Solutions for Fundamentals of Modern Manufacturing, 4/e (published by Wiley)  MPGroover 2010
Answer. (e) and (f).
21.2
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).
21.3
With which one of the following geometric forms is the drilling operation most closely associated:
(a) external cylinder, (b) flat plane, (c) round hole, (d) screw threads, or (e) sphere?
Answer. (c).
21.4
If the cutting conditions in a turning operation are cutting speed = 300 ft/min, feed = 0.010 in/rev,
and depth of cut = 0.100 inch, which one of the following is the material removal rate: (a) 0.025
in3/min, (b) 0.3 in3/min, (c) 3.0 in3/min, or (d) 3.6 in3/min?
Answer. (d).
21.5
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).
21.6
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).
21.7
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).
21.8
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).
21.9
According to the Merchant equation, an increase in rake angle would have which of the following
results, all other factors remaining the same (two best answers): (a) decrease in friction angle, (b)
decrease in power requirements, (c) decrease in shear plane angle, (d) increase in cutting
temperature, and (e) increase in shear plane angle?
Answer. (b) and (e).
21.10
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).
21.11
Which one of the following metals would usually have the lowest unit horsepower in a machining
operation: (a) aluminum, (b) brass, (c) cast iron, or (d) steel?
Answer. (a).
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Solutions for Fundamentals of Modern Manufacturing, 4/e (published by Wiley)  MPGroover 2010
21.12
For which one of the following values of chip thickness before the cut to would you expect the
specific energy in machining to be the greatest: (a) 0.010 inch, (b) 0.025 inch, (c) 0.12 mm, or (d)
0.50 mm?
Answer. (c).
21.13
Which of the following cutting conditions has the strongest effect on cutting temperature: (a) feed
or (b) speed?
Answer. (b).
Problems
Chip Formation and Forces in Machining
21.1
In an orthogonal cutting operation, the tool has a rake angle = 15°. The chip thickness before the cut
= 0.30 mm and the cut yields a deformed chip thickness = 0.65 mm. Calculate (a) the shear plane
angle and (b) the shear strain for the operation.
Solution: (a) r = to/tc = 0.30/0.65 = 0.4615
φ = tan-1(0.4615 cos 15/(1 - 0.4615 sin 15)) = tan-1(0.5062) = 26.85°
(b) Shear strain γ = cot 26.85 + tan (26.85 - 15) = 1.975 + 0.210 = 2.185
21.2
In Problem 21.1, suppose the rake angle were changed to 0°. Assuming that the friction angle
remains the same, determine (a) the shear plane angle, (b) the chip thickness, and (c) the shear strain
for the operation.
Solution: From Problem 21.1, α = 15° and φ = 26.85°. Using the Merchant Equation, Eq. (21.16):
φ = 45 + α/2 - β/2; rearranging, β = 2(45) + α - 2φ
β = 2(45) + α - 2(φ) = 90 + 15 – 2(26.85) = 51.3°
Now, with α = 0 and β remaining the same at 51.3°, φ = 45 + 0/2 – 51.3/2 = 19.35°
(b) Chip thickness at α = 0: tc = to/tan φ = 0.30/tan 19.35 = 0.854 mm
(c) Shear strain γ = cot 19.35 + tan (19.35 - 0) = 2.848 + 0.351 = 3.199
21.3
In an orthogonal cutting operation, the 0.250 in wide tool has a rake angle of 5°. The lathe is set so
the chip thickness before the cut is 0.010 in. After the cut, the deformed chip thickness is measured
to be 0.027 in. Calculate (a) the shear plane angle and (b) the shear strain for the operation.
Solution: (a) r = to/tc = 0.010/0.027 = 0.3701
φ = tan-1(0.3701 cos 5/(1 - 0.3701 sin 5)) = tan-1(0.3813) = 20.9°
(b) Shear strain γ = cot 20.9 + tan (20.9 – 5) = 2.623 + 0.284 = 2.907
21.4
In a turning operation, spindle speed is set to provide a cutting speed of 1.8 m/s. The feed and depth
of cut of cut are 0.30 mm and 2.6 mm, respectively. The tool rake angle is 8°. After the cut, the
deformed chip thickness is measured to be 0.49 mm. Determine (a) shear plane angle, (b) shear
strain, and (c) material removal rate. Use the orthogonal cutting model as an approximation of the
turning process.
Solution: (a) r = to/tc = 0.30/0.49 = 0.612
φ = tan-1(0.612 cos 8/(1 – 0.612 sin 8)) = tan-1(0.6628) = 33.6°
(b) γ = cot 33.6 + tan (33.6 - 8) = 1.509 + 0.478 = 1.987
(c) RMR = (1.8 m/s x 103 mm/m)(0.3)(2.6) = 1404 mm3/s
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22.22
What is the difference between internal broaching and external broaching?
