18 Fundamentals of machining

1. Machining is defined as a process in which: A) Material is added to achieve the final geometry. B) Material is removed to achieve the final geometry. C) Material is melted and re-solidified. D) Material is chemically dissolved.

2. According to the text, the only requirement for a material to be machinable is that it must be: A) Electrically conductive. B) Non-reflective. C) In the solid state. D) Metallic.

3. A semi-finished product used as a starting point for machining is typically produced by: B) Casting. A) Forming or extrusion. C) Welding. D) Additive manufacturing.

4. Near-net shape parts: A) Have less material than the final part. B) Require no machining. C) Have machining allowance or lack precise geometric features. D) Cannot be produced by forging.

5. Machining of semi-finished products generally requires: A) Less material removal than near-net shape parts. D) More material removal than near-net shape parts. C) No material removal. B) Only finishing operations.

6. The main limitation for achievable geometries in machining is: A) Material hardness. B) Tool accessibility. C) Machine size. D) Cutting speed.

7. Machining processes offer the greatest geometric freedom except when compared to: A) Forming processes. B) Casting processes. C) Additive manufacturing processes. D) Powder metallurgy.

8. One reason machining is used in mold and die manufacturing is that: A) Molds cannot be produced by casting. B) Machining is the only process capable of producing any geometry. D) Final stages of mold fabrication require high precision. C) Machining eliminates the need for heat treatment.

9. The main advantage of machining processes is: A) Low energy consumption. B) High production rate. C) Improved geometric quality. D) No tool wear.

10. Dimensional tolerances such as tight cylindrical diameters are typically achieved by: A) Casting. B) Forging. C) Machining. D) Extrusion.

11. Machining can correct geometric defects from other processes, such as: A) Excessive hardness. B) Draft angles causing lack of perpendicularity. C) Porosity. D) Chemical contamination.

12. Surface finish (Ra) values for machining processes are generally: A) Among the roughest. B) In the mid-range. C) Among the most precise. D) Unpredictable.

13. One limitation to achieving high geometric accuracy is: B) Excessive lubrication. A) Tool and workpiece deformation. C) Low cutting temperature. D) High electrical conductivity.

14. Chatter is described as: A) A type of tool wear. B) A resonance phenomenon causing vibrations. C) A thermal expansion effect. D) A surface hardening technique.

15. Residual stresses from previous processes may cause: A) Improved surface finish. B) Increased hardness. C) Warping when material is removed. D) Lower cutting forces.

16. Tool wear affects the machined part by causing: A) Improved dimensional accuracy. B) Reduced temperature. D) Dimensional and geometric deviations. C) Elimination of residual stresses.

17. Machine imperfections such as lack of squareness between axes are due to: B) Tool material. A) Assembly errors and component wear. C) Cutting fluid selection. D) Workpiece geometry.

18. Machining does not alter the bulk mechanical properties of the material because: A) Cutting temperatures are always low. B) The process only affects the surface and sub-surface layers. C) The tool removes all stressed material. D) The workpiece is always cooled.

19. Surface integrity includes not only geometric quality but also: A) Tool life. B) Machine stiffness. C) Metallurgical transformations and microhardness changes. D) Cutting speed selection.

20. In EDM (electrical discharge machining), material is removed by: A) Plastic deformation. B) Chemical dissolution. D) Melting caused by electrical sparks. C) Abrasive erosion.

21. One major economic drawback of machining is that: B) It produces no recyclable waste. A) It generates a high percentage of material waste. C) It requires no auxiliary equipment. D) It consumes less energy than forging.

22. The example of machining a turbine rotor blade shows that material waste can reach approximately: A) 20%. B) 40%. C) 60%. D) 80%.

23. The material removal rate in machining is generally: A) Higher than in forging. B) Higher than in casting. C) Lower than desired for medium and large batch production. D) Independent of the process used.

24. Tool wear is a major cost factor because: A) Machining tools last longer than forging dies. B) Machining tools have very short tool life. C) Tool wear does not affect productivity. D) Tool wear is irrelevant in machining.

25. Sandvik’s cutting data example illustrates that: B) Tools can last several hours without wear. A) Tool life is typically around 15 minutes. C) Tool wear is negligible in modern machining. D) Tool life is independent of cutting speed.

