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HAZARD ANALYSIS AND CRITICAL CONTROL POINT IN TYRE/TUBES MANUFACTURING INDUSTRIES
INTRODUCTION
Hazard Analysis and Critical Control Points (HACCP) is a systematic system of process
control and preventative approach to food safety but we are applying it as a tool like six
sigma etc., on the Tire/Tube Manufacturing Industries that addresses physical, chemical
and biological hazards as a means of prevention rather than finished product inspection.
We apply it in the Tire and Tube Manufacturing industry to get the fruitful results after
applying it as a tool. Identify potential safety hazards, so that key actions, known as
Critical Control Points (CCP’s) can be taken to reduce or eliminate the risk of the
hazards being realized. The system is used at all stages of production and preparation
processes. Today HACCP is being applied to industries other than food.
This method, which in effect seeks to plan out unsafe practices, differs from traditional
“produce and test” quality assurance methods, which are less successful and
inappropriate for highly perishable product.
Objectives
The objectives of the applying HACCP are:
Review the difficulties experienced when applying the HACCP system in tyre and
Rubber industry.
Consider the initiatives and approaches taken by different departments in
implementing HACCP.
Define the role of different departments and their approach in implementing
HACCP.
Develop a strategy for implementing HACCP in Tyre industry, considering different
practical options.
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SCOPE
The purpose of this HACCP analysis is to view results of implementation of the HACCP
In tyre and Rubber Industry and imposed in the different sector to get the better results
in all sectors including the tyre & tube manufacturing Industry and Rubber Industry.
History
Beginning in 1959, the Pillsbury Company embarked on work with NASA to further
develop a process stemming from ideas employed in engineering systems development
knows as Failure Mode & Effect Analysis (FMEA). Through the thorough analysis of
production processes and identification of hazards that were known to occur in the
production establishment, Pillsbury and NASA identified the critical points in the process
at which these hazards were likely introduced into product and therefore should be
controlled.
The establishment of critical limits of specific mechanical or test parameters for control
at those points, the validation of these prescribed steps by scientifically verifiable
results, and the development of record keeping by which the processing establishment
and the regulatory authority could monitor how well process control was working all
culminated in what today is known as HACCP. In this way,
A vital aspect of the establishment's responsibility is to establish and maintain records
that document adherence to the critical limits that relate to the identified critical control
points, thus resulting in continuous self-inspection. Secondly, a HACCP system allows
the regulatory agency to more comprehensively determine an establishment's level of
compliance. A food establishment's use of HACCP requires development of a plan to
prepare safe food. This plan must be shared with the regulatory agency because it must
have access to CCP monitoring records and other data necessary to verify that the
HACCP plan is working.
Using conventional inspection techniques, an agency can only determine conditions
during the time of inspection which provide a "snapshot" of conditions at the moment of
the inspection. However, by adopting a HACCP approach, both current and past
conditions can be determined. When regulatory agencies review HACCP records, they
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have, in effect, a look back through time. Therefore, the regulatory agency can better
ensure that processes are under control.
HACCP SEVEN PRINCIPLES
HACCP is based around seven established principles which are represented
below, however, this flow diagram is designed around HACCP being used with food
production, and nevertheless it is easily adapted to other industries.
Preliminary HACCP activities
a. Principle 1: Hazard Analysis
b. Principle 2: Critical Control Point
c. Principle 3: Critical limits
d. Principle 4: Monitoring
e. Principle 5: Corrective action
f. Principle 6: Verification
g. Principle 7: Record keeping
Identifying hazards and determining critical control points
Principle 1: Conduct a Hazard Analysis
a. Determining the risks of hazards
b. Preparing the Tyre Process flow diagram
c. A typical flow diagram
d. Hazard assessment
e. Preventive measures
Principle 2: Identify Critical Control Points
a. Definition of critical control point
b. Typical critical control points
c. Critical control point guidelines
d. Critical control point decision tree
e. Example of critical control point selection method
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Critical Limits; Monitoring; Corrective Actions
A. Principle 3: Determining critical limits
a. Definition of critical limit
b. Sources of standards
c. Criteria used
Principle 4: Establish procedures to monitor CCP
a. Definition of monitoring
b. Purposes of monitoring
c. Types of monitoring measurements
d. Procedures for monitoring
e. Thermometer usage
f. Other monitoring equipment
g. Monitoring records
h. Examples of monitoring
Principle 5: Take corrective action
a. Definition of corrective action
b. Importance of corrective actions
c. Examples of corrective actions
Verification and Record Keeping
Principle 6: Verification
Principle 7: Record keeping
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Preliminary Steps Developing a HACCP Plan
1. Assemble the HACCP team including one person (consultant, employee, or other
resource) who is HACCP trained.
2. Describe the product and its method of production and distribution, identify and
intended use and consumers of the product.
a) What is the common name of the product
b) How is the product to be used
c) What type of packing
d) What is the length of shelf life of the product, at what temperature
e) Where will the product be sold?
f) What labeling instructions are needed?
g) Is special distribution control needed?
3. Develop and verify the process flow diagram
4. Decide whether the products can be grouped using the process categories
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PRODUCT DESCRIPTION
PROCESS CATEGORY : TYPE MANUFACTURING
PRODUCT: TYRE & TUBE
1. COMMON NAME? TYRE AND TUBES
2. HOW IS IT TO BE USED? USED IN DIFFERENT WHEELS
3. TYPE OF PACKAGE? OEM TYRE PACKING ALSO A BUNDLE OF 10
PCS
4. LENGTH OF SHELF LIFE? 3 MONTHS AT NORMAL CONDITIONS
5. WHERE WILL IT BE SOLD?
CONSUMERS?
INTENDED USE?
WHOLE SALE TO DISTRIBUTOR ONLY
TIRE (INTRODUCTION)
A covering mounted on the rim of a wheel that serves as a cushion and surface for
traction. Tires are used on road vehicles, tractors, aircraft and spacecraft landing gear,
factory and warehouse machinery, and on a variety of other vehicles, including
shopping carts and baby carriages. Tires are made of chemically treated rubber and
fabric. Those for indoor use are generally solid rubber with a smooth surface, while
those used outdoors are pneumatic, or hollow and filled with pressurized air, and have a
traction pattern cut into the surface. This article deals primarily with pneumatic tires.
TYRE HISTORY
Wheel rims were traditionally protected by metal bands. The use of rubber wheels was
not feasible until 1839, when American inventor Charles Goodyear discovered the
process of vulcanization, which made rubber stronger, more elastic, and less sticky. In
1845 the first pneumatic tire was patented by Scottish inventor Robert W. Thomson.
Hundreds of different tire designs using leather, rubber, and other materials were soon
patented. The tire industry did not flourish, however, until pneumatic rubber tires were
refined and patented in 1888 by British inventor John Boyd Dunlop.
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In 1895 the Hartford Rubber Works made the first pneumatic tires in the United States.
This company later became part of the United States Rubber Company, now called
Uniroyal. Leading tire manufacturing firms produce about 300 million tires per year
worldwide for trucks, buses, and automobiles. Many of the manufacturers are based in
Akron, Ohio.
MAIN PARTS OF TYRE
The main parts of the pneumatic tire are the tread, the body, and the beads. The tread
is a thick pad of rubber into which grooves are cut to form cleats or ridges. The tread
provides traction to move and stop a vehicle and to prevent skidding and sliding while a
vehicle is in motion. Tractor and snow tires have especially deep grooves that enable
the tire to move through soft earth or deep snow.
The body gives the tire its strength and form. It consists of layers of fabric permeated
with rubber. The fabric in most passenger-vehicle tire bodies is polyester. Each fabric
layer is called a ply, and the strength of a tire is sometimes described by the number of
plies in its body. Most automobile tires have two plies. The beads of a tire are the two
bands that hold the tire to its wheel. They are located along the tire's inner edges and
are made up of strands of wire surrounded by rubber and covered with fabric.
TYRE SIZES
Pneumatic tires are made in a variety of sizes. The size is usually indicated by a code
such as P205/75R14. The letter P identifies the tire as a passenger-car tire. The
number 205 is the width of the tire measured in millimeters. The number 75 is the tire's
height-to-width, or aspect, ratio. This tire has sidewalls that are 75 percent as high as
the tire is wide. The letter R stands for radial, which is a design type, and 14 means that
the tire will fit a rim 14 in (36 cm) in diameter. A P205/75R14 tire would be used on a
medium-sized car. A large car might use a P225/75R15 tire, and a compact car might
use a P155/80R13 tire.
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Tyre Contents
Tires are made of both natural and synthetic rubber; chemicals, such as carbon black,
oils, and waxes, which are added to strengthen the rubber; and fabric, which may be
nylon, polyester, or steel fabric. Each part of a tire requires its own mix of chemicals and
rubber.
Tyre Manufacturing Process
When a tire is manufactured, raw rubber and chemicals are blended in large mixers with
two steel-toothed paddle wheels that turn against each other. The rubber is heated and
kneaded to a gummy consistency. The mixture is then removed from the mixers and fed
through a pelletizer, which extrudes small rubber pellets.
Meanwhile, fabric is dipped in latex and subjected to a stabilization treatment. The
rubber pellets are again kneaded to a hot, gummy texture. Then the rubber is molded
into a thin coating, which is pressed into each side of the fabric. The coated fabric is cut
into lengths to make one layer, or ply, of the inner body of the tire.
Rubber is also applied to high-tensile bronze-coated steel wire. Several strands of the
rubber-coated wire are wound into a hoop and then sewn with nylon cord to form each
of the two tire beads. Another batch of rubber is fed into an extruder, which forces soft
rubber through a die or opening to create a covering that has the basic shape of the
tread and sidewall.
The fabric, beads, and covering are combined on a tire-building machine. A tire builder
applies layers of fabric to a revolving drum to form the inner core of the tire. The builder
then places a wire bead around each end of the drum, turns the fabric up to cover the
beads, and finally wraps the rubber covering around the other parts.
