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Downloaded From : www.EasyEngineering.net ME6402 - MANUFATURING TECHNOLOGY – II

UNIT-I: THEORY OF METAL CUTTING

PART-A 1. List the various metal removal processes? 2. How chip formation occurs in metal cutting? 3. What is wear? And classify it 4. Mention the cutting fluids? 5. Draw the nomenclature of cutting tool geometry? 6. Compare orthogonal and oblique cutting? 7. Define tool life. 8. What are the objectives and functions of cutting fluids? 9. Briefly explain the effect of rake angle during cutting? 10.www.EasyEngineering.net How do you classify tool wear? 11. What are the factors responsible for built-up edge in cutting ? 12. What is electrochemical wear in tools? 13. List out the essential characteristics of a . 14. Name the various cutting tool materials. 15. Give two examples of orthogonal cutting. 16. What arte the four important characteristics of materials used for cutting tools? 17. What is the function of chip breakers? 18. Name the factors that contribute to poor surface finish in cutting. 19. When will be the negative rake angles are used? 20. State any two difference between orthogonal and oblique cutting 21. What is orthogonal rake system? 22. Why is neither lubrication nor required while cast iron? 23. What is meant by buildup edge? 24. What are the advantages of diamond tools? 25. How is metal removed in metal cutting? PART-B 1. a)Discuss about orthogonal cutting? b) Explain various cutting tool materials?

2. In an orthogonal cutting operation on a work piece of width 2.5mm, the uncut chip thickness was 0.25mm and the tool rake angle was zero degree. It was observed that the chip thickness was 1.25mm.The cutting force was measured to be 900N and the thrust force was found to be 810 N. (a) Find the shear angle. (b) If the coefficient of friction between the chip and the tool was 0.5, what is the machining constant Cm?

3. What is a chip Describe the different types of chips produced during metal machining with neat sketches?

4. Mention the functions of cutting fluids.

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5. Describe the mechanism of metal cutting?

6. List the various tool materials used in industry. State the optimum temperature of each of the tool materials.

7. The Taylor tool life equation for machining C-40 steel with a HSS cutting tool at a feed of 0.2mm/min and a depth of cut of 2mm is given by VTn= C, Where n and C are constants. The following V and T observations have been noted V , m/min 25,35 T , min 90,20 Calculate (1) n and C (2) Hence recommend the cutting speed for a desired tool life of 60min.

8. a)State the parameters that influence the life of tool and discuss? b) What is meant by orthogonal cutting and oblique cutting?

9. Explain “merchant force circle” along with assumptions. www.EasyEngineering.net 10. Explain the geometry of a single point t cutting tool with suitable sketches?

11. Explain the basic actions of cutting fluids

12. What is orthogonal rake system? Show the ORS of the tool analysis with the help of a sketch.

13. What is the use of chip breaker? Discuss the various types of chips produced during metal machining process.

14. Explain the conditions that promote the formation of the following types of chip a) Continuous chips without buildup edge. (b) Continuous chip with buildup edge. (c) Discontinuous chips.

15. What are the standard angles of cutting tool? Illustrate with an example.

16. Describe an expression for the determination of shear angle in orthogonal metal cutting.

UNIT – II: MACHINES

PART-A 1. What are the various thread cutting methods? 2. What is Swiss type automat? 3. Explain the following parts of : (a) Lathe bed (b) Carriage 4. What is an apron? 5. List any four methods by which taper turning is done in a center lathe. 6. Draw a neat sketch of Geneva mechanism used in or automatic indexing. 7. Distinguish between Capstan lathe and Turret lathe. 8. State the different methods of taper turning. 9. Mention four different types of chucks used in a machine shop. 10. What is the purpose of a ? How many types of is there in common use?

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11. What are the advantages of using a collect ? 12. Why is it essential that the cutting point of the tool should be level with the spindle center while Machining taper on a work piece 13. What is the difference between a ram type turret lathe and saddle type turret lathe? 14. Calculate the power required for cutting a steel rod of 50mm in diameter at 200rpm. Assume, Cutting force of 160 kg 15. What are the advantages of automatic ? 16. What are the functions of feed rod and lead screw? 17. Why was power chucks developed? 18. How is thread chased in a lathe? 19. List the three most commonly employed types of single spindle automatics. 20. List the various parts mounted on the carriage 21. What are the types of single spindle automatic lathes? 22. Mention any four specifications? 23.www.EasyEngineering.net What is center gauge that is used in threading? 24. What are programmed automatic lathes? 25. What is the purpose of tumbled gear mechanism of a lathe?

PART-B

1. a) Explain the various taper turning methods? b) Discuss about special attachments of lathe. c) Describe the turret indexing mechanism.

2. a)Discuss about the bar feed mechanism. b) Describe the holding devices in a lathe

3. Explain the following with a neat sketch (i) Taper turning by swiveling the compound rest (ii) Taper turning attachment method (iii) Taper turning with tail stock set over method.

4. Mention the specifications of lathe with a neat sketch.

5. Calculate the change gears to cut a single start thread M16 of 2mm pitch on a Centre lathe, having a lead screw of 6mm pitch. Calculate the depth of cut and number of passes preferred.(A typical set contains the following change gears with number of teeth : 20,25,30,35,40,45,50,55,60,65and 70 .

6. Draw neat sketches of steady and follower rests and brief their applications.

7. a)Describe the constructional features of Swiss type automatic screw machine. b) Discuss the main parts of a turret lathe.

8. Explain the working of Swiss type auto lathe with a neat sketch

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9. a) What is meant by “Tool layout” of a turret lathe? b) Name the various lathe accessories. How does a four jaw chuck differ from a three jaw chuck? Explain the thread cutting operation in a lathe with a neat sketch. Also make a note on knurling, grooving and operations in a lathe.

10. a)Discuss the features of ram type and saddle type Turret. b) Explain the feature of multi- spindle automatics.

11. Describe some of the methods and equipment’s for holding work on a lathe.

12. Briefly explain the principle of working of the sliding head type single spindle automatic Machine

13. a)Describe with a neat sketch a turret automatic screw machine. b) Calculate the time taken for one complete cut on a work piece of 500mm long and 50mm www.EasyEngineering.netdiameter. The cutting speed is 30m/min and the feed rate is 0.5mm/rev.

14. a)Describe the working principle of multi spindle automatics. Give its advantages and application. b) Explain the construction and working principle of a lathe with a sketch.

15. What is lathe carriage? Explain the various parts of a lathe carriage with a neat diagram. . Enumerate the purpose of various attachments used on a center lathe.

16. What is a Swiss- type automatic screw machine? How it functions and what are its main applications?

UNIT – III: SHAPER, AND GEAR CUTTING MACHINES

PART-A 1. Mention the differences between shaper and . 2. What are the differences between and reaming? 3. Briefly describe the importance of quill mechanism. 4. Define the cutting speed, feed and machining time for drilling. 5. What is the difference between up milling and down milling? 6. How do you classify milling cutters? 7. What do you know about straight fluted and fluted drill? 8. What is meant by up milling and down milling? 9. State the differences between a vertical shaper and slotters. 10. Write the differences between drilling and tapping. 11. What are the common work holding devices used on milling machines? 12. What is a shell mill? 13. Give the functions of flutes on taps. 14. List some of the materials of tools. 15. How are work piece held in shaper?

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16. What are the various types of end mills used in milling? 17. What is the difference between a plain milling machine and a universal milling machine? 18. What is gear ?

PART-B 1. a)Explain various milling cutters with neat sketches? b) Discuss various hole making processes. 2. a)Write short notes on gear forming. b) Write short notes on gear shaping &. List the advantages and limitations of gear shaping

3. a)Discuss the principle of operation of a shaper with a neat sketch. b) Describe the working of a crank and slotted link mechanism.

