Introduction to Mechanical Measurements and Metrology taruian
Introduction to Metrology: Definition, objectives of metrology, Material Standards, Wavelength Standards, Classification of standards, Line and End standards, Calibration of End bars. Numerical examples.
Introduction to Mechanical Measurements and Metrology taruian
Introduction to Metrology: Definition, objectives of metrology, Material Standards, Wavelength Standards, Classification of standards, Line and End standards, Calibration of End bars. Numerical examples.
Dynamo meters are the electronic devices that are widely used to the purpose of force analysis in various field of operations. There is various types of dynamometers such as
Lathe tool dynamometer
Milling tool dynamometer
Drilling tool dynamometer
BAHIR DAR UNIVERSITYBAHIR DAR INSTITUTE OF TECHNOLOGY (BiT)FACULTY OF MECHANICAL AND INDUSTRIAL ENGINEERING Rapid Prototyping & Reverse Engineering [MEng6123]
Reverse Engineering
Coordinate Measuring Machine (CMM)
Coordinate Measuring Machines (CMM)
A Coordinate Measuring Machine (CMM) is an electromechanical system designed to perform coordinate metrology.
CMM is a device for measuring the physical geometrical characteristics of an object.
CMM Applications
Types of CMM
Cantilever Type
Moving bridge type
Fixed bridge type
Column type
Gantry type
Horizontal arm type
Portable type
1. Cantilever Type of CMM
2. Moving Bridge type
3.Fixed bridge type
4. Column type CMM
5. Horizontal arm type CMM
6. Gantry type CMM
Types of Probe
Contact probe
Hard probe
Switching probes
Measuring probes
Non-contact probes
Laser probe
Vision probe
Hard Probe
It has a variety of probe tip shape and size based on the application.
Ball/Spherical shape probe used for establishing surface locations.
Tapered or conical probe used for locating holes.
Cylindrical probe used for checking slots and holes in sheet metal.
Switching Probes
3. Measuring Probes
2. Vision Probe
CAUSES OF ERRORS IN CMM
Coordinate metrology is concerned with the measurement of the actual shape and dimensions of an object and comparing these with the desired shape and dimensions.
In this connection, coordinate metrology consists of the evaluation of the location, orientation, dimensions, and geometry of the part or object.
A Coordinate Measuring Machine (CMM) is an electromechanical system designed to perform coordinate metrology.
Surface roughness metrology deals with basic terminology of surface,surface roughness indication methods,analysis of surface traces, measurement methods,surface roughness measuring instruments such as Stylus Probe Instrument, Profilometer, Tomlinson Surface Meter ,The Taylor-Hobson Talysurf etc.This is very useful for diploma,degree engineering students of mechanical,production,automobile branch
Dynamo meters are the electronic devices that are widely used to the purpose of force analysis in various field of operations. There is various types of dynamometers such as
Lathe tool dynamometer
Milling tool dynamometer
Drilling tool dynamometer
BAHIR DAR UNIVERSITYBAHIR DAR INSTITUTE OF TECHNOLOGY (BiT)FACULTY OF MECHANICAL AND INDUSTRIAL ENGINEERING Rapid Prototyping & Reverse Engineering [MEng6123]
Reverse Engineering
Coordinate Measuring Machine (CMM)
Coordinate Measuring Machines (CMM)
A Coordinate Measuring Machine (CMM) is an electromechanical system designed to perform coordinate metrology.
CMM is a device for measuring the physical geometrical characteristics of an object.
CMM Applications
Types of CMM
Cantilever Type
Moving bridge type
Fixed bridge type
Column type
Gantry type
Horizontal arm type
Portable type
1. Cantilever Type of CMM
2. Moving Bridge type
3.Fixed bridge type
4. Column type CMM
5. Horizontal arm type CMM
6. Gantry type CMM
Types of Probe
Contact probe
Hard probe
Switching probes
Measuring probes
Non-contact probes
Laser probe
Vision probe
Hard Probe
It has a variety of probe tip shape and size based on the application.
Ball/Spherical shape probe used for establishing surface locations.
Tapered or conical probe used for locating holes.
