ROUND NUT CAULKING PROCESS OPTIMIZATION AND CRACK ELIMINATION DEPARTMENT OF MECHANICAL ENGINEERING, RGIT, BANGALORE. Page | 1 Chapter 1 COMPANY PROFILE 1.1Bosch India Bosch India a member of Bosch group of companies, Germany. Founded in 1951 then known as MICO pioneered the manufacture of auto spark plugs and diesel fuel injection equipment in India. Access to the international technology of Bosch, with a conscious commitment to quality of its more than 10,000 employees has made MICO the largest manufacturer of diesel fuel injection equipment in the country and one of the world’s largest. In addition, MICO manufactures industrial equipment, auto-electrical, hydraulic gear pumps for tractor applications, electric power tools, packaging machines and Blaupunkt car multimedia systems. An all-India network of more than 4,000 authorized representations ensures widespread availability of both products and after-sales service. From 2007 onwards MICO was called as Bosch India Ltd with a rich history of 125 years. All round the world, the Bosch name stands for competence and product diversity in the following sectors: automotive equipment, power tools and accessories, thermo- technology, household appliances, communication, automation and packaging machines. The “Workshop for Precision Engineering and Electrical Engineering” that Robert Bosch founded in Stuttgart, Germany, in 1886 has grown in the course of more than 100 years to become a global player.
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ROUND NUT CAULKING PROCESS OPTIMIZATION AND CRACK ELIMINATION
DEPARTMENT OF MECHANICAL ENGINEERING, RGIT, BANGALORE. Page | 1
Chapter 1
COMPANY PROFILE
1.1Bosch India
Bosch India a member of Bosch group of companies, Germany. Founded in 1951
then known as MICO pioneered the manufacture of auto spark plugs and diesel fuel injection
equipment in India. Access to the international technology of Bosch, with a conscious
commitment to quality of its more than 10,000 employees has made MICO the largest
manufacturer of diesel fuel injection equipment in the country and one of the world’s largest.
In addition, MICO manufactures industrial equipment, auto-electrical, hydraulic gear pumps
for tractor applications, electric power tools, packaging machines and Blaupunkt car
multimedia systems. An all-India network of more than 4,000 authorized representations
ensures widespread availability of both products and after-sales service. From 2007 onwards
MICO was called as Bosch India Ltd with a rich history of 125 years.
All round the world, the Bosch name stands for competence and product diversity in
the following sectors: automotive equipment, power tools and accessories, thermo-
technology, household appliances, communication, automation and packaging machines. The
“Workshop for Precision Engineering and Electrical Engineering” that Robert Bosch founded
in Stuttgart, Germany, in 1886 has grown in the course of more than 100 years to become a
global player.
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Worldwide, the Bosch group has 221,000 employees today. It has around 250
subsidiaries and associated companies in over 50 countries and a total of 227 manufacturing
sites. There are 18,500 scientists, engineers and technicians engaged in R&D. As a result,
Bosch applies for over 2,000 patents each year. This places the Company at the top in the
entire automotive industry.
In India, the Bosch group has about 18000 employees, and in business year 2007
achieved total consolidated revenue of over Rs 57000 million.
Bosch has grown phenomenally in India, way back since 1922 when the Illies
Company established a Bosch agency in he then British India. The founding of Bosch Ltd. In
1951 spurred off an accelerated growth in the automotive segment which has not stopped till
date. Bosch has strong and voracious presence in the country today at numerous locations in
diverse industry segments-both automotive and non-automotive.
In India, the Bosch Group is comprised of following companies
• Bosch Ltd (formerly ‘Motor Industries Co. Ltd.)
• Robert Bosch Engineering and Business Solutions Ltd.
• Bosch Chassis Systems India Ltd.
• Bosch Rexroth India Ltd.
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Since the first in-line fuel injection pump was produced by Bosch in 1927, countless
numbers of them have reliably kept diesel engines in motion. These “classics of diesel fuel-
injection technology” are still in use today on a large numbers of engines. Their particular
strengths are their durability and ease of maintenance.
Bosch Limited is the flagship of the Bosch Group subsidiaries in India. Founded in
1951, the company is India's largest auto component manufacturer and also one of the largest
Indo - German company in India. The Bosch Group holds close to 70-% stake in Bosch
Limited. The Company is headquartered in Bangalore with manufacturing facilities spread
across the country in five different locations. The plants are TS 16949 and ISO 14001
certified.
