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BHARATI VIDYAPEETH DEEMED UNIVERSITY
COLLEGE OF ENGINEERING, PUNE.
Department of Mechanical Engineering
SEMINAR REPORT ON
CYLINDER HEAD GASKETS
SUBMITTED BY:
MR. TUSHAR DHONDIRAM JADHAV
M.TECH SEMESTER III (MECHANICAL)
UNDER THE GUIDANCE OF:
PROF. D. G. KUMBHAR
(2012 – 2013)
1
BharatiVidyapeeth Deemed University
College of Engineering, Pune – 4110043
CERTIFICATEThis is to Certify that Mr. Tushar Dhondiram Jadhav have carried out a Seminar
report entitled on, “Cylinder Head Gaskets” in college is submitted by in partial
fulfillment of the requirements for the award of degree of Master of Technology in
Mechanical (CAD/CAM) course of Bharati Vidyapeeth Deemed University, College of
Engineering, Pune at college during academic year 2012-2013.
Date:
(Prof. D.G. Kumbhar) (Mr.V.K.Kurkute)
Guide PG Co-ordinator
Prof.Srinivasan Examiner Head of the Department
2
ACKNOWLEDGEMENT
First of all I thank the almighty for providing me with the strength and courage
to present the seminar.
I avail this opportunity to express my sincere gratitude towards
Prof. N. S. Sreenivasan, head of mechanical engineering department, for permitting
me to conduct the seminar. I also at the outset thank and express my profound
gratitude to my seminar guide Prof. D. G. Kumbhar and PG Co-ordinator Prof. V. K.
Kurkute, for their inspiring assistance, encouragement and useful guidance.
I am also indebted to all the teaching and non- teaching staff of the
department of mechanical engineering for their cooperation and suggestions, which
is the spirit behind this report. Last but not the least, I wish to express my sincere
thanks to all my friends for their goodwill and constructive ideas.
Mr.Tushar Dhondiram Jadhav
M. Tech. Mech. (CAD/CAM)
Sem – III
Examination Seat No. : 1211470002
3
Abstract
Gaskets are used to seal leakages between two joints. There has been great
research and development in the field of gasket in late 20 th century. Gasket
development started from simple asbestos sealing and now has reached the stage
where gaskets with multi metallic composition are used in large production.
Head cylinder gaskets have multiple functions bearing pressure, temperature
and do sealing for oil and coolant as well. Different head gaskets have been used
different time periods in the 20th century.
4
Index
Contents Page No.
1. Gasket an introduction 6
2. Cylinder Head gaskets 8
3. Head gasket – Time Zones 12
4. Head gasket – Combustion Sealing 18
5. Bibliography 28
5
Chapter 1
Gasket an Introduction
6
Chapter 1
Gasket an Introduction
Definition: “Any of wide variety of seals or packing’s used between matched
machine parts or round pipe joints to prevent the escape of gas of fluid.”
Flat Gasket for industry in the modern sense were invented by Austrian
engineer Richard Klinger about 100 years ago, based on asbestos and rubber. Due to
their success, these first products attracted numerous imitators, and soon many
materials of various qualities were available. The number of different sealing types
was considerably increased with the development of asbestos free gaskets
The important material properties for gasket materials are:
1. Loading capacity
2. Sealability
3. Elastic behaviour of a gaskets
4. Capacity for chemical resistance against media.
7
Chapter 2
Cylinder Head gasket
8
Chapter 2
Cylinder Head gasket
The tensile strength of a material, expressed by the breaking or tensile strength, is
not of particular importance for quality consideration, because no tensile forces are
usually exerted on gasket, only pressure forces cylinder head gasket
The cylinder head gasket is the most critical sealing application on ay engine.
Typically, it must simultaneously seal:
A. High combustion pressure and temperature
B. Mixture of water and anti- freeze, with its high wicking and wetting.
C. Lubricating oil, with its associated detergents, additives and variable
viscosities either built in or changed with season.
In addition, the head is structural component of engine, i.e. combustion chamber
is formed by the head,block, piston, piston ring and gasket. The gasket shares the
same strength requirements as the other combustion chamber components
The head gasket is used many times either to meter or to block coolant flow for
proper cooling of the engine. It also seals the block- liner intersection in wet liner
engine. Its compressed thickness effect the compression ratio of the engine, and
the importance of the compression ratio control to emission levels, specially in
diesel engines is well known.