Cylindrical probe used for checking slots and holes in sheet metal.
Switching Probes
3. Measuring Probes
2. Vision Probe
CAUSES OF ERRORS IN CMM
Coordinate metrology is concerned with the measurement of the actual shape and dimensions of an object and comparing these with the desired shape and dimensions.
In this connection, coordinate metrology consists of the evaluation of the location, orientation, dimensions, and geometry of the part or object.
A Coordinate Measuring Machine (CMM) is an electromechanical system designed to perform coordinate metrology.
Surface roughness metrology deals with basic terminology of surface,surface roughness indication methods,analysis of surface traces, measurement methods,surface roughness measuring instruments such as Stylus Probe Instrument, Profilometer, Tomlinson Surface Meter ,The Taylor-Hobson Talysurf etc.This is very useful for diploma,degree engineering students of mechanical,production,automobile branch
This is an introductory guidebook for Nastran SOL 200 and will enable new users with fundamental knowledge regarding numerical optimization and how it relates to structural optimization.
u can learn what is research, how to do research, research types, research methods, methodology, how to do literature survey, how to give an oral presentation and how to write thesis, research paper
it talks about the introduction of the book of Little book on Stoicism,
it talks mainly about the importance of Stoicism and main components of Stoicism
Actual cycles for internal combustion engines differ from air-standard cycles in many respects.
Time loss factor.
Heat loss factor.
Exhaust blow down factor.
Theoretical cycle based on the actual properties of the cylinder contents is called the fuel air cycle.
The fuel air cycle takes into consideration the following.
The ACTUAL COMPOSITION of the cylinder contents.
The VARIATION OF SPECIFIC HEAT of the gases in the cylinder.
The DISSOCIATION EFFECT.
The VARIATION IN THE NUMBER OF MOLES present in the cylinder as the pressure and temperature change
Vaccine management system project report documentation..pdfKamal Acharya
The Division of Vaccine and Immunization is facing increasing difficulty monitoring vaccines and other commodities distribution once they have been distributed from the national stores. With the introduction of new vaccines, more challenges have been anticipated with this additions posing serious threat to the already over strained vaccine supply chain system in Kenya.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Courier management system project report.pdfKamal Acharya
It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
3. Limits, Fits & Tolerances
• It is impossible to manufacture any part precisely to a given dimension.
• Even if by chance the part is exact, it is impossible to measure it accurately to prove it.
• If attempts are made to achieve perfect size the cost of production will increase tremendously.
Therefore, some permissible variation has to be allowed.
Limits
The dimension of a manufactured part can only be made to lie between maximum and minimum limits.
Tolerance
The permissible variation in size or dimension is called tolerance. The difference between the maximum and minimum
limit is known as tolerance zone.
System of writing tolerance
Unilateral: - Dimension of a part is allowed only on one side of basic size.
Example − 25+0.00
+0.02
, 25−0.02
−0.00
, 25+0.02
+0.05
Bilateral: - Dimension of a part is allowed both sides of basic size.
Example − 25−0.02
+0.02
, 25−0.03
+0.05
Terminologies
Shaft ― Not only refers to diameter of circular shaft but also to any external dimension of a component.
Hole ― Not only refers to the diameter of hole but also to any internal diameter of a component.
Basic Size ― It is the standard size of a part with reference to which the limits of variation of a size are determined.
Actual Size ― Dimension as measured on manufactured part.
Zero-line ― A straight line drawn to represent the basic size.
Deviation ― The algebraic difference between the actual size and basic size.
Upper deviation ― The algebraic difference between maximum limit of size and corresponding basic size.
Lower deviation ― The algebraic difference between minimum limit of size and corresponding basic size.
4. Fundamental Deviation ― It is one of that two deviations either upper or lower which is nearest tot the zero line for
either hole or shaft.
For hole it is denoted by Capital letters – A, B, C, …… ZA, ZB, ZC.
For shaft it is denoted by small letters – a, b, c, …… za, zb, zc.
Tolerance Grade ― It is an indication of degree of accuracy of manufacture & is designated by “IT” followed by a
number.