The company has excellent R&D and manufacturing capabilities with access to state
of-the-art technology from Bosch. Its strong local competencies, combined with its global
strengths, have given the company market leadership in most of the segment it operates in.
Bosch Limited manufactures and trades in the following three major business sectors
• Automotive Technology
Business divisions: Diesel and Gasoline Fuel Injection Systems, Blaupunkt Car
Multimedia Systems, Auto Electrical and Accessories, Starters and Motors, Energy
and Body Systems.
• Industrial Technology
Business divisions: Packaging Machines, Special Purpose Machines
• Consumer Goods and Building Technology
Business divisions: Power Tools, Security Systems
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1.2 Milestones
1951 - Establishment of the company 1953 construction of the first factory building at
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1999 – Inauguration of Jaipur plant and manufacture of Blaupunkt car audio systems in
India.
2000 - Inauguration of Mico Application centre (MAC), Bangalore plant adjudged “All India
Best Establishment” for the 25th time, Manufacture of one-millionth auto electrical unit at
Naganathapura Plant and QS 9000v certification for Jaipur Plant.
2001 - Launch of Terra-25 packaging machine.
2002 - Production of 25-millionth single-cylinder pump, launch off first Bosch Car Service
outlet, ISO 9001:2000 certification for industrial equipment packaging technology and power
tools divisions and ISO 14001 (Environmental Management System) certification for
Bangalore Plant.
2003 - Production of 10-millionth inline-A pump, TSI6949 certification for all Mico Plants,
ISO 9001:2000 certification for car multimedia division and Blaupunkt crosses the 100,000
mark of car radios that have been sold since its inception.
2004 - ISO 14001:1996 certification for Environmental Management System for all the
plants, Launch of BVK2000A-World’s fastest candy wrapping machine, Launch of Terra 40
packaging machine, introduction of capsule packaging as an anti-spurious measure for
elements, nozzle and delivery valves and launch of ‘Plena Voice Alarm System’ by Bosch
security Systems for emergency evacuation.
2006 - Launch of Bosch brand at Auto Expo 2006 Inauguration of the Common Rail Pump
manufacturing facility at Bangalore
2007 - Inauguration of the Common Rail Injector manufacturing facility at Nasik
Verna. Goa Plant inaugurated for Bosch Packaging Technology Announcement to change
company’s’ name from Motor Industries Company Limited to Bosch Limited. Thus
migrating the brand name MICO to BOSCH.
2008 -Company name changed from Motor Industries Company Limited to Bosch Limited
2009 - Won NDTV Car & Bike Award for Auto Component Manufacturer of the Year.
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1.3 Quality Principles
a) We want satisfied customers. That is why the highest quality of our products and service
is one of our major corporate objectives. This also applies to the quality of the work
carried out in our name by our trading partners, and in their sales and organizations.
b) The customer is the judge of our quality. His or her verdict on our products service is
decisive.
c) Our quality goal is always “zero defects” or “100% quality”.
d) Not only do our customers assess the quality of our products, but also the quality of our
services. Deliveries must be on time.
e) Enquiries, offers, samples and complaints must all be dealt promptly. It is imperative that
agreed deadlines be met.
f) Each employee in the company contributes towards achieving our quality Member of the
Board- to ensure that their work is the highest standard. Anyone who identifies a problem
which may jeopardize quality, but does not have the authority to remedy he must report
the matter immediately to his superior.
g) All work must be without defects from the very beginning. The not only improves
quality, but also reduces costs. Quality increases cost effectiveness.
h) The quality of our products also depends upon the quality of sourced parts. Demand the
highest quality from suppliers, and support them in adhering to our mutual quality goals.
i) Even when painstaking care has been taken, defects can occasionally happen. This is why
we have introduced numerous proven methods and procedures to identify defects at an
early stage.
j) Ensuring that quality goals are achieved is an important management duty. When
assessing the performance of our employees, particular emphasis is placed on the quality
of their work
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1.4 Customers Worldwide
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Chapter 2
DIESEL ENGINE AND COLD STARTING
2.1 Diesel Engine
The diesel engine also known as a compression-ignition engine is an internal
combustion engine that uses the heat of compression to initiate ignition and burn the fuel that
has been injected into the combustion chamber. This contrasts with spark-ignition engines
such as a petrol engine or gas engine, which use a spark plug to ignite an air-fuel mixture.
