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Manufacturing Processes Review Questions: Metal Casting, Forming, and Machining, Cheat Sheet of Macrosociology

University of Hong KongMacrosociology

A series of review questions covering various aspects of manufacturing processes, including the relationship between design and manufacturing, material properties of metals and ceramics, metal casting, metal forming, plastics shaping, and machining. It explores topics such as tensile testing, solidification processes, polymer melt properties, stress-strain relationships, and cutting tool mechanics. The questions aim to assess understanding of key concepts and principles in manufacturing engineering, providing a comprehensive overview of essential topics in the field. It also covers extrusion, rolling, and forging processes, along with the principles of electrochemical and electric discharge machining.

Typology: Cheat Sheet

2022/2023

Uploaded on 07/03/2025

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ENGINEERING MATERIALS
REVIEW QUESTIONS
1. What is the dilemma between design and manufacturing in terms of mechanical properties?
2. In stress-strain curve, list all the names in the boxes as below. Give brief definitions for all of
them.
3. Explain why metallic materials are ductile and conductive why ceramics are brittle and non-
conductive.
4. Explain why thermoplastics are weak compared to ceramics and metallic materials
5. What are the three basic methods by which metals can be strengthened? Give brief descriptions.
6. What is the difference between engineering stress and true stress in a tensile test?
PROBLEMS
1. A tensile test uses a test specimen that has a gage length of 50 mm and a cross sectional area =
200 mm๏„ถ. During the test the specimen yields under a load of 98,000 N. The corresponding gage
length = 50.23 mm. This is the 0.2% yield point. The maximum load of 168,000 N is reached at a gage
length = 64.2 mm. Determine (a) yield strength, (b) modulus of elasticity, and (c) tensile strength.
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Download Manufacturing Processes Review Questions: Metal Casting, Forming, and Machining and more Cheat Sheet Macrosociology in PDF only on Docsity!

ENGINEERING MATERIALS

REVIEW QUESTIONS

  1. What is the dilemma between design and manufacturing in terms of mechanical properties?
  2. In stress-strain curve, list all the names in the boxes as below. Give brief definitions for all of them.
  3. Explain why metallic materials are ductile and conductive why ceramics are brittle and non- conductive.
  4. Explain why thermoplastics are weak compared to ceramics and metallic materials
  5. What are the three basic methods by which metals can be strengthened? Give brief descriptions.
  6. What is the difference between engineering stress and true stress in a tensile test? PROBLEMS
  7. A tensile test uses a test specimen that has a gage length of 50 mm and a cross sectional area = 200 mmเฌถ. During the test the specimen yields under a load of 98,000 N. The corresponding gage length = 50.23 mm. This is the 0.2% yield point. The maximum load of 168,000 N is reached at a gage length = 64.2 mm. Determine (a) yield strength, (b) modulus of elasticity, and (c) tensile strength.

(d) If fracture occurs at a gage length of 67.3 mm, determine the percent elongation. (e) If the specimen necked to an area = 92 mmเฌถ, determine the percent reduction in area.

