Solution
Content
Ans:- 1 ( ), 2 ( ), 3 ( ), 4 ( ), 5 ( )
Ans 2(1) The lathe is a machine tool used principally for shaping articles of metal (and sometimes wood or other materials) by causing the work piece to be held and rotated by the lathe while a tool bit is advanced into the work causing the cutting action. The basic lathe that was designed to cut cylindrical metal stock has been developed further to produce screw threads. Tapered work. Drilled holes. Knurled surfaces, and crankshafts. The typical lathe provides a variety of rotating speeds and a means to manually and automatically move the cutting tool into the work piece. Machinists and maintenance shop personnel must be thoroughly familiar with the lathe and its operations to accomplish the repair and fabrication of needed parts.
Lathes can be divided into three types for easy identification: operator can accomplish more machining jobs with the engine lathes, turret lathes, and special purpose lathes. Small engine lathe than with any other machine tool. Turret lathes lathes can be bench mounted, are lightweight, and can be and special purpose lathes are usually used in production or transported in wheeled vehicles easily. The larger lathes are job shops for mass production or specialized parts. While floor mounted and may require special transportation if they basic engine lathes are usually used for any type of lathe must be moved. Field and maintenance shops generally use a work. Further reference to lathes in this chapter will be about lathe that can be adapted to many operations and that is not too the various engine lathes.
Ans 2(1) Machining is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process. The many processes that have this common theme, controlled material removal, are today collectively known
as subtractive manufacturing, in distinction from processes of controlled material addition, which are known as additive manufacturing. The precise meaning of the term "machining" has evolved over the past two centuries as technology has advanced. During the Machine Age, it referred to (what we today might call) the "traditional" machining processes, such as turning, boring, drilling, milling, broaching, sawing, shaping, planing,reaming, and tapping
Ans 2(2) (1) Tool wear describes the gradual failure of cutting tools due to regular operation.:flank wear in which the portion of the tool in contact with the finished part erodes. 2) Tool Life: - Tool wear is a time dependent process. As cutting proceeds, the amount of tool wear Increases gradually.Tool wear must not be allowed to go beyond a Certain limit in order to avoid tool failure.• Tool life is defined as the time interval for which tool works satisfactorily between two successive grinding or re sharpening of the tool. 3) Tool Material:Carbon steel: Carbon steels having carbon percentage as high as 1.5% are used as tool materials however they are not able to with stand very high temperature and hence are operational at low cutting speed. High speed steel (HSS): These are special alloy steel which are obtained by alloying tungsten, Chromium, Vanadium, Cobalt and molybdenum with steel. HSS has high hot hardness, wear resistance and 3 to 4 times higher cutting speed as compare to carbon steel. Most commonly used HSS have following compositions. Diamond: It is the hardest known material having cutting speed 15 times greater than that for high speed tools Ceramics, Cubic boron nitride (CBN
Ans 3(1) A shaper is a type of machine tool that uses linear relative motion between the work
piece and a single-point cutting tool to machine a linear tool path. Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. A shaper operates by moving a
hardened cutting tool backwards and forwards across the workpiece. On the return stroke of the ram the tool is lifted clear of the workpiece, reducing the cutting action to one direction only. The workpiece mounts on a rigid, box-shaped table in front of the machine
Ans 3(2)
In machining, boring is the process of enlarging a hole that has already been drilled (or cast), by means of a single-point cutting tool (or of a boring head containing several such tools), for example as in boring a gun barrel or an engine cylinder. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole. Boring can be viewed as the internal-diameter counterpart to turning, which cuts external diameters. OR Ans 3(1) A slotting machine is used in cutting different types of slots . it is used for machining irregular shapes, circular surfaces & other pre.marked profiles . Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. A slotter operates by moving a hardened cutting tool backwards and forwards across the workpiece. On the return stroke of the ram the tool is lifted clear of the workpiece, reducing the cutting action to one direction only. The workpiece mounts on a rigid, box-shaped table in front of the machine
Ans 3(2) Drilling is a cutting process that uses a drill bit to cut or enlarge a hole of circular cross-section in solid materials. The drill bit is a rotary cutting tool, often multipoint. The bit is pressed against the workpiece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the workpiece, cutting off chips from what will become the hole being drilled. Ans 4(1) Hot working refers to processes where metals are plastically deformed above their recrystallization temperature. Being above the recrystallization temperature allows the material to recrystallize during deformation. This is important because recrystallization keeps the materials from strain hardening, which ultimately keeps the yield strength and hardness low and ductility high.