4. With a neat sketch explain the column and knee type milling machine and name its main parts.

5.www.EasyEngineering.net With a line diagram, describe the construction of radial drilling machine.

6. Sketch and explain the hydraulic drive of a horizontal shaper.

7. How will you cut the following types of surfaces on milling machines? (a) Flat surfaces (b) Slots and splines

8. Sketch the Quill mechanism .write its main parts and their functions?

9. Describe gear cutting by forming and shaping.

10. a)What are the operations performed on a drilling machine? b) Explain different types of drilling machines with their special features?

11. Discuss the common work holding devices used in , slotters and planners.

12. With simple sketches explain the features of the major elements of twist drill.

13. Explain different types of milling cutters. . 14. a)Explain the hydraulic drive of a horizontal shaper with neat sketches. b) Sketch a twist drill. Write down its main parts and their functions.

15. Write short notes on reaming and operation.

16. Explain how a spur gear is machine in a gear hobbing machine

17. Explain the principle of gear hobbing with neat sketches.

18. Compare gear hobbing with gear shaping

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UNIT – IV: PROCESSES AND BROACHING

PART-A 1. What are the specifications of ? 2. What is honing? 3. Narrate the working principle of abrasive jet machining. 4. What is broaching? 5. What are the specifications of grinding wheel? 6. What is honing? 7. Narrate the working principle of abrasive jet machining. 8. What is gear super finishing? 9. Define hardness of the grinding wheel. 10. Define . 11. What is meant by “grade” and “structure” of a grinding wheel? 12.www.EasyEngineering.net What are all the parameters that would affect the MRR in abrasive jet machining? 13. Mention four important factors that influence the selection of grinding wheel. 14. What is roller burnishing process? 15. State the used in manufacture of grinding wheels. 16. What are the types of surfaces that can be produced using plain cylindrical grinders? 17. What do you mean by loading of grinding wheels? 18. Name two artificial abrasive materials 19. Distinguish between the polishing and buffing process 20. List the some of the materials of broaching tools. 21. What are grinding points? Sketch the various grinding points? 22. What is Tool post grinder? 23. How is grinding wheel designated? 24. List the gear generating process 25. Write any four applications of Abrasive jet machining 26. List four applications of broaching machines. 27. Define broaching.

PART-B 1. Explain the working mechanism of cylindrical and .

2. Explain the working principle and various methods of Centre less grinding with a neat sketch.

3. Discuss the various bonding materials used for making grinding wheels

4. Sketch and explain the three methods of external cylindrical Centre less grinding

5. List the advantages and disadvantages of gear shaping process.

6. Give the specification of grinding wheel.

7. Explain the salient features of a center less and discuss different operations that can be carried in it. Mention some advantages.

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8. Briefly discuss about the different types of abrasives used in a grinding wheel.

9. Explain the gear shaving, gear honing and gear lapping processes.

10. Explain the self-sharpening characteristics of grinding wheel.

11. a)Describe the use of cutting fluids in grinding. b)Explain wheel truing and dressing. 12. Discuss push and pull type broaching machines with neat sketches.

13. With the help of a neat sketch, discuss the working of a surface broaching machine.

14. Discuss various types of broaches. Give out their advantages and disadvantages.

UNIT – V: CNC MACHINING

www.EasyEngineering.netPART-A 1. List the differences between NC and CNC. 2. What are linear bearings? 3. Mention the type of ball screws. 4. What are feed drives? 5. What are the types of motion control system used in NC machines? 6. What is meant by APT language? 7. Compare a closed loop NC system with open loop system. 8. What is a preparatory function? How is it important in CNC programming? 9. State the limitations of CNC machine tools. 10. What is a canned cycle? 11. Define NC. 12. Name the major elements of NC machines. 13. Name the major elements of CNC machines. 14. What are the classifications of NC machines? 15. What is the difference between incremental and absolute system 16. What is the role of computer for NC ? 17. What is point –to – point (PTP) system? 18. What are G-Codes and M-Codes? Give examples. 19. List the commonly used coordinate systems of CNC machine tools. 20. Write down the types of statements in APT language. 21. List the main elements of a NC machine tool 22. What do you understand by „canned cycle‟ in manual part programming? 23. Mention the advantages of stepping motor 24. Define subroutine 25. With reference to CNC manual part programming, state what is linear interpolation? 26. A stepping motor of 200 steps per revolution is mounted on the lead-screw of a NC machine table. The pitch of the screw is 2.5mm/rev. if the stepping motor receives pulses at a frequency of 2000 Hz, What is the linear speed of the table?

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net PART-B 1. a)Narrate the design considerations of CNC machines. b) Discuss about slide ways used in CNC machine tools. c) Describe the spindle drives used in CNC machine tools.

2. List the difference between manual and computer assisted part programming.

3. Explain the following in CNC machining. (a)Linear Interpolation (b) Circular Interpolation (c ) Cubic interpolation 4. Describe the spindle and feed drives. State the requirement of the drives of CNC machine tools.

5. Write the part program for the part shown below. www.EasyEngineering.net

6. Write the part program for drilling holes in the part shown below. The plate thickness is 20mm.

7. Under what conditions of production the numerically controlled machine tools are employed.

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8. Explain the various elements of NC machine with closed loop control system.

9. a)Explain the main difference between point to point and continuous path of numerically controlled machine tools. b) List any five motions and control statements of computer assisted NC programming and explain.

12. Discuss the important design features of CNC machine tools.

13. Write short notes on (a) NC machine tool classification (b)APT programming structure (c)G and M codes (d)CNC machine Vs Conventional Machine

14. a)Define CNC and DNC. With a help of a diagram explain the working of NC machine tool. www.EasyEngineering.netb) How is manual programming of a NC machine done? c) Describe in brief basic components of a tape operated NC machine tool.

15. a)Write short notes on APT language. b) State a few typical applications where the use of would be justified.

16.

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17. Write a CNC program for manufacturing turning component.

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------Compiled by,

C.VELMURUGAN - M.E

Assistant Professor / Mechanical Engineering

PANIMALAR INSTITUTE OF TECHNOLOGY

Chennai-123.

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ME 6402 MANUFACTURING TECHNOLOGY – II L T P C 3 0 0 3

OBJECTIVES:  To understand the concept and basic mechanics of metal cutting, working of standard machine tools such as lathe, shaping and allied machines, milling, drilling and allied machines, grinding and allied machines and broaching  To understand the basic concepts of computer numerical control (CNC) machine tool and CNC programming.

UNIT I THEORY OF METAL CUTTING 9 Mechanics of chip formation, single point cutting tool, forces in machining, Types of chip, cutting tools – Nomenclature, orthogonal metal cutting, thermal aspects, cutting tool materials, tool wear, tool life, Surface finish, cutting fluids and Machinability UNIT II TURNING MACHINES 9 Centre lathe, constructional features, specification, operations – taper turning methods, thread cutting methods, special attachments, machining time and power estimation. Capstan and turret lathes- tool layout – automatic lathes: semi-automatic – single spindle: Swiss type, automatic screw type – multi Spindle:www.EasyEngineering.net UNIT III SHAPER, MILLING AND GEAR CUTTING MACHINES 9 Shaper - Types of operations. Drilling, reaming, boring, and Tapping. Milling operations - types of , Gear cutting – forming and generation principle and construction of gear milling, hobbing and gear shaping processes –finishing of gears UNIT IV ABRASIVE PROCESS AND BROACHING 9 Abrasive processes: grinding wheel – specifications and selection, types of grinding process– cylindrical grinding, surface grinding, Centre less grinding and internal grinding- Typical applications – concepts of surface integrity, broaching machines: broach construction – push, pull, surface and continuous broaching machines UNIT V CNC MACHINING 9 Numerical Control (NC) machine tools – CNC types, constructional details, special features, machining center, part programming fundamentals CNC – manual part programming – micromachining – wafer machining TOTAL: 45 PERIODS OUTCOMES: Upon completion of this course, the students can able to understand and compare the functions and applications of different metal cutting tools and also demonstrate the programming in CNC machining. TEXT BOOKS 1. Hajra Choudhury, "Elements of Workshop Technology", Vol.II., Media Promoters