There are IT01, IT0, IT1, IT2, IT3, IT4, IT5, IT6, IT7, IT8, IT9, IT10, IT11, IT12, IT13, IT14, IT15.
Only tolerances from IT5 are used.
i = 0.45D(1 3⁄ )
+ 0.001D
D = √D1 × D2
𝐃 is geometric mean dimension of dimension steps between which is given basic size is lying.
D1 & D2 are given, D is in mm & 𝐢 is in microns(μ)
IT5 7i IT11 100i
IT6 10i IT12 160i
IT7 16i IT13 250i
IT8 25i IT14 400i
IT9 40i IT15 640i
IT10 64i IT16 1000i
Fits
It is the degree of tightness or looseness between 2 mating parts.
Clearance Fit ― Shaft is always smaller than the hole.
Interference Fit ― The minimum permissible diameter of the shaft is bigger than the maximum allowable diameter.
Transition Fit ― It lies midway between interference fit and clearance fit.
5. Allowance
It is defined as the minimum clearance between the mating parts, and is equal to difference between Lower limit of hole
and Upper limit of shaft (or) maximum interference between the mating parts.
Hole basis system
A hole is created first, shaft is designed based on hole.
Shaft basis system
A shaft is created first, hole is designed based on shaft.
Designation
Example
Find out the limits & tolerances for 50H7d8 and Dimension steps are 30 & 50?
Basic Size = 50mm
Fundamental Deviation for Hole is 𝐇 and tolerance is 𝐈𝐓𝟕.
Fundamental Deviation for Shaft is 𝐝 and tolerance is 𝐈𝐓𝟖.
D = √D1 × D2 = √30 × 50 = 38.7 mm
i = 0.45D(1 3⁄ )
+ 0.001D = 0.45 × 38.7(1 3⁄ )
+ 0.001 × 38.7 = 1.6μm
Tolerance for Hole = IT7 = 16i = 16 × 1.6μm = 25.6μm = 0.0256mm
Tolerance for Shaft = IT8 = 25i = 25 × 1.6μm = 40μm = 0.04mm
Fundamental deviation for hole is denoted as H which is equal to zero (0) i.e., Lower limit for hole is zero.
𝐥𝐢𝐦𝐢𝐭𝐬 𝐟𝐨𝐫 𝐡𝐨𝐥𝐞 = 𝟓𝟎 𝟎.𝟎𝟎
𝟎.𝟎𝟐𝟓𝟔
Fundamental deviation for shaft is given as = −𝟏𝟔𝐃 𝟎.𝟒𝟒
𝛍𝐦 = −16 × (38.7)0.44
= −80 μm
So lower limit of shaft = Fund. Deviation + Tolerance = −0.08 − 0.04 = −0.12mm
So upper limit of shaft = Fundamental Deviation = −0.08
𝐥𝐢𝐦𝐢𝐭𝐬 𝐟𝐨𝐫 𝐒𝐡𝐚𝐟𝐭 = 𝟓𝟎−𝟎.𝟏𝟐
−𝟎.𝟎𝟖
6. Limit gauges
These are the gauges which are used to check the limits of a part. They are of two types GO & NOGO gauges.
• When the component inspected by using GO & NOGO gauges, if the GO gauge is entering and NOGO gauge is not
entering into component, the component is said to be acceptable. If both the gauges are entering (or) both gauges
are not entering, then the component is said to be rejectable.
• GO gauge is always made for the maximum material limit of the component (Upper limit or Lower limit which is
farther from zero line), such that it always enters in the component (shaft or hole).
• The length of GO gauge is at least equal to the length of depth of the part to be inspected.
• NOGO gauge is made for the minimum material limit of the component such that it will not enter into the
component (Hole or Shaft).
• Plug gauges are used for holes and ring gauges are used for shafts.
Max material limit of a component ⇒ {
Smallest hole (L − limit of hole)
Largest shaft (H − limit of shaft)
} Checked by 𝐆𝐎 gauge
Min material limit of a component ⇒ {
Largest hole (H − limit of hole)
Smallest shaft (L − limit of shaft)
} Checked by 𝐍𝐎𝐆𝐎 gauge
Limit gauges for Holes-
Limit gauges for Shafts-
7. Taper gauges-
• If the top surface of component is lying in between the limits of the recess, the component is said to be
acceptable.