Today’s engine manufactures require that the head gasket perform without a
rhetorical operation, seal for extensive periods of time, and “come off clean” so
no scraping of the mating flanges is necessary when the engine is repaired. The
head gasket sometimes needs very high thermal conductivity to transfer heat
efficiently between the block and head. It must be constructed so as to permit
rough handling and extended storage life. The gasket must also performin
temperature ranges well below freezing at start up to over 700 degree Fahrenheit
9
in the combustion seal area during engine operation. It must accept occasional
instances of detonation without failure. This is especially true today, when
premium fuel are sometimes un available and detonation associated with regular
or no lead gas occurs
The gasket must typically withstand combustion pressures of 1000psi in
naturally aspirated spark engines and 300 psi or higher in turbocharged diesel
engines. T0odays gasket must also accommodate greater motions, both thermal
and mechanical, because lighter weight casting and lighter- weight less rigid
materials are being utilized for cylinder heads and engine blocks. As a result of all
these requirements, the gasket is a verity complex product.
For head gasket to seal properly, the head bolts must apply a sufficient
clamping force on the gasket. As the bolts must apply sufficient clamping force on
the gasket. As the bolts are tightened, the gasket is squeezed to provide a seal
between the cylinder head and the engine block deck. Allgaskets relax a certain
amount. This is true even with “no torque” gaskets. The ideal no torque gasket
design compresses sufficiently at installation to conform to and seal minor
surface imperfections. At the same time, the design minimizes relaxation and
maintains adequate clamping force over a long period of time.
By contrast, a retorque designed will relax excessively. This reduces the
tension on the bolts and results in excessive torque loss. If one doesn’t
retorquethis type of gasket engine could lose compression and fluid or
combustion gas leakage will result. Leaking combustion gases can damage the
gasket surface or cause the blow out of an entire gasket section. Loss of coolant
could result in engine overheating leading to engine damage. In addition, a
retorque operation is costly. Any technician knows how time consuming engine
work has become. Tighter engine compartments and emission and electronic
controls make many engines extremely difficult to work on. With a retorque head
gasket, the head bolts typically need to be retorqued up to the engine has been
10
warmed and again after several hundred miles the time needs to gain access to
the head bolts for retorquing will quickly reduce the profit the technician makes
on the job. Also the vehicles owner is inconvenienced because the vehicle needs
to be returned to the facility for retorquing.
11
Chapter 3
Time Zones
12
Chapter 3
Head gaskets – Time Zones
1910-1930
Zone A: Initially, the basic head gaskets for engine were of the sandwich type, with
asbestos millboard centre and either tin- plate or copper on the outer surfaces.
Grommets and eyelets were incorporated in these gaskets, depending on the specific
engine needs. Numerous versions were designed and manufactured
1930- 1950
Zone B: As engines gained sophistication, gasket also gained in sophistication, and a
variety designs were produced. These designs utilized various reinforcements at the
combustion chamber seal for improved sealing. Metal shims and reinforced filler
materials, for example, were incorporated into many constructions
13
1950-1980
Zone C: The embossed steel shim gasket was the next popular gasket to be utilized
on passenger car engine. This gasket had a plastic resin coating applied for micro
sealing purposes. Because it was all metal, good torque retention was inherent with
this gasket. However, as engine displacement increased, the output resulted in
motionsthreat normally could not be accommodated by the elastic response of the
the embossed design. In addition, many times the land areas, especially between
cylinders, were reduced to a point where the legs of the emboss would fall inside the
ports, making adequate sealing impossible.
14
1965-1975
Zone D: With the development of rubber- fibre facing materials by the gasket paper
manufacturers came improved designs. The majority of these design incorporated a
tanged or perforated- core steel sheet, with these new facing materials mechanically
clinched to either side of the core thus providing soft surfaces of sealing material for
water and oil sealing. One of the major requirements of gaskets in this time zone was
that they function without need for a retorque operation on the cylinder head bolts.
Retorquing still is specified on some foreign made engines but is essentially non-
existent in today’sAmerican made engines. While this may not appear a major
requirement, it is indeed major, since the retorque operation greatly aids gasket
performance.
1975-Present
Zone E:graphite facings became popular in this time zone. Graphite has good
sealability and relaxation properties and high heat resistant. One of the newer
constructions eliminates the perforated core and uses an unbroken steel core to
which an adhesive is applied for bonding the facings.
This laminated gasket has been adopted on many of the more difficult sealing
applications. This type of gasket body can be embossed to achieve higher sealing
stress at particular passage ways. Another technique used to seal critical passage
ways on today’s engines involves silk screening to print elastomeric beads at these 15
locations. In addition, many improvements in seal, antistic, and antifret coating have
been incorporated in the latest gasket constructions.
Currently, a new array of lightweight, high output gasoline and diesel engines both
naturally aspirated and turbo charged is being developed. The gaskets industry is
involved in extensive R&D programs designed to seal these new families of engines.