26. Compared to other processes, machining generally requires: A) Lower energy consumption. B) Similar energy consumption. C) Much higher energy consumption. D) No electrical energy.

27. Auxiliary elements such as fixtures, tool holders, and measurement systems: A) Reduce machining costs. B) Have no impact on investment cost. D) Increase overall investment cost. C) Are optional in most machining operations.

28. Recycling costs in machining include the recycling of: A) Only the removed material. B) Only the cutting fluid. C) Removed material, cutting fluid, and worn tools. D) Only worn tools.

29. To reduce manufacturing cost, the number of machining operations should be: A) Increased. B) Minimized. C) Kept constant. D) Ignored during planning.

30. The concept of near‑net shape parts is related to: A) Increasing machining allowance. D) Reducing the need for machining. C) Eliminating forming processes. B) Improving tool wear.

31. Conventional machining processes remove material by: A) Chemical reactions. B) Mechanical stress forming chips. C) Thermal melting. D) Electrochemical dissolution.

32. In drilling, each cutting edge of the drill bit: B) Produces identical chips. A) Produces a different chip. C) Does not produce chips. D) Removes material by abrasion.

33. Abrasive processes differ from conventional ones because: A) The number of active cutting edges is unknown. B) They use perfectly defined tool geometry. C) They do not rely on mechanical forces. D) They remove material in large chunks.

34. In grinding, material is removed by: A) A single cutting edge. D) A rotating wheel with embedded abrasive grains. C) A chemical reaction. B) Electrical discharges.

35. Non‑conventional machining processes remove material using: A) Mechanical cutting edges. B) Abrasive wheels only. C) Non‑mechanical energy sources. D) Manual tools.

36. Electrochemical machining removes material through: A) Melting caused by sparks. B) Abrasion from hard particles. D) A chemical reaction with an electrolyte. C) Mechanical cutting.

37. Water‑jet cutting is usually classified as: A) A conventional process. B) An abrasive process only. C) A non‑conventional process, despite its abrasive nature. D) A thermal process.

38. John Wilkinson’s contribution to machining history was: A) Inventing high‑speed steel. B) Developing the first CNC machine. C) Creating the first machine tool for boring cylinders. D) Inventing the first grinding wheel.

39. Frederick W. Taylor revolutionized machining by: A) Inventing numerical control. B) Developing high‑speed steel cutting tools. C) Creating the first lathe. D) Designing the first forging press.

40. Independent influencing factors in machining include: A) Only the tool and the machine. B) Only the cutting fluid and fixtures. C) Workpiece, machine, tool, fixtures, cutting fluid, and cutting conditions. D) Only the workpiece material.

41. Machinability is defined as the ease with which a metal can be cut: B) With maximum productivity regardless of cost. A) With a satisfactory finish at low cost. C) Only using conventional tools. D) Without generating chips.

42. Although machinability depends on many variables, it is often incorrectly treated as: A) A property of the cutting tool. B) A property of the machine. D) A property of the material. C) A property of the cutting fluid.

43. Proper chip control is important because it: A) Increases cutting temperature. B) Ensures stable cutting and reduces vibrations. C) Eliminates the need for lubrication. D) Prevents tool wear entirely.

44. A material is considered more machinable when: A) It requires higher cutting forces. B) It generates more heat. C) It causes less tool wear and longer tool life. D) It produces discontinuous chips only.

45. Surface integrity is included in machinability evaluation because it: A) Determines chip thickness. B) Reflects the condition of the surface and subsurface layers. C) Measures machine stiffness. D) Indicates tool hardness.

46. In the simplified cutting model, the cutting tool is represented as: B) A cylinder. A) A wedge with two surfaces and an edge. C) A sphere with multiple edges. D) A flat plate.

47. The surface along which the chip slides is called the: A) Clearance surface. B) Flank surface. C) Rake surface. D) Relief surface.

48. The cutting movement is defined as the movement that: A) Positions the tool before cutting. B) Gives continuity to the cutting action. D) Directly removes material. C) Controls chip thickness.

49. In turning, the cutting movement is: A) Linear. B) Performed by the tool. D) Performed by the rotating workpiece. C) Performed during the return stroke.

50. The feed movement in linear cutting processes occurs: A) Simultaneously with the cutting movement. B) Only during the cutting stroke. C) After the cutting and return strokes. D) Only before cutting begins.

