Written Final (Workshop) PDF

Electric Arc Welding 1. What is the primary medium that allows electric arc formation? a) Water b) Gas c) Plasma d) Air 2. Which component protects the weld area from atmospheric contamination in shielded metal arc welding? a) Electrode tip b) Flux coverin...

Electric Arc Welding 1. What is the primary medium that allows electric arc formation? a) Water b) Gas c) Plasma d) Air 2. Which component protects the weld area from atmospheric contamination in shielded metal arc welding? a) Electrode tip b) Flux covering c) Power supply d) Welding clamp CNC Machines 3. CNC stands for: a) Centralized Numerical Control b) Computer Numerical Control c) Computational Network Control d) Complex Network Control 4. Which code specifies the tool number in CNC programming? a) G b) M c) T d) F Drilling Machine 5. What is the most common type of drill used in drilling operations? a) Flat drill b) Twist drill c) Spade drill d) Auger drill 6. What is the primary function of a reamer in drilling operations? a) To create a new hole b) To remove burrs c) To smooth and enlarge an existing hole d) To mark the center of a hole Gas Welding 7. Which gas combination is primarily used in oxy-acetylene welding? a) Oxygen and nitrogen b) Acetylene and propane c) Oxygen and acetylene d) Acetylene and argon 8. A neutral flame in gas welding has which of the following characteristics? a) Excess oxygen b) Excess acetylene c) Equal oxygen and acetylene d) No oxygen Lathe Machine 9. What is the primary operation performed by a lathe machine? a) Grinding b) Turning c) Welding d) Milling 10. Which cutting operation on a lathe involves feeding the tool radially inward? a) Contour turning b) Facing c) Threading d) Parting Milling Machines 11. Which of the following is the primary cutting tool used in milling operations? a) Drill bit b) Milling cutter c) Lathe tool d) Grinding wheel 12. What is the difference between up milling and down milling? a) Direction of cutter rotation relative to feed motion b) Type of cutter used c) Speed of operation d) Depth of cut Sheet Metal Operations 13. What is the first step in sheet metal fabrication? a) Welding b) Cutting c) Marking d) Bending 14. Which bending operation is most commonly used to form a U-shaped profile? a) V-bending b) Stretch flanging c) U-bending d) Curling Safety and First Aid 15. What should be done immediately if a gas cylinder leaks? a) Apply oil to the threads to stop the leak b) Move the cylinder to an isolated area c) Light a flame to burn off excess gas d) Close the cylinder valve and use it later 16. Why should loose clothing not be worn in a workshop? a) It is uncomfortable b) It can get caught in machinery c) It stains easily d) It can cause heat exhaustion Welding Techniques 17. Forehand welding is also known as: a) Forward welding b) Rippled welding c) Backhand welding d) Reverse welding 18. Which type of flame is generally used for welding mild steel? a) Oxidizing flame b) Neutral flame c) Carburizing flame d) Reducing flame Welding Equipment 19. Which part of the oxy-acetylene welding setup mixes oxygen and fuel gas? a) Welding torch b) Regulator c) Nozzle d) Cylinder 20. What material is typically used for welding nozzles due to high thermal conductivity? a) Aluminum b) Stainless steel c) Copper d) Titanium CNC Programming 21. What does the code "G90" specify in CNC programming? a) Incremental positioning b) Absolute positioning c) Circular interpolation clockwise d) Tool change 22. Which axis typically represents the vertical motion in a CNC machine? a) X b) Y c) Z d) W Machining Calculations 23. How is material removal rate (MRR) calculated in a turning operation? a) MRR= 𝑣 × 𝑓 × 𝑑 b) MRR= 𝜋𝑟 2 𝑡 𝑣 c) MRR= 𝑓×𝑑 d) MRR= 𝑓 2 𝑣 24. If the spindle speed is 1200 RPM and the cutting speed is 60 m/min, what is the diameter of the workpiece? a) 15 mm b) 20 mm c) 25 mm d) 30 mm Lathe Machine Operations 25. What is the primary function of a chuck in a lathe machine? a) Hold the cutting tool b) Drive the spindle c) Hold the workpiece d) Adjust feed rate 26. Which operation on a lathe creates threads on a cylindrical surface? a) Parting b) Facing c) Threading d) Drilling 27. What cutting tool orientation is used to cut from right to left? a) Left-hand tool b) Right-hand tool c) Neutral tool d) Chamfering tool Welding Techniques 28. Which welding technique is best suited for thin metals? a) Backhand welding b) Ripple welding c) Forehand welding d) Vertical welding 29. What is the ideal flame for welding copper-zinc alloys? a) Neutral flame b) Oxidizing flame c) Carburizing flame d) Reducing flame CNC Machines and Programming 30. What does "M03" command in CNC programming indicate? a) Program stop b) Spindle stop c) Spindle on clockwise