Answer. Internal broaching is accomplished on the inside surface (hole) of a workpart; while
external broaching is performed on one of the outside surfaces of the part.
22.23
Identify the three basic forms of sawing operation?
Answer. The three forms of sawing are: (1) hacksawing, (2) bandsawing, and (3) circular sawing.
22.24
(Video) For what types of parts are VTLs (vertical turret lathes) used?
Answer: VTLs are used to turn large diameter round parts that are too large to be held in a
horizontal lathe.
22.25
(Video) List the four axes for a vertical machining center (VMC) with a rotational axis on the
table.
Answer: The four axes are the three linear axes: X, Y, and Z; and the rotational axis: B.
22.26
(Video) What is the purpose of a tombstone that is used with a horizontal machining center
(HMC)?
Answer: The tombstone is a multi-sided work holding device (often rectangular) that rotates into
position for machining to occur. Parts are clamped to each of the sides of the tombstone. The
tombstone rotates the next part towards the spindle before the cycle starts.
22.27
(Video) List the three parts of a common twist drill.
Answer: The three parts of a common twist drill are the: 1) shank, 2) flutes, and 3) point.
22.28
(Video) What is a gang-drilling machine?
Answer: A gang drilling machine consist of two or more common drilling machines mounted on
a common base or table. Each machine is setup to perform a different operation on a part. The
operator can move down the line performing each operation in succession.
Multiple Choice Questions
There are 23 correct answers in the following multiple choice questions (some questions have multiple
answers that are correct). To attain a perfect score on the quiz, all correct answers must be given. Each
correct answer is worth 1 point. Each omitted answer or wrong answer reduces the score by 1 point, and
each additional answer beyond the correct number of answers reduces the score by 1 point. Percentage score
on the quiz is based on the total number of correct answers.
22.1
Which of the following are examples of generating the workpart geometry in machining, as
opposed to forming the geometry (two best answers): (a) broaching, (b) contour turning, (c) drilling,
(d) profile milling, and (e) thread cutting?
Answer. (b) and (d).
22.2
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).
22.3
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).
22.4
A facing operation is normally performed on which one of the following machine tools: (a) drill
press, (b) lathe, (c) milling machine, (d) planer, or (e) shaper?
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Solutions for Fundamentals of Modern Manufacturing, 4/e (published by Wiley)  MPGroover 2010
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Answer. (b).
22.5
Knurling is performed on a lathe, but it is not a metal cutting operation: (a) true or (b) false?
Answer. (a). It is a metal forming operation.
22.6
Which one of the following cutting tools cannot be used on a turret lathe: (a) broach, (b) cutoff tool,
(c) drill bit, (d) single-point turning tool, or (e) threading tool?
Answer. (a).
22.7
Which one of the following turning machines permits very long bar stock to be used: (a) chucking
machine, (b) engine lathe, (c) screw machine, (d) speed lathe, or (e) turret lathe?
Answer. (c).
22.8
The twist drill is the most common type of drill bit: (a) true or (b) false?
Answer. (a).
22.9
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).
22.10
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).
22.11
End milling is most similar to which one of the following: (a) face milling, (b) peripheral milling,
(c) plain milling, or (d) slab milling?
Answer. (a).
22.12
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).
22.13
A planing operation is best described by which one of the following: (a) a single-point tool moves
linearly past a stationary workpart, (b) a tool with multiple teeth moves linearly past a stationary
workpart, (c) a workpart is fed linearly past a rotating cutting tool, or (d) a workpart moves linearly
past a single-point tool?
Answer. (d).
22.14
A broaching operation is best described by which one of the following: (a) a rotating tool moves
past a stationary workpart, (b) a tool with multiple teeth moves linearly past a stationary workpart,
(c) a workpart is fed past a rotating cutting tool, or (d) a workpart moves linearly past a stationary
single-point tool?
Answer. (b).
22.15
The three basic types of sawing, according to type of blade motion involved, are (a) abrasive cutoff,
(b) bandsawing, (c) circular sawing, (d) contouring, (e) friction sawing, (f) hacksawing, and (g)
slotting?
Answer. (b), (c), and (f).
22.16
Gear hobbing is a special form of which one of the following machining operations: (a) grinding,
(b) milling, (c) planing, (d) shaping, or (e) turning?
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Solutions for Fundamentals of Modern Manufacturing, 4/e (published by Wiley)  MPGroover 2010
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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.
23.22
(Video) List the two principal categories of cutting tools.
Answer: The two principal categories of cutting tools are (1) single-point cutting tools (used on
lathes) and (2) multi point cutting tools (used on mills, drills, reamers, and taps).
23.23
(Video) According to the video clip, what is the objective in selection of cutting tools for a given
operation?
