Ch04

Manufacturing Processes for Engineering Materials, 5th ed.
Kalpakjian • Schmid
© 2008, Pearson Education
ISBN No. 0-13-227271-7
Surfaces
ISBN No. 0-13-227271-7
FIGURE 4.1 Schematic illustration of the cross-section of the surface structure of metals.The thickness of
the individual layers depends on processing conditions and the environment. Source: After E. Rabinowicz and
B. Bhushan.
Contaminant
Adsorbed gas
Oxide layer
Work-hardened layer
Metal substrate
Beilby (amorphous) layer
1–100 nm
1 nm
1–100 nm
10–100 nm
1–100 mm

ISBN No. 0-13-227271-7
Terminology for Surface Finish
FIGURE 4.2 (a) Standard terminology and symbols used to
describe surface ﬁnish. The quantities are given in µin. (b)
Common surface-lay symbols.
Maximum waviness height
Maximum Ra
Minimum Ra
Lay
125
63
0.005
0.010
0.002-2 Maximum waviness width
Roughness-width cutoff
Maximum roughness width
X
Lay
symbol Interpretation Examples
P
Lay parallel to the line representing the surface
to which the symbol is applied
Lay perpendicular to the line representing the
surface to which the symbol is applied
Lay angular in both directions to line representing
the surface to which symbol is applied
Pitted, protuberant, porous, or particulate
nondirectional lay
X
P
(a)
(b)
Surface profile Error of form Waviness Roughness
+ +=
Flaw
Roughness
height, Rt
Waviness
height
Waviness width
Roughness spacing
Roughness-width cutoff
Lay direction

ISBN No. 0-13-227271-7
Surface Roughness
FIGURE 4.3 Coordinates used for measurement of
surface roughness, used in Eqs. (4.1) and (4.2).
y
a b c de
f g h i j k l
Digitized data
Surface profile
A
Center (datum) line
x
B Ra Roughness
Rq Roughness
Ra =
ya +yb +yc +···+yn
n
=
1
n
n
∑
i=1
yi =
1
l
Z l
0
|y| dx
Rq =
y2
a +y2
b +y2
c +···+y2
n
n
=
1
n
n
∑
i=1
y2
i =
Z l
0
y2
dx
1/2

ISBN No. 0-13-227271-7
Stylus Profilometry
FIGURE 4.4 (a) Measuring surface
roughness with a stylus. The rider
supports the stylus and guards against
damage. (b) Path of the stylus in
measurements of surface roughness
(broken line) compared with the actual
roughness profile. Note that the profile
of the stylus' path is smoother than the
actual surface profile. Typical surface
profiles produced by (c) lapping, (d)
finish grinding, (e) rough grinding, and
(f) turning processes. Note the
difference between the vertical and
horizontal scales.
(a)
Rider
Stylus
Head
Workpiece
(b)
Stylus
Stylus path
Actual surface
5 µm (200 µin.)
(f) Turning
3.8 µm (150 µin.)
(e) Rough grinding
0.5 µm (20 µin.)
0.4 mm (0.016 in.)
(c) Lapping
0.6 µm (25 µin.)
(d) Finish grinding

ISBN No. 0-13-227271-7
Micro-Scale Adhesion
FIGURE 4.5 (a) Schematic illustration of the interface of two contacting surfaces, showing the real
areas of contact. (b) Sketch illustrating the proportion of the apparent area to the real area of contact.
The ratio of the areas can be as high as four to ﬁve orders of magnitude.
N
Microweld
Plastic
Elastic
F
Projected
contact
patches

ISBN No. 0-13-227271-7
Friction in Manufacturing
FIGURE 4.6 Schematic illustration of the relation between friction
force F and normal force N. Note that as the real area of contact
approaches the apparent area, the friction force reaches a maximum
and stabilizes.At low normal forces, the friction force is proportional
to normal force; most machine components operate in this region.
The friction force is not linearly related to normal force in
metalworking operations, because of the high contact pressures
involved.
Ar
<<A Ar
<A Ar
~A
F
N
Frictionforce,F
Normal force, N
Forging, extrusion
Drawing, rolling
Metal cuttingDeep drawing
Stretch forming
Bending
Coulomb Friction
Tresca Friction
µ=
F
N
=
τAr
σAr
=
τ
σ
m =
τi
k

