the presented of gases which gets entrapped during the solidification

process.

Hot cracking : Occurs at high temperature and the size can be very small to be visi

Q. 1. (a) What is the role of mechanization and automation in manufacturing the

products?

Ans. Most of the metals used in industry are obtained as ores. These ores are subjected to

suitable reducing or refining process which convert the metal into a molten form. This molten

metal is poured into moulds to give commercial castings, called ingots. These ingots are furthersubjected to one or more processes to obtain usable metal products of different shapes and sizes.

All these further processes used for changing the ingots into usable products can be classified as

followed :1. Primary Shaping Process : These processes are of two types. Some of these finish theproduct to its usable form whereas other do not, and require further working to finish the

component to the desired shape and size. Castings need re melting of ingots in cupola or some

other foundry furnace and then pouring of this molten metal into metal or sand moulds to obtainthe castings The product obtained through this process may or may not be required to undergo

further operations. Depending upon the function they have to perform. Same is the case with

forging, but a better dimensional accuracy is obtained in forging than casting. Many operations


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like cold rolling, die casting, metal spinning and wire drawing etc. lead to production of directly

usable articles i.e. those which do not need further processing before use. The common

operations or processes which fall under this category are the following :

Unable products can be clarified as follows:

1. Casting

2. Forging3. Power metal forming

4. Gas cutting

5. Extruding6. Rolling

7. Bending

8. Drawing

9. Piercing

10. Shearing11. Squeezing

12. Spinning13. Forming

2. Machining Process : A fairly large no. of components need further processing after the

primary

process. These components are subjected to one or more of the machining operations. Called

secondary process, to obtain the desired shape and dimensional accuracy. Thus, the components undergoing

these secondaryoperations are basically the roughly finished products through primary operations.

The secondary operations are mainly necessary when a very close dimensional accuracy and a

very high

degree of surface finish are required or some such shape is to be produced which is not possiblethr ugh primary operations.These operations require the use of one or more machine tools, various types of cutting tools and

cutters, job holding devices, marking and measuring instruments, testing devices and gauges etc.,

of which a combined application leads to the desired dimensional control and degree of surfacefinish.


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The common machining operations performed for this purpose are following :

1. Turning 2. Threading 3. Knurling4. Drilling 5. Boring 6. Planning

7. Shaping 8. Slotting 9. Sawing

10. Milling 11. Broaching 12. Hobbing13. Grinding 14. Unconventional machining

3. Joining Processes : These processes are used for joining metal parts and in general

fabrication work.Such requirements usually occur when larger length of standard sections are required or when

several pieces

are to be joint together to fabricate a desired structure. In such cases, smaller lengths or pieces

are joinedtogether to give desired length or structure. Temporary or permanent type of fastening is also

enabled by these

processes. The common processes falling in this category are :

1. Welding 2. Soldering 3. Brazing4. Riverting 5. Screwing 6. Press fitting

7. Sintering 8. Adhesive bonding4. Surface Finishing Processes : These processes should not be misunderstood as metalremoving pro-cess in any case as they are primarily intended to provide a good surface finish or

a decorative and or protec-tive coating on to the metal surface. Although a very negligible

amount of metal removal or addition may take place. The common processes employed forobtaining desired surface finish are the following :

1. Buffing 2. Polishing 3. Honing

4. Roverting 5. Tumbling 6. Super finishing

7. Belt grinding 8. Sanding 9. Electroplating

5. Processes Effecting Change in Properties : These processes are employed to impart certain

spe-

cific properties to the metal parts so as to make them suitable for particular operations or uses.

Most physi-cal properties like hardening. Softening and grain refinement etc. call for particular heat

treatment. Heat

treatment not only effect the physical properties. But in most cases also make a marked changein the

internal structure of metal. So is the case with cold and hot working of metals. A few prominent

ones of

these are the following :1. Heat treatment 2. Cold working 3. Hot working 4. Shot peening

. 2. (a) Using sketch or flow chart, show the production process of market form of

steel supply of different shapes or sections.