Answer: The objective when choosing a cutting tool is to safely machine a workpiece in the
shortest amount of time while meeting the part’s quality requirement. Furthermore, the tooling
should be the least costly and least complex to meet the production demands.
23.24 (Video) What are the factors a machinist should know in order to select the proper tooling? List
at least five.
Answer: The factors a machinist must know in order to select the proper tooling are (1)
workpiece starting and finished shape, (2) workpiece hardness, (3) workpiece tensile strength, (4)
material abrasiveness, (5) whether the material breaks into short chips or long stringy chips, (6)
workholding setup, and (6) power and speed capacity of the machine tool.
23.25
(Video) List five characteristics of a good tool material.
Answer: The characteristics of a good tool material are the following, as indicated in the video:
(1) it is harder than the workpiece, (2) it retains hardness at high temperatures, (3) it resists wear
and thermal shock, (4) it has impact resistant, and (5) it is chemically inert.
Multiple Choice Quiz
There are 19 correct answers in the following multiple-choice questions (some questions have multiple
answers that are correct). To attain a perfect score on the quiz, all correct answers must be given. Each
correct answer is worth 1 point. Each omitted answer or wrong answer reduces the score by 1 point, and
each additional answer beyond the correct number of answers reduces the score by 1 point. Percentage score
on the quiz is based on the total number of correct answers.
23.1
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).
23.2
As an alloying ingredient in high-speed steel, tungsten serves which of the following functions (two
best answers): (a) forms hard carbides to resist abrasion, (b) improves strength and hardness, (c)
increases corrosion resistance, (d) increases hot hardness, and (e) increases toughness?
Answer. (a) and (d).
23.3
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).
23.4
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).
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Solutions for Fundamentals of Modern Manufacturing, 4/e (published by Wiley)  MPGroover 2010
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23.5
An increase in cobalt content has which of the following effects on WC-Co cemented carbides (two
best answers): (a) decreases hardness, (b) decreases transverse rupture strength, (c) increases
hardness, (d) increases toughness, and (e) increases wear resistance?
Answer. (a) and (d).
23.6
Steel-cutting grades of cemented carbide are typically characterized by which of the following
ingredients (three correct answers): (a) Co, (b) Fe, (c) Mo, (d) Ni, (e) TiC, and (f) WC?
Answer. (a), (e), and (f).
23.7
If you had to select a cemented carbide for an application involving finish turning of steel, which
C-grade would you select (one best answer): (a) C1, (b) C3, (c) C5, or (d) C7?
Answer. (d).
23.8
Which of the following processes are used to provide the thin coatings on the surface of coated
carbide inserts (two best answers): (a) chemical vapor deposition, (b) electroplating, (c) physical
vapor deposition, (d) pressing and sintering, and (e) spray painting?
Answer. (a) and (c).
23.9
Which one of the following materials has the highest hardness: (a) aluminum oxide, (b) cubic boron
nitride, (c) high-speed steel, (d) titanium carbide, or (e) tungsten carbide?
Answer. (b).
23.10
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).
Problems
Tool Life and the Taylor Equation
23.1
Flank wear data were collected in a series of turning tests using a coated carbide tool on hardened
alloy steel at a feed of 0.30 mm/rev and a depth of 4.0 mm. At a speed of 125 m/min, flank wear =
0.12 mm at 1 min, 0.27 mm at 5 min, 0.45 mm at 11 min, 0.58 mm at 15 min, 0.73 at 20 min, and
0.97 mm at 25 min. At a speed of 165 m/min, flank wear = 0.22 mm at 1 min, 0.47 mm at 5 min,
0.70 mm at 9 min, 0.80 mm at 11 min, and 0.99 mm at 13 min. The last value in each case is when
final tool failure occurred. (a) On a single piece of linear graph paper, plot flank wear as a function
of time for both speeds. Using 0.75 mm of flank wear as the criterion of tool failure, determine the
tool lives for the two cutting speeds. (b) On a piece of natural log-log paper, plot your results
determined in the previous part. From the plot, determine the values of n and C in the Taylor Tool
Life Equation. (c) As a comparison, calculate the values of n and C in the Taylor equation solving
simultaneous equations. Are the resulting n and C values the same?
Solution: (a) and (b) Student exercises. For part (a), at v1 = 125 m/min, T1 = 20.4 min using
criterion FW = 0.75 mm, and at v2 = 165 m/min, T2 = 10.0 min using criterion FW = 0.75 mm. In
part (b), values of C and n may vary due to variations in the plots. The values should be
approximately the same as those obtained in part (c) below.
(c) Two equations: (1) 125(20.4)n = C, and (2) 165(10.0)n = C
(1) and (2) 125(20.4)n = 165(10.0)n
ln 125 + n ln 20.4 = ln 165 + n ln 10.0
4.8283 + 3.0155 n = 5.1059 + 2.3026 n
0.7129 n = 0.2776
n = 0.3894
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4