14 Metal extrusion and metal drawing

1. What force drives the metal through the die in extrusion?. A. Tensile force. B. Compressive force. C. Shear force. D. Bending force.

2. The shape of the extruded product is determined by: A. The temperature of the container. B. The speed of the press. C. The geometry of the die orifice. D. The lubrication used.

3. A key advantage of extrusion is that it: B. Produces only hollow parts. A. Allows large deformations without fracture. C. Requires no tooling. D. Cannot produce complex shapes.

4. Metal drawing differs from extrusion because it: A. Uses compression instead of tension. D. Applies a tensile force to pull the material through the die. C. Cannot produce long products. B. Always requires heating.

5. A common difficulty in drawing is: A. Excessive compression. B. Threading the stock through the die. C. Producing hollow sections. D. Maintaining constant temperature.

6. Wire drawing involves: B. A single reduction stage. A. Multiple consecutive reduction stages. C. Only hot working. D. No risk of fracture.

7. Gold threads used by the Egyptians were produced using: A. Casting and machining. D. Forging, rolling, and drawing. C. Extrusion only. B. Powder metallurgy.

8. Viking-era drawing tools were typically: A. Hydraulic presses. C. Hole‑pattern plates made of stone or metal. B. Steam‑powered dies. D. Water‑cooled rolling mills.

9. During the Renaissance, drawing technology improved through the use of: A. Electric motors. B. Water‑powered wheels and winches. C. Hydraulic cylinders. D. Gas‑powered engines.

10. The first hydraulic press for metal extrusion was developed by: A. Abraham Rees. B. Biringuccio. C. Thomas Burr. D. Leonardo da Vinci.

11. In direct extrusion, the billet is pushed through the die by: A. A tensile force. B. A rotating wheel. C. A ram or plunger. D. A hydraulic cutter.

12. The die land in extrusion is used to: A. Increase friction. B. Achieve final dimensional accuracy. C. Cool the extrudate. D. Remove oxide layers.

13. The relief angle at the die exit helps prevent: A. Excessive elongation. B. Elastic recovery. C. Rubbing between the part and the die. D. Surface oxidation.

14. Extrusion is considered semi‑continuous because: A. It produces only short parts. B. The billet limits the maximum product length. C. The die must be replaced after each pass. D. The ram moves intermittently.

15. A major limitation of hot extrusion is: A. Low ductility of the billet. B. Excessive hardness of the dies. D. Faster die wear due to high temperature. C. Inability to extrude hollow shapes.

16. Aluminum is highly suitable for extrusion because: C. It has a very high melting point. B. It requires extremely high forces. A. It has good ductility and low tool wear. D. It cannot oxidize.

17. Steel and stainless steel extrusion requires: A. Low forces and low temperatures. B. High forces and high temperatures. C. No lubrication. D. Only cold working.

18. The dead zone in extrusion refers to: B. A region where material flows faster. A. A stationary region where material does not flow. C. A zone of maximum temperature. D. A region of high lubrication.

19. Poor lubrication during extrusion tends to: A. Eliminate the dead zone. D. Create a funnel‑shaped dead zone. C. Reduce friction to zero. B. Increase billet ductility.

20. The burnishing effect in extrusion produces: A. A rough surface. B. A matte finish. C. A bright, polished surface. D. A porous surface.

21. The flow pattern shown in Figure 14.7c is undesirable because it leads to: A. Excessive elongation. B. A pipe defect. C. Surface oxidation. D. Die clogging.

22. Hot extrusion typically heats the billet to: A. 10–20% of melting point. B. 30–40% of melting point. C. 50–75% of melting point. D. 90–100% of melting point.

23. Cold extrusion is commonly used for: A. Producing long hollow tubes. B. Net‑shape or near‑net‑shape discrete parts. C. High‑temperature alloys only. D. Thick plates.

24. A key advantage of cold extrusion is: A. Increased oxidation. B. Poor dimensional accuracy. D. Improved surface finish. C. No strain hardening.

25. Direct extrusion is characterized by: C. Material flowing opposite to the applied force. B. No friction between billet and container. A. Material flow in the same direction as the applied force. D. Use of a rotating die.

26. Indirect extrusion reduces required force because: A. The billet is heated more. B. The die is stationary. D. There is no relative motion between billet and container. C. The ram moves faster.

27. Lateral extrusion involves material flow: A. Parallel to the applied force. B. Opposite to the applied force. C. Perpendicular to the applied force. D. In a circular pattern.

28. Combination extrusion is commonly used in: A. Hot rolling. B. Impact extrusion. C. Tube welding. D. Powder metallurgy.

29. Hydrostatic extrusion uses: A. Air pressure. B. A solid ram only. C. A pressurized fluid to transmit force. D. A rotating screw.

30. Impact extrusion is characterized by: A. Very slow ram movement. B. High‑speed deformation at room temperature. C. Use of molten metal. D. No need for a die.

31. Square dies with 90° angles are typically used for: B. Stainless steels. A. Aluminum and other ductile non‑ferrous materials. C. Cast iron. D. Titanium alloys.

32. Dead‑metal zones in square dies help create: A. Higher friction. B. A bright burnished surface. C. A rough matte finish. D. A hollow cross section.

33. Ferrous materials require dies with: A. Larger die angles. D. Smaller die angles. C. No die angle. B. Hollow mandrels.

34. In tube extrusion from a solid billet, the hole is created by: B. A rotating cutter. A. A mandrel integrated into the ram. C. A secondary die. D. A cooling jet.

