Download Advanced Manufacturing Technology and more Exams Mechanical Engineering in PDF only on Docsity!
Term End Examination - May 2013 Course : MEE551 - Advanced Manufacturing Technology Slot: C
Class NBR : 1871
Time : Three Hours Max.Marks:
Answer any FIVE Questions (5 X 20 = 100 Marks)
- a) Describe the process by which metal is removed by a cutting tool in the machining process.
[4]
b) Explain the shear plane model of chip formation using Ernst and Merchant theory. (^) [8] c) In an orthogonal cutting test on an alloy of aluminium, the following values were obtained from experimental data. Rake angle = 15° Thrust force = 350 N Uncut chip thickness = 0.125 mm Width of cut = 3.75 mm Cutting speed = 0.5 m/s Chip thickness = 0.5 mm If the force in the cutting speed direction is 3.5 times that of the thrust force, calculate the average yield shear stress of the work material.
[8]
- a) During machining the maximum temperature is observed at the middle of chip-tool interface. State the reason for the same and also state its effect on the tool wear pattern.
[6]
b) What are the functions of cutting fluids in machining? Suggest some techniques to minimize or if possible eliminate the use of cutting fluids.
[6]
c) Figures below show the defect in the holes produced for certain application. Suggest some abrasive based methods to eliminate these errors and also explain the principle of operation of the process.
[8]
- a) Describe the construction of a gun drill with appropriate diagrams. (^) [8]
b) Explain the physics behind the thermally enhanced machining and also list the benefits and limitations of this process.
[6]
c) Discuss the roller burning process to produce fine surface finish on bearing and seal surfaces.
[6]
- a) Explain the term high speed machining and also discuss the motivating factors for moving towards this technology.
[6]
b) Discuss the tool holders and cutting tools requirements for high speed machining. (^) [10] c) Compare between high speed machining and high performance machining. (^) [4]
- a) Select a suitable nontraditional machining process to drill square blind holes in SiN workpieces and also explain the principle of operation of the process with a neat sketch.
[12]
b) Calculate the metal removal rate (cm^3 /min) in an anodic dissolution process of chromium if the current density available is 500 A/cm^2. (Where atomic weight of chromium is 52 gms, Valancy = 2, Density of chromium = 7.2 gms/ cm^3 )
[4]
c) Write the various process parameters in water jet cutting using the schematic diagram of set-up.
[4]
Term End Examination - May 2012 Course : MEE551 - Advanced Manufacturing Technology Slot: C Time : Three Hours Max.Marks: Answer any FIVE Questions (5 X 20 = 100 Marks)
- a)^ What is meant by built-up-edge (BUE)? With a neat sketch explain the formation of a BUE and also state the conditions which promote the growth of BUE along with its consequences.
[4]
b) The tool life of a high speed steel (HSS) tool and carbide tool have the same tool life of 60 minutes at a cutting speed of 75 m/min. The exponent of tool life in Taylor's equation (n) is 0.15 for HSS while it is 0.2 for carbide. Compare the life of the two tools at a speed of 90 m/min.
[6]
c) Using Merchant's cutting mechanics analysis, derive a relationship between shear energy and frictional energy in terms of rake angle, shear angle and friction angle.
[10]
- a)^ What are the locations where heat is produced in an orthogonal cutting tool? Show their approximate percentages.
[4]
b) Explain how effective cermite is as a cutting tool material in comparison to other cutting tool materials.
[4]
c) State the requirements for hot machining and also discuss the chip formation mechanism in laser assisted machining of ceramics.
[12]
- a)^ It is required to drill a hole of size 20 mm for a length of 400 mm in a long slender part. Suggest a suitable drilling process and also explain the drilling process with appropriate sketches.
[10]
b) Figure below shows the intake manifold of a racing car. In order to improve the performance of the racing car the air paths in the manifold should have very high surface quality to allow more air, fuel, and gasses to pass quickly through the engine components to maximize increased flow velocity. Select a suitable finishing process for the manifold and also discuss the process principle with a neat sketch.
