HSIL CD-II (1)

HSIL Ceramic Division-II 2

SUMMER INTERNSHIP

HINDUSTAN SANITARIES&INDUSTRIES LIMITED

HSIL Limited (Formerly Hindustan Sanitaryware & Industries Limited) is the

flagship Company of the Somany Group and was established in 1962 with a

joint venture of the Group with Twyfords, UK.

HSIL Limited is the largest Indian manufacturer of Sanitaryware products with

a dominant market share of 40% in the industry. HSIL Limited products are

available across the length and breadth of the country and are supported by over

1000 direct dealers and 12000 sub dealers HSIL Limited was the first Company

in India to manufacture Vitreous China Sanitaryware.

HSIL Limited’s installed capacity of 600 tonnes /year at the time of inception

has now reached 32000 tonnes/year (2.8 million pieces /year). This is an

outcome of significant expansion and modernization at Bahadurgarh Plant,

acquisition of Krishna Ceramics Ltd. at Bibinagar in 1989 and its merger into

HSIL Limited (Ceramic Divn.II) followed by extensive modernisation and

expansion.

In sanitaryware, the company has the largest kiln of its kind - 110 metres long,

5.5 metres wide, open-flame microprocessor-controlled, and one of the most

energy efficient kilns in the world. The company extensively uses battery

casting for the highest productivity in sanitaryware in the country.


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ACKNOWLEDGEMENT

The internship opportunity I had with HSIL was a great chance for learning and professional

development. Therefore, I consider myself as a very lucky individual as I was provided with

an opportunity to be a part of it. I am also grateful for having a chance to meet so many

wonderful people and professionals who led me though this internship period.

Bearing in mind previous I am using this opportunity to express my deepest gratitude and

special thanks to the Mr. SWAMINATHAN, AVP of HSIL, CERAMIC DIVISION-II for

giving me this wonderful opportunity to undergo internship training at this esteemed

organization.

I express my deepest thanks to Mr. ANIL, HR at HSIL for taking part in useful decision &

giving necessary advices and guidance and arranged all facilities to make life easier. I choose

this moment to acknowledge his contribution gratefully.

It is my radiant sentiment to place on record my best regards, deepest sense of gratitude to

Mr. S.LAKSHMI NARAYANA (Slip house & Mill house)

Mr. V.L.N MURTHY (Moulding & Casting)

Mr. VIJAY KUMAR (DGM, PRODUCTION)

Mr. RAMAKRISHNA (Glazing)

Mr. VENKATA RAMAIAH (Kiln)

Mr. NEERAJ KUMAR SHARMA (R&D LAB)

For their careful and precious guidance which were extremely valuable for my study both

theoretically and practically. And also my sincere thanks to all the executives, supervisors

and workers for their cooperation.

I perceive as this opportunity as a big milestone in my career development. I will strive to use

gained skills and knowledge in the best possible way, and I will continue to work on their

improvement, in order to attain desired career objectives. Hope to continue cooperation with

all of you in the future.

Sincerely,

T MAHESH NAIK


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INTRODUCTION

Sanitary ware is a division of ceramic wares. It is proven that ceramic sanitary ware wares

are cost effective and good for long run. They are considered to be extremely durable as well

as hygienic. Sanitary wares can with stand more than 400 kg load and excellent resistance to

chemical attacks. Sanitary ware items can be easily cleaned because of its glossy surface

properties. Sanitary ware items are made up of ceramic ware that used in bathrooms. Some

of the sanitary ware products are toilets, washbasins, pedestals, bidet, urinals, sinks, bath

tubs, etc..,

Sanitary ware Meaning: Sanitary – Hygienic and Clean.

Ware – Product / article

Process of Manufacturing:

Sanitary wares are consisting of two types of mixtures of different raw materials. The first

type is called body and the other type is called glaze. The body is mainly a tri-axial

compound i.e. made of clay, quartz & feldspar. On the other hand the glaze is made of

different oxides pertaining to different colors including the basic raw materials of clay, quartz

& feldspar etc. For body making the raw materials like china clays, ball clay, quartz, feldspar

etc. are mixed with water thoroughly to get a uniform slip. They are unloaded in an agitator

i.e. blungers. The slip is screened, magnetic separated and kept in an agitating tank with

addition of required deflocculants. The wares are cast in plaster moulds. The cast wares are

hard felted and kept on open racks or benches for drying and sent for driers for further

drying. The dried wares are tested for cracks and then finished. On the other hand glaze is

prepared in similar way by ball milling, screening and magnetic separation and then the glaze

is used in spray booth to apply on the finished dry body products and the glazed body is sent

for drying & then firing. After firing the fired products are sorted out and packed for sale.

Sanitary ware manufacturing / production process consists of 10 steps from slip preparation

to Packing. They are

1) Slip preparation

2) Glaze preparation

3) Modelling & Moulding

4) Casting

5) Drying

6) Inspection & Spraying

7) Firing

8) Sorting

9) Re fire/Rework

10) Packing


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PRODUCTION FLOW CHART:

Production

Drier

Mill House Department

Casting Department

Moulding/Block making/

Modelling Department Inspection & Glazing

Slip House department

Placing/Kiln Department

Quality Assurance Department

Ware House Department

Re-fire Department


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CONTENTS OF THE REPORT

1. SLIP HOUSE

2. MILL HOUSE

3. MODELLING & MOULDING

4. CASTING

5. INSPECTION & GLAZING

6. KILN

7. LABORATORY


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SLIP HOUSE

In Sanitary ware Manufacturing/Production process slip preparation is the first step. In this

process Slip is produced by mixing ball clay, silica, china clay and feldspar. This

composition is called Tri-axial body. Consist of Body former, Filler and flux. Body former is

plastic material which is required to give strength at the green stage of the sanitary ware.

Filler is non-plastic material which is going to give strength after the firing. Flux is a non-

plastic material which added to the body to reduce the fusion temperature point of the body

during firing. All raw materials are mixed at proper position and brought to required physical

parameters.

Normally following rheological parameters are checked after slip preparations – Fluidity,

Thixotropic of the slip at 1 minute and 5 minute, Half-Liter weight and casting rate.

These parameters will vary depending upon the composition, climate, type of casting and

required casting rate.

Supply slip will be mixture of virgin slip, run off slip & scrap slip. This composition also will

vary according to the availability of the scrap slip available and required casting rate.

Once slip prepared according to the required parameter it will be sent to slip storage tanks.

Whenever slip is required then it will be supplied to casting department for casting.


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Roles and Functions of Ceramic Raw Materials in the Sanitaryware Body:

Ceramic raw materials are usually classified according to their functions in ceramic

manufacture as well as their basic properties. It generally divides the ceramic raw materials

in two basic groups that are the plastic and non-plastic raw materials. Further detail division

depends on the material composition.

Plastic ceramic raw materials involve any clay material that when mixed with water reveals

the property called plasticity. Plasticity may be defined as a property which allows the

deformation of the clay when an external force is removed. A part of the non-plastic ceramic

raw materials acts as a filler, reducing high plasticity or shrinkage of the body when drying

or firing. On the other hand, other non-plastic raw materials are used for fluxing and melting.