The tire parts are then fused together in a tire press, which contains an aluminum mold
with the outline of the tread design and sidewall lettering. As the press closes on the
tire, a rubber bladder inflates and forces the tire, whose outside is still soft rubber, into
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the mold. After curing, the tire is automatically ejected onto a conveyor belt to be
inspected, balanced, and trimmed.
In conventional bias-ply construction, the threads, or cords, of the fabric ply lie at an
angle to the tread line of the tire. In radial tires, the cords run straight across. Radial
tires also have fiberglass or steel belts between the plies and the tread. A bias-belted
tire combines these features and has both angled cords and a belt. This arrangement
strengthens the sidewalls and increases the tire's load-carrying capacity.
FLOW CHART OF THE TYRE AND TUBES MANUFACTURING INDUSTRY
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RUBBER
INTRODUCTION OF RUBBER
Any solid substance that upon vulcanization becomes elastic; the term includes
Natural Rubber (caoutchouc) and Synthetic Rubber. The term elastomer is sometimes
used to designate synthetic rubber only and is sometimes extended to include
caoutchouc as well.
CHEMISTRY AND PROPERTIES
All rubber like materials are polymers, which are high molecular weight compounds
consisting of long chains of one or more types of molecules, such as monomers.
Vulcanization (or curing) produces chemical links between the loosely coiled polymeric
chains; elasticity occurs because the chains can be stretched and the cross-links cause
them to spring back when the stress is released. Natural rubber is a polyterpene, i.e.; it
consists of isoprene molecules linked into loosely twisted chains. The monomer units
along the backbone of the carbon chains are in a CIS arrangement and it is this spatial
configuration that gives rubber its highly elastic character. In gutta-percha, which is
another natural polyterpene, the isoprene molecules are bonded in a trans configuration
leading to a crystalline solid at room temperature. Unvulcanized rubber is soluble in a
number of hydrocarbons, including benzene, toluene, gasoline, and lubricating oils.
Rubber is water repellent and resistant to alkalis and weak acids. Rubber's elasticity,
toughness, impermeability, adhesiveness, and electrical resistance make it useful as an
adhesive, a coating composition, a fiber, a molding compound, and an electrical
insulator. In general, synthetic rubber has the following advantages over natural rubber:
better aging and weathering, more resistance to oil, solvents, oxygen, ozone, and
certain chemicals, and resilience over a wider temperature range. The advantages of
natural rubber are less buildup of heat from flexing and greater resistance to tearing
when hot.
HISTORY
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Pre-Columbian peoples of South and Central America used rubber for balls, containers,
and shoes and for waterproofing fabrics. Mentioned by Spanish and Portuguese writers
in the 16th cent., rubber did not attract the interest of Europeans until reports about it
were made (1736-51) to the French Academy of Sciences by Charles De La
Condamine and François Fresneau. Pioneer research in finding rubber solvents and in
waterproofing fabrics was done before 1800, but rubber was used only for elastic bands
and erasers, and these were made by cutting up pieces imported from Brazil. Joseph
Priestley is credited with the discovery C.1770 of its use as an eraser, thus the name
rubber.
The first rubber factory in the world was established near Paris in 1803, the first in
England by Thomas Hancock in 1820. Hancock devised the forerunner of the
masticator (the rollers through which the rubber is passed to partially break the polymer
chains), and in 1835 Edwin Chaffee, an American, patented a mixing mill and a
calender (a press for rolling the rubber into sheets).
In 1823, Charles Macintosh found a practical process for waterproofing fabrics, and in
1839 Charles Goodyear discovered vulcanization, which revolutionized the rubber
industry. In the latter half of the 19th century the demand for rubber insulation by the
electrical industry and the invention of the pneumatic tire extended the demand for
rubber. In the 19th century wild rubber was harvested in South and Central America and
in Africa; most of it came from the Pará rubber tree of the Amazon basin.
Despite Brazil's legal restrictions, seeds of the tree were smuggled to England in 1876.
The resultant seedlings were sent to Ceylon (Sri Lanka) and later to many tropical
regions, especially the Malay area and Java and Sumatra, beginning the enormous
East Asian rubber industry. Here the plantations were so carefully cultivated and
managed that the relative importance of Amazon rubber diminished. American rubber
companies, as a step toward diminishing foreign control of the supply, enlarged their
plantation holdings in Liberia and in South and Central America.
During World War I, Germany made a synthetic rubber, but it was too expensive for
peacetime use. In 1927 a less costly variety was invented, and in 1931 neoprene was
made, both in the United States. German scientists developed Buna rubber just prior to
World War II. When importation of natural rubber from the East Indies was cut off during
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World War II, the United States began large-scale manufacture of synthetic rubber,
concentrating on Buna S. Today synthetic rubber accounts for about 60% of the world's
rubber production.
TYPES OF RUBBER (Majority used In tyre)
NATURAL RUBBER
Natural rubber is obtained from the milky secretion (latex) of various plants, but the only
important commercial source of natural rubber (sometimes called Pará rubber) is the
tree Hevea Brasiliensis. The only other plant under cultivation as a commercial rubber
source is guayule (Parthenium Argentatum), a shrub native to the arid regions of Mexico
and the SW United States. To soften the rubber so that compounding ingredients can
be added, the long polymer chains must be partially broken by mastication, mechanical
shearing forces applied by passing the rubber between rollers or rotating blades. Thus,
for most purposes, the rubber is ground, dissolved in a suitable solvent, and
compounded with other ingredients, e.g., fillers and pigments such as carbon black for
strength and whiting for stiffening; antioxidants; plasticizers, usually in the form of oils,
waxes, or tars; accelerators; and vulcanizing agents. The compounded rubber is
sheeted, extruded in special shapes, applied as coating or molded, then vulcanized.
Most Pará rubber is exported as crude rubber and prepared for market by rolling slabs
of latex coagulated with acid into thin sheets of crepe rubber or into heavier, firmly
pressed sheets that are usually ribbed and smoked.
An increasing quantity of latex, treated with alkali to prevent coagulation, is shipped for
processing in manufacturing centers. Much of it is used to make foam rubber by beating
air into it before pouring it into a vulcanizing mold. Other products are made by dipping
a mold into latex (e.g., rubber gloves) or by casting latex. Sponge rubber is prepared by
adding to ordinary rubber a powder that forms a gas during vulcanization. Most of the
rubber imported into the United States is used in tires and tire products; other items that
account for large quantities are belting, hose, tubing, insulators, valves, gaskets, and
footwear. Uncoagulated latex, compounded with colloidal emulsions and dispersions, is
extruded as thread, coated on other materials, or beaten to foam and used as sponge
rubber. Used and waste rubber may be reclaimed by grinding followed by
devulcanization with steam and chemicals, refining, and remanufacture.
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SYNTHETIC RUBBER
The more than one dozen major classes of synthetic rubber are made of raw material
derived from petroleum, coal, oil, natural gas, and acetylene. Many of them are
copolymers, i.e., polymers consisting of more than one monomer. By changing the
composition it is possible to achieve specific properties desired for special applications.
The earliest synthetic rubbers were the styrene-butadiene copolymers, Buna S and
SBR, whose properties are closest to those of natural rubber. SBR is the most
commonly used elastomer because of its low cost and good properties; it is used mainly
for tires. Other general purpose elastomers are CIS -polybutadiene and CIS -
polyisoprene, whose properties are also close to that of natural rubber.
Among the specialty elastomers are copolymers of acrylonitrile and butadiene that
were originally called Buna N and are now known as nitrile elastomers or NBR rubbers.
They have excellent oil resistance and are widely used for flexible couplings, hoses, and
washing machine parts. Butyl rubbers are copolymers of isobutylene and 1.3%
isoprene; they are valuable because of their good resistance to abrasion, low gas
permeability, and high dielectric strength. Neoprene (polychloroprene) is particularly
useful at elevated temperatures and is used for heavy-duty applications. Ethylene-
propylene rubbers (RPDM) with their high resistance to weathering and sunlight are
used for automobile parts, hose, electrical insulation, and footwear. Urethane
elastomers are called spandex and they consist of urethane blocks and polyether or
polyester blocks; the urethane blocks provide strength and heat resistance, the
polyester and polyether blocks provide elasticity; they are the most versatile elastomer
family because of their hardness, strength, oil resistance, and aging characteristics.
They have replaced rubber in elasticized materials. Other uses range from airplane
wheels to seat cushions. Other synthetics are highly oil-resistant, but their high cost
limits their use. Silicone rubbers are organic derivatives of inorganic polymers, e.g., the
polymer of dimethysilanediol. Very stable and flexible over a wide temperature range,
they are used in wire and cable insulation.
The main Synthetic Rubbers are outlined below.
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STYRENE BUTADIENE RUBBER (SBR)
A general purpose rubber, which, when compounded with carbon black, behaves
similarly to NR (Tg is higher at about -55°C).
BUTADIENE RUBBER (BR)
A Non-polar rubber likes NR and SBR, with a very low Tg (approximately -80°C). Very
high resilience (very low loss) rubber used in ‘super-balls’, but also commonly used in
combination with NR and SBR in long life rubber tyre treads. Difficult to process unless
blended with another elastomer.
CHLOROPRENE RUBBER (CR)
A polar polymer with improved resistance to attack by non-polar oils and solvents. It has
high toughness, good fire resistance, good weather ability, and is easily bonded to
metals.
(ACRYLO) NITRILE BUTADIENE RUBBER (NBR)
A variation of the Acrylonitrile (ACN) content from 18 to 50% controls polarity and other
properties. High resistance to non-polar oils and fuels (e.g. used in seals, fuel lines,
hydraulic pipes) but high Tg. Improved versions of this much used polymer are
becoming available.
ISO BUTYLENE ISOPRENE (BUTYL) RUBBER (IIR)
This material has a low Tg but has very little ‘bounce’. It has excellent ageing properties
and has a very low permeability to gases, so it is often used as a tubeless tyre liner, as
well as for reservoir linings and other membranes. Chemically modified forms are
frequently used.