Fig 2.1 a v-8 diesel engine
2.1.1 Function
Diesel engines are self-igniting, or in other words the injected fuel ignites without an
ignition spark being necessary. The work cycle is triggered in three stages:
1. Pure air is sucked in first.
2. This air is compressed to 30–55 bar – heating it up to 700–900 °C.
3. Diesel fuel is injected into the combustion chamber.
The high temperature of the compressed air triggers self-ignition, the interior pressure
rises and the engine performs its work. Compared to gasoline engines, self-igniters require
more elaborate injection systems and engine structures. The first diesel engines were not
particularly comfortable or fast drive units. When cold, the hard combustion sequence made
them very loud. They were characterized by a higher performance weight, a lower
performance per liter of capacity and poorer acceleration behavior.
All of these disadvantages have been eradicated by continual development of the injection
technology and the glow plugs. Diesel is now regarded as an equal or better drive source.
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2.2 Cold Starting
A cold start is an attempt to start a vehicle's engine when it is cold, relative to its
normal Operating temperature, often due to normal cold weather. A Cold Start situation is
commonplace, as weather conditions in most Climates will naturally be lower temperature
than typical operating temperature of an engine.
2.2.1 Causes of cold start
More effort is needed to turn over a cold engine for multiple reasons:
• The engine compression is higher as the lack of heat makes ignition more difficult
• Low temperatures cause engine oil to become more viscous, making it more difficult
to circulate.
• Air becomes denser the cooler it is. This affects the air-fuel ratio, which in turn
affects the flammability of the mixture.
2.2.2 Solution to cold start
In order to ensure that the start does not take an inordinate period of time or may
indeed be impossible at lower temperatures, aids are used to support the cold start. They
compensate the poorer starting conditions and initiate the punctual and even ignition for
stable combustion. One component of the cold start support is the glow plug. Thermal
energy, generated by electricity, flows into the combustion chamber to create the ideal
ignition conditions for the injected fuel. If an engine has a divided combustion chamber, it is
indispensable as a cold start aid in order to ensure starts in frequent temperature ranges of 10-
30 °C. Due to the considerable deterioration of the start quality at temperatures below
freezing point, the glow plug is also used for diesel engines with direct injection.
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Chapter 3
GLOW PLUG AND ITS ASSEMBLY SEQUENCE
3.1 Product description
Diesel engines, unlike petrol engines which rely on a spark to ignite the air-fuel
mixture, function due to the auto-ignition of diesel fuel when subjected to high pressures.
Under high pressure, the temperature of the diesel fuel increases to a point where the fuel
self-combusts. In cold weather however, this temperature is not always achieved and glow
plugs assist by heating the air-fuel mixture to assist in cold starting. Heating unit is the major
contributor for heat generation whereas the housing provides means of holding the heating
unit very firmly on the engine cylinder as shown in figure.
3.1.1 Purpose:
Diesel engines have spontaneous ignition, which means that the injected fuel does not
require a spark to ignite it. The high temperature, which occurs as a result of compressing
intake air, is sufficient to ignite the fuel. However, in cold conditions, more energy is
required to help ignition at start because both the intake air and the engine itself are colder
and compression and pumping losses are higher too. Therefore, in diesel engines, glow plugs
are a key factor for every cold start. At low ambient temperatures they heat the combustion
chamber sufficiently to allow stable combustion conditions for the injected fuel. The 'glow
pencil' (rod-like heating element) of the glow plug (which fits in the cylinder head) protrudes
into the glow chamber or pre-combustion chamber. It is most effective when positioned on
the edge of the mixing vortex. If it protrudes too far into the combustion chamber, it impedes
the preparation and formation of an ignitable fuel/air mixture.
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3.1.2 Working Principle:
In older generation diesel engine car, unlike in gasoline engine car, the operator did
not turn the key to the start position and had the engine running immediately. Instead, the
operator turned the key to the on position. The glow plug rely switched on the glow plugs,
and a light on the instrument cluster illuminated as shown in figure , this process is called
preheating or glowing.