The classic or "triaxial" ceramic body consists of three major components: clay (plastic),

quartz which is a non-plastic material and feldspar, that acts as a flux providing the glassy

phase. Typical raw materials normally used in a sanitaryware are clay, feldspar and silica.

Sanitarywares are thus referred to as triaxial bodies, owing to the three mineral types—

clay, silica and feldspar—consistently found in their makeup. Clay is the plastic component,

giving shaping abilities to the unfired product. Silica serves as a filler, lending strength to the

shaped body before and during firing. Feldspar serves as a fluxing agent, lowering the

melting temperatures of the mixture.

Clay:

Clays are formed by alteration, through aging and weathering of rocks such as granite,

feldspar, mica and quartz. At the origin, they are known as residual or primary clays. The

clays are formed at the site of the parent rock and are not transported by any of the various

agencies such as wind and water. Primary clays like china clays are usually found in irregular

pockets with unaltered rocks remaining. Primary clays are normally uncontaminated by non-

clay minerals as most of the primary clays originated from pure feldspar. Most kaolins are

primary clays. The fired color of the china clay is white as it has a high degree of purity.

Therefore, it is suitable for manufacturing sanitaryware. In addition, it is refractory due to its

low impurity content.

If the clays are transported by wind or water from their original point of formation, they are

known as sedimentary or secondary clays. The action of the water tends to grind up the clay

into a much smaller particle size. Sedimentary clays such as ball clays depend on their fine

particle size for remaining in suspension whilst they are being transported. This process of

sedimentation separates the coarse from the fine and only the very fine particles will be

carried to the final deposit. The sedimentary clays are likely to be contaminated with

impurities or accessory minerals that are picked up along the way such as muscovite, quartz,

iron oxide, rutile and garnet. Transported clays are usually made up of clay from various

sources. Sediments from numerous sites are likely to be mixed together with the presence of

carbonaceous matter. Secondary clays are therefore fine-grained and plastic. The fired colour


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is normally more buff than china clay that is usually white. The presence of organic and other

impurities as they were re-deposited in low lying swampy areas may be the root cause of the

darker fired colour. The ball clays are mainly kaolinite but they are much finer than china

clay and the impurities present are also very fine as well. Thus china clay needs less

deflocculants and water, whereas ball clay needs more deflocculants (as more impurities) and

water. Therefore a mixture of both the clays is used in sanitaryware production for desired

characteristics of the body.

The ball clay is the most difficult to disperse and is, therefore, normally processed and

allowed to age prior to final casting slip preparation.

Feldspar

Feldspar is an important and common fluxing material for ceramic bodies as well as glazes

and one of the three essential raw materials for the tri-axial body. Feldspar provides the

glassy phase for the ceramic bodies and they are added to decrease the firing temperature and

thus to reduce cost. It gives white color to the body.

Feldspar play an important role in achieving the vitreous nature of the body and the high

mechanical resistance of the product at the end of the firing stage. Due to the formation of

liquid at early stages it fills all the pore spaces and the body becomes non-porous (vitreous).

Silica

Silica is the most abundant oxide on the earth's crust. Silica as compared to the other raw

materials in the ceramic bodies is relatively cheap. Silica sand is used in the slip as a source

of silica. Addition of silica sand decreases its unfired strength and plasticity. It also reduces

drying shrinkage and increases the whiteness of the fired body. It also gives good strength to

the body.

One of the great advantages of the tri-axial composition is that it makes the formed piece

relatively insensitive to minor changes in composition and in firing time or temperature. This

stability is a result of the wide range of temperatures over which the three ingredients melt to

form glass.


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SLIP -HOUSE PROCESS FLOW CHART:

Batch weighing

Batch raw materials loading in Blunger

After required homogeneous mixing

Blunger Addition (water + electrolyte)

Sieve & Magnet

Virgin slip stored in tank

Slip Properties Test

Supply slip preparation (Virgin + Runoff

+ Scrap)

Send to casting

Supply slip properties test

Raw Materials


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Preparation of slip in slip house:

Ball mills are used for grinding the silica sand and pitcher materials. The raw materials are

stored in different storage chamber. The loaded ball clay raw material is supplied from

hopper to cart and then discharged into blungers. The slip from blunger is supplied to tank

after getting sieved in vibrating sieve (#140mesh).In these sieves magnets are there for

removing the iron particles in slip.

Then that slip is sent to a storage tank. The quartz sand is grinded in ball mill for 6-8 hours.

The china clay is also added to quartz sand for easy unloading. After grinding the quartz

sand, the slurry is stored in another tank. The ball clay slip and quartz sand slip are sent to

measuring tank. From measuring tank, sent to blunger. Now china clay is loaded in hopper

into carts. And from carts added into blunger directly. Now feldspar powder is added directly

in to the blunger. Required amounts of deflocculants is also added. This prepared slip is

called “virgin slip”. This virgin slip is stored in another storage tank.

Scarp slip

Scrap means rejected green and dry wares.These scrap materials are brought from

casting points and inspection booths. These scrap materials mixed properly in blunger with

sufficient water. And barium carbonate is added as deflocculant. The deflocculant is used for

free flow of slip.

Run off:

The run off slip is collected from casting points. The slip unloaded from moulds after getting

required thickness is called RUN OFF SLIP. This slip is also stored in storage tank.

Mixed slip:

It is the combination of scrap, run off and virgin slip. In measuring tank the slips are taken

according to their composition. Now from measuring tank it is to supply tank after

sieving on vibrating sieve (#100mesh) with magnetic separator. The magnets are used for

removing iron content in slip.

The scrap, run off and virgin are mixed according to following composition.

Run off - 60 %

Virgin - 26 %

Scrap - 14 %


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Consistent behaviour of the slip is important in minimising day to day production problems.

Such consistency is essential for the setting of factory production rates which achieve the

most efficient and cost effective manufacture of the finished ware.

SLIP CONTROL:

The most widely used method of casting slip control is based on the measurement of fluidity

and thixotropy by means of a Torsion Viscometer which is simple to use, robust and

relatively low in cost. The results it produces are quickly available and easy to interpret.

Necessary adjustments can be made rapidly to casting slips and re-measurement of fluid

characteristics takes only a few minutes.

MEASUREMENT OF FLUIDITY:

Before taking a measurement of fluidity, the viscometer cylinder is wound through 360

degrees in anti- clockwise direction. With the viscometer beaker in position under the

viscometer, the flywheel pin is released hereby enabling the flywheel to rotate in a clockwise

direction.

The over-swing indicated by the pointer on the flywheel against the graduated scale is

recorded as a measurement of fluidity.

It is important to ensure that the sample of slip is thoroughly stirred immediately prior to the

actual measurement.

Samples taken from production blungers are stirred in the viscometer beaker for exactly one

minute, immediately placed into the measuring position and readings are taken after 5

seconds (it is critical that the time is kept constant to ensure consistent, reproducible results).

