Profile Measurement Full Report
Post on 09-Apr-2016
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CONTENTS
No Content Page
1.0 Title 2
2.0 Objective 2
3.0 Introduction 2
4.0 Apparatus 6
4.1 Industrial Apparatus 7
5.0 Experimental Procedure 8
6.0 Results and Data Analysis 9
7.0 Discussion of Results 12
8.0 Conclusion 14
9.0 Recommendation 15
10.0 References 16
1.0 TITLE : SCREW THREAD MEASUREMENT
2.0 OBJECTIVE
To measure the Major Diameter, Minor Diameter and the Effect Diameter of a Screw Plug
Gauge using Floating Carriage Measuring Machine.
3.0 INTRODUCTION
Floating Carriage Diameter is also commonly known as Effective Diameter Measuring
Micrometer. It use Bench micrometer to hold the workpiece as they look like they are
floating. This instrument is used for accurate measurement of Screw Plug Gauges
dimension such as Major Diameter, Minor Diameter and Effective Diameter. All these
dimensions such as Major Diameter, Minor Diameter and Effective Diameter. All these
dimensions have an important role in the screw plug gauges, since the accurancy and
interchangeability of the component depends on the gauges used. To minimize the effect
of slight errors in the micrometer screws and measuring faces, this micrometer is
fundamentally used as comparator.
Figure 2 : Thread Terminology
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a) Major Diameter : This is the diameter of an imaginary cylinder, co-axial with the screw,
which just touches the crests of an external thread or roots of internal threads. Also
known as Nominal diameter.
Referring to the Figure 3.0
If the micrometer reading over Standard Cylinder = R1
The micrometer reading over Screw Pug Gauge = R2
The diameter of Standard Cylinder = D1
Therefore, Major Diameter of Screw Plug Gauge, Dmajor= D1+(R1+R2)
Figure 3.0 : Screw Terminology
b) Minor Dimension : This is the diameter of an imaginary cylinder, co-axial with screw
which just touches the roots of an external thread. Also referred as root or core
diameter.
Referring to the figure 3.1
If the micometer reading over Standard Cylinder and Core Prisms = R3
The micrometer reading over Screw Pug Gauge and Core Prisms = R4
The diameter of Standard Cylinder = D1
Therefore, Minor Diameter of Screw Plug Gauge, Dminor= D1+(R3+R4)
Figure 3.1
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c) Effective diameter : Also known as Pitch Diameter. It is the Diameter of imaginary
Cylinder,co-axial with the axis of the thread and intersects the flank of the thread and
intersects the flanks of the thread such that width of the threads and width of spaces
between threads are equal.
Referring to the Figure 3
If the micometer reading over Standard Cylinder and Wires = R5
The micrometer reading over Screw Pug Gauge and Wires = R6
The diameter of Standard Cylinder = D1
Therefore, the Diameter with the wire D3= D1+(R5+R6)
Hence, the Effective Diameter, Deff = D3+P where P is the difference between Effective
Diameter and the diameter under the wires as shown in Figure 4
The P calue is a constant depending on the diameter of the wires (d), the pitch (p) and the
type of screw thread, it is found as follows:
Metric Threads (60°) P = 0.86602p –d
Whitworth threads (55°) P = 0.9604p – 1.16568d
British Association Threads (47.5°) P = 1.13634p – 1.43295d
Note : Pitch, p given is 3.5mm
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4.0 APPARATUS
1. A Floating Carriage Diameter Measuring Machine
2. A Set of Core Prism
3. A Set of Calibrated Screw Thread Measuring Wires (Wire Cylinders)
4. A Set of Metric Cylindrical Standards
5. Screw Plug Diameter
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4.1 INDUSTRIAL APPARATUS
1. Micrometer Screw Gauge
2. Vtd Image Processing Measuring Device for Internal Screw Thread Measurement
3. Tool Maker Microscope
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5.0 EXPERIMENTAL PROCEDURE
Major diameter
1. The position of the fiducial indicator and the micrometer anvil and the gauge to
be measure is between or within the range of the micrometer.