Cold working is the plastic deformation of metals below the recrystallization temperature. In most cases of manufacturing, such cold forming is done at room temperature. Sometimes, however, the working may be done at elevated temperatures that will provide increased ductility and reduced strength, but will be below the recrystallization temperature. When compared to hot working, cold-working processes have certain distinct advantages:
Ans 4(2) Forging is a manufacturing process involving the shaping of metal using localized compressive forces. Forging is often classified according to the temperature at which it is performed: "cold", "warm", or "hot" forging
Temperature Forging:- All of the following forging processes can be performed at various temperatures, however they are generally classified by whether the metal temperature is above or below the recrystallization temperature. Drop forging:- It is a forging process where a hammer is raised and then "dropped" onto the workpiece to deform it according to the shape of the die.
OR
4 (1) Deformation is a change in the shape or size of an object due to an applied force. It can be can be a result of tensile (pulling) forces, compressive (pushing) forces, shear, bending or torsion (twisting). Elastic Deformation:- This type of deformation is reversible. Once the forces are no longer applied, the object returns to its original shape. Elastomers and shape memory metals such as Nitinol exhibit large elastic deformation ranges, as doesrubber . However elasticity is nonlinear in these materials. Normal metals, ceramics and most crystals show linear elasticity and a smaller elastic range. Plastic Deformation:- This type of deformation is irreversible. However, an object in the plastic deformation range will first have undergone elastic deformation, which is reversible, so the object will return part way to its original shape. Soft thermoplastics have a rather large plastic deformation range as do ductile metals such as copper, silver, and gold. Steel does, too, but not cast iron. Hard thermosetting plastics, rubber, crystals, and ceramics have minimal plastic deformation ranges. One material with a large plastic deformation range is wet chewing gum, which can be stretched dozens of times its original length.
4(2) Types of Rolling mills Rolling mills may be classified according to the number and arrangement of the rolls. (a): Two high rolling mills (b): Three high rolling mills (c): Four high rolling mills (d): Tandem rolling mills (e): Cluster rolling mills high rolling mills Two high rolling mills may further classified as Reversing mill Non reversing mill A two high rolling mill has two rolls only. Two high reversing mill:
In two high reversing rolling mills the rolls rotate ist in one direction and then in the other, so that rolled metal may pass back and forth through the rolls several times. This type is used in pluming and slabing mills and for roughing work in plate , rail , structural and other mills.
5. A grinding machine, often shortened to grinder, is a machine tool used for grinding, which
is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation. Grinding is used to finish workpieces that must show high surface quality (e.g., low surface roughness) and high accuracy of shape and dimension.
Belt grinder, which is usually used as a machining method to process metals and other materials, with the aid of coated abrasives. Sanding is the machining of wood; grinding is the common name for machining metals. Belt grinding is a versatile process suitable for all kind of applications like finishing, deburring, and stock removal. Bench grinder, which usually has two wheels of different grain sizes for roughing and finishing operations and is secured to a workbench or floor stand. Its uses include shaping tool bits or various tools that need to be made or repaired. Bench grinders are manually operated. Cylindrical grinder, which includes both the types that use centers and the center less types. A cylindrical grinder may have multiple grinding wheels. The work piece is rotated and fed past the wheel(s) to form a cylinder. It is used to make precision rods, tubes, bearing races, bushings, and many other parts. Surface grinder which includes the wash grinder. A surface grinder has a "head" which is lowered, and the work piece is moved back and forth past the grinding wheel on a table that has a permanent magnet for use with magnetic stock. Surface grinders can be manually operated or have CNC controls. Tool and cutter grinder and the D-bit grinder. These usually can perform the minor function of the drill bit grinder, or other specialist tool room grinding operations. Jig grinder, which as the name implies, has a variety of uses when finishing jigs, dies, and fixtures. Its primary function is in the realm of grinding holes and pins. It can also be used for complex surface grinding to finish work started on a mill.
Gear grinder, which is usually employed as the final machining process when manufacturing a high-precision gear. The primary function of these machines is to remove the remaining few thousandths of an inch of material left by other manufacturing methods (such as gashing or hobbling).