It is also important to ensure that the cylinder is fully immersed in the slip being measured.

MEASUREMENT OF THIXOTROPY:

Thixotropy, or the tendency of an undisturbed slip to thicken with time, is an important

property which has a marked effect on casting performance. It is measured by rewinding the

viscometer flywheel immediately after taking the fluidity reading, allowing the slip to stand

undisturbed for 60 seconds, and then re-measuring the over-swing.


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Thixotropy is defined as the difference between the two readings. In some instances, a 5

minute thixotropy reading is also useful.

It is important that the temperature is recorded as temperature can severely affect viscosity

values.

MEASUREMENT OF SLIP DENSITY:

The density of a casting slip is kept within defined limits as variations will affect casting

performance. A low density slip can result in the difficulties with second casts and mould

drying. Conversely, high density slips can lead to casting and pouring difficulties if particle

packing and fluidity parameters are not controlled well.

The measurement of slip density is quite simple. A pre-weighed vessel is filled to a

calibration mark of 500ml and then weighed. The difference in weights represents the weight

of a slip in a given volume. Density of casting slip is expressed in g/cm3.

THE CONTROL OF CASTING SLIP:

It is necessary to specify slip control values which will depend on both the body being used

and the type of ware being produced. The best method of arriving at these values is to

monitor the fluid properties and density of the slip, and then to compare these observations

with casting performance over a period of time. It then becomes possible to relate fluid

properties to casting performance.

This is extremely important in systems as there is a re-use of run-off slip and reconstituted

scraps mixed with virgin slip.

Most casting slips perform satisfactorily when set to a fluidity of between 290 - 310 degrees

overswing and a one-minute thixotropy of between 40-50 degrees, at a density of between

1.7600 to 1.7800 g/cm^3.

To achieve a fluid casting slip, at a suitable solids loading, the clays have to be deflocculated.

A mixture of sodium silicate and sodium carbonate is used, as this system is not too difficult

to adjust. The casting slip control system is most easily understood by knowing how fluid

properties vary with the addition of deflocculant. When sodium silicate or sodium carbonate

is added to casting slip the fluidity increases and the thixotropy decreases. If the deflocculant

is added to excess then a point will be reached where fluidity decreases and thixotropy

increases. This generally serves as an indication of over-deflocculation of the system.


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Sodium silicate tends to give high fluidity slips with low thixotropy, while sodium carbonate

will give lower fluidity slips with higher thixotropy. It is normal practice to use these two

reagents together as this offers the possibility of obtaining high fluidity slips with an

appropriate degree of thixotropy.

The reagents are mixed in a ratio which will give the most effective control over fluid

properties for the given casting slip system. When this mixture is used, a progressive addition

of deflocculant will increase fluidity to a maximum and further additions will have little

effect on the level of fluidity. Thixotropy, however, will decrease steadily as deflocculant is

added and will continue to do so even after fluidity has levelled off. In this way thixotropy

can be adjusted while fluidity is maintained.

If the maximum value of fluidity is too low, then the density of the slip may be reduced by

the addition of water. This will have a marked effect on fluidity, but only a slight effect on

thixotropy. The density of the slip will not need to be drastically reduced as a small decrease

in density results in a large increase in fluidity. The aim of slip control is to keep the density

as high as possible whilst maintaining acceptable fluid properties for effective casting.

AGEING OF SLIP:

Casting slip requires final adjustment prior to use as its fluid properties change with time.

This behavior is the result of the extremely slow rate of reaction between the various

deflocculants and the clay particles in the body system. The ageing characteristics of a body

will vary depending on its make-up. It is usual to age for at least 72hrs in order to obtain

stability prior to casting.

It is normal practice for casting returns and clay scraps to be reprocessed and used in

Returned slips and scraps contain sulphate ions absorbed during contact with mould surfaces.

If this sulphate is allowed to accumulate in returned and reconstituted slip, it will adversely

affect fluid properties and will also be responsible for other faults which may appear later in

the production cycle.

For overcoming the problem of soluble sulphates an addition at the scrap blunger of barium

carbonate is made. The quantity of barium carbonate required is fairly small as the soluble

sulphate levels are also small. The barium carbonate reacts slowly with the soluble sulphate

to form barium sulphate which is inert and will not react adversely with the casting slip.

After storage, fluid properties may be adjusted with deflocculant in the normal way before

the slip is used in production.

CASTING FAULTS:

It is possible to overcome most casting faults by adjusting the control values of the casting

slip. Below are some of the common faults encountered and suggestions which may be taken

to overcome these faults.


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If fluidity is too low it may take too long to fill moulds and also there may be difficulty in the

draining of the slip from the narrow sections (poor draining). This can be cured by increasing

water or deflocculant addition

If thixotropy is too low there may form brittle (i.e.hard casts - difficult to fettle) casts, small

cracks and also small uneven fringes on slip side of cast may be formed. This may be cured

by decreasing deflocculant addition or water addition.

If thixotropy is too high, there may be difficulty in the draining of the slip from the narrow

sections and also may result in soft casts which may be difficult to handle. This may be cured

by increasing deflocculant or water addition.


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MILL HOUSE

Glaze Preparation

In this process glaze is prepared for spraying department. Body preparation and glaze

preparation are parallel process. Different colors of glaze will be prepared according to the

requirement. Raw material of the glaze preparations are zircon, feldspar, quartz, calcite,

china clay, zinc oxide and few more. Raw materials are grinded in ball mill and particle size

is tested before unloaded from ball mill. Glaze will be passed through sieves to remove

coarse particles and magnets to remove iron particles. Sample spraying will be done and fired

to check the final color of the glaze. Glaze should be approved by QA before used in

manufacturing/production. Before supply to the spraying, glaze will be mixed with binder to

give required properties. Density, drying time, fluidity and viscosity are maintained to get

proper spraying. Glazes are formulated as a mixture of ground, powdered ingredients which,

by their nature, do not dissolve but are merely suspended in water.

The following raw materials are used for preparation of glaze:

1. Calcite

2. Quartz

3. China Clay

4. Zircosil

5. Zircolite

6. Zinc Oxide

7. Potash feldspar

8. Soda feldspar

9. Soda ash

10. C.M.C

11. Talcum

Silica is a major glaze component and is added in many forms such as quartz, feldspar into a

glaze. Silica acts as a glass former and is used to control thermal expansion and help impart

acid resistance to the glaze.


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China clay continues to be the primary suspending agent used in ceramic glazes.

Feldspathic minerals, such as soda and potash feldspar continue to be some of the most

commonly used raw materials. These materials are a major source of alkali fluxes in a glaze

as well as silica. Feldspar can be used as either a flux or refractory material in a glaze

depending on the firing temperature.

Alkaline earth oxide materials such as calcium carbonate, and zinc oxide are generally added

as raw materials. These are advantageous because they provide fluxing action without having

a major effect on glaze thermal expansion.