ETHYLENE PROPYLENE RUBBER (EPDM or EPR)
This is a commonly used non-polar rubber in applications that require good ageing
properties, such as in heater and radiator hoses, car door water and draught seals. The
structure of the polymer can be altered to give a fairly wide range of properties and
uses.
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Other more expensive varieties are generally designed to increase the working
temperature range, especially at the high end, and usually contain chemical elements
such as fluorine to increase the stability of the carbon backbone.
SILICONE RUBBER
Silicone rubber is unique in not having a carbon backbone, being –Si-O-Si-O-, and this
extends the useful temperature range noticeably. It has a Tg as low as -127°C
depending on type, and can be used in service at temperatures of 200°C or more for
several years. Further modification with fluorine will give even better performance.
Several other special purpose rubbers are available, including polyurethanes.
CHLOROPRENE RUBBER
Chloroprene rubber, an early synthetic rubber, has been used in many outdoor
applications due to its superior weathering properties and oil resistance. It performs well
compared with Natural Rubber in many ways but can suffer from long term stiffening
(change in properties) and its low temperature performance is not as good as Natural
Rubber.
ENVIRONMENTAL EFFECTS OF RUBBERS:
Unfortunately it has a relatively high reactivity with its environment, with oxygen and
particularly ozone. Ozone causes surface cracking that can rapidly penetrate the
component when even a low threshold value of tensile stress is applied. However, in
components of fairly large cross sectional area, whilst there may be extensive surface
reaction, depending upon the external stress pattern, actual penetration of the oxygen
and ozone can be low, with the inside being protected by the degraded exterior.
MECHANICAL EFFECTS
Articles in shear or compression remain unaffected provided that the surface itself does
not enter a tension mode. This property can be ensured by design. One hundred year
old seals from Victorian water and drainage systems demonstrate this very effectively
as the seals still function. In tension, ozone cracking can propagate quite rapidly
through an otherwise satisfactory sample. This means that the lives and performance of
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thin and thick items made of the same material in the same environment can be very
different.
OILS AND SOLVENTS
Attack by contact with oils is usually restricted to a thin surface layer due to slow
diffusion rates. Lighter solvents will attack the rubber more rapidly, with actual rates
dependent on the type of solvent and the type of rubber. Both oils and solvents will
cause a loss of physical strength, with thin articles being the worst affected.
ADVANTAGES OF NATURAL RUBBER
The major advantage of Natural Rubber, which makes it dominant in many engineering
applications, is its dynamic performance. It has a low level of damping, and its
properties remain fairly constant over the range 1 to 200Hz, and show only slight
increase to 1000Hz. Its combined dynamic properties generally out perform any
synthetic rubbers or combinations available to date. Despite proliferation of general and
special purpose synthetics, Natural Rubber still holds a significant market share
between 30 and 40%.
ADVANTAGES OF SYNTHETIC RUBBERS
Although Natural Rubber, with the benefit of modern compounding, is very satisfactory
for many applications, it is also a strategically important material, a natural crop only
produced in tropical countries and has relatively poor ageing properties. Therefore
synthetic materials have been developed to replace Natural Rubber in a wide range of
applications.
There is now a wide range of synthetics available able to cope with high and low
temperatures, contact with fluids of various types (including at high pressures), and
aggressive or corrosive environments.
VULCANIZATION
Treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance
to solvents, and to render it impervious to moderate heat and cold. Chemically, the
process involves the formation of cross-linkages between the polymer chains of the
rubber's molecules. Vulcanization is accomplished usually by a process invented by
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Charles Goodyear in 1839, involving combination with sulfur and heating. A method of
cold vulcanization (treating rubber with a bath or vapors of a sulfur compound) was
developed by Alexander Parkes in 1846. Rubber for almost all-ordinary purposes is
vulcanized; exceptions are rubber cement, crepe-rubber soles, and adhesive tape. Hard
rubber is vulcanized rubber in which 30% to 50% of sulfur has been mixed before
heating; soft rubber contains usually less than 5% of sulfur. After the sulfur and rubber
(and usually an organic accelerator, e.g., an aniline compound, to shorten the time or
lower the heat necessary for vulcanization) are mixed, the compound is usually placed
in molds and subjected to heat and pressure. The heat may be applied directly by
steam, by steam-heated molds, by hot air, or by hot water. Vulcanization can also be
accomplished with certain peroxides, gamma radiation, and several other organic
compounds. The finished product is not sticky like raw rubber, does not harden with
cold or soften much except with great heat, is elastic, springing back into shape when
deformed instead of remaining deformed as unvulcanized rubber does, is highly
resistant to abrasion and to gasoline and most chemicals, and is a good insulator
against electricity and heat. Many synthetic rubbers undergo processes of vulcanization,
some of which are similar to that applied to natural rubber. The invention of
vulcanization made possible the wide use of rubber and aided the development of such
industries as the automobile industry.
LABORARATORY TESTING RAW MATERIAL.
DBP absorption of Carbon testing.
Viscosity @ 40 °C of OIP.
Percentage purity of ZnO.
Moisture contents checking of Carbon, DIP, Silicon and also rubber according
to the standards.
Rubber Checking by making compound by different formulations check their
Biological properties, Tensile Strength and Hardness etc.
Specific Gravity of all incoming Raw material.
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STANDARD FORMULATION FOR TESTING
TEST FORMULATION OF DIFFERENT RUBBERS
NR SBR RECLAIM
PPHR PPHR PPHR
RSS 100 SBR 100.00 Reclaim 100
ZnO 05 ZnO 04.00 CBS 0.50
St. Acid 03 St Acid 02.00 Sulphur 2.50
Oil 03 Process Oil 08.00 ZnO 5.00
HAF 50 HAF 50.00 St. Acid 3.00
Sulphur 25 Sulphur 1.75
CBS 05 Accelerator 1.25
Total 191.00 Total 167.00 Total 111.00
Ref: Monsanto Rubber Chemical Hand Book.
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INSPECTION AND TESTING PLAN
ResponsibilityRef. Document
TitleDocument # Record
% Sampling
RMS
Assistant Lab
IPS
Laboratory Boy
FPS
Laboratory Boy
Report To Store
Information from Store
Production
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MIXING DEPARTMENT OF TYRE MANUFACTURING UNIT
INTRODUCTION TO MIXING DEPARTMENT
The major and the most important department in the rubber processing industry are the
mixing. Which play a vital role if we apply successfully the HACCP principal the others
next departments are going well and the rejection rate can be reduced.
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DAILY REWORK REPORT MIXING DEPARTMENTDate: ___________ Sr. No. _______
Compound Batches Batches Results Batches % Age Of Remarks
Identification Produced Checked Rework Rework
Tread
Compound
T – 100
T – 200
T – 310
T – 600
Friction
Compound
F – 100
F – 110
F – 600
Bead Wire
Tube
Compound
TB – 400
TB – 500
TOTAL
Remarks:
PREPARED BY LAB INCHARGE
MATERIAL PREPARATION IN BANBURY
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Radial tire manufacturing starts with many kinds of raw materials: pigments, chemicals,
some 30 different kinds of rubber, cord fabrics, bead wire, etc.
The process begins with the mixing of basic rubbers with process oils, carbon black,
pigments, antioxidants, accelerators and other additives, each of which contributes
certain properties to the compound.
These ingredients are mixed in giant blenders called Banbury machines operating
under tremendous heat and pressure. They blend the many ingredients together into a
hot, black gummy compound that will be milled again and again.
CRITICAL CONTROL POINT IN MIXING DEPARTMENT
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First of all we will see the process Flow Chart of the mixing department
First come the store for the issuance of the raw material
Compounding where the material weighing is done
Production both Internal and external mixing
Now the most critical points in the mixing department:
1) Raw material issuance and proper storage, Cool system and temperature.
2) Compounding the most sensitive department of the rubber Industry here a check is
very necessary, which should be done by the third party.
3) In the production the critical points are
i. Skilled persons on the machines
ii. Pressure & Temperature
iii. Consistent Raw Material
iv. Water Supply is ok or not
v. Mastication should be proper
These your are the major sensitive and critical points
Which person controls these
Skilled worker and also the competent management control these parameter
Or
That duty performed by the Laboratory Staff. For controlling & checking purpose
laboratory staff should be trained and know how to work, How to improve the system
and product quality.
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What are the major responsibilities of the middle management or the mixing head of the
department? To ensure that the worker (skilled), working at their respective places or
not. The workers training is the basic need and also provided the protection against the
dust pollution to all the workers according to the requirements.
HOW TO CONTROL THESE CRITICAL POINTS?
Skilled personals on the Machines as Nominated in the Sampling Plan Table: Make
sure it other wise if we change the operator on daily basis it reduced the efficiency of
both worker and machine. So here a need to specify the person at there right place to
increase the productivity and the product quality. Make a Skill Analysis chart for the
skilled worker and defined their duties where they are perfect and not change there
work station to avoid the increase in the rejection rate of the product. The sample of the
skilled Analysis chart is as follow
1) Pressure And Temperature: Trained the workers to check the pressure before the
start of production the specified pressure is 6 to 7 kg for the internal mixing named
as “Banbury”. If it is less or more then report to the production Incharge for the quick
remedial action and stop the production until the pressure reaches to their standard
limits. The temperature also plays a critical role in the mixing of the compound and
result in the excellent or bad quality mixing. The temperatures for the Natural rubber
compound should not exceed then 160ºC for the synthetic rubber (like butyl) should
not exceed then 190ºC if the temperature increased the risk of compound
curing/scorching also increased and the compound useless for the next processing.