d) Spindle speed adjustment 31. What is the purpose of a coolant in CNC machining? a) To clean the workpiece b) To lubricate the cutting tool c) To reduce heat and improve cutting performance d) To improve the finish of the workpiece Drilling Machine Operations 32. What is the purpose of countersinking in drilling? a) Create a hole with a flat bottom b) Create a conical hole for screw heads c) Increase hole diameter d) Smoothen hole edges 33. What is the cutting tool called in a reaming operation? a) Drill bit b) Tap c) Reamer d) Boring bar 34. Which drilling machine is best for heavy and large workpieces? a) Portable drilling machine b) Bench drilling machine c) Radial drilling machine d) CNC drilling machine Gas Metal Arc Welding (MIG) 35. Which shielding gas produces the cleanest weld in MIG welding? a) Argon b) Carbon dioxide c) Helium d) Oxygen 36. In spray transfer mode of MIG welding, what is the nature of the molten metal droplets? a) Large and slow b) Small and rapid c) Large and intermittent d) Tiny and irregular 37. Which transfer method is ideal for thin sheets in MIG welding? a) Spray transfer b) Globular transfer c) Short-circuiting transfer d) Arc transfer Gas Tungsten Arc Welding (TIG) 38. In TIG welding, which type of electrode is used? a) Consumable electrode b) Non-consumable tungsten electrode c) Graphite electrode d) Copper-coated electrode 39. What is the most common shielding gas for TIG welding? a) Argon b) Carbon dioxide c) Nitrogen d) Helium 40. What is one major limitation of TIG welding? a) High heat input b) Requires low skill c) High deposition rate d) Costly for welding thick sections Sheet Metal Operations 41. What is the purpose of blanking in sheet metal fabrication? a) To smooth the sheet b) To cut out a desired shape c) To bend the sheet d) To mark reference points 42. What is the common tool used for marking sheet metal? a) Hammer b) Scriber c) File d) Clamp 43. Which bending operation is used for creating tubular forms? a) Air bending b) Corrugating c) Offset bending d) Tube forming Milling Process 44. Which milling process is used to create rectangular slots? a) Face milling b) Slot milling c) Angular milling d) End milling 45. What is the distinguishing feature of a horizontal milling machine? a) It uses vertical cutters b) The spindle is mounted horizontally c) It is only for soft metals d) It has fewer parts than vertical milling machines 46. Which milling method provides a better surface finish for soft materials? a) Up milling b) Down milling c) Conventional milling d) Straddle milling Welding Safety 47. What is the recommended safety gear for protecting eyes during welding? a) Regular glasses b) Welding helmet c) Face mask d) Sunglasses 48. What is the primary hazard of TIG welding aluminum alloys? a) Fumes b) Arc-eye c) Electrical shock d) Melting of tungsten 49. Why is it essential to ground the arc welding equipment? a) To improve weld strength b) To avoid electric shock c) To enhance weld speed d) To reduce heat distortion Advantages of Electric Arc Welding 50. Which of the following is NOT an advantage of electric arc welding? a) Stronger welds than gas welding b) Portable equipment available c) Easy to weld thin sheets d) Faster than gas welding 51. Which statement best describes an advantage of electric arc welding? a) It is ideal for welding non-metal materials. b) It can weld almost all types of metals and alloys. c) It requires no additional equipment. d) It produces no heat during welding. Disadvantages of Electric Arc Welding 52. Why is electric arc welding less suitable for thin sheets? a) It requires high skill levels. b) It produces excessive heat. c) It cannot generate a stable arc. d) It is slower than gas welding. 53. What is a common disadvantage of electric arc welding? a) Equipment is immobile. b) It is not suitable for high-strength welds. c) The weight of components increases after welding. d) It cannot be automated. Advantages of CNC Machines 54. What is one of the greatest advantages of CNC machines? a) They are inexpensive to install. b) They do not require maintenance. c) They allow for batch production with high accuracy. d) They rely entirely on manual operation. 55. Which of the following is true about CNC machines? a) They reduce operator skill requirements. b) They operate without software updates. c) They cannot run continuously. d) They require manual setup for every operation. Disadvantages of CNC Machines 56. Why might CNC machines lead to unemployment? a) They require minimal operator skills. b) They are unreliable. c) They are difficult to program. d) They have limited application in production. 