Zirconium silicate is the major opacifier used in ceramic glazes.

To prepare a liquid glaze (also called a glaze slurry), all of the glaze ingredients are wet

milled in a ball mill. After the glaze slurry reaches the desired particle size, it is passed

through a screen and a magnetic filter to remove any impurities. The density and viscosity of

the glaze are then adjusted to fit the application, and the finished glaze is ready to be used in

production.

PROCEDURE

The raw materials are taken and batch weighed according to desired proportions.

Batch raw materials are loaded in a ball mill in which water and binders are also

added.

After required grinding hours of grinding, the glaze sample is sent for QA

After approval from QA the batch glaze is transferred through electromagnetic sieve

(to remove any lumps) and then collected in storage drums.

Subsequently binders are added to the glaze and mixed with shear mixer and is again

sieved and magnetic separation is done.

Then the glaze is tested for properties and sent for spraying.

The glaze parameters which are tested are half liter weight, fluidity, drying time, residue,

particle size distribution and fired flow.

Binders such as c.m.c i.e Carboxy Methyl Cellulose and peptopon are added. High amount of

c.m.c may affect the drying time of glaze. After adding CMC into the glaze, it will enhance

the bonding & promote the glaze dispersing, and also enhance the adhesion strength of the

glaze and ceramics. As the flow control agent in ceramic glaze and the high-purity CMC

leaves no ash in the process of burning.


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PROCESS FLOW CHART OF MILL-HOUSE DEPARTMENT:

Raw materials are batch weighed

Batch raw materials loaded in ball mill

Ball mill addition (water + binders)

Glaze sample sent to QA

After required grinding hours

After approval of QA

Batch glaze transfer through electromagnet & sieve

Approved glaze stored in tank

Again electromagnet, sieve & then stored in drums

Binder addition

After binder addition, sieve & electromagnet, then

stored in drums

Supply glaze properties test

Sent for spraying


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MODELLING

PROCESS FLOWCHART OF MODELLING DEPARTMENT:

Plan received from plant head

Model making

Master mould making

POP block making

Send to casting

Block making

QA Approval

Resin block making

Sent for mould production


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Normally, requests for new designs are originated by Marketing and Sales in conjunction

with Manufacturing. After agreement has been reached with regard to the basic design

requirements, working drawing are prepared for the Modelling Department. After approval

of the working drawing, a plaster model of the finished size product will be produced by the

Modeller. This model is then inspected by both marketing and manufacturing to ensure that

this is what is required. After approval, the modeller will then model the new article in its

green size, which will be approximately 12% larger, as they contract during the firing

process.

After modelling the article, a “master mould” is produced. This mould closely resembles the

final working mould that will go into production. After completion of this mould, trial casts

are taken from this mould, and these articles, when taken from the mould will be thoroughly

dried, glazed and fired under normal manufacturing conditions. It is standard practice that

several casts will be taken from this mould because it is at this stage that potential problem

areas can be identified, and corrective action can be taken. After final approval of the fired

article has been obtained, a block or case mould, is produced. This case mould is made from

plaster of paris and resins. It is still possible, although difficult, to make minor changes to the

design on the case mould. The negative (master mould) is used to create a positive model

(case). This case is ultimately used to make the working plaster moulds. The plaster moulds

are often made in several pieces to allow complex designs to be manufactured.

In the preparation of blocks iron frames are used for support of the structure. In resin block

preparation few hardeners are used along with sand for the hardening and strength of the

block.


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MOULDING

In this process required shape and size mould will be produced for casting. All bench and

battery cast moulds used in manufacturing in the sanitaryware industry are made from plaster

of paris. This is a material which is easy to work with and has the advantage that it is

absorbent. All materials provided to the casting departments are in a slurry form, containing a

large proportion of water, the plaster mould will absorb the water from the slip, thus leaving

a semi-hard clay layer on the surface of the plaster mould. The average life of a working

mould is approximately three months or 80 casts and most moulds are only cast once per day.

The moulds themselves may often consist of several pieces, an average number of pieces per

mould is four, although some moulds are much more complex. After producing the moulds

from the 'case mould', the working moulds must be thoroughly dried before being used in

production.

The plaster is hemi-hydrated gypsum. In calcination, the gypsum loses H2O partially and the

crystal structure of gypsum breaks down due to the removal of H2O. While adding water to

the plaster it will then converts in to fine crystals of gypsum. So, while adding water it

changes in to hard lumps.

But for the preparation of mould, the plaster must be converted into slurry, but not hard

lumps. To avoid the formation of hard lumps the proportionate water is taken first and

weighed plaster is dumped in to the water. The plaster and the water ratio are 100:75. While

setting of plaster happens, a reaction occurs between plaster and water which is an

exothermic reaction. In this reaction heat is evolved and it vaporizes the remaining water.

This removal of water causes pores in the mould.

The plaster of Paris is stored in bags in dry atmosphere. This plaster of paris is removed from

bags and dumped in the hopper. This hopper has a normal mesh for avoiding lumps. From

this hopper plaster is moved up through bucket elevator, this elevator is used for transferring

the plaster from hopper to silos. The silos are cylindrical having cone shaped bottom. At the

bottom a screw feeder is provided to discharge the plaster. The screw feeder consists of

screws attached to the shaft. This shaft rotates and while rotating plaster also comes along

with screws and discharges the plaster into drums, placed at the end of screw feeder.

An automatic weighing equipment is provided to control the plaster and water ratio. The

desired proportion of plaster and water is taken to the stirrer. For about 4 minutes, it is

allowed to mixing and the slurry is taken into drums. The block mould is cleaned by using

compressed air, and also wet sponge is applied followed by application of soap solution to

the block mould. Soap solution is used for releasing the mould easily. The male and female

notches and pipes are arranged in required places. Then blocks are set correctly using iron

hoop belts. The plaster slurry which is already prepared is poured into the gap provided

between the top case and block. While pouring the plaster, mould is shaked for uniform

distribution and also for removing air inclusions.


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After initial setting of the plaster the top case is removed and belt is loosed Because to avoid

the stress created due to the expansion of plaster on setting the mould is allowed for final

setting. After final setting the mould is removed from the block. The compressed air is used

for easy removing of mould. After releasing the mould, finishing is done with a hack saw

knife and sent to drier. Before sending the talc powder is applied to moulds so that they don’t

stick with each other in drier. The moulds are put in drier for 4-5 days at 50 to 60°c

temperature. Then these moulds are supplied to casting points.

The different plasters used in modelling & moulding:

Plaster:

α Plaster is hemi-hydrated gypsum [CaSo4 ½ H2O]. The α plaster is prepared by the calcination

of gypsum in damp atmosphere. So while adding the water it sets and has very less porous

nature and high mould strength. The plaster : water of this plaster is 100:50 (consistency ratio).

These Alpha Gypsum casts are harder and stronger with limited absorptive power. They are

used primarily when greater strength is required. Because of their extreme hardness some

Alpha gypsums cannot be carved or scraped after hardening. Alpha Hemihydrate is produced

in many different formulations. You can mix an alpha gypsum with a beta gypsum to increase

the plaster's strength or hardness.