[10]
- a)^ Describe^ your thoughts^ regarding selection^ of cutting tool^ material^ for hard machining and HSM.
[8]
b) Mention the essential requirements and applications of ultra precision machining. (^) [4] c) Describe briefly the diamond grinding of brittle materials. (^) [4] d) What are the benefits of near dry machining? (^) [4]
- a)^ Explain the term ‘driven at the center of gravity (DCG)’ in high speed machining and also list the advantages of DCG.
[4]
b) A cylindrical impression of 8 mm diameter and 2 mm deep is to be made on a tungsten carbide specimen. Feed force is constant and is equal to 10 N. Average diameter of grains in the slurry is 10 μm. Tool oscillates with the amplitude of 30 μm at 20 kHz. Abrasive and water ratio in the slurry is 1. Fracture hardness of tungsten carbide work piece may be taken as 7500 N/mm2 and that of copper tool as 1600 N/mm2. Abrasive grain density is 3800 kg/m3. Calculate the time required to complete the job if only 30 % of pulses are effective. Assume K 1 = 0.25, K 2 =2mm^2 and K 3 =0.5. Make the assumption if necessary.
[10]
Regular Arrear Examination - December 2013 Course : MEE551_20 - Advanced Manufacturing Technology
Time : Three Hours Max.Marks: Answer any FIVE Questions (5 X 20 = 100 Marks)
- a)^ Explain with a neat sketch what you understand by the word^ Orthogonal Cutting and its relevance in metal cutting study. How can orthogonal cutting be realised in practice?
[4]
b) Derive the expression-for shear angle in orthogonal cutting in terms of rake angle and chip thickness ratio.
[6]
c) An orthogonal cutting of steel is done with 10º rake tool, with a depth of cut 2 mm and feed rate of 0.2 mm/rev, the cutting speed is 200 m/min and the chip thickness ratio is 0.31. The vertical cutting force is 1200 N and the horizontal cutting force is 650 N. Calculate from the Merchant’s theory, the various workdone in metal cutting and shear stress.
[10]
- a)^ The tool life of a high speed steel (HSS) tool and carbide tool have the same tool life of 60 minutes at a cutting speed of 75 m/min. The exponent of tool life in Taylor's equation (n) is 0.15 for HSS while it is 0.2 for carbide. Compare the life of the two tools at a speed of 90 m/min.
[6]
b) What is the method generally used for measuring average chip tool interface temperature? Explain its principle with a neat sketch.
[6]
c) Explain the ejector drilling system for producing deep hole holes. [8]
- a)^ List the different heat sources used for hot machining and also write the requirements for hot machining processes.
[8]
b) Can you use magnetic abrasive finishing process to finish ceramic thin plates? If yes, sketch a schematic diagram for the same, else justify your answer.
[6]
c) Discuss briefly the choice of cutting tool materials for hard turning. [6]
- a)^ Write the characteristics of high speed machining.^ [6] b) Describe the control intelligence requirement for high speed machining with specific reference to advanced look-ahead function.
[8]
c) Explain the term high performance grinding, and also discuss the grinding tools for the high speed grinding.
[6]
- a)^ Enlist the requirements that demand the use of nontraditional machining processes.^ [4] b) Derive a theoretical relationship for the determination of the metal removal rate in ECM.
[8]
c) Explain the working principal of ultrasonic machining process and its applications. [8]
- a)^ Describe the working principle of wire EDM. Also, explain how the stratified wire works?
[8]
b) Laser beam machining and Electrical Discharge machining both are thermal processes, however it is found that the first one result in more thermal damage to the machined components than the second one. Is it true? Justify your answer.
[8]
c) Enlist the principal micromachining methods along with the principle in a table format.
