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Groove welds are most closely associated with which one of the following joint types: (a) butt, (b) corner, (c) edge, (d) lap, or (e) tee?
Answer. (a).
What is an autogenous weld?
An autogenous weld is a fusion weld made without the addition of filler metal.
The following are measures of feasibility for several proposed cup- drawing operations; which of the operations are likely to be feasible (three best answers): (a) DR = 1.7, (b) DR = 2.7, (c) r = 0.35, (d) r = 0.65, and (e) t/D = 2%?
Answer. (a), (c), and (e).
2. A lathe can be used to perform which of the following machining operations (three correct answers): (a) boring, (b) broaching, (c) drilling, (d) milling, (e) planing, and (f) turning?
Answer. (a), (c), and (f).
1. Of the following cutting conditions, which one has the greatest effect on tool wear: (a) cutting speed, (b) depth of cut, or (c) feed?
Answer. (a).
4. Oxyacetylene welding is the most widely used oxyfuel welding process because acetylene mixed with an equal volume of oxygen burns hotter than any other commercially available fuel: (a) true or (b) false?
Answer. (a).
In a sheet-metal-cutting operation used to produce a flat part with a hole in the center, the part itself is called a blank, and the scrap piece that was cut out to make the hole is called a slug: (a) true or (b) false?
Answer. (a).
Which of the following would tend to give higher material removal rates: (a) larger grain size, or (b) smaller grain size?
Answer. (a).
5. Which of the following are variations of sheet-metal-bending operations (two best answers): (a) coining, (b) flanging, (c) hemming, (d) ironing, (e) notching, (f) shear spinning, (g) trimming, and(h) tube bending?
Answer. (b) and (c).
Which of the following descriptions applies to a V-bending operation as compared to an edge bending operation (two best answers): (a) costly tooling, (b) inexpensive tooling, (c) limited to 90° bends or less, (d) used for high production, (e) used for low production, and (f) uses a pressure pad to hold down the sheet metal?
Answer. (b) and (e).
The basic milling machine is which one of the following: (a) bed type, (b) knee-and-column, (c) profiling mill, (d) ram mill, or (e) universal milling machine?
Answer. (b).
Weld failures always occur in the fusion zone of the weld joint, since this is the part of the joint that has been melted: (a) true, (b) false?
Answer. (b). Failures also occur in the heat-affected zone because metallurgical damage often occurs in this region.
Which of the following manufacturing processes are classified as material removal processes (two correct answers): (a) casting, (b) drawing, (c) extrusion, (d) forging, (e) grinding, (f) machining, (g) molding, (h) pressworking, and (i) spinning?
Answer. (e) and (f).
1. What are the two principal aspects of cutting-tool technology?
Answer. The two main aspects of cutting tool technology are (1) tool material and (2) tool geometry.
3. Give two examples of machining operations in which generating and forming are combined to create workpart geometry.
Answer. Thread cutting on a lathe and slot milling.
Identify three desirable properties of a cutting-tool material.
Answer. Three desirable properties are (1) toughness to resist fracture failure, (2) hot hardness to resist temperature failure, and (3) wear resistance to prolong the life of the tool during gradual wear.
What are some of the tool life criteria used in production machining operations?
Answer. Tool life criteria used in production include (1) complete failure of the tool, (2) visual observation of flank or crater wear, (3) fingernail test to feel flank wear, (4) sound of the tool, (5) chip disposal problems, (6) degradation of finish, (7) power increase, (8) workpiece count, and (9) length of cutting time for the tool.
4. Describe the turning process.
Answer. Turning is a machining process in which a single-point tool removes material from the surface of a rotating cylindrical workpiece, the tool being fed in a direction parallel to the axis of work rotation.
What are the two principal locations on a cutting tool where tool wear occurs?
Answer. Wear occurs on the top face of the cutting tool as crater wear and on the side or flank of the tool, called flank wear. Portions of flank wear are often identified separately as notch wear.
Name and briefly describe the four types of chips that occur in metal cutting.
The four types are (1) discontinuous, in which the chip is formed into separated segments; (2) continuous, in which the chip does not segment and is formed from a ductile metal; (3) continuous with built-up edge, which is the same as (2) except that friction at the tool-chip interface causes adhesion of a small portion of work material to the tool rake face, and (4) serrated, which are semi-continuous in the sense that they possess a saw-tooth appearance that is produced by a cyclical chip formation of alternating high shear strain followed by low shear strain.