Grit type is generally either aluminum oxide (white, pink, ruby red, brown, grey, etc.) silicon carbide (black or green), ceramic (blue and pink) or any combination of these. Aluminum oxide is by far the most popular. Grit size typically runs from coarse (16 -24 grit), medium (36 - 60 grit) and fine (80-120 grit)
OR 1) Honing is an abrasive machining process that produces a precision surface on a metal
workpiece by scrubbing an abrasive stone against it along a controlled path. Honing is primarily used to improve the geometric form of a surface, but may also improve the surface texture .2) Lapping is a machining process, in which two surfaces are rubbed together with an abrasive between them, by hand movement or by way of a machine. This can take two forms. The first type of lapping (traditionally called grinding), typically involves rubbing a brittle material such as glass against a surface such as iron or glass itself (also known as the "lap" or grinding tool) with an abrasive such as aluminum oxide, jeweller's rouge, optician's rouge, emery, silicon carbide, diamond, etc., in between them. 3) Surface roughness, often shortened to roughness, is a measure of the texture of a surface. It is quantified by the vertical deviations of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small the surface is smooth. Roughness is typically considered to be the high frequency, short wavelength component of a measured surface . 6. Cutting fluid is a type of coolant and lubricant designed specifically for metalworking and machining processes. There are various kinds of cutting fluids, which include oils, oilwater emulsions, pastes, gels, aerosols (mists), and air or other gases. They may be made from petroleum distillates, fats, plant oils, water and air, or other raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant. Or Sheet metal is metal formed by an industrial process into thin, flat pieces. It is one of the fundamental forms used in metalworking and it can be cut and bent into a variety of shapes. Countless everyday objects are constructed with sheet metal. Thicknesses can vary significantly; extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate. Sheet metal is available in flat pieces or coiled strips. The coils are formed by running a continuous sheet of metal through a roll slitter.
The thickness of sheet metal is commonly specified by a traditional, non-linear measure known as its gauge. The larger the gauge number, the thinner the metal. Commonly used steel sheet metal ranges from 30 gauge to about 8 gauge. Gauge differs between ferrous (iron based) metals and nonferrous metals such as aluminum or copper; copper thickness,
Ans 2(1) The lathe is a machine tool used principally for shaping articles of metal (and sometimes wood or other materials) by causing the work piece to be held and rotated by the lathe while a tool bit is advanced into the work causing the cutting action. The basic lathe that was designed to cut cylindrical metal stock has been developed further to produce screw threads. Tapered work. Drilled holes. Knurled surfaces, and crankshafts. The typical lathe provides a variety of rotating speeds and a means to manually and automatically move the cutting tool into the work piece. Machinists and maintenance shop personnel must be thoroughly familiar with the lathe and its operations to accomplish the repair and fabrication of needed parts.
Lathes can be divided into three types for easy identification: operator can accomplish more machining jobs with the engine lathes, turret lathes, and special purpose lathes. Small engine lathe than with any other machine tool. Turret lathes lathes can be bench mounted, are lightweight, and can be and special purpose lathes are usually used in production or transported in wheeled vehicles easily. The larger lathes are job shops for mass production or specialized parts. While floor mounted and may require special transportation if they basic engine lathes are usually used for any type of lathe must be moved. Field and maintenance shops generally use a work. Further reference to lathes in this chapter will be about lathe that can be adapted to many operations and that is not too the various engine lathes.