2. Rao. P.N Manufaturing Tehnology - Metal Cutting and Machine Tools", Tata McGraw-Hill, New Delhi, 2003.

REFERENCES: 1. Riherd R Kie, John E. Neely, Roland O. Merges and Warren J.White Mahine Tool Praties, Prentice Hall of India, 1998

2. HMT, "Production Technology", Tata McGraw Hill, 1998.

3. Geofrey Boothroyd, "Fundamentals of Metal Machining and Machine Tools", Mc Graw Hill, 1984

4. Roy. A.Linderg, Proess and Materials of Manufature, Fourth Edition, PHI/Pearson Education 2006.

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1. Explain the cutting shaping process? The required shape of metal is obtained by removing the Unwanted material from the work piece in the form of chips is called cutting shaping. Ex: turning, drilling, milling, boring, etc

2. Mention the various parts of single point cutting tool? 1. Shank 2. Face 3. Flank 4. Base 5. Nose 6. Cutting edge

3. What is tool signature? The various angles of tools are mentioned in a numerical number in particular order.www.EasyEngineering.net That order is known as tool signature.

4. What is effect of back rake angle &mention the types? Back rake angle of tool is increases the strength of cutting tool& cutting action. It can be classified in to two types 1. Positive rake angle 2. Negative rake angle

5. What is side rake angle & mention its effects? The angle between the tool face & the line parallel to the base of the tool, it is used to control chip flow

6. What are all the conditions for using positive rake angle? 1. To machine the work hardened material 3. To machine low strength ferrous/non-ferrous metals 2. To turn the long shaft of small diameter 4. Small machine with low power capacity

7. When will the negative rake angles be used? 1. To machine high strength alloys 3. When machine tools are more rigid 2. The feed rates are high 4. To give heavy and interrupted cuts

8. Define orthogonal & oblique cutting? Orthogonal cutting: The cutting edge of tool is perpendicular to the work piece axis. Oblique cutting: The cutting edge is inclined at an acute angle with normal to the cutting velocity vector is called oblique cutting process

9. What is cutting force? The sheared material begins to flow along the cutting tool face in the form of small pieces. The compressive force applied to form the chip is called cutting force

10. What is chip thickness ratio? The ratio of chip thickness before cutting to chip thickness after cutting is called chip thickness ratio. Chip thickness ratio, r=tl/t2 = 12/11

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11. What are the purposes of chip breakers? The chip breakers are used to break the chips in to small pieces for the removal, safety & to prevent to machine & work

12. Define machinability of metal? Machinability is defined as the ease with which the material can be satisfactorily machined. 13. What are the factors affecting the machinability? 1. Chemical composition of work piece material. 2. Microstructure of work piece material

14. What is machinability index? It is the comparison of machinability different material to standard material. US material standards for 100% machinability are SAE 1112 hot rolled steel.

Machinability index I= Cutting speed of metal investigated for 20 minute tool life www.EasyEngineering.net Cutting speed of standard steel for 20 minutes tool life 15. How tool life is defined? Tool life is defined as time elapsed between two consecutive tools re- sharpening. During this period tools serves effectively and efficiently.

16. What are the factors affecting tool life? 1. Cutting speed 2. Feed & depth of cut 3. Tool geometry 4. Tool material 17. Express the tailor's tool life equation? Tailors tool life equation: VTn=C V=Cutting speed in m/min T=Tool life in minutes C=Constant n=Index depends upon tool & work.

18. What is the function of cutting fluids? 1. It is used to cool the cutting tool & the work piece. 2. It improves the surface finish as stated earlier. 3. It causes the chips to break up into small parts. 4. It protects the finish surface from corrosion. 5. It prevents the corrosion of work & machine.

19. What are the properties of cutting fluid? 1. High heat absorbing capacities. 2. It should have good lubricant properties. 3. High flash point. 4. It should be odorless. 5. It should be non-corrosive to work & tool.

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20. Mention the various parts single point cutting tool? 1) Shank 2) Face 3) Flank 4) Base 5) Nose 6) Cutting edge

21. Briefly differentiate between orthogonal cutting and oblique cutting?

Orthogonal cutting The cutting edge of the tool is perpendicular to the cutting velocity vector. The chip flows over the tool face and the direction of chip-flow velocity is normal to the cutting edge. The cutting edge clears the width of the work piece on either ends. (i.e. No side flow) The maximum chip thickness occurs at its middle. Oblique cutting The cutting edge is inclined at an acute angle with normal to the cutting velocity vector. The chip flows on the tool face making an angle with the normal on the cutting edge. The cutting edge may or may not clear the width of the work piece. The maximum chip thickness may not occur at the middle.

22. Name any four tools material? www.EasyEngineering.neti. Carbon tool steel ii. High speed steel iii. Cemented carbides iv. Ceramics v. Diamonds

23. What are the factors should be considered for selection of tool materials? i. Volume of production ii. Tool design iii. Type of machining process iv. Physical & Chemical properties v. Rigidity and condition of machine.

24. What are the ways of representing tool life? The following are some of the ways of expressing tool life. 1. Volume of metal removed per grind, 2. Number of work piece machined per grind, 3. Time unit.

25. How the machinability can be evaluated? The following criteria suggested for evaluating machinability. a. Tool life per grind, b. Rate of removal per tool grind, c. Magnitude of cutting forces and power consumption. Surface finish e. Dimensional stability of finished work. f. Heat generated during cutting. g. Ease of chip disposal. h. Chip hardness, shape and size

26. What are the assumptions made in lee and Shaffer's theory? a. The work ahead of the tool behaves as ideal plastic mass b. There exists a shear plane which separates the chip and work piece c. No hardening in chip occurs

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27. What are the cuttings forces acting on the cutting tool? During the cutting process, the following three component of cutting forces acting mutually at right angles

a. Feed force Fx acts in a horizontal plane, but in the Direction opposite to feed.

b. Thrust force Fy acts in a direction perpendicular to the generated surface.

c. Cutting force Fz in the direction of the main cutting motion

28. Name the different types of chip breakers 1. Step type 2. Groove type 3. Clamp type

29. Define Merchant analysis It is done assuming continuous type chip without built up edge (BUE) Produced during cutting

30. Write the assumptions made by merchant circle analysis www.EasyEngineering.net1. The tool is perfectly sharp and it does not make any flank contact with the job, 2. Cutting velocity remains

3. A continuous chip without BUE is produced

4. Chip does not flow to either side

31. Define the following: cutting ratio, Lip angle

Cutting ratio: The ratio of depth of cut to the thickness of the chip after cutting

Lip angle: The angle between tool face and the ground end surface of the flank

32. Name the types of cutting fluids

1. Synthetic fluid (or) chemical fluid

2. Semi-synthetic (or) semi – chemical fluid

3. Emulsion (or) water miscible (or) water soluble oils

4. Cutting oils

5. Gaseous fluids

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1. What is a lathe? Lathe is a machine, which removes the metal from a piece of work to the required shape &size

2. What is the various operations can be performed on a lathe? 1. Turning 6. Thread cutting 11. Grooving 2. 7. Drilling 3. Forming 8. Boring 4. Knurling 9. Recessing 5. Chamfering 10. Tapping