Here the third party or the laboratory staff requires a check and balance. In case of
any disturbance report to the immediate boss. If the temperature is too low the
mixing is not possible and it’s simply wastage of;
i. Labor
ii. Electric Power
iii. Raw Material
iv. Time
- 25 -
To remove these workers are fully skilled and trained. And also the check and report
system required here
2) STORAGE: not more then one day in the case of natural rubber mixed compound
and the storage condition must be according to the standard limits defined in
AASTM, BS etc. like the room temperature and 55% Humidity maximum. In the case
of butyl rubber mixed compound the standard storage condition are the same but the
storage time will be greater then the natural rubber mixed compound. The storage
condition are very critical in the mixed compound both the butyl and natural.
The best way of the mixing is the master batch mixing. In this case the product quality
improved and the scorching risk of the compound also decreased.
3) Consistent Raw Material: Consistency in the raw material is very necessary, if the
raw material varies the product at the end also vary which may take a several days
for the right product. So the sources are the always same.
4) Water Supply: The water supply for the temperature maintaining is a key factor if
the water circulation is not enough or the good then the compound quality also
varies from batch to batch. For the consistency in the end product either in the form
of batch or tyre and tubes.
5) Mastication: what is the mastication? It’s the process in which the long polymer
breaks into smaller one and band is formed or we can say a pre cooking process of
rubber. This point is also play vital role in the mixing of the compound. In case of
poor mastication a number of problem observed like a batch no extrude. The proper
time is needed and skilled worker very necessary for the accurate mastication.
These are the few critical points regarding to the mixing department and we can control
these points by check and measure. And normally that practice did by the laboratory
staff or the quality control/assurance department. To make sure these things not
happened. This will lead us to an improvement of the product and the system.
- 26 -
QUALITY AUDIT REPORT OF MIXING PROCESSDate : Shift:Process Checking
1 Hr 2 Hr 3 Hr 4 Hr 5 Hr 6 Hr 7 Hr 8 Hr
Banbury Big Small Big Small Big Small Big Small Big Small Big Small Big Small Big Small
Air pressure
Banbury Time
Banbury Temp
Dump Temp
Rubber Chemicals & Filler CheckingCompound
1010(NR)21502(SBR)21712(SBR)21203(PBR)21675(IIR)Reclaim
Total3330(N-330)3550(N-550)3660(N-660)4100(CaCO3)
China Clay4110(Whiting)
Total6310(CBS)
6330(TMTD)6340(MBTS)6350(MBT)9610(PVI)6360(Sul)
Total5210(ZnO2)5220(St.Acid)
7410(IPPD)7420(PBN)7430(Wax)
Resin China
Total8510(W/Oil)8520(T/Oil)
Remarks:
Checked by Mixing Foreman Lab Representative Mixing Incharge Lab Incharge
- 27 -
ROLE OF LABORATORY FOR THE IMPROVED QUALITY PRODUCT:
1. Raw Material Testing
2. In Process Testing
3. Finished Product Testing
Raw Material Testing:
Chemical and physical testing of the incoming raw material is one of the important
activity of any industry, chemical testing of the raw material is performed either for
identification of for quality control. Quality control tests are necessary at all stages of the
factory activity from the incoming raw materials through semi-finished product to the
finished product. Quality of the finished product depends a lot on raw material properties
like
i. Percentage Purity
ii. Particle Size
iii. pH
iv. Moisture Content
v. Iodine Value
vi. Acidity
vii. Activity like of Blowing agent
viii. Loss on Ignition
ix. Fineness
x. Bulk Density
xi. Relative Density
xii. Melting
xiii. Ash
xiv. Viscosity at 40º C & 100º C
xv. Flash Point
xvi. Quick Point
- 28 -
xvii. DBP Absorption
xviii. Specific Gravity
In raw materials, generally quality is checked by the chemical analysis and the results
are compared with the standard specification (like ASTM. Standards Volume 9)
The standards formulation for the Rubber testing available from the different rubber
manufacturer like EXXON, MONSANTO etc. the few are as
2. In Process Testing quality checking as a preventive measure to avoid any rejection
or the process loss of the material include these tests
i. Rheological properties
ii. Tensile Strength
iii. Elongation
iv. Mooney Viscosity
v. Plasticity
vi. Specific Gravity
vii. Hardness
viii. Abrasion (DIN Type)
These are the tests for the in process and here again the standards to whom we follow.
3. Finished Product Testing for the continual improving the of the product are:
TYRE TESTING
(a) Weight
(b) Adhesion (both by ply to ply and tread to ply)
(c) Abrasion (DIN TYPE)
(d) Hardness
(e) Specific Gravity
TUBE TESTING
(a) Weight
- 29 -
(b) Thickness
(c) Nozzle Strength
(d) Joint Strength
(e) Body Strength
(f) Elongation
(g) Modulus
(h) Specific Gravity
CHEMICALS USED IN TYRE INDUSTRY
ACCELERATORS & CROSS LINKED
CBS , MBTS , MBT , TMTD , ZEDEC, Sulphur
ANTOXIDANT AND OZONANT
PBN , TMQ , IPPD
PROCESSING OIL
Paraffinic , Aromatic
ACTIVATORS
ZnO , Stearic Acid
FILLER
Carbon Balck [N – 330, N – 550, N – 660]
White Filler [CaCO3, Whiting Normal and Silicates]
Most of the chemicals are used in the tyre industry are poisonous and effect the skin
and lungs from the safety point of view must wear the goggles, Mask and the protective
gloves before the work start. Also the filler like carbon effect the body, lungs and cause
the TB. So the protective measure for the worker should be taken. That will increase the
moral and decrease the absenteeism in the worker due to illness.
- 30 -
TYRE MANUFACTURING
FLOW CHART OF TYRE DEPARTMENT
The compound received from the mixing department is of two types (1) is called the
Tread compound and (2) is called the Topping compound. The Topping is used for the
ply pasting of the Nylon Cord. This is the general flow chart for tyre of any type.
COMPOUND RECEIVED FROM MIXING DEPARTMENT
Compound Re-warmed On the Two-Roll Mill
Feed In the Extruder
Length Cutting
Tread Pasting for Adhesion & Dry It
Nylon Cord Pasting on Four Ball-Calendars
Ply Cutting on Ply Cutter
Tread, Ply & Bead Wire Join Together On Tyre
Building Machine
Send To Curing Section
Market
Quality Section
- 31 -
- 32 -
PROCESS STAGES OF BUILDING A TYRE
THE MAJOR STEPS IN TYRE MANUFACTURING
- 33 -
HOW TIRES ARE MADE
As illustrated below, a tire is made up of several different components.
BASIC INGREDIENTS TO MAKE A TIRE
Rubber
Natural and Synthetic (Hundreds of Polymer Types)
Fabric
Steel, nylon, aramid fiber, rayon, fiberglass, or polyester (usually a combination, e.g.,
polyester fabric in the body plies and steel fabric in the belts and beads of most radial
passenger tires)
Reinforcing chemicals
Carbon Black, Silica, Resins
Anti-degradants
Antioxidants / Ozonants Paraffin Waxes
Adhesion promoters
Cobalt Salts, Brass On Wire, Resins On Fabrics
Curatives
Cure Accelerators, Activators, Sulfur
Processing aids
Oils, Tackifiers, Peptizers, Softeners
- 34 -
The process begins with the mixing of basic rubbers with process oils, carbon black,
pigments, antioxidants, accelerators and other additives, each of which contributes
certain properties to the compound.
These ingredients are mixed in giant blenders Banbury machines operating under
tremendous heat and pressure. They blend the many ingredients together into a hot,
black gummy compound that will be milled again and again.
The cooled rubber takes several forms. Most often it is processed into carefully
identified slabs that will be transported to breakdown mills. These mills feed the rubber
between massive pairs of rollers, over and over, feeding, mixing and blending to
prepare the different compounds for the feed mills, where they are slit into strips and
carried by conveyor belts to become sidewalls, treads or other parts of the tire.
TYRE MANUFACTURING STEPS
1. CALENDERING (Nylon Cord)
(a) Nylon Cord pasting
- 35 -
STEEL CORD CALENDERING
CALENDARING EQUIPMENT:
Calendaring is used for producing unsupported or supported long, thin sheets of
uniform thickness. Many Silastic silicone rubber products lend themselves to this
process.
PREPARING THE RUBBER
Most Silastic silicone rubber requires freshening on a mill before calendering. With
soft, sticky rubber that is difficult to calender, let the rubber set 24 hours after milling.
CALENDER
Either a 3-roll or 4-roll calender may be used. The 4-roll unit offers the advantage of
working air out of the rubber more thoroughly.
A variable-speed main drive should be provided, to give a centre-roll speed range
of .6 to 3 surface metres per minute. In most cases, the calender should be set for
- 36 -
skim coating or "even"; i.e. the centre and bottom rolls turn at the same rate and turn
faster than the top roll. In rare cases, particularly with stiff or highly filled rubber, an
"odd" speed where the centre and bottom rolls turn at different rates gives better
results.
Silicone rubber is usually calendered at room temperature. However, a means of
heating the rolls should be provided; some rubbers may stick less, and thus process
better, with one or more rolls heated. To avoid risk of scorching, the roll temperature
must not exceed the decomposition temperature of the vulcanizing agent used.
To keep the rubber from creeping over the ends of the rolls, use nylon ploughs and
end plates on all but the bottom rolls. Nylon readily takes the contour of the rolls, and
does not give off metal wear particles that might discolour or contaminate the rubber
being calendered.
THE BODY
The body is made up of several layers of different fabrics, called plies. The most
common ply fabric is polyester cord. The cords in a radial tire run perpendicular to the
tread. Some older tires used diagonal bias tires, tires in which the fabric ran at an
angle to the tread. The plies are coated with rubber to help them bond with the other
components and to seal in the air.
A tire's strength is often described by the number of plies it has. Most car tires have two
body plies. By comparison, large commercial jetliners often have tires with 30 or more
plies.
ROTACURE
The rotacure unit is a continuous vulcanizing unit consisting of a heated roll with a
continuous belt around pressing the sheet to the roll during the vulcanization process.
Electrically heated rolls and steam heated rolls are available.