  1. A tensile test for a certain metal provides flow curve parameters: strain-hardening exponent is 0. and strength coefficient is 600MPa. Determine (a) the flow stress at a true strain = 1.0 and (b) true strain at a flow stress = 600MPa
  2. For the copper-nickel phase diagram in Figure below, find the compositions of the liquid and solid phases for a nominal composition of 70%Ni and 30%Cu at 1371 โˆ˜C( 2500 โˆ˜F). Determine the proportions of liquid and solid phases present in the alloy. METAL CASTING REVIEW QUESTIONS
    1. Identify some of the important advantages of casting processes.
    2. What are some of the limitations of casting?
    3. Which casting process is the most important commercially? Why?
    4. What is the difference between a pattern and a core in sand casting?
    5. Why should turbulent flow of molten metal into the mold be avoided?
  1. A riser in the shape of a sphere is to be designed for a sand-casting mold. The casting is a rectangular plate, with length = 200 mm, width = 100 mm, and thickness = 18 mm. If the total solidification time of the casting itself is known to be 3.5 min, determine the diameter of the riser so that it will take 25% longer for the riser to solidify.
  2. A cylindrical riser with diameter-to-length ratio = 1.0 is to be designed for a sand-casting mold. The casting geometry is illustrated in Figure below, in which the units are inches. If the mold constant in Chvorinov's rule = 19.5 min/inเฌถ, determine the dimensions of the riser so that the riser will take 0.5 min longer to freeze than the casting itself. PLASTIC MOLDING REVIEW QUESTIONS
  3. Viscosity is an important property of a polymer melt in plastics shaping processes. what parameters does viscosity depend?
  4. How does the viscosity of a polymer melt differ from most fluids that are Newtonian?
  5. Besides viscosity, what other properties of a polymer melt are important in plastics processing? Briefly define each of the properties identified.
  6. Define die swell in extrusion.
  7. The barrel and screw of an extruder are generally divided into three sections; identify the sections.

6. What are the functions of the screen pack and breaker plate at the die end of the

extruder barrel?

  1. What is drag flow and its role in plastic molding? Describe conditions to obtain drag flow? List some input factors that affect the drag flow rate?
  2. What is back pressure flow? List some input factors that affect the back pressure flow rate?
  3. How to obtain an optimal process in plastic molding and consequently, high quality products? Briefly explain some negative effects of using inappropriate drag flow rate? PROBLEMS
    1. An extruder barrel has a diameter of 120 mm and a length = 3.0 m. The screw channel depth = 8.0 mm, and its pitch 95 mm. The viscosity of the polymer melt is 75 ๐‘ƒ๐‘Ž. ๐‘  , and the head

pressure in the barrel is 4.0 ๐‘€๐‘ƒ๐‘Ž. What rotational speed of the screw is required to achieve a volumetric flow rate of 90 cmเฌท/s?