3. What are principle parts of the lathe? Bed, headstock, tailstock, carriage, cross slide, tool post

4. What are the types of headstock? www.EasyEngineering.netBack geared type, all geared type

5. State the various parts mounted on the carriage? Saddle, compound rest, cross slide, tool post

6. What are the four types of tool post? 1. Single screw 2. Open side 3. Four bolt 4. Four way

7. What is an apron? The integral part of several gears, levers clutches mounted with the saddle for moving the carriage along with lead screw while thread cutting

8. State any two specification of lathe? 1. The height of centers from the bed 5. Width of the bed 2. The maximum length of the bed 6. HP of main motor and rpm 3. swing over the bed 7. Number of spindles required 4. swing over the cross-slide 8. Feeds & floor space

9. List any four types of lathe? 1. Engine lathe 2. Bench lathe 3. Tool room lathe 4. Semi 5. Automatic lathe

10. What is a semi-automatic lathe? The lathe in which all the machining operations are performed automatically and loading and unloading of work piece, coolant on or off is performed manually

11. What is copying lathe? The tool of the lathe follows a template or master through a stylus or tracer

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 12. State the various feed mechanisms used for obtaining automatic feed 1. Tumbler gear mechanism 2. Quick change gearbox 3. Tumbler gear-Quick change gearbox 4. Apron mechanism

13. List any four holding devices? 1. Chucks 3. Face plate 2. Centers 4.

14. What are the different operations performed on the lathe? Centering, straight turning, rough turning, finish turning, shoulder turning, facing, chamfering, knurling, etc

15. Define the term 'Conicity'? The ratio of the difference in diameters of tapers its length k= D-d l Where, d- Smaller diameter www.EasyEngineering.netD-larger diameter 1-length of the work piece

16. State any two specifications of capstan lathe & turret lathe? 1. Number of spindle speed 2. Number of feeds for the turret or saddle

17. Compare the advantage of capstan lathe & turret lathe? 1. Heavier & larger work piece chucking can be done 2. More rigid hence it withstand heavy cuts

18. What is tooling? Planning of operations sequence & preparation of turret or capstan lathe are termed as tool- layout or tooling

19. What are the three stage of a tool-layout? 1. Planning & scheduling 2. Detailed sketching of various machining operation sequence 3. Sketching the plan showing various tools

20. What are the different drives used in copying lathe? 1. Mechanical drives 2. Air drives 3. Hydraulic drives

21. What are the components that can be turned on a copying lathe? 1. Camshaft 2. Crank shat 3. Journal bearings

22. Define automatic lathes. Automatic lathes or simply automats are machines tools in which all the operations required to finish off the work piece are done automatically without the attention of an operator.

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 23. State any four advantages of automatic lathes. 1. Mass production of identical parts. 2. High accuracy is maintained. 3. Time of production is minimized. 4. The bar stock is fed automatically

24. What are the types of single spindle automatic lathe? 1. Automatic cutting off machine. 2. Automatic screw cutting machine. 3. Swiss type automatic screw machine.

25. State the purpose of providing lead cam in single automatic screw cutting machine? The turret slide travel is controlled by a lead cam gives a slow forward and fast return movement to slide.

26. Mention the applications of single spindle automatic screw cutting machine. It is used for producing small jobs, screws, stepped pins, pins, bolts etc. www.EasyEngineering.net 27. What are the advantages of sliding head automatic lathes? The advantage of a sliding head automatic lathe is that long, slender work pieces can be machined with very good surface finish, accuracy and concentricity in sliding head automatic lathes.

28. What are the four major parts of Swiss type automatic lathes? 1. Sliding headstock 2. Cam shaft 3. Tool bracket 4. Auxiliary attachments

29. State the advantages of Swiss type screw cutting machine 1. Wide range of speed 2. Rigid construction 3. Micrometer tool setting 4. Simple design of cams & 5. Tolerance : 0.005-0.0125mm

30. State the principle of multi spindle automats. The principle of the multi spindle automate is that it has a tool slide working on the jobs on all spindles simultaneously.

31. Define cam controlled automats. The operating mechanism for sliding and feeding are actuated by cams through levers and gears.

32. What are the purposes of using cam? 1. To control purposes in automats screw machine. 2. To control the movement of cross slide. 3. To provide uniform rate of feed to tool during machining. 4. Some time to clamp the parts.

33. How the transfer machines works? A transfer Machine is an automatic machine. It indexes or transfers the work piece and its , from station to station while many operations are performed on it

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 34. State the principle of transfer machines. A Transfer Machine is one where several machines are linked together mechanically, electrically or hydraulically.

35. Classify transfer machines. Transfer machines are of three basic types, 1. Rotary indexing table transfer machine 2. Inline transfer machine. 3. Drum type transfer machine.

36. What are three types of rotary systems in rotary indexing transfer machines? 1. The machining heads located outside and around a circular table and operates at its periphery.

2. The heads are fixed around a central column of the machine and operate the components located on the table below them.

3. The components are carried on platens, which are fixed on a drum rotating on a horizontal axis, and machine heads operate from the sides. www.EasyEngineering.net 37. State the advantages of rotary transfer machines 1. A rotary transfer machine is very compact. 2. It is used in presses for peening over rivets, nut running heads for assembling nuts to screws 3. Electric brazing heads for assembly.

38. What are the, different machining operations performed on in-line transfer machines? Machining operations at each station are tapping, reaming, boring, counter boring, chamfering, countersinking, milling and grooving.

39. What are the two types of transfer devices? 1. Rotary transfer devices 2. Hydraulic transfer devices.

40. Describe tumbler gear mechanism It is a feed mechanism which is used to give the desired direction for the feed shaft. It moves carriage via lead screw, in forward, neutral and reverse.

41. Write the necessity of a steady rest A steady rest made of cast-iron base and which can be made to slide over on the lathe bed ways and clamped at any desired position where a support is necessary. They are used for longer length of work piece to prevent deflection.

42. Write the following: Eccentric turning, taper boring and grinding Eccentric turning: A cylindrical work piece has two separate axis of rotation. One being out of centre to the other, the work piece is termed as eccentric and turning of different surface of the work piece is known as eccentric turning Taper Boring: It is similar to the external taper turning operation and is accomplished by rotating the work on a chuck or a face plate and feeding the tool at an angle to the axis of rotation of the work piece. Grinding: It is the operation of removing metal in the form of minute chips by feeding the work against a rotating abrasive wheel known as grinding wheel.

43. Name the types of Draw back collets; push out collets, dead length collets

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net UNIT III – SHAPER, MILLING AND GEAR CUTTING MACHINES

1. What is shaper? The machine, which is having a reciprocating type of machine tool with a single point cutting tool, used to produce flat surfaces called as Shapers

2. List any four important parts of a Shaper? Table, Tool head, Ram, Cross rail

3. How the feed & depth of cut is given to the shaper? Feed is given by rotating the down feed screws of tool head, depth of cut is given by rotating by raising or elevating the table

4. Mention any four-shaper specification? 1. Maximum length of stroke 5. Floor space required 2. Type of driving mechanism 6. Weight of the shaper www.EasyEngineering.net3. Power of the motor 7. Cutting to return stroke ratio 4. Speed &feed available

5. How the planer differs from the shaper? In planner-the work reciprocate while the tool is stationary. In shaper-the tool reciprocate while the work is stationary

6. State the use of planer? The planer is used for machining heavy & large casting Ex. lathe bed ways, machine guide ways

7. What is meant by drilling? Drilling is the process of producing hole on the work piece by using a rotating cutter called drill 8. What is gang -drilling machine? When a number of single spindles with essential speed & feed are mounted side by side on one base and have common worktable is known as gang -drilling machine

9. Mention any four specification of drilling machine? 1. Maximum size of the drill in mm that the machine can operate 2. Table size of maximum dimensions of a job can mount on a table in meter 3. Maximum spindle travel in mm 4. Number of spindle speed & range of spindle speeds in r.p.m.