What are the parameters that have the greatest influence in determining the ideal surface roughness Ri in a turning operation?
The ideal surface roughness is determined by the following geometric parameters of the machining operation: (1) tool nose radius and (2) feed. In some cases, the end cutting edge and end cutting edge angle of the single-point tool affects the feed mark pattern on the work surface.
What are the criteria by which machinability is commonly assessed in a production machining operation?
The machinability criteria include (1) tool wear and tool life, (2) forces and power, (3) surface finish, and (4) ease of chip disposal.
1. Which one of the following conventional machining processes is closest to grinding: (a) drilling, (b) milling, (c) shaping, or (d) turning?
Answer. (b).
Which of the following are the two main functions of a cutting fluid in machining (two best answers): (a) improve surface finish on the workpiece, (b) reduce forces and power, (c) reduce friction at the tool- chip interface, (d) remove heat from the process, and (e) wash away chips?
Answer. (c) and (d).
Most sheet metalworking operations are performed as which one of the following: (a) cold working, (b) hot working, or (c) warm working?
Answer. (a).
Reaming is used for which of the following functions (three correct answers): (a) accurately locate a hole position, (b) enlarge a drilled hole, (c) improve surface finish on a hole, (d) improve tolerance on hole diameter, and (e) provide an internal thread?
Answer. (b), (c), and (d).
2. Cast cobalt alloys typically contain which of the following main ingredients (three best answers): (a) aluminum, (b) cobalt, (c) chromium, (d) iron, (e) nickel, (f) steel, and (g) tungsten?
Answer. (b), (c), and (g).
1. In a turning operation, the change in diameter of the workpart is equal to which one of the following: (a) 1 x depth of cut, (b) 2 x depth of cut, (c) 1 x feed, or (d) 2 x feed?
Answer. (b).
2. MIG welding is a term sometimes applied when referring to which one of the following processes: (a) FCAW, (b) GMAW, (c) GTAW, or (d) SMAW?
Answer. (b).
3. When cutting a ductile work material, an increase in cutting speed will generally (a) degrade surface finish, which means a higher value of Ra or (b) improve surface finish, which means a lower value of Ra?
Answer. (b).
5. The chip thickness ratio is which one of the following: (a) tc/to, (b) to/tc, (c) f/d, or (d) to/w, where tc = chip thickness after the cut, to = chip thickness before the cut, f = feed, d = depth, and w = width of cut?
Answer. (b).
7. In using the orthogonal cutting model to approximate a turning operation, the chip thickness before the cut to corresponds to which one of the following cutting conditions in turning: (a) depth of cut d, (b) feed f, or (c) speed v?
Answer. (b).
Of the following abrasive materials, which one has the highest hardness: (a) aluminum oxide, (b) cubic boron nitride, or (c) silicon carbide?
Answer. (b).
3. Resistance-welding processes make use of the heat generated by electrical resistance to achieve fusion of the two parts to be joined; no pressure is used in these processes, and no filler metal is added: (a) true or (b) false?
Answer. (b). Pressure is applied in RW processes and is key to the success of these processes.
1. Welding can only be performed on metals that have the same melting point; otherwise, the metal with the lower melting temperature always melts while the other metal remains solid: (a) true, (b) false?
Answer. (b). Welding can be accomplished between certain combinations of dissimilar metals using solid state welding processes.
6. Which one of the four types of chip would be expected in a turning operation conducted at low cutting speed on a brittle work material: (a) continuous, (b) continuous with built-up edge, (c) discontinuous, or (d) serrated?
Answer. (c).
A roughing operation generally involves which one of the following combinations of cutting conditions: (a) high v, f, and d; (b) high v, low f and d; (c) low v, high f and d; or (d) low v, f, and d, where v = cutting speed, f = feed, and d = depth?
Answer. (c).
Smaller grain size in a grinding wheel tends to (a) degrade surface finish, (b) have no effect on surface finish, or (c) improve surface finish?
Answer. (c).
The holding force in drawing is most likely to be (a) greater than, (b) equal to, or (c) less than the maximum drawing force?