The speed of the rotacure can be adjusted to the speed of the calander so that a
continuous vulcanization of calandered sheet is possible. The supporting cloth can be
- 37 -
removed in an online process and the finished sheet can be rolled by winding
equipment or cut into sheet as needed.
The Belts
In steel-belted radial tires, belts made from steel are used to reinforce the area under
the tread. These belts provide puncture resistance and help the tire stay flat so that it
makes the best contact with the road.
Cap Plies
Some tires have cap plies, an extra layer or two of polyester fabric to help hold
everything in place. These cap plies are not found on all tires; they are mostly used on
tires with higher speed ratings to help all the components stay in place at high speeds.
MAKING UNSUPPORTED SHEET
Unsupported sheet is usually made by calendering onto a liner, which is stripped off
after vulcanizing. Suitable liner materials include plastic film, holland cloth, and cotton
or nylon fabric treated for free release.
- 38 -
Feed the milled rubber to the calender as illustrated, and insert the liner between the
calendered rubber and the bottom roll. To start calendering onto the liner, it may be
necessary to cut the rubber away from the centre roll whet the liner first comes through
the rolls, calander the desired gauge onto the liner, and wind it onto a hollow core.
MAKING SUPPORTED SILICONE RUBBER SHEET
Silastic silicone rubber may be calendered onto untreated fabrics such as glass,
nylon, Nomex high-temperature nylon, Orlon, Dacron, rayon and cotton. To apply
Silastic silicone rubber to both sides of the fabric, the usual practice is to calender the
rubber to the first side and partially vulcanize. Partial vulcanization takes 10 to 30
seconds at 150 to 315°C -the time and temperature depends on the thickness of
rubber, vulcanizing agent, and heat-stability of the fabric. Heating for this brief interval
can be accomplished by passing the calendered material over a hot drum or by
feeding it through a hot-air vulcanizing unit. If the supported sheet is wound onto a
core for storage or vulcanizing, use a liner as described under "Making Unsupported
Silastic Silicone Rubber Sheet" to prevent adhesion between layers.
Insert the liner next to the bottom roll -Polyethylene liner should be used if the
calendered sheet is not to be vulcanized. Mylar®, Kodacel, or holland cloth should be
- 39 -
used when the calendered sheet is to be vulcanized with a core (aluminum or steel) that
will withstand the heat of vulcanization.
2. BEAD WIRE PRODUCTION UNIT
Bead is another important component of Tyre, shaped like a hoop, is called a bead. It
has high-tensile steel wire forming its backbone, which will fit against the vehicle's wheel
rim. The strands are aligned into a ribbon coated with rubber for adhesion, then wound
into loops that are then wrapped together to secure them until they are assembled with
the rest of the tire.
CHAFER STRIPS
Next come two layers of ply fabric, the cords. Two strips called apexes stiffen the area
just above the bead. Next, a pair of chafer strips is added, so called because they
resist chafing from the wheel rim when mounted on a car.
- 40 -
- 41 -
SPECIFIC SIZE BEAD WIRE:
Bead wire also called the skeleton and backbone of the tyre, which will give the support
and life to the tyre without the bead wire, the tyre itself nothing. If the bead wire is not
proper and according to the requirements then the following problems like bead out,
bead crush are commonly observed. Rim size adjustment is very difficult if the size is
not proper and poor building of bead wire will result in wire separation. If the joint of the
bead wire is not suitable then the problem of bead crushes also seen. So if the bead
wire is not of good quality the result will high rejection rate.
3. PREPARATION OF TREAD AND SIDEWALL
The Sidewall
The sidewall provides lateral stability for the tire, protects the body plies and helps
keep the air from escaping. It may contain additional components to help increase
the lateral stability.
The Tread
The tread is made from a mixture of many different kinds of natural and synthetic
rubbers. The tread and the sidewalls are extruded and cut to length. The tread is just
smooth rubber at this point; it does not have the tread patterns that give the tire
traction.
- 42 -
TYRE BULIDING
OVERVIEW OF TYRE BUILDING
TIRE ASSEMBLY
All of these components are assembled in the tire-building machine. This machine
ensures that all of the components are in the correct location and then forms the tire into
a shape and size fairly close to its finished dimensions.
- 43 -
After building the green tyre it is transferred to the painting machine, where anti-blemish
chemicals are applied
TYRE ASSEMBLY MACHINE
CARCASS BUILDING
- 44 -
Bead wires are set at the applicators. Bead joint has to be in the right place to avoid tyre
imbalance.
Inner Liner Mounting
Inner liner is set at the drum and rotated around the drum at one turn. The joint is cut
with a hot knife. Inner liner is set end to end so that the diagonal cutting seam is at the
top. The ends are joined manually.
Body Ply Mounting
- 45 -
Cord ply ends are set at the drum and rotated around the drum at one turn. The cord is
cut by hand with a join of 2-5 overlapping wires. The join is pressed carefully together at
the edges.
Bead Wire Mounting and Turn-Up
Bead wire mounting and turn-up is done automatically. Bead wire applicators bring the
beads to the carcass. Edges are turned up with bladders over the beads and stitched
tightly.
Cap Ply: Mounting and Joining
- 46 -
The ends of the nylon cap ply, is set at the drum in the middle of the steel belts. Bandage is
wound on top of the steel belts 1-2 times. The bandage is cut with scissors.
Tread Mounting
Tread is pulled onto the drum automatically. Tread is set end to end and joined
automatically.
SIDEWALL MOUNTING AND JOINING
- 47 -
Sidewall ends are set at the drum and rotated around the drum at one turn. Sidewall is
set end to end and the seam is fastened together manually.
TREAD PACKAGE
Steel belt tables go down on the drum automatically. Steel belt is joined by cutting it with
a hot knife and setting the ends together.
First and Second Stage Coupling
- 48 -
Carcass (1st stage) and tread (2nd stage) packages are joined automatically. The
carcass is set at the flanges of the carcass drum, pressurized, fastened to the tread
package and stitched together.
Green Tyre
At this point the tire has all of its pieces, but it's not held together very tightly, and it
doesn't have any markings or tread patterns. This is called a green tire.
The tire building machine pre-shapes radial tires into a form very close to their final
dimension to make sure the many components are in proper position before the tire
goes into the mold.
CRITICAL CONTROL POINTS IN TYRE BUILDING (GREEN TYRE) PROCESS
NYLON CORD PASTING
If the Nylon Cord Pasting is not done properly will lead to cord visible/naked and the
poor quality tyre produced, that will leads to the poor bonding with the tread of ply and
the increased in process loss. The ultimate result Rejection rate will increased. So the
remedial action is to check the machine before start and also adjust the adjustments
according to the given specifications.
- 49 -
NYLON CORD CUTTING
Nylon Cord Cutting is the key factor in the tyre industry. The pasted cord cutting
according to the specification is very necessary. In cutting both the Width and Angle
requirement are very accurate other wise these problems are Poor overlapping of cord
will result in poor quality tyre. If the width is not equal on both side result in wobbling, if
the angle variation is very high then the standards will result in bead crush and the
lesser angle will result in bead out. The pasted cord cutting play a vital role in poor
shape of the tyre and we can also call him the backbone of the tyre.
EXTRUSION
Extrusion of treads according to specification like width, Weight, and result are play a
vital role in the manufacturing of the tyre. If this thing is not accurate then these
problems will occur:
If the tread Width is more then the specifications then the flash produced and in the
reverse case the wobbling of the tyre is not controlled. The less width also result in cut
mark,
If the Weight of the tread is high the abrasion increased and the life decreased of tyre,
more drag due to high weight of tread result in lesser the engine life also. If the Length
of the tread is not cut accurately wobbling is not controlled, and the joint mark also seen
on the tyre.
Extrusion Temperature: one of the majors factors for the smooth extrusion by the
control on temperature otherwise the following defects are seen
Burning, premature vulcanization results poor quality of tyre, size variation in length,
width and weight seen. All these variation in the extrusion process controlled by
checking the temperature of extruder. So before operating the extruders, checks the
water and steam supply is ok and up to the standards requirement.
- 50 -
VENTING:
This process is done for the release of air trap between plies and tread during green
tyre building (This process is done only in the Nylon cord not in Steel cord). If venting is
not done properly it will cause air bubbles in tyre, tyre will be rejected in quality.
TYRE BAGGING
Done by hydraulic pressure between two plates before vulcanization or by the bagging
machine out before green tyre mounted in Curing Machine (Mould).
Tyre Curing
The next step is to run the tire into a curing machine, which functions something like a
waffle iron, molding in all of the markings and traction patterns. The heat also bonds all
of the tire's components together. This is called vulcanizing. After a few finishing and
inspection procedures, the tire is finished.
CURING PRESS AND MOULD
The curing press is where tires get their final shape and tread pattern. Hot molds like
giant waffle irons shape and vulcanize the tire. The molds are engraved with the tread
pattern, the sidewall markings of the manufacturer and those required by law.
Tires are cured at over 300 degrees for 12 to 25 minutes, depending on their size. As
the press swings open, the tires are popped from their molds onto a long conveyor that
carries them to final finish and inspection.
- 51 -
POST CURING PROCESS
After Curing Tyre mounted on Post Curing Machine and Pressured it cooled
down and become in Proper Shape.
QUALITY INSPECTION OF CURED TYRE
If anything is wrong with the tire – if anything even seems to be wrong with the tire, even
the slightest blemish – it is rejected. Some flaws are caught by an inspector's trained
eyes and hands; others are found by specialized machines.
Inspection doesn't stop at the surface. Some tires are pulled from the production line
and X-rayed to detect any hidden weaknesses or internal failures. In addition, quality
control engineers regularly cut apart randomly chosen tires and study every detail of
their construction that affects performance, ride or safety.
- 52 -
Fault Inspection Stage Preventive Action Corrective Action
In process Final
Air Bubble Punching Machine
After Curing Venting not properly done/ Moulds vent hole block/Check power stashers
Check Punching Machine, that green tyre punched properly/ power stasher use properly at Tyre Building Machines.