10. List any four machining operations that can be performed on a drilling machine? 1. Drilling 2. Counter sinking 3. Tapping 4. Trepanning

11. What are the different ways to mount the drilling tool? 1. Fitting directly in the spindle 2. By using a sleeve 3. By using a socket 4. By means of chucks

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 12. What is boring? Boring is a process of enlarging &locating previously drilled holes with a single point cutting tool

13. What are the application of boring? The boring machine is designed for machining large &heavy work piece in mass production work of engine frame, cylinder, machine housing etc

14. Specify the importance of boring machine? 1. A jig boring machine is a precision boring machine used for boring accurate holes at proper center to center distances. 2. The machining accuracy of holes produce by this machine tool lies within a range of 0.0025mm.

15. What is reaming? It is the secondary operation after the drilling operation has been performed to produce the accurate hole or finish the hole.

16. What is counter boring? www.EasyEngineering.netIt is used to enlarge the end of the hole cylindrically and the enlarge hole forms the square shoulders with original hole. . 17. List the types of drill. 1. Flat or spade drill 2. Straight fluted drill. 3. Two lip twist drill 4. Centre drill.

18. What is the advantage of flute? The flute is the helical groove. It is used to remove the chip through the helical groove and the cutting fluid will enter through the flute surface.

19. What is primary clearance? The portion of the land removed to provide clearance immediately behind the cutting edge.

20. What is secondary clearance? The portion of the land removed to provide clearance behind the primary clearance or circular land. 21. What is the type of milling machines? 1. Column and knee type milling machine 2. Manufacturing of fixed table type. 3. Planer type 4. Special type.

22. What are the special attachments made in the universal milling machine? 1. Dividing head 2. Vertical milling attachments 3. Rotary attachment 4. Twist drill 5. 23. What is vertical milling machine? In vertical milling machine the spindle is mounted vertical or perpendicular to the table.

24. What are the parts used in the column and knee type milling machine? 1. Base 2.Column 3. Knee 4.Table 5.Over hanging arm 6.Front brace 7.Arbour

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 25. What is meant by indexing?

It is the operation of dividing the periphery of a work piece into any number of equal parts. In cutting spur gears, equal spacing of teeth on the blank is performed by indexing.

26. What is bevel gear?

A bevel gear is one in which the tooth are cut so that they radius from the apex of a cone and lie on the conical surface.

27. Name the different methods of indexing 1. Direct indexing 2. Plain or simple indexing 3. Compound indexing 4. Differential indexing www.EasyEngineering.net5. Angular indexing 28. Write down the material for milling cutter

The milling cutter may be made of high speed steel, super high speed steel, non-ferrous cast alloys or cemented carbide tipped.

29. Name the various milling processes 1. Peripheral milling 2. Face milling 3. End milling 4. Down milling and 5. up milling

30. What are the specifications of the milling machine? 1. The table length &width. 2. Number of spindle speeds &feeds. 3. Power of driving motor.

31. Mention the various movements of universal milling machine table? 1. Vertical movement-through the knee. 2. Cross vise movement-through the saddle.

32. State any two comparisons between plain &universal milling machine? 1. In plain milling machine the table is provided with three movements, longitudinal, Cross & vertical. In universal milling machine in addition to these three movements, there is a forth movement to the table. The table can be swiveled horizontally & can be fed at angles to the milling machine spindle. 2. The universal milling machine is provided with auxiliaries such as dividing head, vertical milling attachment, etc. Hence it is possible to make spiral, bevel gears, twist , etc on universal milling machine.

33. What are the cutter holding devices? 1. Arbors 2. Adaptors 3. Collets

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 34. List the various type of milling attachment? 1. Vertical milling 2. Universal milling 3. High speed milling 4. Rotary 5. Slotting 6. Rack milling

35. Write any ten nomenclature of plain milling cutter? Body of cutter, cutting edge, face, fillet, gash, lead, land, outside diameter, root diameter, cutter angles

36. What are the advantages of up-milling process? 1. It does not require a backlash eliminator. 2. Mild surface does not have built up edge.

37. What are the down milling processes? 1. Cutter with higher rake angle can be used. This reduces power requirements. www.EasyEngineering.net2. Cutter wear is less because chip thickness is maximum at the start of cut.

38. List out the various milling operations? 1. Plain or slab milling. 4. Face milling. 2. Angular milling. 5. Gang milling. 3. End milling. 6. Gear cutting.

39. What does term indexing mean? Indexing is the process of dividing the periphery of a job into equal number of divisions.

40. What are the three types dividing heads? 1. Plain or simple. 2. Universal. 3. Optical.

41. What is cam milling? Cam milling is operation of producing cams in the milling machine by the use universal dividing head & a vertical milling attachment.

42. What are the different types of thread milling? 1. Thread milling by single form cutter. 2. Thread milling by multi form cutter.

43. What are the other forming methods for manufacturing gears? 1. Gear cutting by single point form tool. 2. Gear cutting by shear speed shaping process. 3. Gear broaching. 4. Template method. 5. Gear milling using a formed .

44. List the gear generating process? 1. Gear shaping process. 2. Gear planning process. 3. Gear hobbing process.

45. Mention the applications of gear shaping process? 1. Gear shaping used for generating both internal & external spur gears. 2. Helical gears can also be generated using special attachments.

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46. What are the limitations of gear hobbing? 1. Internal gears cannot be generated. 2. Hobbing process cannot be applied very near to shoulders.

47. What are the advantages of gear planning process? 1. Any given model can be cut using a single cutter. 2. It is a simple flexible & accurate method of generating gears.

48. List the various gear finishing processes? 1. Gear shaving. 2. Gear burnishing. 3. Gear grinding. 4. Gear lapping.

49. Mention the advantages limitations of gear shaving process? Advantage: The process can be used for both internal & external gears.

Limitations: This process is only applicable to unhardened gears. www.EasyEngineering.net 50. What are the purposes of gear grinding process? 1. To improve the surface Finish of teeth. 2. To increase the accuracy of the teeth.

51. What is gear lapping? Gear lapping is also employed for hardened gear teeth by an abrasive action

52. Write the formula for calculating index change gears in gear Hobbing? For Index change gear: Driving Teeth - Indexing constant X Number of teeth of hob Driven Teeth Number of teeth to be cut.

53. Name the different types of hobbing? Different types of hobbing arc classified under the direction of feed of hob are: a) Axial hobbing b) Radial hobbing c) Tangential hobbing. 54. Explain axial hobbing process? a) Gear blank is brought towards the hob for required depth. b) Table slide is then clamped. 55. What are the advantages of gear hobbing? The advantages of gear hobbing are: a) The method is versatile and can generate spur, helical, worm and worm wheels. b) It is rapid, economical and highly productive.

56. Give any three differences between gear hobbing and gear milling? Gear Hobbing: a) Hob operates on several teeth at a time. b) It is not necessary to disengage cutter and work before indexing. c) Gear hobbing is faster process than gear milling. Gear Milling: a) Milling machine can cut only one tooth at a time. b) It requires cutter and work to get disengaged before indexing can occur. c) It is slower process compared to gear hobbing process.

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UNIT-IV ABRASIVE PROCESSES AND BROACHING

1. State the purpose of grinding? 1. To remove small amount of metal from work pieces & finish then to close tolerances. 2. To obtain the better surface finish. 2. Name the various factors required for selection of grinding wheel?

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3. What are the specifications of grinding wheel? o Type of bond o Grit or grain size o Grade o Structure o Abrasive o Manufacturer’s Code

4. What is meant by “grade” and “structure” of a grinding wheel? . Grade or hardness indicates the strength with which the bonding material holds the abrasive grains in the grinding wheel. . Structure denotes the spacing between the abrasive grains or in other words the density of the wheel. 5. What is meant by dressing &truing?  The process of loading & breaking away the glazed surface so that, new sharp abrasive particles are again present to work for efficient cutting is called dressing.  Truing is a process of trimming the cutting surface of the wheel to run true with the axis.