2. A suitable Standard Cylinder was placed between the center the Standard
Cylinder should have diameter within 1mm of the actiual major diameter of
workpieace. The micrometer deum reading R1 is been noted
3. The standard was removed and was replaced with the Screw Plug Gauge to be
measured. The micrometer drum R2 is been taken.
4. The major diameter, Dmajorwas evaluated
Minor diameter
1. The position of the fiducial indicator and the micrometer anvil and the gauge to
be measure is between or within the range of the micrometer.
2. A suitable Standard Cylinder was placed between the center. The selected
prism was been inserted between the standard and the anvils. The hanging
prism should be vertical. The reading on micrometer drum R3 was taken.
3. The standard was removed and was replaced with the Screw Plug Gauge to be
measured. The prism was inserted between the thread grooves and the anvils
and the micrometer reading R4 was taken.
4. The Minor Diameter, Dminorwas evaluated
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Effective Diameter
1. A suitable Standard Cylinder was placed between the center. The Standard
Cylinder should have diameter within 1mm of the actual diameter of
workpiece.
2. The wires selected were inserted in position between Standard Cylinder and
micrometer anvils. The wires were selected accordance N.P.L
recommendation. The reading on micrometer drum R3 was taken.
3. The Standard Cylinder was replaced with Screw Plug Gauge. Note the
micrometer reading R2 with the wre inserted in the thread grooves.
4. The Effectice Diameter, Deff was evaluated.
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6.0 RESULTS AND DATA ANALYSIS
Micrometer
reading
over
standard
cylinder,R1
(mm)
Micromete
r reading
over screw
plug
gauge , R2
(mm)
Micrometer
reading
over
standard
cylinder
and core
prisms, R3
(mm)
Micromete
r reading
over tread
and core
prisms, R4
(mm)
Micrometer
reading
over
standard
cylinder
and wire,
R5 (mm)
Micrometer
reading
over screw
thread and
wire, R6
(mm)
sleve 3.5 3.5 10.5 7.5 7.5 4.5
Thimble 0.47 0.35 0.12 0.04 0.46 0.18
Sub
Thimble
0.002 0.002 0.000 0.006 0.004 0.002
Sub Sleve 0.0016 0.0010 0.0002 0.0010 0.0020 0.0014
Total 3.9756 3.8530 10.6202 7.5470 7.9660 4.6832
Sample calculation
To determine R1
= Sleve + Thimbe + Sub-Thimble + Sub-Sleve
= 3.5 + 0.47 + 0.004 + 0.0016
=3.9756
*Repeat the same calculation method to find R2, R3, R4,R5,R6
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Major Diameter Of Screw Plug Gauge
Where D1 is diameter of standard cylinder = 30mm
Dmajor = D1 + (R2 - R1 )
= 30 + (3.8530 – 3.9756)
= 29.8774 mm
Minor Diameter Of Screw Plug Gauge
Dminor = D1 + (R4 – R3 )
= 30 + (7.5470 – 10.6202 )
= 26.9268 mm
Effective Diameter
Diameter under the wire, D3
D3 = D1 + (R6 – R5 ).
= 30 + (4.6832 – 7.9660 )
= 26.7172 mm
Metric Threads (60o), P = 0.86602p – d
Where is p = 3.5 mm and d = 2.083 mm
P = 0.86602(3.5) – (2.083)
= 0.9481 mm
Therefore,
Deff = D3 + P
= 26.7172 + 0.9481
= 27.6653 mm
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Comparison between theoritical value and experiment value
Theoritical Value ( mm ) Experimental Value (mm)
Major Diameter 30.000 29.8774
Minor Diameter 26.211 26.9268
Effective Diameter 27.727 27.6653
Percentage Error =
Experimental−TheoriticalTheoritical
Major Diameter Percentage Error =
29.8774−30.00030.000
Minor Diameter Percentage Error =
26.9268−26.21126.211
= 2.73 %
Effective Diameter Percentage Error =
27.6653−27.72727.727
= 0.22%
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7.0 DISCUSSION OF RESULTS
Based on the experiment, the geometrical parameter of the specimen, which is screw
plug gauge, was measured by using profile projector to check the profile. The screw plug
gauge parameters that are needed to measure are major diameter, minor diameter and
effective diameter. From the specimen, the dimension of ISO metric thread and identification
of threads can be known. For instant, M30-3.5-ISO 6H where M is metric standard thread
angle 60°, 30 is major diameter (mm), 3.5 is pitch of thread (P) and ISO 6H is matrix standard
table (tolerance).