[4]
- a) Explain a CNC micro turning processes and also discuss the effect of minimum chip thickness and cutting forces in micro turning.
[10]
b) Describe in detail the steps in LIGA processes for microfabrication. [10] ⇔⇔⇔
b) What are metal-matrix composites (MMC’s)? Give examples of industrial applications of MMC’s.
[3]
- a) Give examples of surface modification techniques where there is no change in the chemical composition of the surface.
[3]
b) How does the electrical conductivity of a metallic glass ZrCu compare with its crystalline counterpart? Account for the difference.
[3]
- a) Briefly explain why fracture strength of ceramic materials increases with decreasing specimen size.
[3]
b) Name two commonly used case hardening processes for steels involving change in the chemical composition of the surface layers. Compare them with respect to the dopants used and process temperatures involved.
[3]
- a) Would you expect a crystalline ceramic material such as alumina to strain harden at room temperature? Justify your answer.
[3]
b) State the advantages and disadvantages of ceramic materials with reference to mechanical behavior.
[3]
PART – B (8 X 8 = 64 Marks) Answer any EIGHT Questions
- Explain in detail the steps involved in heat treatment of precipitation hardenable wrought aluminum alloy 2024.
- Explain, using relevant phase diagram, why a 0.2% carbon steel carburizes much more easily at 1150K than Armco iron (iron with no carbon).
- Explain in detail the phenomenon of transformation toughening occurring in partially stabilized zirconia.
- What are the different grades of cobalt-containing 18% Ni maraging steels commercially available? Indicate the proof strength levels of each of these grades. What is the element whose level steadily increases with increase in proof strength? Explain how this element controls the proof strength of the steel.
- The following data were obtained for an aluminum alloy. Show that the behavior of the aluminum alloy is consistent with the Hall–Petch relationship; determine σ 0 and k for the material. Aluminum Alloy Grain size d (μm) Yield strength σy (MN/m^2 ) 42 223 16 225 11 225 8.5 226 5.0 231 3.1 238
- Explain schematically how carbon is present in the microstructure of
White cast iron Grey iron Malleable iron Nodular iron Relate this to the % elongation obtained in a tensile test.
- Explain in detail how microalloying leads to achievement of high strengths.
- Four major microstructural features found in steels are ferrite, pearlite, lath martensite and plate martensite, Heat treatment importantly influences the occurrence of these features. Shown in the figure below in parts a, b, c and d respectively are these features. Discuss in detail the different strengthening mechanisms operating in each case.
Regular Arrear Examination - December 2013 Course : MEE557 - Advanced Materials and Processing
Time : Three Hours Max.Marks: PART – A (6 X 4 = 24 Marks) Answer ALL Questions
- a)^ Define true strain in terms of engineering strain.^ [2] b) A 25 cm long rod with a diameter of 0.25 cm is loaded with a 4500 N weight. If the diameter decreases to 0.22 cm, compute (i) final rod length (ii) engineering stress and strain at this load.
[2]
- Which are the refractory metals of industrial importance? What is required to be done to use them at high temperatures?
- Would you expect crystalline silicon carbide to strain harden at room temperature? Justify your answer.
- What are the advantages and limitations of ion implantation technique for modification of surfaces?
- How does the electrical conductivity of the metallic glass NbNi compare with its crystalline counterpart? Account for the difference.
- State^ the^ advantages^ and^ disadvantages^ of^ ceramic^ materials^ with^ reference^ to mechanical behavior. PART – B (6 X 6 = 36 Marks) Answer any SIX Questions
- a)^ Describe the phenomenon of fatigue and bring out the role of mean stress.^ [3] b) The fatigue limit of 1045 steel is 300 MN/m^2 , when the mean stress is zero. The tensile strength of this steel is 750 MN/m^2. Estimate the safe stress amplitude for this material when the mean stress is 250 MN/^2.
[3]
- a)^ What are metal-matrix composites? Give examples of where they find application in industry.