Time will show even newer concepts being utilized in the head gaskets for these
engines
A new line-up of gaskets incorporating multiple layers of embossed, spring
temper stainless steel with rubber coatings has become popular. These gaskets
16
exhibit little exchange during engine operation use of spring temper stainless for
embossed layers results in high elastic recoveries.
17
Chapter 4
COMBUSTION SEALING
18
Chapter 4
COMBUSTION SEALING
In most cases, atinplate or zinc-plate armor is used for sealing the combustion
gases of spark ignition engines. The thickness of the armor is a function of the
thicknesses and type of facing material. The overlap and heel are sized for the
specific engine, to establish a proper unit seal load at the combustion chamber. The
heel may be sized differently at various positions around the combustion chamber in
order to obtain the proper unit loading at these positions. High-output engines
and/or turbocharged engines normally require stainless steel armor for improved
high-temperature and fatigue resistance. Types 430,304 and 321 stainless steel are
commonly used.
19
In the case of diesel applications, an armored gasket is not generally adequate. Only
armors of a certain thickness can be formed and imbedded into given gasket bodies,
and the thicknesses that normally fill these requirements are not structurally
sufficient to withstand the high combustion pressures of most diesel engines. As a
result other means for sealing combustions are necessary for these applications. The
most popular incorporates low carbon steel ring. This ring gives a high unit sealing
stress at very low loading and is widely used in today’s diesel engines. The wire is
butt welded and general attached to the gasket body by means of a stainless steel
armor wrapping. In some cases, the wrapping may be tabbed to reduce the load
20
required to imbed the armor into the body, thus increasing the loading on the wire
ring.
In some case stainless steel, wires are needed to withstand the heat and
fatigue characteristic inherent in particular engines. An example is the case where
precombustion chambers experience high thermal and mechanical movements.
There are some gaskets where more than one wire may be utilised to achieve the
desired sealing requirements of the engine.
Armored embossed metal is also used to seal combustion in number of
engines. Varying the height and the width of emboss results in a wide range of load-
compression properties. When embossing is made from the core of the gasket body
variation in the thickness tolerance are minimised since the emboss and the core are
made from the same piece of metal. Stainless or low carbon steel are used as
armors.
21
Diesel engines frequently have wet liners, and the gasket is usually charged
with sealing the intersection of the liner and the crankcase. During engine operation,
there is motion between the liner and the block and the likelihood of erosion of the
liner seat is high. As a result, coolant can leak to the top the deck; the gasket is
required to seal at this location. In some case, the soft surface tis used to seal; in
other cases , the heel of the armor is extended to cover the intersection for sealing
purposes. Engine testing normally dictates which is better. Some manufacturers are
using room temperature vulcanizing (RTV) silicon to seal this application.
22
There are other engines that have liner design that incorporate ridges and, in
some cases, grooves in the cylinder head. This results in coining, or imbedding, of the
gasket for improved combustion gas sealing. Another gasket design used on ridged
liner engines is a thick (0.080”) steel plate. i.e. embossed for improved combustion
sealing.
23
24
A unique gasket, which is used to seal very large diesel engines, uses copper
clad steel that has been etched away at various locations. The etching removes the
copper from specific areas there by permitting high unit loading at other location for
improved combustion gas sealing.
25
One of the items to be considered in the design of combustion sealing is bore
distortion. Some of the designs may need supplementary aids to keep bore distortion
within acceptable limits. A few of the techniques used for this include the extending
the combustion armor heel at specific locations, overlapping the heel around the
gasket body, generally at the ends of the gasket, and depositing beads or areas of
rigid materials at preselected points. All of these techniques essentially change the
load transmitting characteristics of the gasket and are useful for minimizing head
bending as well as reducing bore distortion.
26
In some engines, the back to back location of exhaust valves results in high
thermal growth in the area between cylinder bores. If excessive, this growth can
result in combustion leakage. One means of improving the sealing in this area is to
incorporate a metal shim in the gasket at this location. The shim acts as a stopper,
permitting the gasket to resist the thermal growth and enhance sealing.
Air cooled engines have somewhat reduced requirements regarding head
gasket sealing. Since there are no cooling water passage ways slight combustion gas
leakage can be permitted as long as:
1) Engine performance is not affected
2) The gasket is not affected by leakage.
Most of the gaskets for these engines consist of metal tanged core on both
outer surfaces and a high temperature resistant fibrous core material. Because these
engines are made mainly from aluminium high thermal motions occur. The metal
surfaces of the gasket permit head and block motions to occur without serious effect
to the gasket’s sealing ability. Embossed metal gaskets are also used on these
engines, especially when high heat transfer through the gasket is required
27
Bibliography:
1) Gasket and Gasketed joint by John H. Bickford
2) Google.
3) Wikipidea
28