ISBN No. 0-13-227271-7
Coefficient of Friction in Metalworking
Coefficient of Friction (µ)
Process Cold Hot
Rolling 0.05-0.1 0.2-0.7
Forging 0.05-0.1 0.1-0.2
Drawing 0.03-0.1 —
Sheet-metal forming 0.05-0.1 0.1-0.2
Machining 0.5-2 —
TABLE 4.1 Coefficient of friction in metalworking processes.

ISBN No. 0-13-227271-7
Effect of Lubrication
FIGURE 4.7 (a) The effects of lubrication on barreling in the ring compression test. (a) With good lubrication,
both the inner and outer diameters increase as the specimen is compressed; and with poor or no lubrication,
friction is high, and the inner diameter decreases.The direction of barreling depends on the relative motion of
the cylindrical surfaces with respect to the ﬂat dies. (b) Test results: (1) original specimen, and (2-4) the
specimen under increasing friction. Source: A.T. Male and M.G. Cockcroft.
(b)
1 2 3 4
Good lubrication Poor lubrication
(a)

ISBN No. 0-13-227271-7
Ring Compression Test
FIGURE 4.8 Charts to determine friction in ring compression tests: (a) coefﬁcient of friction, µ; (b) friction factor, m. Friction is
determined from these charts from the percent reduction in height and by measuring the percent change in the internal diameter
of the specimen after compression.
Reduction in height (%)
70
60
50
40
30
20
10
0
210
220
Reductionininternaldiameter(%)
0 10 20 30 40 50 60 70
0.7
0.5
0.3
0.2
0.15
0.10
0.05
m = 1.0
Reduction in height (%)
Original dimensions
of specimen:
OD = 3/4 in.= 19 mm
ID = 3/8 in.= 9.5 mm
Height =1/4 in.= 0.64 mm
0.40
0.30
0.20
0.15
0.12
0.10
0.08
0.09
0.07
0.06
0.05
0.04
0.03
0
~0.02
0.055
240
250
230
220
210
0
10
Reductionininternaldiameter(%)
20
30
40
50
60
70
80
100 20 30 40 50 60 70
µ=0.577
(a) (b)

ISBN No. 0-13-227271-7
Proﬁle Evolution Due to Wear
FIGURE 4.9 Changes in originally (a) wire-brushed and (b) ground-surface
proﬁles after wear. Source: E.Wild and K.J. Mack.
Scale:
25 µm
250 µm
(a)
Unworn
Worn
(b)
Unworn
Worn

ISBN No. 0-13-227271-7
Adhesive Wear Model
FIGURE 4.10 Schematic illustration of (a) asperities contacting, (b) adhesion between two asperities,
and (c) the formation of a wear particle.
(a) (b) (c)
Plastic zone
(microweld)
Hard
Soft Metal transfer
(possible wear
fragment)
Archard Wear Law:
V = k
LW
3p
Unlubricated k Lubricated k
Mild steel on mild steel 10−2 to 10−3 52100 steel on 52100 steel 10−7 to 10−10
6040 brass on hardened tool steel 10−3 Aluminum bronze 10−8
Hardened tool steel on 10−4 on hardened steel 10−9
hardened tool steel Hardened steel 10−9
Polytetraﬂuoroethylene (PTFE) 10−5 on hardened steel 10−9
on tool steel
Tungsten carbide on mild steel 10−6
TABLE 4.2 Approximate order of magnitude for the wear coefﬁcient, k, in air.