35. Spider dies are suitable only for: A. Steel. B. Titanium. C. Aluminum and some of its alloys. D. Nickel alloys.

36. In spider dies, the material re‑joins in the: A. Mandrel cavity. B. Weld chamber. C. Cooling zone. D. Die land.

37. Lubricants cannot be used in spider‑die extrusion because: A. They react with steel. D. They prevent proper welding of the strands. C. They increase die wear. B. They cool the billet too quickly.

38. Hollow cross‑section dies divide the metal flow into: A. Two strands. B. Three strands. C. Four or more strands. D. A single continuous strand.

39. In hollow‑section extrusion, the strands weld together when: A. The billet cools. B. Pressure increases in the second die. C. The mandrel retracts. D. Lubricant is applied.

40. Modern die design for hollow profiles is mainly performed using: A. Trial‑and‑error. B. Manual sketches. C. FEM simulation software. D. Casting molds.

41. The most common extrusion press configuration is: A. Vertical mechanical press. B. Horizontal hydraulic press. C. Inclined pneumatic press. D. Rotational screw press.

42. The moving crosshead in a hydraulic press allows: B. Cooling of the billet. A. Separation from the die stack to shear the billet butt. C. Rotation of the die. D. Lubrication of the mandrel.

43. Tie rods in an extrusion press ensure: A. Faster extrusion. B. Correct alignment of ram and container. C. Better cooling. D. Lower friction.

44. Vertical hydraulic presses are mainly used for: A. Hot extrusion. D. Cold extrusion. C. Tube extrusion only. B. Impact extrusion.

45. Mechanical presses are preferred for: B. Large hollow profiles. A. Small components produced in large batches. C. Thick steel billets. D. High‑temperature alloys.

46. Aluminum billets are typically heated to: A. 100–200 °C. B. 250–300 °C. C. 430–500 °C. D. 700–800 °C.

47. Stretching after extrusion is used to: A. Increase hardness. B. Remove surface oxides. D. Correct straightness and eliminate twisting. C. Reduce cross‑sectional area.

48. Aging treatment in aluminum extrusion improves: A. Ductility. B. Hardness through precipitation. C. Electrical conductivity. D. Surface roughness.

49. Surface cracking in extrusion is mainly caused by: B. Low extrusion speed. A. Excessive surface temperature. C. High lubrication. D. Small die angles.

50. Pick‑ups on extruded surfaces are caused by: A. Air bubbles. B. Embedded surface oxides torn from the billet. C. Excessive lubrication. D. Mandrel misalignment.

51. In metal drawing, the cross section is reduced by applying: B. Compressive force. A. Tensile force. C. Shear force. D. Bending force.

52. Although a tensile force is applied, the stresses inside the die are mainly: A. Tensile. B. Shear. C. Compressive. D. Torsional.

53. Wire drawing refers specifically to drawing: A. Short rods. B. Thick bars. D. Products hundreds of meters long. C. Hollow tubes.

54. Drawing force increases when: A. Reduction of area decreases. B. Friction decreases. C. Final cross‑section area increases. D. Die angle increases.

55. Increasing the die angle generally causes the drawing force to: A. Increase. B. Decrease. C. Remain constant. D. Become unpredictable.

56. The theoretical maximum reduction of area in drawing is: A. 25%. B. 45%. C. 63%. D. 80%.

57. In practice, typical reductions for fine wires are: A. 5–10%. B. 15–25%. C. 40–50%. D. 60–70%.

58. Drawing is usually performed as a: B. Hot process. A. Cold process. C. Semi‑solid process. D. Casting process.

59. The approach angle in drawing dies typically ranges from: A. 1° to 3°. B. 6° to 15°. C. 20° to 30°. D. 45° to 60°.

60. Drawing dies are commonly made of: A. Aluminum alloys. B. Copper. C. Tool steels and carbides. D. Stainless steel sheets.

61. Lubrication in drawing is important because it: A. Increases friction. B. Reduces die life. D. Reduces force and temperature. C. Prevents metal flow.

62. Dry lubrication involves: A. Immersing the die in oil. B. Coating the material surface with lubricant. C. Cooling the die with water. D. Using only metallic lubricants.

63. Tube drawing cannot: A. Reduce tube thickness. B. Improve surface finish. C. Produce tubes from a solid rod. D. Use mandrels.

64. Using a mandrel in tube drawing allows: A. Faster drawing speeds. B. Better control of inner diameter and wall thickness. C. Elimination of lubrication. D. Production of solid bars.

65. A draw bench typically uses: B. Multiple dies in series. A. A single die with hydraulic or chain‑drive pulling. C. Rotating drums for winding. D. A mandrel fixed to the ram.

66. Draw benches are commonly used for bars with diameters: A. Less than 5 mm. B. 5–10 mm. C. 10–20 mm. D. Greater than 20 mm.

67. Wire drawing benches (bull blocks) use: A. Stationary dies only. B. Rotating drums to pull and wind the wire. C. Hydraulic presses. D. Mandrels inside the wire.

68. Proper control of drum speeds in wire drawing is needed to avoid: B. Excessive lubrication. A. Yielding out of the die. C. Reduction of friction. D. Increase in die angle.

69. Seams in drawn products are: A. Internal voids. B. Longitudinal surface scratches. C. Cracks caused by overheating. D. Mandrel marks.

70. Residual stresses in drawn products may lead to: A. Improved ductility. B. Reduced hardness. C. Cracking, corrosion, or warping. D. Increased electrical conductivity.