57. Which is a disadvantage of CNC machines compared to manual machines? a) They require more operator intervention. b) They are more expensive to purchase. c) They are less precise. d) They cannot produce complex designs. Advantages of TIG Welding 58. Which of the following is a key advantage of TIG welding? a) High deposition rate b) Superior quality welds c) Requires no shielding gas d) Faster welding speeds than MIG welding 59. What makes TIG welding suitable for thin materials? a) High deposition rates b) Precise heat control c) Lack of shielding gas d) Large arc size Disadvantages of TIG Welding 60. Why is TIG welding less commonly used for thick materials? a) It produces weak welds. b) It requires excessive shielding gas. c) It is slower and more costly. d) It creates a lot of spatter. 61. What is one limitation of TIG welding? a) It cannot weld stainless steel. b) It is limited to horizontal welding positions. c) It requires a higher skill level than MIG welding. d) It only uses consumable electrodes. Advantages of Gas Welding 62. Why is gas welding considered versatile? a) It is limited to one type of metal. b) It can be used for pre-heating and brazing. c) It does not require any safety equipment. d) It requires only one gas for operation. 63. What is the benefit of oxy-acetylene gas welding? a) It uses low temperatures. b) The welder can control the temperature of the weld zone. c) It is faster than electric arc welding. d) It requires no filler material. Disadvantages of Gas Welding 64. Which is a common disadvantage of gas welding? a) It has high equipment costs. b) It is slow compared to arc welding. c) It produces weak welds. d) It cannot weld ferrous metals. 65. Why is skill important in gas welding? a) It requires exact pressure adjustments. b) The process is highly automated. c) The filler material needs constant replacement. d) Welders need to manipulate the torch and filler rod effectively. Advantages of MIG Welding 66. What is one of the primary benefits of MIG welding? a) High-quality welds with minimal cleaning b) Suitable for all types of materials without adjustments c) No shielding gas required d) Highly portable equipment 67. Which factor contributes to the efficiency of MIG welding? a) High welding speeds and continuous operation b) Use of non-consumable electrodes c) High heat distortion on thin materials d) Complex setup procedures Disadvantages of MIG Welding 68. Why is MIG welding less effective for outdoor applications? a) It uses a weak arc. b) Shielding gas can be disrupted by wind. c) It cannot weld ferrous metals. d) The process is too slow. 69. Which of the following is a limitation of MIG welding? a) High skill level required b) Limited to manual operation c) Equipment is more expensive than traditional stick welding d) Cannot use consumable electrodes Advantages of Resistance Spot Welding 70. Which is an advantage of resistance spot welding? a) Adaptability to automation for high-rate production b) Ability to weld very thick plates c) Excellent tensile strength of joints d) No requirement for power supply 71. Why is resistance spot welding commonly used for sheet metals? a) It uses minimal heat b) It provides high welding speeds and accuracy c) It does not require electrodes d) It requires no maintenance Disadvantages of Resistance Spot Welding 72. Which is a disadvantage of resistance spot welding? a) Low speed of operation b) Adds weight to the final product c) High material wastage d) Requires highly skilled operators 73. What is a common limitation of spot welding? a) It cannot weld non-ferrous metals. b) It requires significant power and adds unfavorable line power demands. c) It creates welds with high tensile and fatigue strength. d) It cannot join two sheets. Advantages of Plasma Arc Welding (PAW) 74. Why is plasma arc welding suitable for precise applications? a) It has excellent heat focus and temperature control. b) It uses consumable electrodes. c) It operates without shielding gas. d) It generates no heat distortion. 75. What makes plasma arc welding a versatile process? a) It can cut and weld with the same setup. b) It eliminates the need for automation. c) It avoids arc wandering completely. d) It operates without external power. Disadvantages of Plasma Arc Welding (PAW) 76. What is a drawback of plasma arc welding compared to other welding methods? a) It generates weak joints. b) It cannot weld thin metals. c) Equipment cost is significantly higher. d) It cannot produce automated welds. 