ISBN No. 0-13-227271-7
Abrasive and Other Wear
FIGURE 4.11 Schematic illustration of abrasive
wear in sliding. Longitudinal scratches on a
surface usually indicate abrasive wear.
Chip
Hard particle
FIGURE 4.12 Types of wear observed in a single die used for
hot forging. Source: After T.A. Dean.
CL
2 5 1 5 3 4 2 1
5 1 5 3 4 1
Top die
Ejector
Bottom die
Erosion
Pitting (lubricated dies only)
Thermal fatigue
Mechanical fatigue
Plastic deformation
1
2
3
4
5

ISBN No. 0-13-227271-7
Regimes of Lubrication
FIGURE 4.13 Regimes of lubrication generally occurring in metalworking
operations. Source: After W.R.D.Wilson.
Boundary film
(a) Thick film (b) Thin film
(d) Boundary(c) Mixed
Tooling
Lubricant
Workpiece

ISBN No. 0-13-227271-7
Roller Burnishing
FIGURE 4.14 Examples of roller burnishing of (a) the ﬁllet of a stepped shaft, (b) an
internal conical surface, and (c) a ﬂat surface.
Roller
Workpiece
(a)
Roller
Burnished
surface
(b)
Roller
(c)

ISBN No. 0-13-227271-7
Thermal Wire Spraying
FIGURE 4.15 Schematic illustration of thermal wire spraying.
Wire or rod
Oxygen
Gas nozzle Air cap
Combustion chamber
Workpiece
Molten
metal spray
Deposited coating
High-velocity gas
Fuel gas

ISBN No. 0-13-227271-7
ChemicalVapor Deposition
FIGURE 4.16 Schematic illustration of the chemical vapor deposition process.
Carrier gases
TiCl4
Stainless steel retort
Tools to be coated
Graphite shelves
Exhaust scrubber
Exhaust
Electric furnace

ISBN No. 0-13-227271-7
Electroplating
FIGURE 4.17 (a) Schematic illustration of the electroplating process. (b) Examples of electroplated
parts. Source: Courtesy of BFG Electroplating.
(a) (b)
+ -
Sacrificial
(copper) anode
Cu++
Cu++
Cu++
Cu++Cu++
SO4
--
SO4
--
SO4
--
H+
H+
H+
H+
H+
SO4
--
SO4
--
SO4
--
Part to be plated
(cathode)
Agitator
Heating coils

ISBN No. 0-13-227271-7
Coordinate Measuring Machine
FIGURE 4.18 (a) A coordinate measuring machine with part being measured; (b) a touch
signal probe measuring the geometry of a gear; (c) examples of laser probes. Source:
Courtesy Mitutoyo America Corp.
Machine stand
z-axis spindle
Probe adapter
Measuring table
(b)
(c)
Probe
Computer
controller

ISBN No. 0-13-227271-7
Dimensional Tolerancing
FIGURE 4.19 (a) Basic size, deviation, and tolerance on a shaft, according to the ISO system.
(b)-(d)Various methods of assigning tolerances on a shaft. Source: L.E. Doyle.
(a)
(b) (c) (d)
Basicsize
Minimum
diameter
Minimum
diameter
Maximum
diameter
Maximum
diameter
Basicsize
Zero line or line
of zero deviation
Tolerance
Tolerance
Lowerdeviation
Lowerdeviation
Upperdeviation
Upperdeviation
Shaft
Hole
Bilateral
tolerance
mm
in.
40.00 + 0.05
- 0.05
1.575 + 0.002
- 0.002
Unilateral
tolerance
mm
in.
40.05 + 0.00
- 0.10
1.577 + 0.000
- 0.004
Limit
dimensions
mm
in.
40.05
39.95
1.577
1.573