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Ans. Plain Carbon Steels : The principal factors affecting the properties of plain carbon steels

are the carbon content and microstructure. Carbon is the principal determinant of many

performance properties. It has a strengthening and hardening effect. At the same time, it lowersductility, as evidenced by a decreases in elongation and reduction of area. In addition, a rise in

carbon content lower machinability and decrease weldability.

The microstructure is determined by the composition of steel, i.e. carbon, manganese, silicon,phospho-rus and sulphur which are always present and residual elements including oxygen,hydrogen and nitrogen and by the final rolling, forging or heat treatment operation.

Classification of Plain Carbon Content:I. According to the Carbon Content: On the basis of carbon content plain carbon steels are

commonly

divided as :

1. Low carbon or mild steel 0.05-0.30% carbon2. Medium carbon steel 0.30 - 0.60% carbon3. High carbon steel 0.60-1.50% carbon4. Tool steel (high carbon) 0.90-1.50% carbon

2. According to Deoxidation Practice : Steels are often identified as to the degree of

deoxidation resulting during steel production :

(i) Killed Steels : They are strongly deoxidised, and are characterised by high composition andprop-erty uniformity. All forging steels and, in general, all steels containing more than 0.25%

carbon are killed. The essential quality of killed steels is soundness.

(ii) Semi-killed or Balanced Steels : They are inu'mediate between those of killed and rimmedsteels and have variable degree of uniformity. Structural steels containing 0.15 to 0.25% carbonare generally semi-killed. Plates and structural products are normally made from semi-killed

steel.

(iii) Rimmed Steels : In rimming, steel is partially deoxidised steels with less than 0.15% carbonare used rimmed. In rimmed steel, the aim is to produce a clean surface low in carbon content

sheets and strips made from rimmed steels have excellent surface-quality and cold-forming

characteristics.


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Q. 2. (b) Name the various engineering material properties in detail. How will

you determine the mechanical properties? Specify the common tests involved in

determining them.

Ans. Properties of Engineering Material: Property of a material is a factor that influencesquantitative or qualitatively the response of a given material to imposed stimuli arid constraints.

Different materiel proper

ties are :1. Mechanical properties 2. Physical properties

3. Electrical properties 4. Magnetic properties

5. Thermal properties 6. Chemical properties

1. Mechanical Properties :

o Strength : Defined as the ability of material to withstand various forces.o Toughness : It is the ability of a material to withstand shatter or it opposes

rapture.


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o Elasticity : It is the ability of a material to deform under load and return it tooriginal size and shape when load is removed.

o Plasticity : !t is exact opposite of elasticity. It is the state of material which hasbeen loaded beyond its elastic limit so as to cause material to deform

permanently.o

Ductility : This is the team used for plastic deformation occurring due to tensileload, it is the ability of material to withstand bending or elongation.

o Malleability : It is the property due to which material may be hammered or sounddue to which sheets with rapture.

o Hardness : It is the ability of a body to withstand scratching or indentation byanother hard body.

o Machinability : It is the ability of the material to cut and shaped with ease.o Rigidity : It is the measure of materials ability not to defect under load.

Q. 3. (a) Name the various types of tools and equipment used for making woodenpattern and core coxes.

Ans. Pattern-making Tools : The tools used in pattern making do not differ much from theseused in general carpentry work, described earlier, except a few special tool which are particularly

needed in this trade. The principal types of these tools are described below :

1. Planning Tools : Apart from the common types of planes viz., jack plane trying plane and

smoothing plane, used in carpentry, the following are the other planes are used in pattern making

:

(b) Robbet Plane : It is used tor planing into lower and against perpendicular faces. Its size is

determined by the width of the blade.


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(a) Block Plane : It is a small and light weight plane carrying an adjustable blade. It is used by

only one hand and a popular size is 15 cm long having a 40 mm wide blade.

1. Router Plane : It carries a chisel-like biade and is used for planning the bottom surfacesof small grooves and other depressions. The blade can be adjusted to cut at differentdepths below the face of the plane.