If the car had been running very recently, or if the ambient temperature was hot, the
wait to start light might not come on; in this case, the operator may proceed to turn the key to
the start position and start the engine without having to wait. When internal sensor detect that
the core of the engine block has reached a certain designated temperature, when a certain
amount of time elapses, the glow plug relay switches off the wait to start light. A preheating
cycle usually lasts for 2 to 5 seconds. The operator then proceeds to turn the key to start
position, as in a gasoline engine. The glow plug relay switches off the glow plugs after the
engine is running (or, in older cars, at the same time the “wait to start” light goes out). In
some newer cars, glow plugs continue to operate for upto180 seconds after engine start to
keep the engine within emission regulations, as combustion efficiency is greater.
3.1.3 Parts of a Glow plug:
The above figure shows the complete design of element sheathed metal glow plug.
The glow plug consists mainly of the plug body, the tubular heating element or glow tube (4)
with the heating coil (1) and regulating coil (3) and the connecting bolt(7) . The tubular
heating element consist of hot gas and corrosion resistant element sheath which encloses a
filament surrounded by a compressed electrically insulating magnesium oxide powder(2) that
conducts heat very well .
During mechanical compression, the powder is pressed so tightly together that the
coli rest as if it were cast in cement. This makes it so stable that the thin wires of the heating
and regulating coil can permanently stand up to all oscillations. The filament is made up of
two resistors in series, the heating coil and regulating coil. The heating coil is welded into the
cap of the element sheath for grounding.
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The regulating coil is in contact with terminal stud; its resistance is characterized by a
large temperature co-efficient, which establishes the connection to vehicle electrical system.
The non-corrosive glow tube is pressed gas tight into the housing (5). Additionally, the plug
is sealed to the connecting point by an O-ring (8) or a plastic part.
The glow plug takes the electrical energy from the battery. An electronic glow time
control device deals with the control. The filament is made of high temperature resistance
material (kanthal). A glow plug has a housing provided with an internal passage which is
bounded by an inner circumferential surface and has an open front end. An elongated glow
pin is carried by the housing rigid therewith and extends with radial clearance through the
passage .a forward portion of the pin is located inwardly adjacent to the open front end of the
passage and ignition of fuel takes places in the region of this forward front end portion.
Round pin connected (10) provides connection between connecting bolt and vehicle
connecting system
3.1.4 Characteristics of the glow plug:
� Shorter heating time:
Glow plug must ensure a high temperature to support ignition in as short a
time as possible and must maintain this temperature regardless of, or align it to suit,
the ambient conditions.
� Compact form:
Modern diesel engines with common rail or multi point fuel injection and 4-
valve technology can offer only limited space , however, this means the space
required by the glow plug must be minimized, which leads to very thin and long form
� Exact alignment to suit the combustion chamber:
The glow plug must be protruded sufficiently into combustion chamber or pre
chamber. This is the only way to provide the heat right where it is needed. It must not
protrude too far into the combustion chamber also.
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3.1.5 Functions:
Strong current of 11v flows through the connecting bolt to the regulating coil and to
the heating coil at the start of pre-heating. It heats up to the starting temperature
(approx. 850°C) in 2-5 seconds and makes the heating zone glow. This raises the temperature
of regulating coil even more, which was already hot due to electric current.
In the start phase the glow spreads rapidly right up, close to the plug body after 2-5
seconds and temperature increases above (1000°C) and become constant. Consequently,
electrical resistance rises and current is reduced to such an extent that glow tube cannot be
damaged. This means that the glow plug cannot overheat. After the engine starts, in the after
glow or post glow phase the glow plug continues to operate more than 180 seconds to
improve the initial operation and to reduce blue smoke emission and combustion noise.
The current draw and total heating output of glow plug decreases the temperature
approaches steady state conditions. An alloy is used in the glow plug ; its resistance grows
with temperature . This means that the regulating coil can be designed in such a way that it
permits greater current to pass into the heating coil at the start, once the target temperature
has been reached. This means that the start temperature is reached faster, and remains safely
within the permitted range due to the rather controls.
The phases of glow plug and the heating behavior of glow plug is shown below.
Note:
� Rapiterm glow plugs operate with 7V
� High speed metal glow plug operates with 5V.
� Metal glow plug operates with 11V.
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3.2 Introduction to Glow Plug Manufacturing Operations
3.2.1 Process Route:
The figure below shows the process route of glow plug employed at the company.
The phase 1 of process route is involved in the assembly of the heating unit and phase 2 for
housing unit. A total of 260m2 space is occupied by two phases. The main project focus is
based on the Caulking operation.