6. What is process of lapping? Lapping is a surface finishing process used for producing geometrically accurate lat, cylindrical &spherical surfaces

7. How the center less grinder operates? The center less grinder operates with two wheels as the cutting wheel, to remove the excess stock and a regulating wheel which is used to control the speed of rotation of the work and the rate of feed.

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 8. What are the advantages of center less grinding?  The work pieces are suppressed through the wheels  No tendency for chatter and deflection of the work piece.  Easy size control of the work.  No need of chucking or mounting of the work piece.

9. What is broaching? Broaching is a process of machining a surface with a special multipoint cutting tool called broach which has successfully higher cutting edges in a fixed path

10. Indicate any two specification of a broaching machine? 1. Maximum length of stroke in mm 2. Maximum force developed by the slide in tones

11. What are the advantages and limitation of broaching? Advantages: www.EasyEngineering.net1. Roughing, semi finishing & finishing cuts are completed in one pass of the broach 2. Broaching can be used for either external or internal surface finish Limitation: 1. High initial cost of the broach tool compare to other tools 2. Job work or batch work is not advisable due to the high tool cost..

12. What are the different operations that can be performed on a broaching machine? 1. Broaching splines 2. Broaching a key way

13. Give some applications of broaching. By internal broaching, splined holes, key ways internal gear serration, square and hexagonal holes and holes with different shapes are broached. By surface broaching, flat surface and surface different contour, external splines.

14. What are the advantages of broaching? 1. The rate of production is very high 2. High accuracy and very good surface finish are obtained 3. Less skilled operator is sufficient 4. Cutting fluid can be effectively applied 5. Both internal and external surfaces can be broached.

15. What are the limitations of broaching? 1. Cost of the broach is very high 2. Not suitable for producing small number of work piece. 3. Very large surface cannot be broached.

16. What are the types of broaching machines? The types of broaching machine are 1. Horizontal broaching machine 2. Vertical broaching machine 3. Continuous broaching machine

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 17. How broaches are classified? Broaches are classified as 1. According to the type of surface broached i) Internal broaches ii) External broaches 2. According to the method of operation i) Push broach ii) Pull broach 3. According to the operations performed on the work piece i) Surface broach ii) Key way broach iii) Round hole broach iv) Spline broach

18. What is meant by push broach? A push broach is pushed through the work during cutting. During broaching the broach comes under compressive load. To avoid bending, the push broach is made short. Because of this, only less amount of material is removed by the broach.

19. What is meant by pull broach? A pull broach cuts the material while it is pulled through the work piece. During pulling the broach comes under tensile load. So it is not bending during machining. So the broach can be made longer. Also, more amount of material can be easily removed by the broach. www.EasyEngineering.net 20. Name some broaching operations. The broaching operations are 1. Surface broaching 2. Hole broaching 3. Key way broaching 4. Spline broaching

21. List the various parts of pull type broach. The various parts of pull type broach are 1) Pull end 2) Front pilot 3) Roughing and semi finishing teeth 4) Finishing teeth 5) Rear pilot 6) Land 7) Clearance angle 8) Rake (or) face angle 9) Pitch

22. Give a summary of the abrasive of their application for different operation?

ABRASSIVE APPLICATION (1) Aluminum Cleaning, Cutting and Deburring (2) Silicon Carbide. Faster cleaning, Cutting. (3) Glass Heads Matt polishing, cleaning (4) Rushed glass Peening and cleaning.

UNIT-V CNC MACHINING

1. Define NC machine Numerical control machine cane be defined as a form of programmable machine in which the process are controlled by a program of numbers, letters, and symbols.

2. List the various types of NC machines. 1. Point to point NC system 2. Straight cut NC system 3. Contouring NC system

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 3. List the various components of DNC. 1. Central computer 2. Bulk memory which stores the NC part programs 3. Telecommunication lines 4. Machine tools 4. State the advantages of CNC 1. An increase in flexibility 2. An improvement in the possibilities for correcting errors in part programming 3. The possibility of using the computer's peripheral equipment 4. Tape and reader are used only once for improved reliability

5. What are the types of CNC? 1. Hybrid CNC 2. Straight CNC

6. What is meant by hybrid CNC? In hybrid CNC, the controller consists of soft wired and hardwired logic circuits.

7. Mention the main difference between CNC and DNC www.EasyEngineering.netCNC system can do operations on only one machine at a time. But involves that at a time a large central computer to direct the operations of a number of separate NC machines.

8. State any four applications of CNC. 1. machines 2. Press working machine tools 3. Assembly machines 4. Inspection machines

9. State the various types of CMM in practical applications. a) Cantilever construction b) Bridge construction c) Column construction d) Gantry construction

10. List the methods of creating part programming. a) Manual part programming b) Computer-assisted part programming (CAD/CAM based programming system) c) Manual data input d) Computer automated part programming

11. What are the data essentially needed to prepare a part program? 1. Job dimension/work piece 2. Work holding (damping, chucking) 3. Feed /Cutting speed 4. Finished dimension with tolerance 5. Sequence of operation 6. Types of tools 7. Mounting of tools. 12. Define absolute and incremental programming. In absolute programming the distance at any point at any instant will be from the origin(X=0, Y=0) whereas in incremental programming the instant point will be noted as (X=0, Y=0). Further measurement will be made from the particular point only.

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net 13. Define Subroutine. If the same machine operation, which was carried out already, is to be performed at many positions on the work piece it can be executed by means of a program called as Subroutines.

14. What is meant by APT program? Apt program is used to command the cutting tool through its sequence of machining process. APT is also used to calculate the cutter positions. APT is a three dimensional system controlling up to five axes including rotational co-ordinates.

15. Mention the types of APT language. 1. Geometric statements 2. Motion statements 3. Postprocessor statements 4. Special control or Auxiliary statements

16. What is FTP NC? The objective of machine tool control system to move the cutting tool to a predefined location.www.EasyEngineering.net

17. What do you mean by machining center? The machining center in a control machines is an automatic tool changing arrangement that is designed to perform a variety of machining operations, with large number of cutting tools and provided with a continuous path CNC system. 18. Where is the common path contouring used? Common path contouring is used in grinding machine and routes.

19. What is a part program? Part program is a high level language program containing the instructions for-machining a part on sheets with respect to various standard words / codes and symbols.

20. What is post processing? Post processing is a computer program that takes a generalized part program output and adopts it to a particular machine control unit / machine tool combination. It is the basic intelligence required to change the program into computer language.

21. Name the language used in CNC programming. The language used in CNC programming is APT (Automatically Programmed Tool). 22. Write the various types of tape readers. The various types of tape readers are: a) Electromagnetic tape reader. b) Magnetic tape reader. c) Photo electrical tape reader. d) Pneumatic tape reader.

23. Write the order of the instructions in a part program. The order of the part program is • Preparatory function. • Feed function. • Tool function. • End of block

24. What is meant by manual part programming? Manual part programming is a process of writing programs which consist of a set of instructions to carry out the machining of the work.

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Downloaded From : www.EasyEngineering.net 25. Write the disadvantages of manual part programming. The disadvantages of manual part programming are: a) It is difficult to perform several co-ordinate calculations for complex shapes. b) Setting of the tool can be done to an approximate dimension and the difference is adjusted by suitable external switches set.

26. What is preparatory function? It is word address format represented by the letter G, followed by a numerical code for the operation of the control unit to instruct the machine tool.

27. What is tool length offset? When tools with different length are used, then the difference in their lengths with respect to a datum is known as offset of each tool.

