The document discusses surface roughness measurement and terminology, including common symbols used to describe surface finish. Methods for measuring surface roughness with a stylus are presented, as well as typical surface profiles produced by different machining processes. Formulas for calculating average roughness (Ra) and root mean square roughness (Rq) are also provided.

1. Chapter 33
Surface Roughness and Measurement;
Friction, Wear, and Lubrication
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

2. Surface Structure of Metals
Figure 33.1 Schematic illustration of a cross-section of the surface structure of
metals. The thickness of the individual layers depends on both processing
conditions and processing environment. Source: After E. Rabinowicz and B.
Bhushan.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

3. Terminology and Symbols
Related to Surface Texture
Figure 33.2 (a) Standard terminology and
symbols used to describe surface finish.
The quantities are given in μin. (b)
Common surface lay symbols.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

4. Surface-Roughness
Figure 33.3 Coordinates used for
surface-roughness measurement using
Eqs. (33.1) and (33.2).
!
Ra =
a + b + c + d +K
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
n
Rq =
a
2
+ b
2
+ c
2
+ d
2
+K
n

5. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Surface
Roughness
Figure 33.4 (a) Measuring surface roughness with a stylus. The rider supports the
stylus and guards against damage. (b) Path of the stylus in surface-roughness
measurements (broken line) compared to the actual roughness profile. Note that the
profile of the stylus path is smoother than that of the actual surface. (c) through (f)
Typical surface profiles produced by various machining and surface-finishing processes.
Note the difference between the vertical and horizontal scales.

6. Real Contact Area
Figure 33.5 Schematic illustration of the interface of two bodies in contact
showing real areas of contact at the asperities. In engineering surfaces, the
ratio of the apparent-to-real areas of contact can be as high as 4 to 5 orders
of magnitude.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

7. Ring-Compression Test
Figure 33.6 Ring-compression test between flat dies. (a) Effect of lubrication on
type of ring-specimen barreling. (b) Test results: 1. original specimen and 2. to 4.
increasing friction. Source: After A. T. Male and M. G. Cockcroft.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

8. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Friction
Coefficient Chart
Figure 33.7 Chart to determine friction coefficient from a ring-compression test.
Reduction in height and change in internal diameter of the ring are measured; then μ is
read directly from this chart. For example, if the ring specimen is reduced in height by
40% and its internal diameter decreases by 10%, the coefficient of friction is 0.10.

9. Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Worn
Surfaces
Figure 33.8 Changes in original (a) wire-brushed and (b) ground-surface
profiles after wear. Source: After E. Wild and K. J. Mack

10. Adhesive and Abrasive Wear
Figure 33.9 Schematic illustration of (a) two contracting asperities, (b)
adhesion between two asperities, and (c) the formation of a wear particle.
Figure 33.10 Schematic illustration of abrasive wear in sliding.
Longitudinal scratches on a surface usually indicate abrasive wear.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

11. Types of Wear in Hot Forging Die
Figure 33.11 Types of wear observed in a single die used
for hot forging. Source: After T. A. Dean.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

12. Lubrication Types
Figure 33.12 Types of lubrication generally occurring in
metalworking operations. Source: After W. R. D. Wilson.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.