During the experiment, the major diameters have been measured three times and the
average major diameter can be calculated. The average diameter is 29.959 mm and the actual
major diameter is 30.00 mm. The experimental major diameter varies slightly from the actual
major diameter. The percentage error can be calculated which is 24.83%. The average minor
diameters have been measured and calculated which is 24.89 mm but the actual minor
diameter is 25 mm. By comparing the actual minor diameter and the measured diameter the
percentage error is 19.94%. The effective diameter has been measured which is 27.67 mm
whereas the actual effective diameter is 27.5 mm.
There are many possibility ways that errors might occur in readings for each time the
readings are taken. There may occur due to miss alignment of the specimen since there is no
fix location to set the specimen in a correct coordinate. Other possible errors are parallax error
which occurred when eyes positioning is misplaced during setting the alignment. The error
also may be involved due to the system error where apparatus or machine is not well
calibrated. Besides, students’ familiarity towards the machine may affect the error where
students may not handle properly during the experiment.
Other than that, for the result obtained from the coins, we found 0.178mm diameter
marbles in each hole of the congkak on the 10 cents coin. As we counted all the marbles, the
total marbles that can be found on the 10 cents coin are 45. For the new 20 cents coin, we
found the B,N and M letter between the big flower and small flower. Other than that, for the
new 50 cents we also found the B,N and M letter at the floral design.
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There are necessary precautions which must be implementing to minimize the error
during the experiment. Students need to know how to handle properly throughout the
experiment and full attention must be given when conducting the experiment.
1. The surface of the specimen is needed to be clean from all contaminant such as oil,
dust, moisture and many more to ensure the accurateness of each reading.
2. The specimen must be placed at the correct position where the projector can show the
image clearly so that readings can be taken correctly.
3. Eyes level must be placed perpendicular to the readings to avoid parallax error.
8.0 CONCLUSION
In a nutshell, we can conclude that the experiment is successfully conducted as we has
fulfill the objective of the experiment which is to check the profile and measure the
geometrical parameters of the given specimen (screw thread) by using profile projector.
For the coins experiment, the purpose of the result obtained from the coins is for the
national security so that people cannot duplicate our coins from our country easily.
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From the profile projector, major diameter, minor diameter and effective diameter of
the specimen can be determined. By comparing between the experimental data and actual
data, the value that we obtained was closed to the standard value. Hence, we consider the
experiment is successful as the percentage errors are more likely below than one percent.
9.0 RECOMMENDATION
1. Other optical system than using profile projector is Coordinate Measuring Machine
(CMM) where the measurement data taken from CMM is more precise and less error
contribute to the experiment. The measurements are more likely defined by a probe
attached to the third moving axis. This machine can be manually controlled or it may
computer controlled.
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2. It is recommended for the profile projector to have a high resolution and a more
focusing lens to have a sharp view on the screw thread so that when alignment is being
adjusted, there would be no flaw or error exists throughout the experiment.
3. Before given to the students, it would be recommended if the technician could check
the screw plug gauge quality if any defects could detect prior to experiment. Thus, it
can minimize the errors.
10.0 REFERENCES
1. Serope Kalpakjian & Steven R. Schmid, Manufacturing Processes for Engineering
Materials, 4th Edition, Illinois Institute Of Technology, Prentice Hall, 2003.
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2. Serope Kalpakjian, W.R. Schmid, Manufacturing Technology and Fundamental, 5th
edition, Prentice Hall, 2004.
3. http://www.engineersedge.com/screw_threads_chart.htm
4. http://www.threadcheck.com/the-three-wire-method-of-measuring-pitch-diameter/
technicalinfo/
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