Answer. (c).
Which of the following are characteristics of the orthogonal cutting model (three best answers): (a) a circular cutting edge is used, (b) a multiple-cutting- edge tool is used, (c) a single-point tool is used, (d) only two dimensions play an active role in the analysis, (e) the cutting edge is parallel to the direction of cutting speed, (f) the cutting edge is perpendicular to the direction of cutting speed, and (g) the two elements of tool geometry are rake and relief angle?
Answer. (d), (f), and (g).
A tap is a cutting tool used to create which one of the following geometries: (a) external threads, (b) flat planar surfaces, (c) holes used in beer kegs, (d) internal threads, or (e) square holes?
Answer. (d).
Which one of the following abrasive processes achieves the best surface finish: (a) centerless grinding, (b) honing, (c) lapping, or (d) superfinishing?
Answer. (d).
A lathe is used to perform which one of the following manufacturing operations: (a) broaching, (b) drilling, (c) lapping, (d) milling, or (e) turning?
Answer. (e).
Explain the difference between roughing and finishing operations in machining.
Answer. A roughing operation is used to remove large amounts of material rapidly and to produce part geometry close to the desired shape. A finishing operation follows roughing and is used to achieve the final geometry and surface finish.
Which of the following is not a common ingredient in cemented carbide cutting tools (two correct answers): (a) Al2O3, (b) Co, (c) CrC, (d) TiC, and (e) WC?
Answer. (a) and (c).
1. A machinability rating greater than 1.0 indicates that the work material is (a) easier to machine than the base metal or (b) more difficult to machine than the base metal, where the base metal has a rating = 1.0?
Answer. (a).
1. The feature that distinguishes fusion welding from solid-state welding is that melting of the faying surfaces occurs during fusion welding but not in solid-state welding: (a) true or (b) false?
Answer. (a).
2. In general, which one of the following materials has the highest machinability: (a) aluminum, (b) cast iron, (c) copper, (d) low carbon steel, (e) stainless steel, (f) titanium alloys, or (g) unhardened tool steel?
Answer. (a).
A circular sheet-metal slug produced in a hole punching operation will have the same diameter as (a) the die opening or (b) the punch?
Answer. (a).
5. What is the difference between threading and tapping?
Answer. A threading operation is performed on a turning machine and produces an external thread, while tapping is normally performed on a drilling machine and produces an internal thread.
1. What are the advantages and disadvantages of welding compared to other types of assembly operations?
Answer. Advantages: (1) it provides a permanent joint, (2) joint strength is typically as high as the strength of base metals, (3) it is most economical in terms of material usage, and (4) it is versatile in terms of where it can be accomplished. Disadvantages: (1) it is usually performed manually, so labor cost is high and the skilled labor to perform it is sometimes scarce, (2) welding is inherently dangerous, (3) a welded joint is difficult to disassemble, and (4) quality defects are sometimes difficult to detect.
Why is the oxyacetylene welding process favoured over the other oxyfuel welding processes?
Answer. Because acetylene and oxygen burn hotter than other oxyfuels.
How does a boring operation differ from a turning operation?
Answer. Boring produces an internal cylindrical shape from an existing hole, while turning produces an external cylindrical shape.
Why do costs tend to increase when better surface finish is required on a machined part?
Answer. Costs tend to increase when better surface finish is required because additional operations such as grinding, lapping, or similar finishing processes must be included in the manufacturing sequence.
What are the parameters of a machining operation that are included within the scope of cutting conditions?
Answer. Cutting conditions include speed, feed, depth of cut, and whether or not a cutting fluid is used.
Dry machining is being considered by machine shops because of certain problems inherent in the use of cutting fluids. What are those problems associated with the use of cutting fluids?
Answer. Cutting fluids become contaminated over time with a variety of contaminants, including tramp oil, garbage, small chips, molds, fungi, and bacteria. In addition to causing odours and health hazards, contaminated cutting fluids do not perform their lubricating function as well as when they are fresh and clean.
6. What are some of the possible defects in drawn sheet-metal parts?
Answer. Drawing defects include (1) wrinkling, (2) tearing, (3) earing, and (4) surface scratches
4. Define drawing in the context of sheet metalworking.
Answer. Drawing is a sheet metalworking operation used to produce cup- shaped or box-shaped, or other complex-curved, hollow parts. Drawing is accomplished by placing a piece of sheet metal over a die cavity and then using a punch to push the metal into the cavity.