Bead Out Bead wire Machine
After Curing Bead over size Adjust Bead wire size properly according to specification.
Ply Separation Calendaring/ Tyre Building Machines
After Curing Ply is not according to specification/ card used not according to specification.
Check Calendaring process / and must be adjusted calendering roller speed/ Tread card according to specification.
Mould Out Curing After Curing Mould Adjustment Moulds both parts adjusted and tighten properly.
Wobbling Check at Tyre Building Machines
At Wobbling Machine
Check Plies and Tread Joint not at same place
Tyre Builder must be trained / plies and Tread joint must not be overlapped.
Under Curing Mould
Timer
After curing Less Curing time/Less
Steam Pressure
Curing Time/Steam pressure adjusted properly according to standard
Same Angle At Post Curing Machine
Quality Inspection
Tyre Builder used plies at same angle
Tyre Builder must be trained/ plies angle must be opposite
Foreign Matter At all tyre Building stages
After Curing Foreign object mixed in Tyre contents i.e Metal/wood pieces.
Ensure Cleaning at all tyre Build stages.
- 53 -
LABORATORY TESTING (DESTRUCTIVE TEST) OF FINISHED PRODUCTS
(TYRE)
Hardness
Abrasion
S.G
Ply to Tread Adhesion
Weight
CRITICAL CONTROL POINTS IN CURING OR VULCANIZATION OF TYRES
Steam pressure (less under cure tyre, burning and bubble bead wire ply and tread,
hardness increases, reversion / sticking seen on the tyre)
Hydraulic Pressure The proper hydraulic is required for the quality production of tyre
and its most critical point in the manufacturing of tyre. The accurate hydraulic pressure
is used for the proper shaping of tyre. The standard hydraulic pressure is almost 100
Kg/cm2. If the hydraulic pressure is less then the standard the tyre de shaped and the
flash between two parts of mould (Male and female). And the second problem that is
seen if the hydraulic pressure is decreased the undercure tyre in the result.
Air Pressure: Both the air and steam pressure is very necessary for the proper
vulcanization of the tyre. The standard air pressure is 15-17 kg/cm2, which is required, is
required for the proper curing and shaping of tyre.
Bagging and Shaping:
Done by hydraulic pressure between two plates before vulcanization or by the bagging
machine
Time (Curing):
The proper time as need for the cooking as look that here we cook the tyre according to
the said specification and requirement. If we are not given the proper time the under
cure tyre at the end we received
- 54 -
Mould Alignment:
If the mould are not aligned then the flash produced on the tyre and also the tyre de-
shaped.
After Curing
Debagging
Post Curing
HOW TO CONTROL THESE CRITICAL POINTS?
Skilled personals at the Machines: Make sure it other wise if we change the operator
on daily basis it reduced the efficiency of both worker and machine. So here a need to
specify the person at there right place to increase the productivity and the product
quality.
- 55 -
DAILY REWORK REPORT MIXING DEPARTMENTDate: ___________ Sr. No. _______
Compound Batches Batches Results Batches % Age Of Remarks
Identification Produced Checked Rework Rework
Tread Compound
T – 100
T – 200
T – 310
T – 600 Friction
Compound
F – 100
F – 110
F – 600
Bead Wire Tube
Compound
TB – 400
TB – 500
TOTALRemarks:
PREPARED BY LAB MANAGER
- 56 -
Pressure And Temperature: Trained the workers to check the pressure before the
start of production the specified pressure is 6 to 7 kg for the internal mixing named as
“Banbury”. If it is less or more then report to the production Incharge for the quick
remedial action and stop the production until the pressure reaches to their standard
limits. The temperature also plays a critical role in the mixing of the compound and
result in the excellent or bad quality mixing. The temperatures for the Natural rubber
compound should not exceed then 160ºC. For the synthetic rubber (like butyl) should
not exceed then 190ºC
If the temperature increased the risk of compound curing/scorching also increased and
the compound useless for the next processing. Here the third party or the laboratory
staff requires a check and balance. In case of any disturbance report to the immediate
boss. If the temperature is too low the mixing is not possible and it’s simply wastage of;
Labor
Electric Power
Raw Material
Time
- 57 -
QUALITY AUDIT REPORT OF MIXING PROCESSDate : Shift:Process Checking
1 Hr 2 Hr 3 Hr 4 Hr 5 Hr 6 Hr 7 Hr 8 Hr
Banbury Big Small Big Small Big Small Big Small Big Small Big Small Big Small Big Small
Air pressure
Banbury Time
Banbury Temp
Dump Temp
Rubber Chemicals & Filler CheckingCompound
1010(NR)21502(SBR)21712(SBR)21203(PBR)21675(IIR)Reclaim
Total3330(N-330)3550(N-550)3660(N-660)4100(CaCO3)
China Clay4110(Whiting)
Total6310(CBS)
6330(TMTD)6340(MBTS)6350(MBT)9610(PVI)6360(Sul)
Total5210(ZnO2)5220(St.Acid)
7410(IPPD)7420(PBN)7430(Wax)
Resin China
Total8510(W/Oil)8520(T/Oil)
Remarks:
Checked by Mixing Foreman Lab Representative Mixing Incharge Lab Incharge
- 58 -
Consistent Raw Material: Consistency in the raw material is very necessary, if the raw
material varies the product at the end also vary which may take a several days for the
right product. So the sources are the always same.
Water Supply: The water supply for the temperature maintaining is a key factor if the
water circulation is not enough or the good then the compound quality also varies from
batch to batch. For the consistency in the end product either in the form of batch or tyre
and tubes.
Mastication: what is the mastication? It’s the process in which the long polymer breaks
into smaller one and band is formed or we can say a pre cooking process of rubber.
This point is also play vital role in the mixing of the compound. In case of poor
mastication a no. Of problem observed like a batch no extrude. The proper time is
needed and skilled worker very necessary for the accurate mastication.
These are the few critical points regarding to the mixing department and we can control
these points by check and measure. And normally that practice done by the laboratory
staff or the quality control/assurance department. To make sure these things not
happened. This will lead us to an improvement of the product and the system.
MARKING ON TYRE
There's a lot of useful information molded into the sidewall of a tire. It shows the name
of the tire, its size, whether it is tubeless or tube type, the tire grade, speed rating, the
maximum load, maximum inflation, an important safety warning, and more. Click an
area within the tire graphic to learn about the individual fields of information. (Following
the graphic is a scrollable summary of this information.)
- 59 -
Tire Type" defines the proper use of the tire. P means this is a passenger car tire. If the
tire had an LT then the tire would be for a light truck.
"Tire Width" is the width of the tire measured in millimeters from sidewall to sidewall.
This tire is 215 millimeters.
"Aspect Ratio" is the the ratio of the height of the tire's cross-section to its width. 65
means that the height is equal to 65% of the tire's width.
"Construction" tells you how the tire was put together. The "R" stands for radial, which
means that the body ply cords, which are layers of fabric that make up the body of the
tire, run radially across the tire from bead to bead. A "B" indicates the tire is of bias
construction, meaning that the body ply cords run diagonally across the tire from bead
to bead, with the ply layers alternating in direction to reinforce one another.
"Wheel Diameter" is the width of the wheel from one end to the other. The diameter of
this wheel is 15 inches.
"Load Index" is a number corresponds to the maximum load in pounds that a tire can
support when properly inflated. You will also find the maximum load in pounds and in
kilograms molded elsewhere on the tire sidewall.
"Speed Rating" is a number that corresponds to the maximum service speed for a tire.
"H" means that the tire has a maximum service speed of 130 mph. Please note that this
rating relates only to tire speed capability, and is NOT a recommendation to exceed
legally posted speed limits; always drive within the legal speed limits. Speed Rating
Chart.
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"DOT" means the tire is compliant with all applicable safety standards established by
the U.S. Department of Transportation (DOT). Adjacent to this is a tire indentification or
serial number; a combination of numbers and letters with up to 12 digits.
"UTQG" stands for Uniform Tire Quality Grading, a quality rating system developed by
the Department of Transportation (DOT).
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FLOW CHART FOR THE TUBE DEPARTMENT
This is the general type of flow chart for any tube manufacturing unit.
Compound received from Mixing Department
Compound Re-warmed On The Two-Roll Mill
Feed In The Extruder
Length Cutting
Send To Curing Section
Quality Section Curing Conditions steam
pressure is 13 kg & air inside pressure is 8 kg per Cm
Square
Market
Splicing SectionHere the two ends of the
tube join together
- 62 -
PROCESS FLOW DIAGRAM OF TUBE MANUFACTURING UNIT
PRODUCTION OF TUBES AND CRITICAL POINTS
Critical control points in Tubes.
1. Steam Pressure should be 10 ½ Kg outside, 7-9 Kg inside in side steam is
necessary, check before the start of production. If the steam pressure is high,
sticking because of over curing observed also burning and porosity on the
surface of Tube and at nozzle will appear. If the steam pressure is low, under
cure and balloon problem will be seen in this case, here again we need skilled
- 63 -
worker who check the Machine and gauges before the start of work to avoid
these problems.
2. Mould Temperature: If the mould temperature is low or high it has the same
effect on the product as of high or low steam pressure, here we must control the
steam pressure and the same problems will appear. The mould temperature will
be in control. The second thing in controlling the mould temperature is Blow. This
case has seen when the curing press in stationary mood then the Blow is very
important. The purpose of Blow is to remove water contents in the press which
decrease the mould temperature and will result in the above said problems.
SPLICING Just after extrusion, the 2nd step is splicing, the critical control points of splicing
are:
i. Air Pressure.ii. Butting Pressure.
iii. Cutter Temperature.
iv. Cleaning of Dies.
(i) Air Pressure: Should be 6Kg almost but may be different according to
machine specification. The air pressure play a key roll in the manufacturing of
tubes, if the pressure is less Joint will be open and if pressure will be high the
same problem will seen.
(ii) Butting Pressure.
(iii) Cutter Temperature should be around 230 °C, but it may vary with thickness
and machine model. Here we seen the same problem as above said.