Plaster: plaster is hemi-hydrated gypsum [CaSo4 ½ H2O]. The plaster is prepared by

the calcination of gypsum in open atmosphere. While adding the water it has comparatively

slow setting, high porous and less mould strength. Beta Hemihydrates are known as industrial

plasters. They require more water to make a workable slurry because of their irregular

crystalline structure. They require 100:75 ratio of plaster to water (consistency ratio). Beta

Gypsums are not as hard as the alpha gypsums. That's why they are easier to carve and scrape.

Because of their high water absorptive power, they make excellent pottery molds.

Thus α plasters are used in block making for its strength and β plasters are used in casting of

moulds for good water absorption.


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CASTING

It is a process, in which slip (a water-based suspension) is poured into a plaster mould, which

by its porosity creates capillary forces and removes liquid from the suspension (slip). When

the liquid is absorbed into the plaster mould, the powder particles are forced towards the

mould walls and a consolidated layer is gradually built up. When a desirable layer thickness

has been obtained, the casting process is stopped either by having the excess slip removed, or

by letting the casting fronts approach each other in the centre of the piece to form a solid

body. After a certain period of drying the shaped piece can be released from the mould for

further drying. The advantages of slip casting as a forming method are mainly that complex

geometries can be shaped, and good material homogeneity is generally achieved.

There are mainly two types of casting:

Solid casting: Casting proceeds until the casting fronts approach each other and a

solid body has been obtained.

Drain casting: When a desirable thickness has been reached the excess slip is

removed.

The process of casting mainly includes slip being poured into the mold and allowed to form

casting layer on the mold. Then the excess slip is drained through drain hole. Now casted

ware is allowed to dry and then released from mold. In this stage the ware is known as green

ware. Few holes are punches in the body using templates This green ware is allowed to dry in

atmospheric temperature for one to three days before sent to drier. Before sending to drier

this green ware is finished to smooth joint edges, repair small cracks, small pin holes, bad

finishing and etc. once this ware is ready it will be sent to drier for drying.

Bench Casting:


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It follows the concept of drain casting. In this casting method the moulds are arranged on the

benches and hence called bench casting, since casting is done on the benches. Before casting,

we need to make sure it is clean- both inside and out. Debris inside will imbed casting and be

difficult to remove. Debris on the outside can fall into the cavity or the slip. So first cleaning

of moulds is done by using compressed air. After cleaning the conditioning of mould is done

which includes applying water using wet sponge on hollow part of the mould and applying

talcum powder (as lubricant) on the solid parts of the mould for easy release of the casted

piece. Subsequently setting of moulds is done and the moulds are tightened using iron hoop

belts and wooden wedges. Then the slip is poured into the moulds manually using pipes

(having mesh at its opening to prevent any foreign material) and also moulds are filled

slowly to remove air inclusions in the slip which may lead to the formation of pin holes.

After the slip is poured into the mold, it is allowed to form casting layer on the mold. Then

the excess slip is drained through drain hole and allowed to dry for some time. After

demoulding required holes are punched into the green body using templates. And allowed for

natural drying for 2-3 days and then sent to the drier after proper finishing.

In this type of casting modifications to moulds can be made with relative ease, small numbers

of pieces can be cast efficiently, and the slip making technology is well established.

However, this method poses several challenges. The process is labor-intensive. Additionally,

significant space is required to produce the ware, making the process capital-intensive. Other

restrictions include a short mould life and a limitation on the number of pieces cast per day.

Battery casting:

It also follows the concept of drain casting. . In this battery casting the moulds are arranged

one by one like batteries. In this casting the moulds are placed on the iron plates which are

having bearing at the bottom. These bearings are used for free movements of moulds. These

bearings are connected to tracks.

Battery Casting line system consists of 2casting benches being aligned at the left and right of

a central slip supply and a central slip return system. The moulds are connected to each other

by means of appropriate distance pieces of plaster or metal and by means of a tightening and

clamping device they are held together at the end of the casting bench.There are 30-45

mobile moulds installed on movable special trolleys and with one end is fixed frame ,while

other end is movable tightening screw trolley. The inclination of complete bench can be set


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us per required degree of slope. But the moulds are inclined towards the operation side,

which will be emptying all moulds for its return line slip.

Parallel to the casting bench, depositing benches (Storage Racks) are provided at the outside,

serving for depositing the demoulded pieces.

The slip supply of each mould is made by pipeline being attached below the casting benches

and controlled by corresponding valves. Each mould is connected to this pipe system by a

plastic hose and fitted with a shut-off valve. Before filling of the moulds, the slip is allowed

to drain flow for about4-5 min to remove the air inclusions that may be caused due to change

in pressure of flow i.e. allowed to drain unter constant flow is attained. Slow filling causes

thickness variation. So the pressure of the slip is controlled. The mould is filled properly with

slip.

Battery casting offers greater productivity and a relatively low mold cost. Additionally, more

pieces can be produced in the space available, which reduces the capital required for this

method compared to bench casting methods. The skills required to produce ware by this

method are also lower than bench casting.

Battery casting is one type of casting which required less space for more moulds. Battery

casting machines can be used for washbasins, water closets, Traps and other simple

sanitaryware products. Complex patterns like one piece toilets are not suitable for battery

casting. However, this method also holds challenges. Mold life is short, and larger runs of the

same items are usually required because the speed with which the molds are turned over

naturally produce more ware.

Advantages:

1. High productivity (Nearly double) compared to traditional bench casting methods.

2. Ease of mould handling as the mould need not be lifted and only need to be slided in

the rail.

3. Minimized the possibility of mould breakage and damages (chipping) that often

happens in bench casting.

4. Space required is very low compared to bench tradition casting.

5. More than one product from a mould is possible for small/Accessories products like

‘P’ or ‘S’ traps.

Limitation:

1. Producing complex patterns like one piece water closet are much difficult.


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2. Switching from benching to Battery casting needs some design changes in mould.

The process flow chart of battery casting:

DRYING:

The point of drying is to simply remove water from the body without causing any damage.

Green pieces from casting will be sent to drier. In drier, Green M.O.R of the ware is

improved by removing the mechanically combined water from the ware. Moisture content of

green ware after drier will be approximately less than 1%.Drying process will take from 5-

6.5hrs depending upon various factors such as temperature, humidity, moisture content and

so on. The drier will be loaded at once and unloaded at once, this type of drier is called batch

drier. During this drying process the ware will lose its weight and also shrink in size. The

temperature is maintained carefully controlled (about 60-67). If the body has moisture in it,

when fired the moisture will turn into steam and expand, and if the steam cannot escape from

the piece fast enough, it will blow the piece up, thus it is essential to dry the ware before

firing.


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Before sending to the ware drier, pieces are naturally dried for 2-3 days depending on

whether the climate is arid or humid.