28. Give a brief note on Canned Cycle. The canned cycle simplifies and shortens the programming in such way whenever any one of the above operation is required. www.EasyEngineering.net 29. Name the various motors

Spindle motor: DC Shunt motor (separately excited), three phase AC induction motor Feed motor; DC Servo Motor, AC Servo Motor and Stepper Motor

30. Write any five requirements of spindle drive

1. High rotational accuracy

2. It should be compact

3. It should have wide and constant power bans

4. It should have high dynamic stiffness and damping

5. It should have high load capacity

6. Quick clamping should be possible

7. It should have high speed range

*******************************ALL THE BEST****************************

Compiled by,

K.ELAVARASAN – B.E, M.Tech Assistant Professor / Mechanical Engineering

PANIMALAR INSTITUTE OF TECHNOLOGY

Chennai – 123

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net Additional Questions

1. Comparison of single spindle and multi spindle automatic lathes (Any 4-Points)

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2. Comparison between the capstan and turret lathe. (Any 4-Points)

Capstan lathe Turret lathe

Turret of a capstan lathe is mounted on a Turret of a turret lathe is mounted on a short slide or ram slide which slides on the saddle which slides directly on the bed saddle.

Thus in a capstan lathe, travel of the turret Turret saddle moves on total length of bed, is dependent upon the length of the travel this enables the turret to be moved in entire of the ram. This limits the maximum length length of the bed and can machine longer of work to be machined in one setting. work.

Maximum size of bar that a capstan lathe Turret lathes are capable of turning bars can accommodate is 60 mm in diameter. 125 to 200 mm in diameter and absorbing up to 50h.p. in the main drive.

Capstan lathes are suitable for bar work. Larger and heavier chucking works are usually handled on a turret lathe.

In capstan lathe hand feeding is easy as the In case of turret lathe hand feeding is a hexagonal turret can be moved forth and laborious process due to the movement of back more rapidly without moving saddle the entire saddle unit. unit.

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Write short notes on heat zones in cutting. During machining, the generated heat is distributed between the work piece, chip and tool. Only a negligible amount of heat is dissipated to the ambient air. There are three heat zones in metal cutting.  The shear zone  The chip-tool interface zone  The work-tool interface zone

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Difference between gear shaping and gear hobbing

S. No Gear shaping Gear hobbing

Gear tooth is cut one by one All teeth of gear are cut simultaneously till the 1. completion of process

2. Accuracy is good but it is a slow process Accuracy is good and the process is fast

Only spur and bevel gears can be cut. Worm All type of gears such as spur, helical and worm 3. gears cannot be cut gears can be cut

4. Process is manual or semi - automatic Process is automatic

5. Internal gears can be cut Internal gears cannot be cut

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What is gear finishing? Why is it done? The process of making gear tooth surface smooth by reducing the surface roughness is called gear finishing. None of the methods of gear manufacturing on any machine produce gears of very accurate dimensions and shape. Any error crept in the gears during production for any reason lead to noisy performance of the gear box. Irregular wear of the teeth and uneven load distribution on the teeth are the factors enough to cause an early failure of the gears.so applying methods of finishing after the gear have been cut on the machine.

Define grinding ratio It is defined as the volume of material removed per unit volume of wheel wear. Grinding ratio increases with less wheel wear and higher metal removal

Compare bulk and surface micromachining processes

S. No. Elements involved Bulk machining Surface micromachining

Size, thickness and mass of Large size Small size 1. www.EasyEngineering.netfeatures

2. Use of wafers Used on both sides Used on one side

Vertical dimensions One or more wafer thickness is It is limited by thickness of 3. used deposited layers

Wafer bonding It needs wafer bonding It does not usually use wafer 4. bonding

5. Common sensing mechanism Piezo-resistive / Capacitive Resonant / capacitive

Critically towards end of Thinned wafers may be fragile Utmost cleanliness is 6. process required to protect the structure

7. Integration with IC technology It is not very much It can be made IC compatible

What is the importance’s of Nose Radius?

Nose radius is favorable to long tool life and good surface finish. A sharp point on the end of a tool is highly stressed; Short lived and leaves a groove in the path of cut. There is an improvement in surface finish and permissible cutting speed as nose radius is increased from zero value.

Define Metal Cutting

Metal cutting or machining is the process of by removing unwanted material from a block of metal in the form of chips.

Define ASA system

In the ASA system, the angles of tool face, that is, its slope, are defined in two orthogonal planes, one parallel to and the other perpendicular to, the axis of the cutting tool, both planes being perpendicular to the base of the tool.

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net Differentiate automatic and semi-automatic lathe

S. No. Automatic lathe Semi-automatic lathe

All processes including loading and Both loading and unloading are done manually 1. unloading are done automatically

2. It is used in mass production It is used in batch production

3. Production time and cost are less Production time and cost are more

Number of machines can be controlled Only one or two machines can be controlled by 4. by single operator at a time single operator at a time

5. Initial cost of the machine is high Initial cost of the machine is low

How the feed and depth of cut is given to the shaper? Justify your answer (6) www.EasyEngineering.net Depth of cut: It is given by rotating the down feed screws of tool head or by raising or elevating the table. Feed: In shaper, there are three types of feeds. 1. Vertical feed it is given by rotating the down feed screws of tool head or by raising or elevating the table at the end of return stroke after tilting the apron to some angle. 2. Cross feed it is given by moving the table perpendicular to ram movement by rotating the cross feed screw at the end of the return stroke. 3. Angular feed it is given by rotating the down feed screw at the end of the return stroke after tilting the tool head to the required angle and tilting the apron to some angle. Give the functions of flutes on taps

 It provides cutting edges

 It conducts the cutting fluid to the cutting region

 It periodically reverse the rotation to break the chip formed to avoid breakage during cutting process

 It acts channels to carry away the chips formed by cutting action

Briefly describe the importance of quill mechanism

If the taper shank of drill is smaller than the taper in the spindle hole, a sleeve is used. The sleeve with drill is fitted in the hole of the spindle. The sleeve has outside taper surface. This fits into the tapered hole of the spindle.

What is a shell mill?

A shell mill is a large type of face or end mil that mounts on to a arbor, rather than having an integral shank. Typically there is a hollow or recess in the centre of the shell mill for mounting hardware on to a separate arbor.

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net What do you mean by differential indexing? Here the indexing is done by combination of two movements  The movement of the index crank similar to the simple indexing  The simultaneous movement of the index plate when the crank is turned.

Why is milling machine a versatile machine? In this machine, one or more number cutter can be held at a time. This is superior to other machines as regards accuracy and better surface finish and is designed for machining a variety of tool room work. That is why it is called a versatile machine.

Draw the nomenclature of a standard drill

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What is the difference b/w plain and universal milling machine?

S. No. Plain milling machine Universal milling machine

1. It is provided with three table It is provided with four table movements: movements: Longitudinal, Cross, Longitudinal, Cross, Vertical, swiveling Vertical. of the table horizontally.

2. More rigid and heavier in It is particularly suitable for tool room construction. Suitable for heavier work and for special machining milling operations. operations.

Define “Micro machining” with the help of an example Micromachining is used to fabricate three-dimensional microstructures and it is the foundation of a technology called Micro-Electro-Mechanical-Systems (MEMS). Bulk micromachining and surface micromachining are two major categories (among others) in this field.

Distinguish a fixed zero and floating zero

 Fixed zero point is the reference point for CNC machine, which is set by the manufacturer. It cannot be changed.  Floating zero point is the reference point on the work piece, which is set by the programmer. It can be set at any point on the work piece by the programmer.

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net State the functions of the following G & M Codes

G00 G03 M06 M03

GOO-Rapid traverse of the tool G03-Circular Interpolation clockwise M06-Tool Change M03-Spindle on clockwise

What is the balancing grinding wheel? . If wheels become out of balance through wear and cannot be balanced by truing or dressing, they should be removed from the machine and discarded.