77. Why is plasma arc welding not ideal for beginners? a) It is too slow for efficient production. b) It requires high skill levels to maintain precision. c) It cannot be used in automated processes. d) It only works with consumable electrodes. Advantages of Vertical Milling Machines 78. Which is a significant advantage of vertical milling machines? a) Easy access for observation during operation b) Suitable for high-speed turning operations c) Requires no lubrication during operation d) More compact than lathes for large materials 79. What makes vertical milling machines popular for workshops? a) Simplicity in operation and adaptability to a variety of jobs b) They operate faster than horizontal milling machines c) They are inexpensive to maintain d) They require no specialized tools Disadvantages of Vertical Milling Machines 80. What is one drawback of vertical milling machines? a) Inability to perform end milling b) Limited capacity for heavy-duty operations c) Cannot perform operations on small workpieces d) They are unable to use multiple cutters 81. Why might vertical milling machines be less efficient for large-scale production? a) Their spindles are not adaptable. b) They have slower speeds. c) Their design limits workpiece size and load. d) They require excessive lubrication. Advantages of Sheet Metal Operations 82. What is the primary advantage of using sheet metal operations? a) The processes are inexpensive and versatile. b) They require specialized, high-cost machines. c) Sheet metal cannot be used for complex designs. d) It only works for small-scale production. 83. Why is sheet metal fabrication commonly used in industries? a) It eliminates the need for automation. b) It allows for the mass production of lightweight components. c) It reduces the overall strength of the product. d) It is limited to small workpieces. Disadvantages of Sheet Metal Operations 84. What is a common limitation of sheet metal operations? a) Requires advanced CNC technology. b) Limited strength in formed products compared to solid metal. c) Inability to cut or bend materials. d) Does not allow high-speed production. 85. Which aspect makes sheet metal forming less suitable for very thick materials? a) High material waste b) Requires excessive force and specialized tools c) Poor surface finish d) Limited marking capabilities Advantages of Safety Equipment and Practices 86. Why is wearing goggles essential in a workshop? a) They provide aesthetic value. b) They protect eyes from flying chips and debris. c) They reduce operator fatigue. d) They improve the precision of operations. 87. What is the purpose of a fire extinguisher rated for "A, B, C" approval? a) Suitable for various types of fires, including electrical, gas, and standard combustibles. b) Reduces heat distortion during operations. c) Prevents chemical reactions in welding processes. d) Eliminates the need for smoke detectors. Disadvantages of Ignoring Safety Practices 88. What is a common consequence of wearing loose clothing in workshops? a) Reduced productivity b) Increased risk of getting caught in machinery c) Poor communication with team members d) Reduced efficiency in manual operations 89. Why is it important to ground arc welding equipment? a) To improve weld appearance b) To avoid electric shock hazards c) To reduce the heat generated during welding d) To enhance arc stability Advantages of Gas Welding 90. Which is a notable advantage of gas welding? a) Precise temperature control allows for welding a variety of metals. b) No training is required for operators. c) It is faster than plasma arc welding. d) It is completely automated. 91. What makes gas welding adaptable for pre-heating processes? a) High portability and temperature control. b) Elimination of additional gases. c) Low skill requirement for operation. d) Extremely rapid operation speed. Disadvantages of Gas Welding 92. What is the limitation of gas welding compared to electric arc welding? a) It cannot use filler materials. b) It produces weak welds. c) It is slower and requires more skill. d) It is unsuitable for small projects. 93. Why might gas welding be considered hazardous? a) It involves low-intensity flames. b) Acetylene gas is unstable under high pressure. c) It uses non-combustible gases. d) The process eliminates the need for shielding. Advantages of Spot Welding 94. What makes spot welding efficient for automotive industries? a) It allows rapid, high-strength sheet metal joints. b) It reduces overall equipment costs. c) It does not require electricity. d) It eliminates the need for any pressure. 95. What is the benefit of automation in spot welding? a) Higher weld quality with minimal operator intervention. b) Reduction in power consumption. c) Elimination of all weld defects. d) Improved tensile strength across all joint types. Disadvantages of Spot Welding 96. Why does spot welding increase material costs? a) It requires extra reinforcement materials. b) It uses consumable electrodes. c) It adds weight due to overlapping joints. d) It damages adjacent materials. 