• If the top surface is going above the upper limit of recess (or) below the lower limit of recess the component is
said to be rejectable
Design of limit gauges
Basic Principle
According to basic principle no rejectable component is allowed to accept, but there is no problem in rejecting the
acceptable component.
Taylor’s Principle
• GO-Gauge is made for the maximum material limit if the component and it has to incorporate as many
dimensions (length, breadth & height) as possible to inspect in one stroke at one stage.
• NOGO-Gauge is made for the minimum material limit of the component. Separate NOGO gauges must be used for
each and every dimension i.e., separate for length and breadth and height.
• We can’t use separate limit gauges for GO gauge and 1 gauge for NOGO.
If we use following GO & NOGO gauges for hole of l=25.03 & b=40.06,
This component satisfies both GO & NOGO condition but it should be rejected actually but if Taylor principle (one gauge
for GO & separate gauges for diff. dimensions for NOGO) is used the NOGO gauge passes through hole which rejects the
component.
→ If Taylor principle is violated, then it accepts rejectable components and basic principle in design of limit
gauges will be violated.
8. Principle of provision of limits and tolerances on limits
Whenever the limit gauges used for inspection of the components also has to be manufactured in industry. Therefore, it
is difficult to manufacture the limit gauges to the exact dimensions.
It is required to provide limits and tolerances on limit gauges such that basic principle in designing of limit gauges
should not be violated.
Tolerances for limit gauge should be 10% of work tolerance (tolerance for hole or shaft)
Gear Tolerance = work allowance = 10% of work tolerance
On the limit gauges it is recommended to provide only unilateral tolerances.
Example (Hole)
Hole → 20−0.04
+0.06
mm ⇒ work tolerance = 0.06 − (−0.04) = 0.1 mm
Gear tolerance = 10% of work tolerance =
10
100
× 0.1mm = 0.01mm
Work allowance = 10% of work tolerance =
10
100
× 0.1mm = 0.01mm
Limit gauges are designed such that it may reject accepted components but should not accept rejectable components.
For GO limit gauge, as it has surface contact with component it is given wear allowance. For NOGO limit gauge, it has only
gear tolerance.
Example (Shaft)
9. Angular Measurement
Taper and Internal diameter measurement
tan
θ
2
=
O2A
O1A
=
r2 − r1
(h1 + r1) − (h2 + r2)
Two rollers of radius r1, r2 and height gauge
tan
θ
2
=
O2A
O1A
=
r2 − r1
(h2 − r2) − (h1 − r1)
tan θ =
y
h1 + r1
w = r1 + r1 sec θ + y
y = (h1 + r1) × tan θ
𝐰 = 𝐫𝟏 + 𝐫𝟏 𝐬𝐞𝐜 𝛉 + (𝐡 𝟏 + 𝐫𝟏) × 𝐭𝐚𝐧 𝛉
11. Single Dove tail
tan
θ
2
=
r2 − r1
(m2 − r2) − (m1 − r1)
Other provision one roller of radius ‘r’, slip gauges and micro meter.
tan θ =
S2 − S1
m1 − m2
Double dovetail
𝐭𝐚𝐧
𝛉
𝟐
=
𝐫𝟐 − 𝐫𝟏
(
𝐒 𝟏
𝟐 + 𝐫𝟏) − (
𝐒 𝟐
𝟐 + 𝐫𝟐)
12. Internal Diameter Measurements
Micro meter
Measurement of internal diameter using inside micro meter is similar to that of the outside diameter. But used for
measurement of plane inside diameter only.