Ans 2(1) Machining is any of various processes in which a piece of raw material is cut into a desired final shape and size by a controlled material-removal process. The many processes that have this common theme, controlled material removal, are today collectively known
as subtractive manufacturing, in distinction from processes of controlled material addition, which are known as additive manufacturing. The precise meaning of the term "machining" has evolved over the past two centuries as technology has advanced. During the Machine Age, it referred to (what we today might call) the "traditional" machining processes, such as turning, boring, drilling, milling, broaching, sawing, shaping, planing,reaming, and tapping
Ans 2(2) (1) Tool wear describes the gradual failure of cutting tools due to regular operation.:flank wear in which the portion of the tool in contact with the finished part erodes. 2) Tool Life: - Tool wear is a time dependent process. As cutting proceeds, the amount of tool wear Increases gradually.Tool wear must not be allowed to go beyond a Certain limit in order to avoid tool failure.• Tool life is defined as the time interval for which tool works satisfactorily between two successive grinding or re sharpening of the tool. 3) Tool Material:Carbon steel: Carbon steels having carbon percentage as high as 1.5% are used as tool materials however they are not able to with stand very high temperature and hence are operational at low cutting speed. High speed steel (HSS): These are special alloy steel which are obtained by alloying tungsten, Chromium, Vanadium, Cobalt and molybdenum with steel. HSS has high hot hardness, wear resistance and 3 to 4 times higher cutting speed as compare to carbon steel. Most commonly used HSS have following compositions. Diamond: It is the hardest known material having cutting speed 15 times greater than that for high speed tools Ceramics, Cubic boron nitride (CBN
Ans 3(1) A shaper is a type of machine tool that uses linear relative motion between the work
piece and a single-point cutting tool to machine a linear tool path. Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. A shaper operates by moving a
hardened cutting tool backwards and forwards across the workpiece. On the return stroke of the ram the tool is lifted clear of the workpiece, reducing the cutting action to one direction only. The workpiece mounts on a rigid, box-shaped table in front of the machine
Ans 3(2)
In machining, boring is the process of enlarging a hole that has already been drilled (or cast), by means of a single-point cutting tool (or of a boring head containing several such tools), for example as in boring a gun barrel or an engine cylinder. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole. Boring can be viewed as the internal-diameter counterpart to turning, which cuts external diameters. OR Ans 3(1) A slotting machine is used in cutting different types of slots . it is used for machining irregular shapes, circular surfaces & other pre.marked profiles . Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. A slotter operates by moving a hardened cutting tool backwards and forwards across the workpiece. On the return stroke of the ram the tool is lifted clear of the workpiece, reducing the cutting action to one direction only. The workpiece mounts on a rigid, box-shaped table in front of the machine
Ans 3(2) Drilling is a cutting process that uses a drill bit to cut or enlarge a hole of circular cross-section in solid materials. The drill bit is a rotary cutting tool, often multipoint. The bit is pressed against the workpiece and rotated at rates from hundreds to thousands of revolutions per minute. This forces the cutting edge against the workpiece, cutting off chips from what will become the hole being drilled. Ans 4(1) Hot working refers to processes where metals are plastically deformed above their recrystallization temperature. Being above the recrystallization temperature allows the material to recrystallize during deformation. This is important because recrystallization keeps the materials from strain hardening, which ultimately keeps the yield strength and hardness low and ductility high.
Cold working is the plastic deformation of metals below the recrystallization temperature. In most cases of manufacturing, such cold forming is done at room temperature. Sometimes, however, the working may be done at elevated temperatures that will provide increased ductility and reduced strength, but will be below the recrystallization temperature. When compared to hot working, cold-working processes have certain distinct advantages:
Ans 4(2) Forging is a manufacturing process involving the shaping of metal using localized compressive forces. Forging is often classified according to the temperature at which it is performed: "cold", "warm", or "hot" forging
Temperature Forging:- All of the following forging processes can be performed at various temperatures, however they are generally classified by whether the metal temperature is above or below the recrystallization temperature. Drop forging:- It is a forging process where a hammer is raised and then "dropped" onto the workpiece to deform it according to the shape of the die.
OR
4 (1) Deformation is a change in the shape or size of an object due to an applied force. It can be can be a result of tensile (pulling) forces, compressive (pushing) forces, shear, bending or torsion (twisting). Elastic Deformation:- This type of deformation is reversible. Once the forces are no longer applied, the object returns to its original shape. Elastomers and shape memory metals such as Nitinol exhibit large elastic deformation ranges, as doesrubber . However elasticity is nonlinear in these materials. Normal metals, ceramics and most crystals show linear elasticity and a smaller elastic range. Plastic Deformation:- This type of deformation is irreversible. However, an object in the plastic deformation range will first have undergone elastic deformation, which is reversible, so the object will return part way to its original shape. Soft thermoplastics have a rather large plastic deformation range as do ductile metals such as copper, silver, and gold. Steel does, too, but not cast iron. Hard thermosetting plastics, rubber, crystals, and ceramics have minimal plastic deformation ranges. One material with a large plastic deformation range is wet chewing gum, which can be stretched dozens of times its original length.
4(2) Types of Rolling mills Rolling mills may be classified according to the number and arrangement of the rolls. (a): Two high rolling mills (b): Three high rolling mills (c): Four high rolling mills (d): Tandem rolling mills (e): Cluster rolling mills high rolling mills Two high rolling mills may further classified as Reversing mill Non reversing mill A two high rolling mill has two rolls only. Two high reversing mill:
In two high reversing rolling mills the rolls rotate ist in one direction and then in the other, so that rolled metal may pass back and forth through the rolls several times. This type is used in pluming and slabing mills and for roughing work in plate , rail , structural and other mills.