(iv) Cleaning of Dies: If the dies are not cleaned joint mark will appear on the
tube.
Here also skilled operator is required for accuracy and precision.
EXTRUSION
Temperature Control
Vacuum work proper.
Nozzle Punching should be proper and also check here that a cut do not present
under the nozzle otherwise tube will burst in the press.
LABORATORY TESTS
- 64 -
COMPOUND: Testing which are prepared in MKNG Department.
Tensile Strength (Elongation Modules) checked on tensometer.
Hardness: Checked be hardness tests Shore A.
Scorch Time: Rheological proprieties by Rheometer at 180 °C (Butyle) and 160 °C
for (NR) .
Abrasion: (DIN Type) A tensile sheet hardness and Bheological properties
checked / cured at fixed temperature should be 160 °C. The temperature accuracy is
needed here other wise the result too much vary from the standards.
LABORARATORY TESTING FINISH PRODUCT.
Nozzle Paste: is one of the most critical point there is no moisture, no contamination
seen in the room, the paste should be properly mixed and uniform in viscosity not too
thin or thick but have the adverse effect on the nozzle.
If the solution is thick the paste not dry and result in the nozzle open and also if the
paste thin the same case will happened and if there is any dirt then the same case
Extrusion: control the weight, width and thickness this step is common and the most
critical point
Problems: if the tube overweight balloon and under-cure tubes are the end result. If the
width is increased the creez will be the result. If the case reverse the width is less then
the standard then the thin and burning will occur. If the tubes are shorter in length the,
thin, joint open and joint mark is observed. If the length is greater then the overlap is
seen on the nozzle of the tube.
LENGTH CUTTING
SPLICING: here the critical point is the temperature of the cutters and the butting pressure, also the air pressure that should be 6 – 7 KG
CURING critical points are as follow:
1) Steam Pressure
2) Air Pressure
3) Mould temperature
- 65 -
HACCP FORM / REPORTS FORMATS
HACCP PLAN
Process Category:
Product:
CCP # and Location
Critical Limit
Monitoring Procedures and
frequency
HACCP Records
Verification Procedures and
Frequency
Corrective Action
Signature: _____________________________ Date: _____________________
- 66 -
HAZARD ANALYSIS - RAW PRODUCT, GROUND
Process Step
Tyre Safety Hazard
Reasonably Likely to occur?
Basis If yes in Column 3, what measures could be applied to prevent, eliminate, or reduce
the Hazard to an acceptable level?
Critical Control Point
Mixing
Department
Chemical: Yes
Biological: Yes
Physical: Foreign
Contamination
Yes
Tyre Building Chemical:
Biological:
Physical:
Tyre
Curing
Biological:
Chemical:
Physical:
- 67 -
HAZARD IDENTIFICATION/PREVENTIVE MEASURES
PROCESS CATEGORY:
PRODUCT:
PROCESS STEP PRODUCT SAFETY HAZARD PREVENTIVE MEASURE
Approved By: ____________________________ Date: _____________________
- 68 -
HACCP DEVELOPMENT FORM : CORRECTIVE ACTION
PROCESS CATEGORY:
PRODUCT:
Process Step /CCP
Critical Limit Monitoring Procedures(Who/What/When/How)
Corrective Action
- 69 -
HACCP DEVELOPMENT FORM : MONITORING PROCEDURES AND FREQUENCY
PROCESS CATEGORY:
PRODUCT:
Process Step/ CCP
Critical Limit Monitoring Procedures(Who/What/When/How)
- 70 -
GLOSSARY OF TYRESAlignment
(Tracking)
The setting up of the factory specification for any given vehicle. This should be carried
out by the vehicle main dealer. Unnecessary alignment or "tracking" is one of the most
common forms of overcharging by tyre depots.
All Season
Tyres
Tyres designed to be used all year round. May have Winter tyre design, or winter tyre
compound compromise.
Aquaplaning
The process of water building up in front of a moving tyre until it lifts the tyre away from
the road causing loss of control.
Aspect ratio
The ratio of the sidewall to the width of the tyre tread expressed as a percentage So a
tyre of 220mm width with a sidewall height of 110mm would be a 50Aspect Ratio, or
50 profile tyre.
Asymmetrical
Tyre tread patterns which vary from one side of the tread to another, ie, they are not
symmetrical. If these tyres are non-directional they must be fitted with the outside
sidewall on the outer face of the wheel. If they are also directional they will also be
handed left and right as well.
BS AU 159f
The British Standard for tyre repairs for vehicles used on the road. We carry out all tyre
repairs to this British Standard. (see Tyre Repairs)
Balance
Weights
The weights used for balancing. Used to be mostly lead but now being replaced by
alloy. On high performance cars with alloy wheels, where possible, we use "stick-on"
weights positioned out of sight on the inside of the wheel.
Balancing
The process of balancing to remove the slight differences in a tyre and wheel
assembly to account for wheel run out and imbalances in tyre production. This
eliminates steering vibration. We do not charge extra for this service.
Balancing
Beads /
Compounds
Powder, or beads added to commercial vehicle tyres to offer wheel balancing using the
laws of physics to even out imbalances.
Bead
The area of the tyre that is in contact with the wheel rim. The bead carries a multi-layer
steel band that and a shape that retains the tyre on the rim.
Beaded edge
This is a veteran tyre held in the rim by a rubber bead carried in a lip in the wheel rim.
Its own pressure retained it in place.
Bias-belted
Tyre
This is a development of the Crossply tyre, using radial technology over a crossply
style structure. Some American market tyres are still manufactured as bias-belted.
- 71 -
Butyl Liner
A fine inner layer in a radial tyre (usually) that prevents sudden loss of air in the event
of a puncture.
C3MMichelin's computer controlled tyre manufacturing process allowing short production
runs at very high levels of conformity.
Calendaring
Part of the tyre manufacturing process.
Camber
The deviance from the vertical of the tyre centre line when the vehicle is at its normal
ride level. Incorrect camber may cause uneven tyre wear.
Cap Band
This layer of nylon protective material applied to some high performance and SUV
tyres to prevent delamination.
Carbon Black
Rubber is grey in colour, Carbon Black is added as a filler, to provide a uniform colour,
and to increase wear resistance.
Carcass
The body of the tyre onto which the sidewall and tread are built.
Casing
The body of the tyre onto which the sidewall and tread are built.
Caster
The angle of inclination of the spin axis and to the vehicle in a vertical aspect. This
retains the steering wheels in an "ahead" position.
Clincher Tyre
This is a veteran tyre held in the rim by a rubber bead carried in a lip in the wheel rim.
Its own pressure retained it in place.
Contact Patch
The area of tyre tread in contact with the road at any given time. This varies during
acceleration, braking and cornering. It can be affected by tyre pressure, temperature,
and compounds and tread design.
Conti SSR Continental's run flat tyre system with self supporting sidewalls.
Cross-ply Tyre
The replacement for the "clincher". This is the bias-belted or cross ply tyre which has a
steel bead wire to retain the tyre on the rim, and a series of cross ply carcass strength.
DOT Codes
The US Government coding given to tyre factories. This data can help to identify the
place and date of origin of the tyre. Dot Codes are available on the Internet.
De-
vulcanization
The chemo-mechanical process which causes the tyre compound to break down, often
through heat build up due to under-inflation. Can cause tyre failure. Also a process
used in recycling vulcanized rubber.
Deformation
The "give" in a tyre interacting with the road and the driver input. A tyre with little give
will handle differently from a tyre with lots of give. A tyre should have a compromise for
the best performance on the road.
- 72 -
De-lamination
The process where a tyre that is faulty, or has been run under-inflated may break
down, causing its tread layer to become separated from the casing.
Diagonal Tyre
The replacement for the "clincher". The cross ply tyre has a steel bead wire to retain
the tyre on the rim, and a series of cross ply belts to give the carcass strength.
Directional
A tyre with a tread pattern that must be fitted in an indicated orientation. Often a
chevron shaped pattern which assists the removal of water under the tyre.
Disposal charge
A fee charged by many tyre depots to pay for the cost of disposing of the scrap tyre.
We do not make a charge for this disposal which we carry out in an environmentally
friendly way.
E Marking
All car tyres sold from 1st July 1997 must carry an 'E' marking. They certify that the
tyre complies with the dimensional, performance and marking requirements.
Economy
A new tyre of fair quality that we sell at a lower price than Mid Range. Naturally the
performance of this range will also be lower.
Euphori@ Pirelli's Run Flat system.
Fabric
The materials used in the tyre belt are woven and will be constructed from a blend of
textiles and fine wires.
Footprint
The area of tyre tread in contact with the road at any given time. This varies during
acceleration, braking and cornering. It can be affected by tyre pressure, temperature,
compound and tread design.
Grooves
Lateral - drain water to sides of the tyre. Circumferential - evacuate water to the rear of
the tyre or "store" it. The number of grooves increases as the tyre width increases.
Harmonics
An annoying harmonic vibration and audible noise which can cause discomfort for the
occupants. This is a big issue for car and tyre manufacturers at the design stage.
Hysterisis
The resistance to deformation of the rubber in a tread block. The level of hysterisis in
any given tyre dictates the heat it will generate in use, and therefore the rate at which it
will deteriorate. High hysteresis is good as it helps the tyre resist "slip".
Land Sea ratio
The ratio of tyre tread in contact with the road and the voids designed for removing
water. Tread pattern blocks equate to land, grooves equate to sea.
Lateral
Acceleration
The forces acting on a tyre to pull it sideways during cornering.
Load Rating
This is shown on the sidewall of the tyre to indicate the maximum load the tyre is rated
for.
- 73 -
Locking bolt
A security device to prevent the theft of (usually) alloy wheels. Typically one per wheel
is fitted. If your vehicle has locking bolts it is important not to loose the "key". However,
if you have lost the "key" we can usually overcome the problem, but we do make a
charge for this. Price on application.