ISBN No. 0-13-227271-7
Tolerances by Process
FIGURE 4.20 Tolerances and surface roughness obtained in various manufacturing processes.
These tolerances apply to a 25-mm (1-in.) workpiece dimension. Source: After J.A. Schey.
0.5 1 2 4 8 16 32
Surface roughness, Ra (µin.)
63 125 250 500 1000
0.005
0.01
0.05
0.1
0.5
1.0
2.0
0.025 0.05 0.1 0.2 0.4 0.8 1.6 3.2 6.3 12.5 25 50 µm
2000
N1 N2 N3 N4 N5 N6 N7 N8 N9 N10 N11 N12 ISO No.
0.100
0.010
0.001
0.0001
Tolerancerange(in.)
mm
Broach, reamFinish mill
ECM-EDM
Finish grind, finish turn, bore
Rough, grind, turn
Shape, plane, rough
m
ill
Drill, punch
Plaster
Shell
Sand
cast
Polish, lap, hone
Precision blankCold draw
Cold extrude, roll
Investment cast
Hot roll, extrude, forge
Zn die
Al-die cast
Powder met
Permanent mold

ISBN No. 0-13-227271-7
Frequency Distribution
FIGURE 4.21 (a) A plot of the number of shafts measured
and their respective diameters.This type of curve is called a
frequency distribution. (b) A normal distribution curve
indicating areas within each range of standard deviation.
Note: The greater the range, the higher the percentage of
parts that fall within it. (c) Frequency distribution curve,
showing lower and upper speciﬁcation limits.
(b)(a)
(c)
99.73%
95.46
68.26
-4! +4!-3 -2 -1 +1 +2 +30
Frequencyofoccurrence
13.00 13.05
2
0
10
8
6
4
Diameter of shafts (mm)
12.95
(numberofshafts)
13.00 13.05
2
0
10
8
6
4
Diameter of shafts (mm)
12.95
Lower
specification
Upper
specification

ISBN No. 0-13-227271-7
Control Charts
0.12
0.08
0.06
0.04
0.02
0 LCLR
UCLR0.10
Range,R(mm)
R (average
range)
Time
(a)
13.04
13.02
13.01
13.03
12.99
12.98
12.97
12.96
0
13.00
Averagediameter,x(mm)
Average of 5 samples
Average of next 5 samples
Average of next 5 samples
Time
LCLx
x (average of
averages)
(b)
UCLx
__
FIGURE 4.22 Control charts used in statistical quality
control. The process shown is in good statistical control,
because all points fall within the lower and upper control
limits. In this illustration, the sample size is ﬁve, and the
number of samples is 15.

ISBN No. 0-13-227271-7
Constants for Control Charts
Sample Size A2 D4 D3 d2
2 1.880 3.267 0 1.128
3 1.023 2.575 0 1.693
4 0.729 2.282 0 2.059
5 0.577 2.115 0 2.326
6 0.483 2.004 0 2.534
7 0.419 1.924 0.078 2.704
8 0.373 1.864 0.136 2.847
9 0.337 1.816 0.184 2.970
10 0.308 1.777 0.223 3.078
12 0.266 1.716 0.284 3.258
15 0.223 1.652 0.348 3.472
20 0.180 1.586 0.414 3.735
TABLE 4.3 Constants for Control Charts.

ISBN No. 0-13-227271-7
Control Chart Trends
Time
(c)
Time
(b)
Time
Tool changed
(a)
x
__
UCLx
_
LCLx
_
UCLx
_
LCLx
_
UCLx
_
LCLx
_
Averagediameter,x(mm)
_
Averagediameter,x(mm)Averagediameter,x(mm)
__
FIGURE 4.23 Control charts. (a) Process begins to become
out of control, because of factors such as tool wear. The
tool is changed, and the process is then in good statistical
control. (b) Process parameters are not set properly; thus,
all parts are around the upper control limit. (c) Process
becomes out of control, because of factors such as a sudden
change in the properties of the incoming material.

ISBN No. 0-13-227271-7
Micrometers
Display examplesDigital gages
Floppy
disk drive
Bar-code reader
CRT
Printer
(c)
(a) (b)
FIGURE 4.24 Schematic illustration showing integration of digital gages with a miniprocessor
for real-time data acquisition and SPC/SQC capabilities. Note the examples on the CRT
displays, such as frequency distribution and control charts. Source: Mitutoyo Corp.

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