97. What is a limitation of resistance welding on joints? a) It weakens the base material. b) It cannot weld multiple layers simultaneously. c) It has low tensile and fatigue strength. d) It produces excessive spatter. General Workshop Practices 98. Why is regular maintenance of equipment essential in workshops? a) To increase the operation time of tools. b) To prevent mechanical accidents and ensure reliability. c) To eliminate the need for safety procedures. d) To reduce operator training requirements. 99. What is a basic rule for operating machines safely? a) Always rush to meet deadlines. b) Leave machines running unattended for efficiency. c) Understand machine operations before starting work. d) Test machines without securing the workpiece. 100. Why should compressed air is not used to clean machines? a) It may damage the machine's bearings and endanger eyes. b) It increases the power consumption of machines. c) It can leave oil residues on the machine. d) It is not effective for cleaning purposes. CNC Machines and Programming 101. Which code specifies the end of a program in CNC? a) G01 b) M30 c) T01 d) G90 102. What is the primary purpose of a G-code in CNC programming? a) To define coolant settings b) To establish operating conditions c) To specify tool numbers d) To control spindle speed  103. What axis is typically used for horizontal movement in CNC machines? a) Z-axis b) W-axis c) Y-axis d) X-axis 104. What does the G02 command signify in CNC? a) Circular interpolation, clockwise b) Circular interpolation, counterclockwise c) Linear interpolation d) Absolute positioning 105. What parameter is controlled by the F-code in CNC programming? a) Spindle speed b) Feed rate c) Tool change d) Coolant on/off 106. How is incremental positioning defined in CNC? a) Each position is based on the absolute origin. b) Each position is based on the last specified position. c) Each position is set manually. d) Each position is a predefined absolute value. Electric Arc Welding 107. What is the purpose of flux in arc welding? a) To cool the electrode b) To shield the arc from atmospheric contamination. c) To increase the welding speed d) To regulate the current flow 108. Which type of polarity in DC welding concentrates more heat on the base metal? a) Alternating current polarity b) Reverse polarity c) Straight polarity d) Balanced polarity 109. What is a typical application of DC reverse polarity welding? a) Welding thick metals b) Welding thin sheets c) Producing narrow, deep welds d) Joining cast iron  110. How is the arc initiated in shielded metal arc welding? a) By heating the electrode to its melting point b) By creating a high-pressure gas shield c) By striking the electrode against the workpiece, like striking a match d) By preheating the workpiece surface Gas Welding 111. What is the primary purpose of a neutral flame in oxy-acetylene welding? a) To oxidize the base metal b) To add carbon to the weld c) To ensure no chemical change in the metal d) To increase the welding speed 112. Which component of the welding setup mixes oxygen and acetylene? a) Welding nozzle b) Mixing chamber in the welding torch c) Regulator d) Hose valve 113. In gas welding, which flame is used for brazing operations? a) Neutral flame b) Carburizing flame c) Oxidizing flame d) Combustion flame 114. Which gas is commonly used with acetylene for oxy-fuel welding? a) Carbon dioxide b) Nitrogen c) Oxygen d) Argon Drilling Machine and Operations 115. What is the primary purpose of a center punch in drilling? a) To enlarge a drilled hole b) To smooth the edges of a hole c) To mark the center location for drilling d) To create threads in a hole 116. Which type of drilling machine is used for precision drilling in small workshops? a) Portable drilling machine b) Radial drilling machine c) Bench drilling machine d) CNC drilling machine  117. In a radial drilling machine, how is the drill positioned over the workpiece? a) By tilting the table b) By moving the radial arm c) By rotating the spindle d) By shifting the workpiece manually 118. What operation is performed to smooth the surface of an already drilled hole? a) Countersinking b) Counterboring c) Reaming d) Boring Machining Safety 119. What is the primary reason for removing loose jewelry before using a lathe? a) It interferes with the cutting operation. b) It may get caught in spinning machinery. c) It conducts electricity. d) It distracts the operator. 