Name and sketch the five joint types.
Answer. Five joint types are (1) butt, (2) corner, (3) lap, (4) tee, (5) edge.
What are the functions of a grinding fluid?
Answer. Functions of a grinding fluid include (1) reducing friction, (2) removing heat, (3) washing away chips, and (4) reducing workpiece temperature.
2. Distinguish between generating and forming when machining workpart geometries.
Answer. Generating refers to the creation of work geometry due to the feed trajectory of the cutting tool; examples include straight turning, taper turning, and profile milling. Forming involves the creation of work geometry due to the shape of the cutting tool; common examples include form turning and drilling.
Name some of the abrasive operations available to achieve very good surface finishes.
Answer. High finish abrasive processes include honing, lapping, superfinishing, buffing, and polishing.
1. Why are abrasive processes technologically and commercially important?
Answer. Important reasons include (1) applications on all types of materials, (2) very fine finishes, and (3) close tolerances.
Describe each of the two types of sheet-metal-bending operations: V- bending and edge bending.
Answer. In V-bending, the sheet metal is bent between a V-shaped punch and die. Included angles ranging from very obtuse to very acute can be made with V-dies. Edge bending involves cantilever loading of the sheet metal. A pressure pad is used to apply a force Fh to hold the base of the part against the die, while the punch forces the part to yield and bend over the edge of the die.
What is the fundamental difference between a fusion weld and a solid state weld?
Answer. In a fusion weld, the metal is melted. In a solid state weld, the metal is not melted.
2. What distinguishes machining from other manufacturing processes?
Answer. In machining, material is removed from the workpart so that the remaining material is the desired part geometry.
7. Describe the difference between up milling and down milling?
Answer. In up milling, the cutter speed direction is opposite the feed direction; in down milling, the direction of cutter rotation is the same as the feed direction.
1. Define machinability.
Answer. Machinability can be defined as the relative ease with which a material can be machined using an appropriate cutting tool under appropriate cutting conditions.
5. What are some of the simple measures used to assess the feasibility of a proposed cup-drawing operation?
Answer. Measures of drawing feasibility include (1) drawing ratio DR = D/Dp; (2) reduction r = (D - Dp)/D; and (3) thickness-to-diameter ratio, t/D; where t = stock thickness, D = blank diameter, and Dp = punch diameter.
Discuss the reasons why most welding operations are inherently dangerous.
Answer. Most welding operations are carried out at high temperatures that can cause serious burns on skin and flesh. In gas welding, the fuels are a fire hazard. In arc welding and resistance welding, the high electrical energy can cause shocks that are fatal to the worker. In arc welding, the electric arc emits intense ultraviolet radiation that can cause blinding. Other hazards include sparks, smoke, fumes, and weld spatter.
What are some of the new problems introduced by machining dry?
Answer. Problems with dry machining include (1) overheating the tool, (2) operating at lower cutting speeds and production rates to prolong tool life, and (3) absence of chip removal benefits that are provided by cutting fluids in grinding and milling.
Define resistance welding.
Answer. RW consists of a group of fusion welding processes that utilize a combination of heat and pressure to accomplish coalescence of the two faying surfaces. Most prominent in the group is resistance spot welding.
1. What are the differences between rotational parts and prismatic parts in machining?
Answer. Rotational parts are cylindrical or disk-shaped and are machined on a turning machine (e.g., a lathe); prismatic parts are block-shaped or flat and are generally produced on a milling machine, shaper, or planer.
Describe the shielded metal arc-welding (SMAW) process.
Answer. SMAW is an arc-welding process that uses a consumable electrode consisting of a filler metal rod coated with chemicals that provide flux and shielding.
6. What are some of the important welding defects?
Answer. Some of the important welding defects are (1) cracks, (2) cavities, (3) solid inclusions, (4) incomplete fusion, and (5) imperfect shape or contour of weld cross section.
What is the heat-affected zone (HAZ) in a fusion weld?
Answer. The HAZ is a region of base metal surrounding the fusion zone in which melting has not occurred, but temperatures from welding were high enough to cause solid state microstructural changes.