Greenware that is of even thickness throughout is left to dry uncovered. Greenware that has

parts of varying thickness, especially small thin parts sticking out from larger masses is

wrapped loosely in polythene covers and allowed to dry slowly and evenly. If left to dry

uncovered, the thinner parts will dry and shrink faster than the thicker parts and may crack

where they join.

As the body is getting dried, the grains of material shrink together to fill the space occupied

by the water. It is this shrinkage that brings the danger of damage to the ware during drying.

If one side dries more than the other one, shrinkage of the former one will be more than that

of the latter and hence the piece will either warp or crack.

When hollow forms are built, holes are punched for allowing the steam to escape. Otherwise

a hollow piece, without a hole can become a grenade. The holes are made large enough, so

that when the clay naturally shrinks from moisture loss.

Air circulation:

High pressure fans mounted on the roof recirculate air from the dryer and discharge the re-

heated air vertically downwards into air distribution cones for horizontal discharge through

the product setting. This creates a highly turbulent and variable atmosphere in the dryer

meaning that all product surfaces are exposed to an intermittent flow of drying air stream.

Waste Heat from the kilns further reduces the energy costs.

At the end of the drying cycle, which is of 5-6 hrs, it is normal to incorporate a 'cooling

period' to reduce the temperature of the ware back to a 'handleable' condition

Fully automatic Switchgear and Control Panels are located at the dryers. Inside of the

chamber, is made to hold ware trolleys so that drying goods can be taken in and out quickly.

Warm air from a cooling kiln is introduced from one side and a fan provides a draught across

the chamber through the ware racks. A constant movement of air over the drying ware is as

important as heat. The air is not saturated with water by just passing through the chamber

once, so in order to economize, most of the air is recirculated by the fan. A centrifugal fan is

used for this. The centrifugal fan at the same time draws hot air from the kiln via a duct

system. Rapid circulation of air is more energy-efficient for drying than high temperature.


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INSPECTION & GLAZING

In this section ware will be inspected for defects. Defected wares will be repaired or rejected

depending upon the defect. Thoroughly checked wares will be sent for glaze spraying.

INSPECTION

In inspection, it is important to ensure that each piece of sanitaryware has been correctly

manufactured. It is the job of the clay inspection team to examine each piece and to rectify

any minor faults that may be apparent. This is a most important section of the factory, as any

ware that may be sub-standard that slips through this department without rectification will

probably be a reject piece after firing. The dried ware which are unloaded from drier are

inspected in inspection booths. In inspection booth the ware is checked for the defects like

pin holes, crack, bad finishing, leveling, chipping e.t.c.

These defects are repaired by rubbing with sand paper and blade by placing them on pallets.

If the piece is not repairable, it is rejected. Wet sponge is applied to ware for checking cracks

and pin holes and also for removing dust and smoothening the ware. By applying sponge to

ware crawling can be avoided. After checking the ware, if it is good the inspector stamps the

inspection number.

GLAZE SPRAYING:

Glaze is reduced into a fine spray i.e. collection of moving droplets as a result of atomization

(the process of breaking up bulk liquids into droplets).Glaze received from the MILL

HOUSE department will be used for spraying and they are stored in tanks. Different colors

are sprayed on wares as per the production schedule. Spraying will be done by manual

method. The glaze is sprayed by using spray gun. In the spray gun the glaze and compressed

air are combined and sprayed through a nozzle of diameter 1.6 mm which facilitates the

dispersion of glaze into a spray.

-AIR (AIR SPRAY) ATOMIZATION:

In air spray atomization, fluid (glaze) emerging from a nozzle at low speed is surrounded by

a high speed stream of air. Friction between the liquid and air accelerates and disrupts the

fluid stream and causes atomization.

The energy source here is air pressure. The operator can regulate the flow rate of fluid

independently of the energy source. (The glaze tank’s pressure of capacity 235-250 liters is

approximately 3.5 kg/ cm^2 and that of atomization pressure is 6 kg/cm^2).


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GLAZING FLOWCHART:

Green ware drier

De-dusting of trolleys

& Green wares

Green ware Inspection

The dried ware after inspection is put on carrousel. The carrousel is rotating through the

After inspection sent for greenware

spraying

After glaze dried

Carousel & Manual Spraying

Glazed ware sent to kiln for firing


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glazing booth. On it, rotating stands are fitted and the wares are put on stand. The carrousel

moves with certain speed which is adjusted for different patterns. For smaller patterns the

carrousel moves fast and for bigger patterns, it move slowly. The rotating stands are used for

easy spraying of glaze on ware.

The ware put on rotating stand is sprayed in first booth for first coating and passed on to

second booth for second coating. So, for every piece two coatings are given. After glaze

spraying, scraping of the ware is done with the help of round blade. While spraying it is seen

that at corners lot of glaze is not deposited, excess glaze is removed by sponging smoothly.

On spraying the spray gun must not be too close, to avoid air packing under the surface of the

glaze. Then the Hindware logo is stamped to wares and are kept on trolley and send to kiln.

Each carrousel has 8 inspection booths and 4 glazing booths. There is also a washer & drier

for cleaning of the pallets. Care has to be taken to ensure that the ware is completely glazed

in all appropriate areas and that no rippling of the glaze during application is allowed. The

glaze itself consists of the following minerals: zircon, flespar, quartz, calcite, kaolin, zinc

oxide. It is most important at this stage that all glaze is thoroughly tested by the laboratory to

ensure it complies with the required specifications.

The glaze is lost during the spraying process in the form of overspray. Manual operatives are

deployed to scrape down this glaze (also from the sides of the spray booths) and sent for the

MILL HOUSE department for further processing. This glaze is referred to as RECLAIMED

GLAZE, which can be reused for spraying by mixing it with the fresh glaze in desired

proportions after proper processing.


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KILN

Firing is the final and important process in the sanitaryware production. Conversion of low

strength product into high strength, durable and chemical resistant product is achieved during

firing. Sanitaryware firing temperature can go up to 1220°C, it varies accordingly depending

on the composition of raw materials used.

The firing process is the process where clay, which have been compacted, are heated to a

temperature where useful properties will be developed. It encompasses physical and chemical

changes in the ceramic body accompanied by a loss of porosity and a subsequent increase of

density. The compacted body becomes bonded together in a matrix by vitrification.

Vitrification is the process of progressive reduction and elimination of porosity with the

formation of glassy phase as a result of heat treatment. Glass formation typically starts at

1100°C and accelerates with further increase in temperature. Once the desired amount of

porosity is obtained, the cooling is started. During cooling, the glassy phase freezes and

becomes rigid to form a strong bond with the crystalline phase of the body.

During the vitrification process, the following physical changes takes place in the ceramic

body:

Shrinkage due to loss of open pores

Development of closed pores

Development of glassy phase

Normally two types of kilns are used in sanitaryware manufacturing industry.

Tunnel Kiln:

Tunnel kiln is a continuous kiln that is made up of a straight tunnel with arched or flat top.