120. Which of the following is NOT a proper workshop safety practice? a) Wearing goggles at all times b) Using compressed air to clean machines c) Removing ties and scarves before working d) Ensuring proper grounding of electrical equipment 121. Why is it dangerous to measure a part while it is rotating on a lathe? a) It produces an inaccurate measurement. b) It may damage the measuring tool. c) The measuring tool may get pulled into the spinning part. d) It slows down the operation. Lathe Machines 122. What is the primary motion of a lathe machine? a) Rotation of the workpiece b) Linear movement of the tool c) Oscillation of the tool d) Stationary positioning of the workpiece 123. Which operation on a lathe is used to cut off apart from the workpiece? a) Chamfering b) Facing c) Parting d) Contour turning  124. What is the main purpose of the tailstock on a lathe? a) To hold the cutting tool b) To rotate the workpiece c) To support the workpiece from one end d) To adjust spindle speed 125. How is the cutting speed (v) calculated for a lathe operation? 𝜋×𝐷×𝑁 a) v= 1000 𝐷 b) v= 𝑁 𝑁2 c) v= 𝐷 𝐷 d) v= 2 126. What is the function of the lead screw on a lathe machine? a) To rotate the workpiece b) To change the spindle speed c) To cut threads d) To adjust the tailstock Milling Machines 127. What operation in milling creates a flat surface on the workpiece? a) End milling b) Face milling c) Angular milling d) Slot milling 128. Which milling operation is used to create keyways or pockets? a) Form milling b) Angular milling c) Slot milling d) End milling 129. What is a key feature of down milling? a) The cutter rotates opposite to the feed direction. b) The chips become progressively thicker. c) The cutter rotates in the same direction as the feed. d) It is used for hard materials. 130. Which component supports the free end of the arbor in a horizontal milling machine? a) Saddle b) Yoke c) Knee d) Column  131. What is the purpose of a “form milling cutter”? a) To create curved surfaces or special contours b) To cut straight slots c) To create angular surfaces d) To remove burrs Drilling Operations 132. What type of drill is used for producing holes with a flat bottom? a) Twist drill b) Spade drill c) Flat drill d) Auger drill 133. In counterboring, what happens to the hole? a) It is made deeper. b) It is widened at one end. c) It is smoothed along its walls. d) It is threaded internally. 134. What is the ideal cutting speed for tapping operations compared to drilling? a) Half the drilling speed b) Double the drilling speed c) Same as the drilling speed d) One-third the drilling speed 135. What type of machine is used for heavy-duty drilling operations on large workpieces? a) Bench drilling machine b) Portable drilling machine c) Radial drilling machine d) Sensitive drilling machine Safety Practices 136. Why should hair be tied back when working in a workshop? a) To prevent it from falling into the workspace b) To avoid distractions during operations c) To prevent it from being caught in rotating machinery d) To maintain cleanliness in the workspace 137. Why should you never touch a running machine with your hands? a) It slows down the operation. b) It may damage the machine’s components. c) It poses a high risk of injury or amputation. d) It reduces the machine’s efficiency.  138. What is the primary reason for ensuring proper earthing in arc welding equipment? a) To stabilize the arc b) To improve welding speed c) To avoid electric shock d) To reduce current consumption 139. Why is it important to clean machines after use? a) To reduce maintenance costs b) To ensure they function properly for the next operation c) To save time during future use d) To reduce wear on the tool Plasma Arc Welding 140. How does plasma arc welding differ from gas tungsten arc welding (GTAW)? a) It uses a consumable electrode. b) It focuses on the arc with higher velocity and temperature. c) It does not require shielding gas. d) It uses alternating current only. 141. Which inert gas is commonly used in plasma arc welding? a) Oxygen b) Helium c) Nitrogen d) Carbon dioxide 142. What is the approximate maximum temperature achieved in plasma arc welding? a) 10,000°C b) 17,000°C c) 25,000°C d) 35,000°C General Welding Processes 143. What is the primary difference between fusion welding and solid-state welding? a) Fusion welding involves heating materials until they melt, while solid-state welding does not. b) Solid-state welding uses shielding gas, while fusion welding does not. c) Fusion welding uses friction, while solid-state welding uses electric arcs. d) Fusion welding involves non-metallic materials, while solid-state welding is only for metals. 