5. A grinding machine, often shortened to grinder, is a machine tool used for grinding, which
is a type of machining using an abrasive wheel as the cutting tool. Each grain of abrasive on the wheel's surface cuts a small chip from the workpiece via shear deformation. Grinding is used to finish workpieces that must show high surface quality (e.g., low surface roughness) and high accuracy of shape and dimension.
Belt grinder, which is usually used as a machining method to process metals and other materials, with the aid of coated abrasives. Sanding is the machining of wood; grinding is the common name for machining metals. Belt grinding is a versatile process suitable for all kind of applications like finishing, deburring, and stock removal. Bench grinder, which usually has two wheels of different grain sizes for roughing and finishing operations and is secured to a workbench or floor stand. Its uses include shaping tool bits or various tools that need to be made or repaired. Bench grinders are manually operated. Cylindrical grinder, which includes both the types that use centers and the center less types. A cylindrical grinder may have multiple grinding wheels. The work piece is rotated and fed past the wheel(s) to form a cylinder. It is used to make precision rods, tubes, bearing races, bushings, and many other parts. Surface grinder which includes the wash grinder. A surface grinder has a "head" which is lowered, and the work piece is moved back and forth past the grinding wheel on a table that has a permanent magnet for use with magnetic stock. Surface grinders can be manually operated or have CNC controls. Tool and cutter grinder and the D-bit grinder. These usually can perform the minor function of the drill bit grinder, or other specialist tool room grinding operations. Jig grinder, which as the name implies, has a variety of uses when finishing jigs, dies, and fixtures. Its primary function is in the realm of grinding holes and pins. It can also be used for complex surface grinding to finish work started on a mill.
Gear grinder, which is usually employed as the final machining process when manufacturing a high-precision gear. The primary function of these machines is to remove the remaining few thousandths of an inch of material left by other manufacturing methods (such as gashing or hobbling).
Grit type is generally either aluminum oxide (white, pink, ruby red, brown, grey, etc.) silicon carbide (black or green), ceramic (blue and pink) or any combination of these. Aluminum oxide is by far the most popular. Grit size typically runs from coarse (16 -24 grit), medium (36 - 60 grit) and fine (80-120 grit)
OR 1) Honing is an abrasive machining process that produces a precision surface on a metal
workpiece by scrubbing an abrasive stone against it along a controlled path. Honing is primarily used to improve the geometric form of a surface, but may also improve the surface texture .2) Lapping is a machining process, in which two surfaces are rubbed together with an abrasive between them, by hand movement or by way of a machine. This can take two forms. The first type of lapping (traditionally called grinding), typically involves rubbing a brittle material such as glass against a surface such as iron or glass itself (also known as the "lap" or grinding tool) with an abrasive such as aluminum oxide, jeweller's rouge, optician's rouge, emery, silicon carbide, diamond, etc., in between them. 3) Surface roughness, often shortened to roughness, is a measure of the texture of a surface. It is quantified by the vertical deviations of a real surface from its ideal form. If these deviations are large, the surface is rough; if they are small the surface is smooth. Roughness is typically considered to be the high frequency, short wavelength component of a measured surface . 6. Cutting fluid is a type of coolant and lubricant designed specifically for metalworking and machining processes. There are various kinds of cutting fluids, which include oils, oilwater emulsions, pastes, gels, aerosols (mists), and air or other gases. They may be made from petroleum distillates, fats, plant oils, water and air, or other raw ingredients. Depending on context and on which type of cutting fluid is being considered, it may be referred to as cutting fluid, cutting oil, cutting compound, coolant, or lubricant. Or Sheet metal is metal formed by an industrial process into thin, flat pieces. It is one of the fundamental forms used in metalworking and it can be cut and bent into a variety of shapes. Countless everyday objects are constructed with sheet metal. Thicknesses can vary significantly; extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate. Sheet metal is available in flat pieces or coiled strips. The coils are formed by running a continuous sheet of metal through a roll slitter.
The thickness of sheet metal is commonly specified by a traditional, non-linear measure known as its gauge. The larger the gauge number, the thinner the metal. Commonly used steel sheet metal ranges from 30 gauge to about 8 gauge. Gauge differs between ferrous (iron based) metals and nonferrous metals such as aluminum or copper; copper thickness,