Shuttle kiln:

Shuttle kiln is a chamber kiln that is used in sanitaryware manufacturing industry.

Hindware uses gas-fired tunnel kilns. This kilns run 24 hours a day. It is an uneconomical

proposition to switch these kilns, off and on to suit the market requirements. The temperature

control throughout the kiln in pre-heating, firing and cooling is closely controlled.


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The kilns are complemented by a fully automated kiln car handling system. The whole car

movement both in the kiln and out of the kiln is automatically controlled by micro-

processors, thus removing the arduous manual work. Pushers move the train of cars non-stop

at a predetermined rate. This method is ideal for high volume continuous production process.

Kiln furniture (cars) system which is used to support green ceramics during the firing

process, is light weight and very thermal shock resistant which translates into low fuel cost

and long life.

The materials used for kiln furniture are:

Cordierite

Mullite

Silicon Carbide

90-99% Alumina

Zirconia

Cordierite is the least expensive type kiln furniture and is the most widely used. It is also

relatively light in weight and has no thermal expansion and therefore, excellent thermal

shock resistance. Cordierite plates with holes form the shelves in furniture.

Mullite is more expensive than Cordierite and can be used at high temperatures. It is heavier

but is very strong, and therefore, can be made with thinner cross section. It too has good

thermal shock resistance. In addition to these, ceramic fiber is also used.

Silicon Carbide (SiC) has very high tensile strength, thus used in shelving. The advantage of

this material as shelving is strength, high thermal shock resistance.

Alumina is a little more expensive than mullite, however it can be used at very high

temperature. Zirconia is also used where alumina cannot be used for chemical reasons.

Sprayed ware will be loaded in kiln car. At least 1/2‘’ spacing is given between all the

pieces because pieces will expand during the firing cycle before it contracts and shrinks.Dust

and other impurities are removed from ware by air blower. Sanitary ware kiln have three

zones, pre heating, firing and cooling zones. In pre heating zone mechanically and

chemically combined water has been removed from the ware. At firing zone all the raw


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material are fused together and glaze are fused evenly. At cooling zone sudden cooling is

done to create glossy surface. Once product fired, it will be moved to sorting area.

Kiln is used for firing the glazed ware and to convert the weak ware into a strong article

having low porosity and also to form a glassy phase which flows into the pores between the

particles and solidifies on cooling.

The car pushing time of a car is about 11minutes. For every 11 minutes a car is pushed out of

kiln. The cycle time of the kiln is about 12-14 hrs depending on once fire or refire.

The kiln has four zones

1. Pre – heating zone

2. Heating zone

3. Rapid cooling zone

4. Cooling zone

1. Pre –heating zone:

The pre- heating zone is from about 212°c to 411°c .Physically combined water and

chemically combined water are taken off in pre – heating zone. In order to decrease

the rate of reactions, temperature is increased slowly. .

Thermocouples are placed on roof of the kiln to indicate the temperature in each

module.

On the first module contravec fan is placed to avoid the heat from going out through the kiln

entrance. On the 2nd module exhaust fan is placed for sucking the waste gases. On the 7th

module induced tempering air fan is placed to circulate the heat throughout the pre- heating

zone.

2. Heating zone:

Body vitrification and glaze maturing takes place in heating zone. The pore spaces are filled

with glassy bond by melting of the feldspar in the body. The clay is converted into mullite

and free silica.


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3(Al2O3 2SiO2 2H2O) 3Al2O3 2SiO3 + 4SiO2

Burners are provided for firing the wares in firing zone, its temperature is about 12040c to

12180c.

3. Rapid cooling zone:

In rapid cooling zone, rapid cooling fan is placed for cooling the ware with pumping air. The

rapid cooling fan is placed for a sudden decrease in temperature. Fast cooling is done to

avoid crystallization of the glazes. At this stage, gradual freezing to melts, beginning of

recrystallization, consolidation of the glassy phase, etc., happen.

4. Cooling zone:

1. Slow cooling

2. Final cooling

The slow cooling fan is placed for cooling the ware by pumping air. Slow cooling is done to

avoid development of cooling stresses. Slow cooling is carried out to even out the body

temperature at different areas. Because quartz conversion will takes place after this stage.

The recuperation air fan is placed for utilization of the waste heat. This recuperation air fan

sucks the air from the kiln supplies to the driers through ducts. At the kiln exit, blowers are

placed for cooling the wares to the room temperature. This is final cooling zone.

The reactions during firing can be grouped into the following categories:

Loss of physical water, in the drier.

Oxidation: It is important to oxidize all the carbon and volatilize it out of the ceramic

otherwise it may form black coring also sulphides will oxidize.

Decomposition: The dehydroxylation of clay sometimes called the loss of chemical

water occurs.

Some materials that undergo decomposition are

Hydrates decompose to give off water

Carbonates for carbon dioxide & sulphates for sulpur dioxide

Kaolin to meta-kaolin and meta-kaolin to mullite and silica with an increase in

volume.


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Quartz transformation:

Silica undergoes several polymorphous modifications on heating which are as follows

Below 573°C- alpha quartz

573-867°C- beta quartz

867-1470°C-tridymite

1470-1710°C-cristobalite

above 1710°C-liquid

Any cristobalite or tridymite will remain on cooling but the majority of the silica

grains never transform beyond beta quartz. When cooled below 600°C, beta quartz

transforms abruptly to alpha quartz with a sudden volume change. Slow cooling

between 600-500°C is often required to prevent cracking. The larger the piece and the

greater the silica content, the slower the cooling during the transformation. The

sudden change of alpha to beta quartz on heating at 573°C does not cause as much

strain in the green ceramic body as cooling.

Sanitary ware firing Defects:

Belching of colored ware – Firing happened at reduction atmosphere. Insufficient air

supply given to the kiln.

Black Core – Insufficient soaking temperature during firing. Organic rich raw

materials are used.

Less glossiness – Some of the reasons for less glossiness are insufficient firing,

devirtification of glaze.

Bloating of wares – this defects happens when the thickness of the body is high so the

evolved gas cant able to escape from the ware.

Dunting – Fast firing up to 700 ºC. Temperature uniformity varies at different area of

the wares.


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LABORATORY

In the lab, the tests from raw materials to fired ware are as following :

1. Raw materials testing

2. Plaster testing

3. Particle size test

4. Flow test for glaze

5. Water absorption

6. Slip for testing

7. MOR

8. Auto clave test

9. Loss on Ignition

10. T.D.S test for sample clay material

1. Testing of raw material:

Residue test:

Daily the raw materials are brought from storage chambers and broke in to small pieces. Mix

the material properly and make four parts. Take the material from each part and weigh

200gms on weighing balance. The material is sieved at bottom of tap water on #200 mesh.

After sieving the residue is taken in to bowl and put in drier for dry. Now again weigh on

balance.

Acid test:

Take the raw material and weighed 100gms. After that take a bowl with some amount of

water. The weighed material is poured in water. After some time add HCL (hydro chloric

acid) in that material. If the material is good no reaction is takes place.