[3]
b) Which are the phases present when you look at the microstructure of dual phase steels? How does this microstructure compare with that of low carbon steels? How do the tensile properties of low carbon steels compare with those of dual phase steels?
[3]
- a)^ Using the method of sputtering, what are the materials that can be physical vapor deposited?
[3]
b) What are piezoelectric ceramics? Mention some commonly used ones. (^) [3]
- a)^ Briefly explain why fracture strength of ceramic materials increases with decreasing specimen size.
[3]
b) Which grade(s) of commercially pure titanium would you recommend for a part, where strength is not much of concern but manufacture of the part involves extensive forming? Justify your answer.
[3]
- a)^ Give examples of surface modification techniques where there is no change in the chemical composition of the surface.
[3]
b) In what way do oxide strengthened superalloys stand out in the material group of Superalloys?
[3]
- a)^ Why do materials deform even if they are designed to perform within the elastic limit?
[3]
b) If the Larson-Miller parameter for a given alloy is found to be 26, estimate the expected reduction in rupture life if the absolute temperature were increased from 1100 to 1250K. Take the constant C as 20
[3]
- a)^ Explain how Ni-Cr-Mo low alloy steel containing 0.4 % carbon is superior to plain carbon steel containing 0.4% carbon with reference to heat-treatability and mechanical properties.
[3]
b) What is TZM molybdenum? Show schematically how high temperature performance of TZM molybdenum compares with that of pure molybdenum. Account for the difference in the performance.
[3]
PART – C (5 X 8 = 40 Marks) Answer any FIVE Questions
- Explain how the phenomenon of transformation toughening is exploited to produce tough zirconium oxide based ceramic matrix composites.
- Explain how carbon is present in the microstructure of the following variants of cast iron. Use schematic diagrams to draw the distinction. White cast iron Grey iron Malleable iron Nodular iron Relate this to the % elongation measured in a tensile test.
Term End Examination – November 2012 Course : MEE557 - Advanced Materials and Processing Slot: F
Class NBR : 2742
Time : Three Hours Max.Marks:
PART - A (6 X 4 = 24 Marks) Answer ALL the Questions
- a) Define true strain in terms of engineering strain. (^) [2] b) A 25 cm long rod with a diameter of 0.25 cm is loaded with a 4500 N weight. If the diameter decreases to 0.22 cm, compute (a) final rod length (b) engineering stress and strain at this load.
[2]
- How does the electrical conductivity of the metallic glass AuSi compare with its crystalline counterpart? Account for the difference.
- Which are the refractory metals of industrial importance? What is required to be done to use them at high temperatures?
- Would you expect crystalline zirconium dioxide to strain harden at room temperature? Justify your answer.
- State the advantages and disadvantages of ceramic materials with reference to mechanical behavior.
- What are the advantages and limitations with reference to use of ion implantation technique? PART – B (6 X 6 = 36 Marks) Answer any SIX Questions
- a) Describe the phenomenon of fatigue and bring out the role of mean stress. (^) [3] b) The fatigue limit of 1045 steel is 300 MN/m^2 , when the mean stress is zero. The tensile strength of this steel is 750 MN/m^2. Estimate the safe stress amplitude for this material when the mean stress is 250 MN/^2.
[3]
- a) Why do materials deform even if they are designed to perform within the elastic limit?
[3]
b) If the Larson-Miller parameter for a given alloy is found to be 26, estimate the expected reduction in rupture life if the absolute temperature were increased from 1100 to 1250 K.
[3]
- a) Explain how medium carbon (0.4% C) Ni-Cr-Mo low alloy steel is superior to plain carbon steel containing 0.4% carbon with reference to heat-treatability and mechanical properties.
[3]
b) What is TZM molybdenum? Show schematically how its high temperature performance compares with that of pure molybdenum. Account for the difference in the performance.