Two balls of diameter ‘d’ and slip
D = 2d + s
Two balls of diameter d1, d2 and depth gauge
D = r2 + r1 + O1A
(O1A)2
= (O1O2)2
− (O2A)2
= (r1 + r2)2
− ((h1 + r1) − (h2 + r2))
2
Three balls of radius ‘r1’ and fourth ball of radius ‘r2’ and depth gauge
D
2
= r1 + O1A
D = 2(r1 + O1A)
O1A = √(O1O2)2 − (O2A)2
O1A = √(r1 + r2)2 + (H − (r1 + r2 + h))2
Pin method
OQ = OP + PQ
OP = √OP2 − AP2 = √L2 − (S 2⁄ )2
OP × PQ = AP × PB
PQ =
AP × PB
OP
=
S
2 ×
S
2
√L2 − (S
2⁄ )
2
13. Surface Finish
• Surface texture is a characteristic quality of an actual surface due to small departures from its original
geometric form which occurring at regular or irregular interval tend to form a pattern or texture on surface.
• Roughness is the short wavelength irregularities arising from the production process which comprise
individual scratch or tool marks.
• The Lay is tool marks or scratch marks taken collectively which characterizes the particular process.
• Waviness is the longer wavelength irregularities upon which roughness is super imposed. Waviness may be
induced by vibration, imperfect turning of a grinding wheel, chatter, heat treatment.
Quantitative parameters used in measurement of surface finish
Maximum Peak to valley height (Rt)
Rt = maximum peak to minimum valley = h4 − v5
As the value of Rt is increasing, the surface finish of given surface is
becoming poor.
If two surfaces have same Rt, it doesn’t mean they have same roughness.
Rt is not a good measure of roughness.
To overcome this, ten-point average (Rz) is used.
Rz =
(h1 + h2 + h3 + h4 + h5) − (v1 + v2 + v3 + v4 + v5)
5
Average Roughness (Ra)
This is also called ‘centre line average’ (CLA).
Ra =
A1 + A2 + A3 + A4 + ⋯ + An
L
=
∑ Ai
L
=
A
L
L = Sampling length
A = Total Area
Sampling length has some standard values like 0.025, 08, 0.25, 0.8, 2.5, 8.25mm. But 0.8mm, 2.5mm are commonly used
sampling lengths to find surface finish.
Ra =
|h1| + |h2| + |h3| + ⋯ + |hn|
n
×
1000
V. M
=
1
L
∫ h
L
0
dl
Ra =
∑ Ai
L
×
1
H. M
×
1000
V. M
14. Root mean square value (RMS)
RMS = √
h1
2
+ h2
2
+ h3
2
+ ⋯ + hn
2
n
= √
1
L
∫ h2
L
0
𝑑𝑙
RMS = 1.1Ra
⇒ Rz < Ra < Rt
⇒ Rz < Ra < RRMS < Rt
If two or more surfaces are having the same values of Ra, Rt, Rz indicates that both surfaces have same value of surface
roughness.
Form factor (K)
𝐾 =
𝐴𝑟𝑒𝑎 𝑜𝑓 𝑚𝑒𝑡𝑎𝑙
𝐴𝑟𝑒𝑎 𝑜𝑓 𝑟𝑒𝑐𝑡𝑎𝑛𝑔𝑙𝑒
=
𝐴 𝑚
𝐿 × 𝑅𝑡
𝐾 > 0.8 → 𝑔𝑜𝑜𝑑 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑓𝑖𝑛𝑖𝑠ℎ
Designation of Surface finish
ISO Method
Roughness values Ra
Micro meters (µm)
Roughness N
ISO Grade Numbers
𝐍−𝟐𝟓%
+𝟓𝟎%
50 N12 37.5-75
25 N11 18.75-37.5
12.5 N10 9.6-18.75
6.3 N9 4.8-9.6
3.2 N8 2.4-4.8
1.6 N7 1.2-2.4
0.8 N6 0.6-1.2
0.4 N5 0.3-0.6
0.2 N4 0.15-0.3
0.1 N3 0.08-0.15
0.05 N2 0.04-0.08
0.025 N1 0.02-0.04
Indian Method
Symbol Ra (μm) Roughness grade number
▽▽▽▽ <0.25 N1, N2, N3
▽▽▽ <0.252 to 1.6 N4, N5, N6
▽▽ 1.6 to 8 N7, N8, N9
▽ 8 to 25 N10, N11
∼ >25 N12
15. Representation of surface finish on drawings
Example
The meaning of symbol is on the given surface is the surface finish to be obtained is 1.2
to 1.4 microns with shaping operation, such that the direction of lay is ⏊lar to the length
of workpiece and after shaping (machining) the sample length taken to find surface
roughness is 2.5 mm.
