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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.

- 60 -

"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).

- 61 -

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