51. The penetration movement is used to: A) Remove chips from the cutting zone. B) Position the tool and define the volume of removed material. C) Increase cutting speed. D) Reduce tool wear.

52. Cutting speed is defined as: B) The rotational speed of the spindle. A) The instantaneous speed of a point on the cutting edge. C) The velocity of chip flow. D) The speed of the feed mechanism.

53. Typical cutting speeds for steel machining are: A) 10–50 m/min. B) 50–150 m/min. C) 200–400 m/min. D) 800–1200 m/min.

54. Feed in rotary cutting processes is expressed in: A) mm/min. B) mm/rev. C) m/min. D) mm/s.

55. Depth of cut is best defined as: B) The chip thickness after deformation. A) The distance between raw and machined surfaces. C) The distance the tool travels per revolution. D) The maximum tool penetration speed.

56. Turning typically uses: A) Two active cutting edges. D) A single active cutting edge. C) Multiple abrasive grains. B) A chemical reaction to remove material.

57. In drilling, the cutting movement is generally performed by: A) The workpiece. B) The tool. C) Both tool and workpiece equally. D) The feed mechanism only.

58. Milling is characterized by: B) A single cutting edge. A) A rotating tool with multiple active edges. C) A stationary tool and rotating workpiece. D) No feed movement.

59. In a boring machine, the cutting and feed movements are performed respectively by: A) Tool (cutting) and tool (feed). B) Workpiece (cutting) and tool (feed). C) Tool (cutting) and workpiece (feed). D) Workpiece (cutting) and workpiece (feed).

60. Linear cutting processes are less productive mainly because: A) They use multiple cutting edges. B) They require a return stroke without cutting. C) They cannot remove metal. D) They operate at extremely low speeds.

61. The orthogonal cutting model assumes that the cutting edge is: B) Parallel to the cutting speed. A) Perpendicular to the cutting speed. C) Inclined at an arbitrary angle. D) Helical with respect to the tool axis.

62. Oblique cutting differs from orthogonal cutting because: A) It uses no cutting edge. B) The cutting edge is at 90° to the cutting speed. C) The cutting edge is not perpendicular to the cutting speed. D) It produces no chips.

63. The transient surface is defined as: A) The final machined surface. B) The raw surface before machining. D) The temporary surface generated as the chip separates. C) The surface of the tool in contact with the chip.

64. The rake surface is the tool surface: A) That contacts the transient surface. B) Along which the chip slides. C) That supports the tool holder. D) That defines the clearance angle.

65. The clearance angle (α) prevents: A) Chip curling. B) Tool overheating. C) Friction between the tool and the transient surface. D) Chip adhesion to the rake surface.

66. Increasing rake and clearance angles results in: B) A larger wedge angle β. A) A sharper wedge with smaller β. C) A stronger cutting edge. D) A thicker tool cross‑section.

67. The undeformed chip thickness (h) is primarily dependent on: A) Cutting speed. B) Depth of cut. C) Feed. D) Tool material.

68. According to volume conservation, real chips are: A) Thinner and longer than undeformed chips. B) Thicker and shorter than undeformed chips. C) Identical in shape to undeformed chips. D) Independent of deformation.

69. The Pijspanen model describes chip formation as: A) Melting and resolidification. D) Sliding of flakes like cards in a deck. C) Abrasive wear of the surface. B) Chemical dissolution.

70. According to Merchant’s theory, the shear plane orientation is the one that: B) Maximizes chip thickness. A) Minimizes shear strain energy. C) Maximizes friction. D) Minimizes cutting speed.

71. The secondary deformation zone is caused by: A) Shear stress in the shear plane. B) Pressure and friction on the rake surface. C) Elastic rebound of the workpiece. D) Tool vibration.

72. The friction force on the rake surface is denoted as: A) Fφ. B) Nc. C) Fγ. D) R′.

73. The angle of friction (ρ) is defined by the relationship: A) μ = sin ρ. B) μ = cos ρ. D) μ = tan ρ. C) μ = 1/ρ.

74. The cutting force (Fc) is the component of the resultant force: A) Perpendicular to the cutting movement. B) Parallel to the cutting movement. C) Along the shear plane. D) Along the rake surface.

75. The thrust force (Nc) acts: A) In the direction of chip flow. B) Opposite to the cutting speed. C) Normal to the cutting force. D) Along the shear plane.