144. Which of the following is a solid-state welding process? a) Gas metal arc welding (GMAW) b) Friction welding c) Submerged arc welding (SAW) d) Plasma welding  145. What is the primary purpose of a shielding gas in welding? a) To cool the weld area b) To protect the weld pool from atmospheric contamination c) To increase welding speed d) To adjust electrode melting rate Miscellaneous Topics 146. What does the term “machining time” depend on in drilling operations? a) Length of the hole, feed, and speed b) Diameter of the drill only c) Depth of cut only d) Material hardness only 147. What material is commonly used for high-speed drills? a) Low-carbon steel b) High-speed steel (HSS) c) Cast iron d) Aluminum 148. Which safety device should always be present in a workshop to deal with fire hazards? a) Fire blanket b) Fire extinguisher c) Welding curtain d) Cooling fan 149. Why is it essential to keep welding hoses away from sparks or heat? a) To prevent chemical reactions b) To avoid leaks and potential fires c) To improve hose flexibility d) To increase welding speed 150. In welding, what is the primary cause of porosity in welds? a) Excessive heat input b) Trapped gases during solidification c) Improper shielding gas flow d) Use of wrong electrode Lathe Machine 151. What is the primary function of a lathe machine? a) Milling materials b) Drilling holes c) Turning cylindrical workpieces d) Welding metal parts 152. Which part of the lathe machine holds the workpiece in place? a) Tailstock b) Headstock c) Chuck d) Carriage Answer: c) Chuck Milling Machine 153. What type of machine is used for cutting flat or contoured surfaces in materials? a) Lathe machine b) Drilling machine c) Milling machine d) Grinding machine 154. Which of the following is true about vertical milling machines? a) The spindle is mounted horizontally b) The table can only move vertically c) They are used for cutting larger workpieces d) The spindle is mounted vertically Drilling Machine 155. What is the main purpose of a drilling machine? a) To cut external threads b) To remove material using rotating tools c) To create holes in materials d) To mill flat surfaces 156. Which type of drilling machine is commonly used for heavy-duty operations? a) Radial drilling machine b) Bench drilling machine c) Portable drilling machine d) CNC drilling machine CNC Machine 157. What does CNC stand for? a) Computer Numerical Control b) Computer Network Control c) Central Numerical Control d) Common Numeric Control 158. Which of the following is NOT a type of CNC machine? a) CNC lathe b) CNC milling machine c) CNC plasma cutter d) CNC belt sander Grinding Machine 159. Which machine is primarily used to smooth and finish the surface of workpieces? a) Lathe machine b) Milling machine c) Grinding machine d) Drilling machine 160. What type of grinding machine is commonly used for surface grinding operations? a) Universal grinder b) Surface grinder c) Cylindrical grinder d) Bench grinder Welding Machines 161. Which of the following is used for electric arc welding? a) Stick welding machine b) Plasma cutter c) CNC lathe d) Milling machine 162. What is the primary purpose of a TIG welding machine? a) To perform high-speed welding of thick metals b) To weld using a non-consumable tungsten electrode c) To create circular welds d) To cut metals using high pressure Plasma Cutting Machine 163. What is the main function of a plasma cutting machine? a) To weld two metal pieces together b) To cut metal using a high-velocity stream of ionized gas c) To grind surfaces to smoothness d) To drill holes in materials 164. Which of the following is a major advantage of plasma cutting? a) It produces minimal heat distortion b) It can cut only ferrous metals c) It requires no power supply d) It is slower than other cutting methods Surface Finishing Machines 165. What is the purpose of a surface finishing machine? a) To weld materials b) To improve the surface quality of a material c) To cut large workpieces into smaller sections d) To drill holes in materials 166. Which machine is commonly used for polishing or smoothing workpieces? a) Lathe machine b) Surface grinder c) Milling machine d) CNC plasma cutter Shaping Machine 167. What is the main application of a shaping machine? a) To perform precise grinding operations b) To cut and shape large workpieces c) To create cylindrical workpieces d) To make deep holes 168. What type of motion does a shaping machine use? a) Continuous rotary motion b) Reciprocating motion c) Linear feed motion d) Circular motion Hydraulic Press Brake 169. What is a hydraulic press brake primarily used for? a) Milling operations b) Bending sheet metal c) Turning cylindrical parts d) Cutting hard metals 170. Which machine component provides the force to bend materials in a hydraulic press brake? a) Electric motor b) Hydraulic piston c) Pneumatic compressor d) Gearbox Iron Worker Machine 171. What is the main function of an ironworker machine? a) To weld and join materials b) To cut and shape large pieces of metal c) To drill holes in metal sheets d) To perform surface finishing operations 172. Which of the following