[3]
- (^) a) What are metal-matrix composites (MMC’s)? Give examples of industrial applications of MMC’s.
[3]
b) In dual phase steels, which are the phases present in the microstructure? How does their microstructure compare with that of low carbon steels? How do the tensile properties of dual phase steels compare with those of low carbon steels?
[3]
- a) What are the materials that can be physical vapor deposited by sputtering? (^) [3]
b) What are piezoelectric ceramics? Mention some commonly used ones. (^) [3]
- a) Briefly explain why fracture strength of ceramic materials increases with decreasing specimen size.
[3]
b) What grade of titanium would you recommend for a part, where strength is not much of concern but manufacture of the part involves extensive forming? The part is to operate at room temperature. Justify your answer.
[3]
- a) Give examples of surface modification techniques where there is no change in the chemical composition of the surface.
[3]
b) In what way do oxide strengthened superalloys stand out in the material group of Superalloys?
[3]
PART – C (5 X 8 = 40 Marks) Answer any FIVE Questions
- Explain in detail the steps involved in heat treatment of precipitation hardenable aluminum alloys.
- Explain the phenomenon of transformation toughening in the context of ceramic matrix composites. Give examples of composites toughened in this manner.
Term End Examination - May 2012 Course : MEE557 - Advanced Materials and Processing Slot: D
Time : Three Hours Max.Marks:
PART - A (6 X 4 = 24 Marks) Answer ALL Questions
- State the advantages and disadvantages of ceramic materials with reference to mechanical behavior.
- Name two commonly used case hardening processes for steels involving change in the chemical composition of the surface layers. Compare them with respect to the dopants used and process temperatures involved.
- Would you expect a crystalline ceramic material to strain harden at room temperature? Justify your answer.
- What are refractory metals of industrial importance? What is required to be done to use them at high temperatures?
- How does the electrical conductivity of a metallic glass compare with its crystalline counterpart? Account for the difference.
- a) Define true strain in terms of engineering strain. (^) [2] b) A 25 cm long rod with a diameter of 0.25 cm is loaded with 4500 N. If the diameter decreases to 0.22 cm, compute (i) final rod length (ii) true stress and true strain at this load and (iii) engineering stress and strain at this load.
[2]
PART - B (6 X 6 = 36 Marks) Answer any SIX Questions
- a) Briefly explain (i) why there may be significant scatter in the fracture strength for a given ceramic material and (ii) why fracture strength increases with decreasing specimen size.
[3]
b) What are piezoelectric ceramics? Mention some commonly used ones. [3]
- a) What grade of titanium would you recommend for a part, manufacture of which involves extensive forming? Justify your answer.
[3]
b) Is Ti-15Mo-5Zr an Alpha Near-alpha Alpha+Beta or Beta alloy? Give basis for your answer.
[3]
- a)^ In dual phase steels, which are the phases present in the microstructure? How does their microstructure compare with that of low carbon steels? How do the tensile properties of the two types of steel compare?
[3]
b) What is TZM molybdenum? Show schematically how its high temperature performance compares with that of pure molybdenum. Account for the difference in the performance.
[3]
- a)^ What are metal-matrix composites (MMC’s)?^ Give examples of industrial applications of MMC’s.
[3]
b) Explain how medium carbon (0.4% C) Ni-Cr-Mo low alloy steel is superior to plain carbon steel containing 0.4% carbon with reference to heat-treatability and mechanical properties.
[3]
- a) Why do materials deform even if they are designed to perform within the elastic limit?
[3]
b) If the Larson-Miller parameter for a given alloy is found to be 26, estimate the expected reduction in rupture life if the absolute temperature were increased from 1100 to 1250K.
[3]
- a) What are the advantages and limitations with reference to use of ion implantation technique for producing PVD coatings?
[3]
b) Explain, taking example of a turbine blade of a high performance jet engine, how the bulk and surface of a component may have totally different demands placed on them.
[3]
