seminar about Surface Roughness of material

1. Experiment No. 3
Surface Roughness
Presentation
Prepared by: lawk abdulrahman - rebwar ali –
Khogr kamal - Mhamad karim

2. • Outline
 Objective
 Count equipment's used.
 Explain the general theory.
 Experiment procedure.
 Surface Roughness Measuring Instruments
 A discussion on the experiment.

3. • Objective
 Studying the effects of cutting conditions on the surface
quality of a turned part.
 Parameter influence on the surface roughness
• Theory
 What are the main parameters that influence on the surface
roughness .

4. • Introduction
 Surface Roughness:- series of peaks and troughs of varying heights,
depths, and spacing. Surface roughness is defined as the shorter
frequency of real surfaces relative to the troughs. A product’s exterior
cover, a vehicle’s dashboard, a machined panel---the differences in
appearance, specifically whether something is shiny and smooth or
rough and matte, are due to the difference in surface roughness.
Surface roughness not only affects the object’s appearance, but it also
produces texture or tactile differences.
Ceramic surface Paper fiber Gold-plated surface
6000 × 1000 × 400 ×

5. • equipment's
 Lathe machine
 Surface roughness measuring instrument

6. • Equipment's (cont.)
 Double tools with specified approach angles and
different nose radius equals (r=0) and (r>0)
 Mild steel shaft

7. • Theory
Surface roughness: is the degree of unevenness of the
surface of a solid material.
Surface waviness: is the measurements of a more widely
spaced component of a surface texture.

8. • Theory (cont.)
 factors due to machining parameters, such as feed rate,
cutting speed, and depth of cut,
 factors due to cutting tool parameters, such as tool wear, tool
geometry, tool material, and tool coating,
 factors due to machining and machine tool conditions, such as
dry or wet turning, type of cutting fluid, method of fluid
application, machine tool rigidity, and chatter vibration, and
 factors due to workpiece material properties, such as
hardness, microstructure, grain size, and inclusions.
 the main parameters that influence on the surface
roughness

9. • Theory (cont.)

10. • Theory (cont.)
 The importance of surface finish on machine parts:
 For many engineering applications, the finish on a
surface can have a big effect on
1) the performance and
2)durability of parts.
 Rough surfaces generally wear more rapidly and have
greater friction coefficients than smooth surfaces.

11. Theory (cont.)
 Methods of surface finish measuring:
1)Pick to valley height methods: Peak to valley height
measures the maximum depth of the surface
irregularities over a given sample length and largest
value of the depth is accepted for the measurement.
R = Maximum peak to valley height
V=Valley
P = Peak

12. • Theory (cont.)
2) Root mean square method: The roughness is measured
as the average deviation from the nominal surface. Let,
h1,h2, ... are the heights of the ordinates and L is the
sampling length

13. • Theory (cont.)
3) The center line average method: The surface roughness
is measured as the average deviation from the nominal
surface.

14. • Surface Roughness Measuring Instruments
Method Contact type Non-contact type
Measuring instrument
Contact-type roughness
tester
Atomic force microscope
(AFM)
White light interferometer Laser microscope
Measurement resolution 1 nm < 0.01 nm < 0.1 nm 0.1 nm
Height measurement range
up to 1 mm
up to 0.04"
< 10 μm <
0.39 Mil
< a few mm
< a few fractions of an inch
< 7 mm
< 0.28"
Measurable range
a few mm a few
fractions of an inch
1 to 200 μm 0.04 to
7.87 Mil
40 μm to 15 mm
1.57 Mil to 0.59"
15 μm to 2.7 mm
0.59 Mil to 0.11"
Angular characteristic - Poor Fair Good
Data resolution - VGA VGA SXGA
Measurement site positioning - Optional Built-in optical camera Built-in optical camera
Damage to samples Contact Contact Non-contact Non-contact

15. • Discussion
 The depth of cut positively influenced surface roughness: roughness increased
with increase in depth of cut (Fig. 1). This trend is because higher values of
depth of cut produce more thrust force , which increases roughness due to a
greater deformation of the chip that is more violently pushed against the
machined surface.
Fig. a Fig. b
FIg. 1. Roughness plotted against depth of cut for turned annealed AISI
1020 steel, with a cutting speed of (a) 20 mm/min; and (b) 70 m/min.

16. • Discussion (cont.)
 Figure 2 shows the effect of feed rate on surface roughness. Similar to depth of
cut, roughness raises constantly with feed rates, but in a much greater slope.
This fact is related to the grooves left along the surface of the machined
sample as the cutting tool moves, whereby with an increase in feed rate a
greater separation between consecutive positions occurs. The experimental
results showed that the roughness differences corresponding to a fixed cutting
speed and depth of cut.
FIg. 2. Roughness plotted against feed rate for the turned annealed AISI
1020 steel,

17. • Discussion (cont.)
 Regarding the effect of cutting speed on surface roughness, the latter decreased
with higher values of cutting speed (Fig. 3). The main reason for this can be that
at higher cutting speeds the temperature increases because the material removal
is more violent, producing the phenomenon of softening that improves the cutting
process and thus diminishes superficial roughness when the turning is performed
at a low speed, a subsurface material fracture occurs, which contributes to
increasing surface roughness; by increasing the cutting speed this effect
disappears. The results showed differences in roughness for fixed feed rate and
depth of cut.
FIg. 3. Roughness plotted against cutting speed for the turned annealed AISI 1020
steel,. with a feed rate of (a) 0.05 mm/rev; (b) 0.15 mm/rev; and (c) 0.25 mm/rev.

18. • References
 [1] U.B. Abou El-Atta, Surface roughness assessment in three-dimen-
 sional machined surfaces for some manufacturing operations, M.Sc.
 Thesis, Industrial Production Engineering Department, University of
 Mansoura, Egypt, 1991.
 [2] E.C. Teague, F.E. Scire, S.M. Baker, S.W. Jensen, 3-Dimensional
 stylus profilometry, Wear 83 (1) (1982) 1±12.
 [3] T. Pancewicz, I. Mruk, Holographic contouring for determination of
 three-dimensional description of surface roughness, Wear 199 (1)
 (1996) 127±131.
 [4] B.G. Rosen, Representation of 3-dimensional surface topography in
 CAD-systems and image processing, Int. J. Mach. Tools Manuf. 33 (3)
 (1993) 307±320.