M+S Mud and Snow tyre: A wide range of which are available from etyres.
MIRSPirelli's computer controlled tyre manufacturing process, which allows short production
runs at very high levels of conformity.
Major RepairA major repair is where a damaged tyre can be repaired using a reinforced internal
patch and a Hot Vulcanisation process. More common on Commercial, agricultural and
earthmover tyres but also used on some car tyres.
Mid Range tyreA new tyre of fair quality that we sell at a lower price than the main brands of
Bridgestone, Firestone, Michelin, Pirelli etc. Naturally the performance of this range will
also be lower.
MuThe coefficient of the average grip of a tyre on a wet surface. A specification used in
tyre design and testing.
Multi-purpose
Off Road Tyre
Grooved at 35 per cent with 8 - 12 mm grooves, few sipes. Looks similar to
conventional car tyre.
Natural RubberUsed in tyre construction, but not the best material to provide grip.
Nitrogen
An alternative to air for inflating tyres. Nitrogen molecules are larger than those of
oxygen and so are less susceptible to osmotic loss through the tyre casing. Tyres
therefore stay at the correct pressure for longer. Being inert there is also the argument
that nitrogen can reduce deterioration of the tyre from inside. Can also assist in
maintaining an even temperature. However these benefits are marginal because air
already contains 78% nitrogen.
Nut/Bolt
Torque
The correct "tightness" for wheel nuts/bolts. See chart in Caring For Your Tyres.
OEM
Original Equipment Manufacturer - so a tyre may be from an OEM, but not be OE fit.
Original
Equipment
(OE)
The original brand of tyre or battery that was fitted by the car manufacturer. There may
be more than more than one OE brand fitment.
Oversteer
When the driver corners and the rear wheels lose grip and the rear of the car starts to
slide sideways.
- 74 -
PAX
Michelin's run flat technology that requires special wheel rims and Tyre Pressure
Monitoring System (TPMS).
Profile
The ratio of the sidewall to the width of the tyre tread. Expressed as a percentage ie. a
tyre of 220mm width with a sidewall height of 110mm would be a 50Aspect Ratio, or
50 profile tyre.
Puncture
Treatments
A range of aftermarket tyre additives that can be used to minimise air loss in the event
of a puncture. Some offer "permanent" repairs, others offer a "get you home" repair.
Radial Tyre
This is the carcass design originally developed by Michelin using parallel carcass belts
for the sidewalls and crossed belts for the crown of the tyre. All modern car tyres are
radial.
Regrooving
The process of cutting new grooves into worn tread to extend the life of truck tyres . An
illegal operation on car, 4x4 and light commercial tyres.
Remoulding
A recycling process where a tyre is buffed back to its casing, repaired and rebuilt using
fresh tread compound. We only sell remoulded tyres in very exceptional cases.
Repairable
Area
The area of the tyre tread where a puncture repair can be made to British Standard
BSAU 149. We will send you a free gauge on request to freefone 0800 028 9000.
Retreading The process of replacing the tread layer on a tyre. Generally reserved for commercial,
agricultural and industrial tyres.
Road tyre Generally designed with a land/sea ratio of 30 per cent void. 6 - 9mm deep.
Rolling
Resistance
The amount of energy required to overcome the static mass of the tyre. This can be
affected by design, load and pressure.
Run-Flat
A tyre designed to run at low or no pressure to enable the driver to reach a place of
safety, or even complete the journey. Read more here.
SSTDunlop "run-flat" system. Initial letters stand for Self Supporting Technology.
Sealants A range of aftermarket tyre additives that can be used to minimise air loss in the event
of a puncture. Some offer "permanent" repairs, others offer a "get you home" repair.
- 75 -
Shoulder area The edge of the tread where it meets the sidewall. Its design is key to cornering
characteristics on road tyres and important in attaining grip on off road tyres.
Sidewall The side of the tyre between the rim and the tread. This carries all the tyre
identification data, load rate, speed rating and manufacturing data.
Silica
A filler obtained from sand and used to improve grip in the wet and extend tyre life.
Sipes
Narrow slits in the tread blocks designed to pump water away and to create more
leading egdes to increase grip in winter and wet weather tyres. (See Reading Your
Tyre)
Slip
That element of the deformation of the tread block in cornering, or braking before it
breaks away.
Snowflake
USA and Canada: This additional marking on an M+S tyre shows that the tyre meets
legally prescribed test criteria and advises that it has good winter properties.
Space saver
A spare tyre of a smaller size than the road tyres. The purpose of the reduced size is
to save space and reduce weight. Designed to get you home, these tyres have a
slower maximum speed and are designed to be only used on a temporary basis .
These tyres have been banned in New Zealand. Certain cars, such as Porsche use an
un-inflated spare and a small electric compressor.
Specialist Off
Road Tyre
Land Sea ratio of 40 per cent. Usually grooved to 15mm depth, very blocky tread
pattern.
Speed Rating
The maximum continuous speed the tyre is rated for. (See Reading Your Tyre)
Sports tyre
Generally the Land Sea ratio is higher in a sports tyre and there are few, or no sipes.
Standing Wave
A wave of deformation in front and behind the contact patch of a rolling tyre. Too great
a standing wave creates heat build up and tyre de-vulcanisation.
SulphurTransforms rubber from an elastic to plastic state to be moulded and vulcanized.
Synthetic Butyl
Rubber (SBR)
60 per cent of rubber used in tyres is synthetically manufactured from crude oil. SR
has a high level of Hysterisis.
Textiles
The materials used in the tyre belt are woven and to from a blend of textiles and fine
wires.
- 76 -
Toe in/out
The deviation of the centreline of the tyre from a true fore and aft position. Too much
"toe" will result in excessive and uneven tyre wear.
Torsional
distortion
The forces creating a twisting distortion in the sidewall during acceleration and braking.
Tread
separation
The process where a tyre that is faulty, or has been run under-inflated may break
down, causing its tread layer to become separated from the casing.
Treadwear
Indicator
A bar of rubber moulded into the base of the tread, positioned in at least three points
around the tyre. When level with the tread pattern the tread is worn down to a point
where the tyre should be replaced.
Tubed
A tubed tyre requires the use of an inflatable inner tube. Such tyres are susceptible to
rapid deflation when punctured.
Tubeless
A tubeless tyre is usually a radial tyre with a thin butyl rubber liner that seals around
penetrations helping to prevent instant loss of pressure in the event of a puncture.
Tyre Pressure
Tyre pressure is the measurement of the volume of air inside the tyre when it is
inflated. Formally measured in pounds per square inch (psi) now measured in bar. (1
bar = 14.503774 psi) . Pressure will gradually reduce and therefore regular checking
and topping up is necessary to maintain the vehicle manufacturers recommended
pressure. (See vehicle owners manual). Never inflate a tyre to a greater pressure than
the maximum that is indicated on the sidewall of the tyre.
Tyre Pressure
Monitoring
System
(TPMS)
A method of monitoring tyre pressure from inside the car whilst the vehicle is in use.
Usually a RFID device inside the wheelwell, or attached to the tyre sends data to an
onboard display to alert the driver to pressure loss in the tyre. It may also be based on
the differential in the vehicle's ABS system, but the latter, though cheaper, is thought to
be unreliable.
Tyre Repairs
Tyre repairs should only be carried out by specially trained personnel using
professional equipment.
Tyron
An bolt-on emergency runflat system ideally suited for caravans and trailers, but can
also be fitted to cars. Use of TPMS is advised.
Understeer
When the car "fails" to respond to steering and ploughs straight on.
- 77 -
Valve
Usually made of rubber, with a metal core assembly and a plastic, screw-on dust cap.
Allows the tyre to be inflated to the correct pressure. Available in two standard lengths,
short for most alloy wheels, long for steel wheels which have a plastic wheel-trim.
Certain types of commercial vehicle, such as the Ford Transit, require a high pressure
rubber valve. Many high performance cars are fitted with metal "bolt-in" valves. Our
prices always include supplying and fitting a new rubber valve. For metal valve prices
please call our call centre on 0800 028 9000.
Valve cap
A plastic, screw-on, cap to prevent dirt from entering the valve.
Vulcanisation
The process of cooking "green" rubber compounds to create a hard plastic rubber that
retains its form for tyre use.
Vulcanisation
(Cold)
Repairs using the cold vulcanisation process are only permitted if the tyre has suffered
superficial penetration damage in the tread area and only if the damage does not
extend beyond 6 mm - measured on the inside of the tyre. The hole itself must be filled
and the damage on the inside of the tyre sealed off. Inserting an inner tube without
repairing the damage is not permitted. Sealing the damaged area by means of a
puncture spray should only be regarded as a temporary measure in an emergency.
( See Tyre Repairs)
Vulcanisation
(Hot)
Hot Vulcanisation is the process of heating a tyre to retread or carry out a major repair.
Damage that extends to the bead, belt or beyond must be repaired by hot
vulcanization.( See Tyre Repairs)
Wheel Size
Wheel Size this is the actual diameter of the wheel. This is usually measured in inches
however, a few vehicles manufactures still use metric wheels.
Width
Width is the measurement of the lateral flat part of the tread.
Winter Tyres
A misnomer as this implies use in snow and ice Winter tyres should ideally be used at
temperatures below 7 degrees Celsius. We sell a range of winter tyres and pre fitted
tyre/wheel assemblies that are ideal for Continental and Scandinavian use.
- 78 -
References:
1. The Vanderbilt Rubber hand book, Ed. By Robert . O . Babbit
2. Natural Rubber science and technology, A.D Roberts.
3. Introduction to rubber Technology by Manrice Morton.
4. Rubber technology and Manufacture by C.M Blow.
5. Rubber Materials and there compounds by J.A Brydson.
6. Testing of Rubber by R.P Brown.
7. ASTM standards for specification 2004.
8. Monsanto Rubber Guide
9. Materials Information Service, edited by Stephen Harmer.
10. Internet Web Sides
www.oen.bmjjournals.com
www.tirebusiness.com
Recommended