Methods of finding Surface finish
Touch Inspection
This is a comparison method, we can only find which surface rough compared to other and cannot be accessed the
degree of surface finish and flaws can’t be detected.
Visual Inspection
Judging the surface finish by naked eye and is always likely to misleading when we go for smooth surface, so it is used
only for rough surface.
Surface Photograph
In this method magnified photographs of the surface are taken with different types of illumination.
Micro Interferometer
Here an optical flat is placed on the surface to be inspected and illuminated by a monochromatic source of light.
Wallace Surface Dynamometer
The surface finish can be measured through friction. A pendulum is allowed to swing over surface jus by touching, the
time of swing determines the roughness.
Reflected Light Intensity
It is based in the direction in which the light is reflected.
Direct Instruments
Tanlinson Surface meter
As the workpiece is moving the stylus is finding the peaks & valleys. The
arm is moving up and down which rotates the pointer due to friction. When
the pointer is rotating, it removes smoke from the glass producing
magnified version of surface structure. Now by measuring the heights of
irregularities the values of Ra, Rt & Rz can be calculated.
16. Surface Profilograph
As the workpiece is moving the stylus is finding peaks and valleys.
The L-shaped arm is rotating w.r.t pivot and it reflects the light
incident on it.
The reflected light incident on sensitized paper, because the drum is
connected to work table, it is also rotating and producing magnified
version of surface structure.
Talyserf
𝐡(peak/valley height) ∝ difference in 𝐄𝐌𝐅
As the workpiece is moving, the stylus is finding the peaks and valleys.
The arm is getting tilting and the gap between arm & AB and arm & AC
will be changing which produces different amounts of EMF in AB & AC.
This difference in EMF is directly proportional to the heights of the
irregularities. By connecting output of voltmeter to the amplifier it is
possible to get any amount of magnification.
Abbot’s Profilometer
It acts as a simple transformer. As workpiece moves the stylus finds peaks & valleys.
The Y type of stamp is moving up and down. So, that the length of the core in the
transformer is changing. EMF generated in the secondary winding of a transformer
is varying. By measuring EMF generated in secondary winding the heights of the
irregularities of a surface are estimated. i.e., height of irregularities re directly
proportional to EMF.
Piezo electric crystal
Height of irregularities ∝ EMF
As the work piece is moving the stylus is finding the peaks & valleys. The arm is
moving up & down. The movement of the arm produces deflection in the
piezoelectric crystal material.
Due to deflection EMF is induced in the piezoelectric crystal and by measuring
this EMF the heights of irregularities of the surface can be estimated.
Perthometer
Because the EMF generated by the piezoelectric crystal is in the order of milli or micro volts, the output of piezoelectric
crystal can be connected to computer. So that the computer can generate the surface irregularity diagram, measures the
heights of irregularities and calculate the values of Ra, Rt, Rz and giving the output in the form of surface irregularity
diagram along with the values of Ra, Rt, Rz. this is called Perthometer.
Plastic replica technique
Because of limited size of the platform the above equipment can’t be used for the measurement of surface finish of a very
large surfaces and also for finding surface finish of internal surfaces like hole. Because the arm and stylus are not
accessible to move inside the hole.
So, for above cases the surface finish can be measured by using plastic replica technique.
In plastic replica technique a heated thermos plastic piece is kept on the surface and apply a little amount of force so that
the soft plastic metal is flowing into the each and every surface irregularity. Continue to apply the force until the plastic
piece is brought down to room temperature. Now take out the plastic piece, the surface finish produced in the plastic
piece is same as that of the actual surface. Therefore, plastic piece is kept on the platform of any of the above surface
finish measuring equipment and measure surface finish, only thing is peaks becomes valleys and vice versa.