3. For what is the bend allowance intended to compensate?
Answer. The bend allowance is intended to compensate for stretching of the sheet metal that occurs in a bending operation when the bend radius is small relative to the stock thickness. In principle the bend allowance equals the length of the bent metal along its neutral axis.
In addition to cutting speed, what other cutting variables are included in the expanded version of the Taylor tool life equation?
Answer. The expanded version of the Taylor equation can include any of the following: feed, depth of cut, and/or work material hardness.
4. What are the basic factors that affect surface finish in machining?
Answer. The factors that affect surface finish are (1) geometric factors such as type of operation, feed, and tool shape (nose radius in particular); (2) work material factors such as built-up edge effects, and tearing of the work surface when machining ductile materials, which factors are affected by cutting speed; and (3) vibration and machine tool factors such as setup and workpart rigidity, and backlash in the feed mechanism.
Distortion (warping) is a serious problem in fusion welding, particularly arc welding. What are some of the techniques that can be taken to reduce the incidence and extent of distortion?
Answer. The following techniques can be used to reduce warping in arc welding: (1) Welding fixtures can be used to physically restrain movement of the parts during welding. (2) Heat sinks can be used to rapidly remove heat from sections of the welded parts to reduce distortion. (3) Tack welding at multiple points along the joint can create a rigid structure prior to continuous seam welding. (4) Welding conditions (speed, amount of filler metal used, etc.) can be selected to reduce warping. (5) The base parts can be preheated to reduce the level of thermal stresses experienced by the parts. (6) Stress relief heat treatment can be performed on the welded assembly, either in a furnace for small weldments, or using methods that can be used in the field for large structures. (7) Proper design of the weldment itself can reduce the degree of warping.
Identify the four forces that act upon the chip in the orthogonal metal cutting model but cannot be measured directly in an operation.
Answer. The four forces that act upon the chip are (1) friction force, (2) normal force to friction, (3) shear force, and (4) normal force to shear.
Identify the mechanisms by which cutting tools wear during machining.
Answer. The important tool wear mechanisms are (1) abrasion, (2) adhesion, (3) diffusion, and (4) plastic deformation of the cutting edge.
What are the five principal parameters of a grinding wheel?
Answer. The parameters are (1) abrasive material, (2) grit size, (3) bonding material, (4) wheel structure, which refers to the relative spacing of grains, and (5) wheel grade, which refers to the bond strength of the wheel in retaining abrasive grains.
What are some of the principal abrasive materials used in grinding wheels?
Answer. The principal abrasive grit materials include (1) aluminum oxide, (2) silicon carbide, (3) cubic boron nitride, and (4) diamond.
1. Name the principal groups of processes included in fusion welding.
Answer. The principal groups of processes included in fusion welding are (1) arc welding, (2) resistance welding, (3) oxyfuel welding, and (4) other category such as EBW and LBW.
Identify some of the reasons why machining is commercially and technologically important.
Answer. The reasons include the following: (1) it is applicable to most materials; (2) it can produce a variety of geometries to a part; (3) it can achieve closer tolerances than most other processes; and (4) it can create good surface finishes.
1. What are the three basic categories of material removal processes?
Answer. The three basic categories of material removal processes are (1) conventional machining, (2) abrasive processes, and (3) nontraditional processes.
1. Identify the three basic types of sheet metalworking operations.
Answer. The three basic types of sheet metalworking operations are (1) cutting, (2) bending, and (3) drawing.
Name the three most common machining processes.
Answer. The three common machining processes are (1) turning, (2) drilling, and (3) milling.
Name the three modes of tool failure in machining.
Answer. The three tool failure modes are (1) fracture failure, (2) temperature failure, and (3) gradual wear.
What are the two basic categories of cutting tools in machining? Give two examples of machining operations that use each of the tooling types.
Answer. The two categories are (1) single-point tools, used in operations such as turning and boring; and (2) multiple-edge cutting tools, used in operations such as milling and drilling.
Identify the two forces that can be measured in the orthogonal metal cutting model.
Answer. The two forces that can be measured in the orthogonal metal cutting model are (1) cutting force and (2) thrust force.
Name the two main categories of cutting fluid according to function.
Answer. The two functional categories of cutting fluids are: (1) coolants and (2) lubricants.