2. Circular Plane : It carries a flexible bottom face made of steel which can be adjusted toany curva-ture to plane different size of convex and concave surfaces.

(e) Plough Plane : It is a type of moulding plane and is used for molting grooves of different

shapes andsizes on the edges.

(0 Core Box Plane : This plane is specially designed for pattern making. It is mainly used for

planing semi-circular and tapered concave surfaces which commonly occur in core-box making.The plane consists of two mutually is normal beds with the cutting blade fitted exactly in their

middle.

(g) Spoke Slave: It is mainly used for planing and shaping curved shape on the edges of thewood pieces. Thus, it is of great help in forming a pattern of irregular shape. It is actually a sort

of small plane provided with handles on the both sides-while working it is held in both hands and

either pushed or pulled, as convenient.

(h)Drawknife : It is also a tool similar to spoke shave in operating use. However, it carries afixed blade, whereas the blade of a spoke shave is adjustable. A useful form of this tool is

illustrated in this figure.


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2. Sawing Tools : In additional to those, the following tools are frequently used in pattern-making.

1. Coping Saw : It is used for cutting curved and irregular shapes in thin pieces of woodsuch as plywood or this boards. It consists of a metallic frame fitted with a fine and

narrow blade and wooden handle, as shown.

2. Bow Saw : It is used for the same purpose as coping saw, but for heavier cutting. Thestring provided at the top helps in adjusting the blade.

3. Mitre Box : It is a very useful tool in pattern making. It holds the work in position and atthe same time guides the saw to lake square or angular cut as desired. The job is heldfirmly on the bed and the saw moves inside vertical guides fitting in the frame. Thecircular disc carries graduations in degrees to set the saw at a desired inclination with

respect to the work. The saw used, known mitre saw, is nothing but an over sized back

saw.

3. Marketing and Layout Tools : In addition to the common markets and layout tools describedin

carpentry work, the following tools are used in pattern making.

(a) Contraction Scale or Shrinkage Rule : This scale is exclusively used pattern making only.

Since every metal contracts after solidification, finished size of the pattern should be made larger

than the finished

size of the casting by an amount equal to shrinkage that takes place in metal duringsolidification, in order that casting size after contraction is same as desired. This allowance,

called contraction or shrinkage allowance, when added to the ordinary scale, gives contraction

scale.(b) Dividers : Dividers are commonly used for making small circles, dividing equally, marking

arcs and transferring measurements from one piece to other.

(c) Trammels : It is also known as a beam compass. It is used for same purpose as dividers, but

for larger work i.e.. for such work, which is beyond the capacity of common dividers. A commontype of beam compass is shown in the figure.


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(d) Callipers : Top measuring and comparing inside and outside diameters, various sizes ofinside and outside callipers are used in pattern making. The size of a calliper is determined by

target diameter or thickness that can be measured with it.

Q. 3. (b) Classify the molding processes. Using figures show various steps for

making a sand mold.

Ans. First one half of pattern is placed with its flat surface on two mould board, and drag section

of the flask is set over the pattern on the same board is shown in the figure. After powdering thepattern will lycopo-dium, talc, or graphite a 15 to 20 mm.

Layer of facing sand is riddled over pattern. The drag is then filled by layers of green sand

mixture from 70 to 100 mm thick, compacting each layer with hammer. The top of mould is


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rammed without end of a hammer. The object of ramming sand is to consolidate it, thereby

preventing cavity of mould from being enlarged by pressure of the metal.

After the sand is rammed, a strickle is used to scrape of b excess sand level with the top of flask.The mould is then vented by sticking it with a fine stiff wire at numerous places. The vent holes

should not reach the pattern by 15 to 20 mm as otherwise they may spoil the mould. Moreover,

the metal may run into vent holes during pouring. These vent holes permit the escape of gasesgenerated in mould when the molten metal comes in contact with moist sand.

A small amount of loose sand is sprinkled over mould and bottom board is placed on top. The

drag is rolled over, moulding board is removed, and the upper surface is sprinkled with parting

sand. The parting sand is used to prevent the joints between the halves of mould from adhering toone another when two parts of moulding box are separated.