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3.2.2 Components of Glow Plug
The heating unit of glow plug consists of four major components; Connector, Heating
element, Tube and O-ring shown in figure. The assembly sequences of these components are
explained further in this chapter.
1. Caulking:
Caulking is one of several different processes to seal joints or seams in various
structures and some types of piping. In this process the connector being in form of a pipe and
the gap between the heating element and the connector is sealed by caulking process as
shown in figure.
The figure depth being 0.15 ± 0.05mm.
2. Tig Welding:
The glow is TIG welded to the heating element as shown in figure after the caulking
process. The parameters in this process are welding bead being 0.6mm, a resistance of 1800
± 1500,
current of 26-28 Amps and Argon gas 10-15 Lt/min as a shielding gas used in this process.
3. Oven:
The main function of this process is to remove all the moistures caused from manual
handling of the tig welding parts. In this process, both the tig welded components and the
MgO powder is dried to 300°C for 10 minutes in drying oven. No chemical and mechanical
properties changes in due course of heating time
4. MgO filling and O-ring Pressing:
The aim of this process is to fill MgO powder in between the annular spaces of
Nicrofer tube and connector for easy conduction of temperature. In this the collector and tube
are held tightly by two fingers and stretched to specified length as shown in figure and
vibrated for tight and uniform compaction of the powder, later the viton ring is inserted in
and presses tightly between the connector and Nicrofer tube; this is done to prevent MgO
from spilling.
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5. Pre-Swaging:
The main function of this process is to ensure MgO powder is within the tube. In this
process, swaging i.e. reduction of the outer diameter of tube will take place. This reduction
process is very critical for next process. The reduction in the diameter is the result of
continuously rotating swaging dies on the stationary heating unit as shown in figure
6. Swaging:
Multistage swaging process is the one of the most critical and core of heating unit.
The name itself indicates Swaging of heating unit takes place at different levels under single
machine. Swaging is one of the core process to of the heating unit. Swaging involves
continuously rotating swaging hammers that will continuously hammers the part fed in the
machine. For the swaging process to work efficiently the work parts remains stationary
against the swaging dies. Swaging process results in the reduction in entire body diameter i.e.
called as “Longitudinal strain” and also results in increase in total length of heating unit
length called “Lateral stain”.
7. Facing:
The main aim of this process is to cut the total length of heating unit after swaging to
desired length as per customer requirements. Simple cutting and chamfering machine is
dedicated to this process.
8. Thread Rolling:
The main function of this process is to knurl the heating unit as per DIN 82 RGE 05
with 450 chamfer angle. This chamfer is necessary to hold the terminal cap as shown on parts
of glow plug.
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9. X-Ray Inspection:
X-ray inspection is an Non Destructive technique where the glow plugs are placed on
Acrylic Tray as shown in figure and the tray is placed inside a X-ray machine. After viewed
with help of computer the L3 length is checked for rejections. The X-ray machine takes 10-
75 seconds to scan each Acrylic Tray assembly with glow plugs.
10. Visual Inspection:
Visual inspection of glow plugs are checked for rust, crack and damage,
O-ring projection(±) 1.0mm ,bulge burs and uniform weld cup on the tube
11. Assembly:
Assembly mainly includes hydro pressure pressing (pressure 4-6 bar and load = 150
to 600kgf) of the housing onto the heating unit, gas tightness is used to check for leakages
and mounting of the terminal cap. The housing is indicated in green color and terminal cap in
brown as shown in figure.
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3.2.3 Process Flow Chart of Glow Plug
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Chapter 4
Round nut in glow plug
4.1 Round nut (rim nut)
A round nut is a small flat piece of metal made of aluminum with a threaded hole. It
is fastened onto connector pin of glow plug and it has a distinctive shape compared to the
normal nuts which are typically square or hexagonal. The shape of the nut is similar to that of
a pulley and it has a groove on its surface. The groove is such that the tip of caulking tool can
fit into it.
Fig 4.1(a) Side view
Fig 4.1(b) Top view
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4.1.1 Geometry of the Round Nut
Fig 4.2 Drawing of the nut.
Several types of glow plugs are being manufactured in Bosch; they differ from each
other depending on the vehicle in which they are used. They are classified based on their dia,
i.e. dia 4, dia 5 and dia 6 glow plugs which are used in different vehicles. The above given
geometry is of dia 5 glow plug.