  1. An extruder has diameter = 80 mm and length = 2.0 m. Its screw has a channel depth = 5 mm, flight angle = 18 degrees, and it rotates at 1rev/sec. The plastic melt has a shear viscosity = 150 Pas. Determine the extruder characteristic by computing ๐‘„เญซเญŸเญถ and ๐‘เญซเญŸเญถ and then finding the equation of the straight line between them.
  2. Consider an extruder in which the barrel diameter = 115 ๐‘š๐‘š and length = 3.5 ๐‘š. The extruder screw rotates at 60 ๐‘Ÿ๐‘’๐‘ฃ/๐‘š๐‘–๐‘›; it has channel depth = 9 ๐‘š๐‘š and flight angle = 20โˆ˜. The plastic melt has a shear viscosity = 86 ๐‘ƒ๐‘Ž. ๐‘ . Determine: (a) ๐‘„เฎฝเฏ เฏ”เฏซ and ๐‘ƒเญซเญŸเญถ, (b) the shape factor ๐พเฏฆ for a circular die opening in which ๐ทเฏ— = 8 ๐‘š๐‘š and ๐ฟเฏ— = 19 ๐‘š๐‘š, and (c) the values of ๐‘„เฏ and ๐‘ƒ at the operating point. METAL FORMING REVIEW QUESTIONS
  3. What are desirable metallic materials in metal forming?
  4. What are factors to be considered in metal forming?
  5. What is bulk deformation? What distinguish between metal forming and sheet metal forming? Name main processes of metal forming.
  6. Provide the working temperature of cold, warm, and hot working relative to melting temperature of the material
  7. Indicate some of the advantages of cold working relative to warm and hot working.
  8. In what case does metal forming require hot working? Why does not sheet metal forming have hot working?
  9. Why true stress and true strain are used in metal forming?
  10. What is flow stress? Draw stress-strain curve indicating the flow stress and average flow stress.
  11. Distinguish between hot rolling and cold rolling PROBLEMS Flow Curve in Forming
  12. The strength coefficient = 550MPa and strain hardening exponent = 0.22 for a certain metal. During a forming operation, the final true strain that the metal experiences = 0.85. Determine the flow stress at this strain and the average flow stress that the metal experienced during the operation.
  13. A metal has a flow curve with parameters: strength coefficient = 850MPa and strain-hardening exponent = 0.30. A tensile specimen of the metal with gage length = 100 mm is stretched to a length = 157 mm. Determine the flow stress at the new length and the average flow stress that the metal has been subjected to during the deformation
  1. Identify some of the reasons why machining is commercially and technologically important.
  2. Name the three most common machining processes.
  3. What are the two basic categories of cutting tools in machining? Give two examples of machining operations that use each of the tooling types.
  4. What are the parameters of a machining operation that are included within the scope of cutting conditions?
  5. Explain the difference between roughing and finishing operations in machining.
  6. What is an orthogonal cutting operation? And why is the orthogonal cutting model useful in the analysis of metal machining?
  7. Name and briefly describe the four types of chips that occur in metal cutting (include the conditions to form those chips)
  8. Identify the four forces that act upon the chip in the orthogonal metal cutting model but cannot be measured directly in an operation.
  9. Identify the two forces that can be measured in the orthogonal metal cutting model. And by what device?
  10. Describe in words what the Merchant equation tells us and what lessons learnt from Merchant equation
  11. What are two main motions in machining? Distinguish between drilling, turning, and milling based on those motions
  12. What is shear angle? And how does it influence cutting force and chip thickness?
  13. What is rake angle? What are advantages and limitations of machining using positive and negative rake angles?
  14. What is Built-up-Edge (BUE)? And how it is considered undesirable in machining? PROBLEMS
  15. In an orthogonal cutting operation, the tool has a rake angle = 15โˆ˜. The chip thickness before the cut = 0.30 mm and the cut yields a deformed chip thickness = 0.65 mm. Calculate (a) the shear plane angle and (b) the shear strain for the operation.
  16. In Problem 1, suppose the rake angle were changed to 0โˆ˜. Assuming that the friction angle remains the same, determine (a) the shear plane angle, (b) the chip thickness, and (c) the shear strain for the operation.
  17. The cutting force and thrust force in an orthogonal cutting operation are 1470 N and 1589 N, respectively. The rake angle = 5โˆ˜, the width of the cut = 5.0 mm, the chip thickness before the cut = 0.6, and the chip thickness ratio = 0.38. Determine (a) the shear strength of the work material and (b) the coefficient of friction in the operation.
  1. An orthogonal cutting operation is performed using a rake angle of 15o, chip thickness before the cut = 0.3 mm and width of cut =2.5 mm. The chip thickness ratio is measured after the cut to be 0.55. Determine (a) the chip thickness after the cut, (b) shear angle, (c) friction angle, (d) coefficient of friction, and (e) shear strain.
  2. The orthogonal cutting operation described in previous Problem (4) involves a work material whose shear strength is 276 MPa. Based on your answers to the previous problem (4), compute (a) the shear force, (b) cutting force, (c) thrust force, and (d) friction force. NON-CONVENTIONAL MACHINING REVIEW QUESTIONS
  3. Briefly explain working principle of electrochemical machining (ECM)
  4. Briefly explain working principle of electric discharge machining (EDM)
  5. What are the functions of dielectric fluid in electric discharge machining (EDM)?
  6. Describe differences and similarities between electrochemical machining (ECM) and electric discharge machining (EDM) JOINING
  7. Define the term fusion weld
  8. What is the fundamental difference between a fusion weld and a solid-state weld?
  9. Name and sketch the five joint types.
  10. Why is it desirable to use energy sources for welding that have high heat densities?
  11. Define what an electrical arc is. What is the difference between arc and spark?
  12. Describe submerged arc welding
  13. Define resistance welding