operations can be performed by an ironworker machine? a) Sheet metal punching b) Surface grinding c) Precision welding d) Cutting small rods only Band Saw 173. What does a band saw primarily used for? a) Turning workpieces into shapes b) Milling materials into thin layers c) Cutting materials into desired shapes or lengths d) Drilling holes in materials 174. Which feature of a band saw makes it suitable for cutting irregular shapes? a) Fixed cutting direction b) A rotating blade that moves in a continuous loop c) High spindle speed d) Use of abrasive materials Written Questions for CNC Programming 1. Basic Structure Write a basic CNC code to perform a linear interpolation from point X1.0,Y1.0 to X2.0,Y2.0 at a feed rate of 200 mm/min. Answer: G90 ; Absolute positioning G01 ; Linear interpolation X2.0 Y2.0 ; Move to X2.0, Y2.0 F200 ; Feed rate 200 mm/min 2. Rapid Positioning Write the CNC code to move the tool quickly to position X50,Y25,Z10 without cutting. Answer: G00 X50 Y25 Z10 ; Rapid move to X50, Y25, Z10 3. Absolute and Incremental Positioning a) Write a CNC code using absolute positioning (G90) to move to X40,Y40. b) Rewrite the same movement using incremental positioning (G91) if the current position is X20,Y20. Answers: a) G90 ; Absolute positioning X40 Y40 ; Move to X40, Y40 b) G91 ; Incremental positioning X20 Y20 ; Move 20 units from current position (X20, Y20)  4. Tool Change Write a CNC program to: o Start the spindle clockwise (M03) at 1000 RPM. o Perform a tool change to tool number 5. o Move the tool to X0,Y0. Answer: M03 S1000 ; Spindle clockwise at 1000 RPM T05 ; Tool change to Tool 5 G00 X0 Y0 ; Rapid move to X0, Y0 5. Drilling Cycle Write a CNC program to drill a hole at X20,Y30 with the following parameters: o Use G81 (drilling cycle) o Spindle speed: 800 RPM o Depth: 10 mm o Feed rate: 100 mm/min Answer: G81 ; Drilling cycle X20 Y30 ; Hole location Z-10 ; Drill to a depth of 10 mm F100 ; Feed rate of 100 mm/min S800 ; Spindle speed 800 RPM M03 ; Spindle on clockwise 6. Circular Interpolation Write a CNC code to create a clockwise circular arc from X10,Y10 to X20,Y20 with a radius of 15 mm. Answer: G02 ; Circular interpolation, clockwise X20 Y20 ; End point of the arc R15 ; Radius of 15 mm  7. Subprograms Write a CNC program to use a subprogram: o The main program moves the tool to X0,Y0. o The subprogram (O100) performs a rectangular pattern at X20,Y20,X20,Y40,X40,Y40, and X40,Y20. Answer: Main Program: G00 X0 Y0 ; Rapid move to X0, Y0 M98 P100 ; Call subprogram O100 M30 ; End of program Subprogram (O100): O100 ; Subprogram start G00 X20 Y20 ; Move to X20, Y20 G01 Y40 ; Move to X20, Y40 X40 ; Move to X40, Y40 Y20 ; Move to X40, Y20 M99 ; Return from subprogram 8. Coolant Control Write a CNC program to: o Turn the coolant on before machining (M08). o Perform linear interpolation to X50,Y50. o Turn the coolant off (M09). Answer: M08 ; Coolant on G01 X50 Y50 ; Linear interpolation to X50, Y50 M09 ; Coolant off  9. Thread Cutting Write a CNC program to perform thread cutting on a workpiece from X10,Z0 to X20,Z−10 with a pitch of 1.5 mm. Use the G76 thread cutting cycle. Answer: G76 P010060 Q1000 R0.05 ; Thread cutting cycle, with parameters G00 X10 Z0 ; Move to X10, Z0 G01 Z-10 F1.5 ; Thread cutting from Z0 to Z-10 with pitch of 1.5 mm M30 ; End of program 10. Spindle and Feed Rate Control Write a CNC code to: o Start the spindle counterclockwise at 1500 RPM (M04). o Move the tool linearly at a feed rate of 300 mm/min to X100,Y50. Answer: M04 S1500 ; Spindle counterclockwise at 1500 RPM G01 X100 Y50 ; Linear interpolation to X100, Y50 F300 ; Feed rate 300 mm/min 11. Return to Origin Write a CNC code to return the tool to the origin X0,Y0,Z0 after completing an operation. Answer: G00 X0 Y0 Z0 ; Rapid move to origin (X0, Y0, Z0)  12. Stop and Restart Write a CNC code to: o Stop the program temporarily (M00). o Restart and continue with a feed rate of 250 mm/min. Answer: M00 ; Program stop G01 X50 Y50 ; Resume operation F250 ; Feed rate 250 mm/min 13. CNC Code Explanation For the code below, explain the function of each line: o N10 G90 G01 X50 Y50 F200 o N20 M03 S1200 o N30 G02 X70 Y70 R20 o N40 M05 o N50 G00 Z10 o N60 M30 Answer: N10: Line number 10. G90: Absolute positioning. G01: Linear interpolation (cutting mode). X50 Y50: Move to position X50,Y50X50, Y50X50,Y50. F200: Feed rate of 200 mm/min. N20: Line number 20. M03: Spindle on clockwise. S1200: Set spindle speed to 1200 RPM. N30: Line number 30. G02: Circular interpolation clockwise. X70 Y70: End point of the circular movement. R20: Radius of 20 mm. N40: Line number 40. M05: Spindle stop.  N50: Line number 50. G00: Rapid move. Z10: Move to Z10 position. N60: Line number 60. M30: End of program (reset to start).