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4.1.2 Materials Used In Round Nut
Aluminium round nuts are used in Bosch.Aluminium is a relatively soft, durable, lightweight, ductile and malleable metal with appearance ranging from silvery to dull gray, depending on the surface roughness.
4.1.3 Properties of Aluminum:
a) Light Weight
Aluminium is a very light metal with a specific weight of 2.7 g/cm3, about a third that of
steel. For example, the use of aluminium in vehicles reduces dead-weight and energy
consumption while increasing load capacity. Its strength can be adapted to the application
required by modifying the composition of its alloys.
b) Corrosion Resistance
Aluminium naturally generates a protective oxide coating and is highly corrosion resistant.
Different types of surface treatment such as anodising, painting or lacquering can further
improve this property. It is particularly useful for applications where protection and
conservation are required.
c) Electrical and Thermal Conductivity
Aluminium is an excellent heat and electricity conductor and in relation to its weight is
almost twice as good a conductor as copper. This has made aluminium the most commonly
used material in major power transmission lines.
d) Ductility
Aluminium is ductile and has a low melting point and density. In a molten condition it can be
processed in a number of ways. Its ductility allows products of aluminium to be basically
formed close to the end of the product’s design.
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4.1.3 Position of the Nut:
The assembly process of the glow plug involves torqueing of the round nut onto the
connector bolt of the glow plug and then caulking. The round nut is thus positioned on top of
the glow plug where electrical system of the vehicle connects to the glow plug.
Fig 4.3 Nut on the glow plug
As shown in the fig 4.3, the round nut is fastened onto the connecting bolt and it is in contact
with the insulating washer. This glow plug assembly is then placed vertically inverted into
the caulking fixture such that the nut will sit onto the bottom screw of the fixture. Shown in
fig 4.4.
Fig 4.4 glow plug inside fixture
Nut
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Chapter 5
CAULKING
5.1 Caulking process
Caulking is one of several different processes to seal joints or seams in various
structures and some types of piping. The oldest form of caulking is used to make the seams
in wooden boats or ships watertight, by driving fibrous materials into the wedge-shaped
seams between boards. A related process was formerly employed to join sections of cast iron
sewage pipes.
5.1.1 Definition of caulking
Caulking is also the term to describe the process used to make riveted iron or
steel ships and boilers watertight or steam tight.
The same term also refers to the application of flexible sealing compounds to close up gaps
in buildings and other structures against water, air, dust, insects, or as a component in fire
stopping. In the tunneling industry, caulking refers to the sealing of joints in segmental
precast concrete tunnels, commonly by using concrete.
5.2 Caulking of Round nut
As we know round is fastened to the round pin connector (connection terminal) by
using twisting force. Later for further stability and to avoid loosening up of round nut during
actual working round nut is subjected to caulking process.
The caulking takes place inside the groove of round nut. The round nut is caulked on two
sides which are opposite to each other.
After caulking a small dent like structure is visible at the caulked region. Later it will be sent
inspection department.
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Fig 5.1(a) nut before caulking Fig 5.1(b) nut after caulking
Fig 5.2 cross section of round nut.
5.3 Need for caulking
The glow plug is used in diesel engines. The vehicles with diesel engines being heavy
duty vehicles there will be very high vibrations caused during working (movement) and thus
there are chances of loosening of round nut.
Loosening of round nut causes several problems in vehicles like
� Short circuit of wires.
� Unable to start during cold conditions due to no proper connection.
� Takes more time to produce heat.
To avoid above conditions caulking of round nut is very important.
ROUND NUT CAULKING PROCESS OPTIMIZATION AND CRACK ELIMINATION
DEPARTMENT OF MECHANICAL ENGINEERING, RGIT, BANGALORE. Page | 25
5.3.1 Advantages of caulking of round nut
� It provides more stability and secures the fastening.
� It prevents loosening up of round nut.
� Thus avoid short circuiting of wires.
� Helps round nut to withstand high vibration force acting on it during working.
5.4 Components used in caulking process
All the components used in caulking process is enclosed in a rigid fixture. It consists
ROUND NUT CAULKING PROCESS OPTIMIZATION AND CRACK ELIMINATION
DEPARTMENT OF MECHANICAL ENGINEERING, RGIT, BANGALORE. Page | 43
Control chart:
Control charts for analyzing the stability of a process. As shown in the graph , the points marked in blue are controlled , which are within the range.
The points marked red are uncontrolled and are exceeding the range