The remaining half of the pattern and cope section of flask are then assembled as shown in thefigure. Tapered wooded pegs to serve as sprue and riser are placed in proper position on the

pattern which is ridded over with facing sand and then cope is filled with green sand.

Following these operations wooden pegs are withdrawn from cope and a funnel shaped opening

is scooped out at the top of sprue to form the pouring basin.

An iron bar is now pushed down to pattern and rapped sideways so as to loosen pattern in themould. This rapping facilities removal of pattern and prevents any sand from sticking to the

pattern.

Q. 4. Differentiate among gas welding, arc welding and resistance welding using,heating methods types, tools and equipment used, set ups, merits, demerits and

general applications.


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Q. 5. (a) Name common types of accidents.

Ans. Accident : An industrial accident may be defined as "an occurrence which interrutps and

inferes with the orderly progress work in an industrial establishment." Types of Accidents :1. Near accident i.e. accident with no damage and injury.2. Trivial 3. Minor

4. Serious 5. Fatal


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Q. 5. (b) What are the adverse effects of accidents on the owner of the factory (in

term of indirect and direct costs), effects on employee and effects on the society?

Ans. Common Sources of Accidents :

o Revolving shafts, spindles, bars, mandrels and tool like dulls, seamers, boringbars and chuks etc.

o Projecting sharp edges or nips of belt and chain drives.o Projecting nips between sets of resolving parts viz, gears, rolls and friction wheel

etc.

o Projecting fasteners on revolving parts-like be heads, carters, pins, screws andnuts.

o Nips between meshing racks and pinions.o Mips between crank handles for machine control and fixed parts.o Grinding wheels and stones.o High speed rotatingcages such as in hydoexhactors.o Discontinuous rotating parts, such as boxs, open a run pulleys and gear wheel etc.

Q. 5. (c) Specify the human, environmental and mechanical causes of

industrial accidents.

Ans, Mechanical Cause :(i) Continuous use of old, poorly, maintained or unsafe equipment.

(ii) Unsafe design and construction of building material.

(iii) Violation of prescribed safety rules.(iv) Untested boilers or pressure vessels.

(v) Improper plant layout.

Environment Cause :(i) Defective and inadequate illumination causes glares, shadows and eye strains.

(ii) Presence of dust, homes and smokes.

(iii) Temperature and humidity-low temperature causes shivering and too high

temperature, cause head-ache and sweating and also fatigue to operator. Too high a

humidity may cause uneasiness and drowsiness.Human Cause :

(i) Operation without authority

(ii) Operating at unsafe speed.(iii) Improper use of tools.

Unsafe Personnel Factors:

Ignorance, forgetfulness and day-dreaming.


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Lack of knowledge or skill. Conditions prevailing at home. Mental worries.

Q. 6. (a) Using neat sketches specify the various forging operations.

Ans. Forging Operations : A no. of operations are used to change the shape of the raw materialto the finished form. The typical forging operations are :

1. Upsetting : It is the process of increasing the thickness of a bar at the expense of its length

and is brought about by end pressure. The pressure may be obtained by driving the end of bar

against the anvil, by supporting on the anvil and helting with the hammer, by placing in suragedblock hole and hitting with the hammer. Fig. (a) shows the effect of heavy hammer blows on a

uniformly heated bars (b) Shows effect of high

hammer blows, local upset may be obtained as shown at (c) and at (d) by heating only the end orthe middle of the bar.

2. Drawing Down or Swaging : It is the process of length of a bar the expense of its width orthickness or both. Fig A, B and C illustrates this operation. A represents the original stack. B

shows stack after hammer-ing with a straight peen hammer or with a top piller and sledge and C

shows the finished forging after the flatter has been used.

3. Setting Down : It is a localized drawing down or swaging operation as illustrated in the

higher. In other words, it may be said as the process of local thinning down effected by the sethammer or set.

4. Punching : It is the process of producing holes generally cylindrical, by using

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