. Wheels should be tested for balance occasionally and rebalanced if necessary.

. Wheels that are out of balance not only produce poor work but may put undue strains on the machine. Small wheels may be balanced by milling a short recess on the inside www.EasyEngineering.netof the flanges and filling with lead. Large wheels should be placed on a balancing stand and balanced by moving weights around a recessed flange.

. Now-a-days, grinding wheel mounts are provided with devices to enable balancing to be done whilst the wheel is running and between grinding operations.

What are the conditions that would allow a continuous chip to be formed in metal cutting?

o Ductile material o Smaller depth of cut o High cutting speed o Large rake angle o Sharp cutting edge o Proper cutting fluid o Low friction between tool face and chips

What are the methods of external cylindrical Centre less grinding? i. Through feed center less grinding ii. Plunge or in-feed center less grinding iii. End feed center less grinding

Describe: Sputtering Sputtering is achieved by bombarding a target with energetic ions and knocking off the atoms from a target material and transporting them to the wafer where they get deposited

Name the types of etching

i. Wet etching

ii. Dry etching

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net Explain Slide and Slide ways In general machine tools are provided with tables, slides, carriages etc., to carry the work pieces or cutting tools etc., these parts are sliding in nature and mounted on the ways that are fixed on the other parts (column, housing, bed or knee) of the machines known as sliding ways.

What is automatic pallet changer? For machines with automatic pallet changer (ATC) the table is replaced by pallet. The pallet when transferred from the pallet changer on the machine gets located and clamped with heavy clamping force either hydraulically or mechanically. The function of pallet changer is to interchange the pallet on the machine which has the finished component and the other pallet with newly loaded component.

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List some of the canned cycle and mention its use G81 – Drill cycle G82 – Dwell cycle G79 – Basic mill cycle G83 – Peck drill cycle G85 – Bore cycle G80 – Cancel Cycle List out some of the important NC languages APT - Compact II ADAPT - PROMPT EXAPT - CINTURN II

What are the four statements used in APT language? 1. Geometric statements 2. Motion statements 3. Post processor statements 4. Auxiliary statements

Why are the balls re-circulating screws used in CNC machines? Ball screws are primarily employed in feed mechanism in machine tools. The advantages are as follows: i. In the ball screw the lead between the threads of the screw and the nut is not transmitted by direct contract, but through spherical balls. Balls rotate between the helical grooves of the screw and nut in a manner that function in a ball bearing. An essential feature is the provision of recirculation of balls. ii. Low coefficient of friction in the order of 0.004 iii. Higher transmission efficiency allows larger thrust loads to be carried with less torque iv. By preloading the assembly, clearances and consequent backlash can be eliminated. The accuracy of ball screw is high.

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What is adaptive control? The automatic monitoring and adjustments of machining conditions in response to variations in the operation performance is called adaptive control

What are the interpolations used in CNC Systems? i. Linear interpolation ii. Circular interpolation iii. helical interpolation iv. cubic/parabolic interpolation

Define DNC Direct numerical control is also called distributive numerical control. It is a technology that permits a single computer to be networked with one or more machines that use CNC

What are the common types of tool magazines? The concept of the ATC is that the range of tools for a specified job shall be made available for automatic selection and positioning. ATC can be: i. Drum type – for holding small number of tools store in periphery of drum www.EasyEngineering.netii. Chain type – for more number of tools (30 – 40 or more tools can be used)

What are the desirable characteristics of tool magazines? i. Tool magazines must be capable of holding enough tools needed for performing complete operation for work pieces on the machining centers

ii. As the magazine gets larger, the space needed is more and more expensive and hence the magazine has to be compact and as simple as possible iii. Interchange of tools should not interfere with the work piece space and tool space. This means that the tool magazine should be located outside the working space of the machine tool

iv. Easier and safer manual exchange of tools in the tool magazine during loading and unloading should be facilitated

v. All preparatory works for tool exchange should be made during machining

What are the advantages of AC spindle drives over DC drives? AC spindle motors are now preferred for the main drive by CNC machine tool designers due to a variety of reasons as follows: i. AC motors are reliable than DC motors under several operating conditions ii. AC motors are being free of brushes and other wearing parts do not require frequent maintenance iii. The unique stator cooling system in AC motors result in high speed output characteristics with compact size iv. AC drive units provide stable and smooth operation with reduced vibration and noise from low speed to high speed.

Give the four methods of achieving rolling action in slide ways i. Vee & Flat roller ii. Linear ball bushing iii. Rotax Tychoway iv. Dexter ball slide

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Give the requirements of a good slide way system A good slide way mush possess Low coefficient of friction at varying slide velocities Minimum difference between static and dynamic friction coefficient Positive slope for friction velocity characteristics Low rate of wear High stiffness at the sliding points Sufficient damping Give the advantages of re-circulating ball screw and nut assembly. High efficiency (over 90%) Reversibility Reduces wear and has longer life without loss of accuracy No stick slip in the sliding metal to metal contact is substituted by rolling contact www.EasyEngineering.net List some of the materials of broach tools i. HSS (Alloy steel and ) ii. Tin coated carbides iii. Aluminum iv. Brass v. 12L14

List any four applications of broaching machines i. Straight and helical slots ii. External surface of various shape iii. External and internal gears iv. Holes of cross sectional shapes

How does loading differ from glazing in grinding process?  A glazed wheel has cutting particles which are dull worn out bond. It will not allow the dulled particles to be torn of the wheel. A glazed wheel increases the smoothness of the wheel-face and it decreases its cutting capacity

 The loaded wheel has particles of the metal being ground adhering to it. They prevent the wheel from cutting freely due to openings and pores of the wheel-face filled up with metal.

Define the terms loading and glazing  During the operation, the chips formed get entrapped in the inner granular space of abrasive particles called loading  The surface of the wheel becomes smooth and it gets a glassy appearance known as glazing of the wheel.

What is shear plane? The material of work piece is stressed beyond its yield point under the compressive force. This causes the material to deform plastically and shear off. The plastic floe takes place in a localized region is called shear plane.

Downloaded From : www.EasyEngineering.net Downloaded From : www.EasyEngineering.net What is Swiss type Automates. These are designed for machining long accurate parts of small diameter, such as 4 to 25 mm. An exclusive feature of these machines is the longitudinal travel of the headstock, or of a quill carrying the rotating work spindle.

Mention the typical operations carried on automatic lathes.  Centering,  Boring,  Knurling,  Cutting off,  Reaming,  Thread cutting,  Drilling and  spot facing.

What are the design requirements of CNC machine spindles? High stiffness Running accuracy www.EasyEngineering.net Axial load carrying capacity Thermal stability Axial freedom for thermal expansion High speeds of operation

What is meant by Machine datum? It is the origin of the co-ordinate system with the lathe. It is on the mounting flange of the main spindle and the turning axis. It cannot be changed by the user of the machine. It is fixed by the manufacturer and programmed into the computer. The point generally has the coordinates X=0, Z=0

What is orthogonal rake system? Orthogonal rake system is one of the methods to describe the tool signature or tool designation. It consists of seven parameters to describe the tool. As per this system, the tool signature is designated in the following sequence. For example, if the tool signature is 5 10 6 6 5 90 1  Angle of inclination--5˚  Normal rake angle--10˚  Side relief angle--6˚  End relief angle--6˚  End cutting edge angle--5˚  Approach angle--90˚  Nose radius—1mm

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Draw the nomenclature view of a single point cutting tool

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------ALL FOR THE BEST------Compiled by,

K.ELAVARASAN – B.E, M.Tech. Assistant Professor / Mechanical Engineering

PANIMALAR INSTITUTE OF TECHNOLOGY

Chennai – 123

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