76. Classical cutting models are difficult to apply because: A) They assume zero friction. B) They require constant temperature. D) Real processes have a deformation region, not a single shear plane. C) They ignore tool geometry.

77. The coefficient of friction between chip and tool is uncertain because: A) It depends on chip color. B) Temperature increases and chip adhesion occur. C) It is constant for all materials. D) It is measured directly during cutting.

78. Tool wear complicates force prediction because it: A) Reduces chip thickness. B) Eliminates the secondary deformation zone. C) Creates a wear land that increases friction. D) Prevents chip formation.

79. The specific cutting force (kc) is defined as the force required to remove: A) A chip of 1 mm thickness only. B) A chip with undeformed area of 1 mm². C) A chip of any size. D) A chip of 1 mm³ volume.

80. Specific cutting energy (Ec) differs from specific cutting force because it: B) Is measured directly with a dynamometer. A) Refers to unit volume instead of unit area. C) Is independent of chip thickness. D) Cannot be used to calculate power.

81. The sign of the rake angle is defined with respect to: A) The shear plane. B) The tool holder axis. C) A reference plane normal to the cutting movement. D) The workpiece surface.

82. A positive rake angle (γ > 0°) generally results in: A) More difficult penetration into the material. B) A thicker chip. D) Easier penetration and a thinner chip. C) No change in chip thickness.

83. When the rake angle becomes negative, the shear angle: A) Increases. B) Decreases. C) Remains constant. D) Becomes zero.

84. A smaller shear angle produces: A) A thinner chip. B) A longer chip. C) A thicker chip. D) No chip at all.

85. Cutting forces tend to: B) Increase as the rake angle increases. A) Decrease as the rake angle increases. C) Remain constant regardless of rake angle. D) Depend only on feed.

86. A highly positive rake angle reduces tool robustness because: A) It increases friction. B) It increases the wedge angle β. C) It reduces the resistant section near the cutting edge. D) It increases the clearance angle.

87. Positive cutting geometries are typically used for: A) Heavy roughing operations. D) Machining slender parts or finishing operations. C) Interrupted cuts only. B) High‑temperature alloys exclusively.

88. Negative cutting geometries are preferred when: A) The tool must withstand large cutting forces. B) Machining thin or flexible parts. C) Producing very smooth surfaces. D) Cutting forces must be minimized.

89. A desirable chip type for cutting stability is one that: A) Varies constantly in cross‑section. B) Has a uniform section. C) Is extremely short. D) Is extremely long.

90. Long continuous chips negatively affect productivity because they: A) Increase cutting speed. B) Improve surface finish. C) Accumulate and require machine stoppage. D) Reduce tool wear.

91. Very short chips tend to: A) Improve tool life. B) Be less aggressive on the cutting edge. D) Increase tool wear. C) Reduce non‑productive time.

92. Chip accumulation on the machined surface can: A) Improve surface finish. B) Reduce temperature. C) Worsen surface quality and increase heat concentration. D) Have no effect on the process.

93. From a safety perspective, longer chips are: A) More dangerous than short chips. B) Less dangerous than very short chips. C) Equally dangerous as short chips. D) Not relevant to safety.

94. A continuous chip is formed when: A) Plastic deformation occurs without fracture. B) The chip fractures at regular intervals. C) The material is brittle. D) The cutting speed is extremely low.

95. A discontinuous chip is typically associated with: A) Pure plastic deformation. B) No vibration. C) Fractures occurring periodically. D) Very ductile materials.

96. A Built‑Up Edge (BUE) forms due to: A) Low pressure and low temperature. B) High pressure and high temperature near the cutting edge. C) Excessive lubrication. D) Very low feed.

97. A BUE negatively affects surface quality because: A) It reduces chip thickness. B) It increases tool rigidity. C) It modifies the rake angle unpredictably. D) It eliminates friction.

98. The recommended way to avoid BUE formation is to: B) Reduce cutting speed. A) Increase cutting speed. C) Increase depth of cut. D) Reduce clearance angle.

99. Segmented or serrated chips are caused mainly by: A) Excessive lubrication. D) Material anisotropy. C) Very high ductility. B) Low cutting temperature.

100. Increasing feed generally causes the chip to become: A) Longer and thinner. B) Shorter and thinner. C) Thicker. D) Independent of feed.