Moisture content test:

Take the raw material and weight 100gms on weighing balance. Now the weighed material is

put in drier for one hour at 110°C. After one hour again it is weighed and the reading is

noted.

Moisture content (%) = Initial – Final *100

Initial


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2. Plaster testing:

Take 525 ml of water in one beaker. Take another beaker and weigh 700gms of plaster of

Paris on beaker. Pour the plaster of Paris in 525ml beaker. Add the powder for 2 minutes and

2minutes soaking and 2 minutes mixing.

This process is 100: 75 ratios. After mixing pour the plaster in bars. Before pouring apply the

soap solution for bars and moulds and Put that up to setting. Soap solution is used for easily

removing. After setting remove the bar moulds.

The plaster is poured in brass ring. After pouring lift the brass ring suddenly. The plaster is

spread roundly to certain area. The spread area is calculated is spread value.Take one

cylindrical mould and pour the remaining plaster in it. After setting the bars and this

cylindrical piece are put in drier for four days. After four days the cylindrical piece is

weighed and put in water absorption. The bars are put in M.O.R (Modules Of Rupture)

machine and check the MOR.

3. Particle size test (Manual):

Take the glaze and pour above half of the density bottle and add water. After that weigh the

density bottle. The reading is noted. After that take 1000 ml of cylindrical beaker and add 2%

of sodium hexa Meta phosphate solution. Now pour the glaze in cylindrical beaker and add

the ice pieces in beaker and pour cold water up to 1000ml mark. Now stirring the solution for

one minute. Then UN disturb for 17minutes. After 17min put hydro meter in beaker. It shows

the reading up to which reading it dips. Note the reading and remove the hydro meter.

PARTICLE SIZE DETERMINATION (PSD):

Malvern Master Size Micro:

The instrument used for PSD is Malvern Master Size Micro-UUK Product. We can measure

the size of the particle from 0.3 to 300 Microns.

Measurement Principle:

Based on the laser diffraction method the master size analysis particle size of the Raw

materials.

Laser Diffraction:

Laser diffraction particle size analysis is based on the phenomenon that all particles scatter

light at a range of angles, which is a characteristic of their size large particles scatter at small

angles and vice versa.

The master size micro comprises a Helium-Neon laser as a light source, which illuminates

the dispersed particles in the measuring zone. this is then focused by a Fourier lens to a


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detector. Which consists of a large number of photosensitive elements radiating out ward

from the centre. a never property of a Fourier lens is that it collets the scattered light from an

ensemble of particles, and over lays the common angles of scattering on the detector array

the intensity of the scattered light is measure and using an optical model(Mietheory) of

calculate the scattering patern and a mathematical deconvolution procedure, a volumetric

particle size distribution is calculated that best mathes the measured patern.

The master size micro produces volume –based measurements of ensemble of particle

sampled at a rate of 500snaps per second. Simultaneously from all detectors. This means that

the system is exceptionally suitable for the detection of rogue coarse particles.

4. Flow test for Glaze:

Take the glaze and pour in the mould. After some time it dry, the glaze remove from the

mould by using hack saw blade. After removing put in drier for 2 hours, after 2 hours remove

from drier.

Take one small cylindrical mould for getting the glaze cylindrical shape. It is occurred by

tapping the bolt in the mould. Now the cylindrical shape of glaze piece is weighed 200gms.

The extra material is removed by rubbing on sand paper. The 200gms glaze piece is put in

flow mould by add C.M.C to mould because to stick the glaze piece to mould. After that send

for firing in kiln. After completion of firing, the glaze is flow to some distance in flow meter.

The distance is calculated by using vernier calliperse.

5. Water absorption:

Take one pattern ware and break the ware. Take three pieces from top, middle and bottom by

using hammer. Mark for each piece by pencil for determining. Then see the thickness for

each piece and note the reading. After that put in drier for 1 to 2 hours. After drying remove

the pieces from drier and put for cooling. Then see the weights in weighing balance. Then put

the pieces in vaccume chamber for one hour. After that put in water heater machine for half

an hour. Switch off the heater and kept for total night. Morning weigh the pieces and note

the reading. This is saturated weight. The % of water absorption is calculated by using

formula.

Saturated wt – fired wt x 100

W/A = fired weight

The result is noted.

6. Slip testing:

The below tests are for slip. They are

1. Litre weight


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2. Fludity&Thixotropy

3. Casting rate

4. Residue

5. Shrinkage

6. Deformation

7. M.O.R

Casting rate:

First we take slip from one point of casting. This casting slip is poured in bowl mould and

kept for one hour. After one hour, unload the slip and keep it for half an hour for drying.

After half an hour cut a piece and check the casting rate by using vernier calipers.

Fluidity & thixo:

Fluidity and thixo is checked by using torsion visco meter. First we set the visco meter at

zero. Take a beaker and pour the slip in that and stirring for one minute. After

stirring put the beaker just below the visco meter and release it. The pointer shows the

reading. Put the beaker for one minute without disturbing. Again put the beaker below the

visco meter and release, the pointer shows reading. This reading is thixo.

Half litre weight:

Take 500ml. beaker and pour the slip in that beaker. Before pouring the slip weigh the empty

beaker. After pouring again weigh the beaker. Note the reading.

After testing the slip of supply tank it can be supplied to casting points

Residue:

Take 500ml of slip and pour in to 200# mesh. The slip is sieved by adding water in 200

mesh. After sieving some material is remaining on the sieve. The remaining material is put in

drier for one hour at the temperature of 1100c. After one hour remove the material from drier

and weigh using weighing balance.

Shrinkage:

Take the bar moulds and cleaned properly after that pours the slip in the mould. Put the

mould up to slip setting. Then release the moulds and remove the bar pieces. Now take the

vernier and mark at zero and 100mm. After marking put in drier for 2 hours at the

temperature of 110c. After drying see the shrinkage by using vernier (L1). After that put for

firing and again see the fired shrinkage (L2).

Shrinkage = (L1 – L2) /L1 x 100


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Deformation:

Take the slip and pour in bar moulds. After setting release the moulds, and remove the

articles and give finishing. After that put in drier for 2 to 3 hours at the temperature of 110c.

After drying remove the bars and put in stand are send to firing after completion of firing, to

see the deformation.

7. M.O.R

M.O.R means modules of rupture. Take the fired bars and put on the stands of M.O.R

machine. The M.O.R machine consists of dial gauge which shows the reading. While starts

the machine, the shaft slowly pushes up the bar and the pressure is showing by dial gauge.

When the bar break at which pressure is showing by dial gauge is the reading of the M.O.R.

8. Auto clave test:

Take five types of selected wares and break the wares. Bring five pieces from that wares and

place on auto clave in metal frame. The water level is above of the wares on metal frame.

Close the auto clave and tighten the bolts of lids strongly. For not leakaging of steam on

heating. Heat the auto clave by using gas cylinder. The heat is given from bottom of the auto

clave. The pressure is increasing slowly and the reading is shown in dial gauge. The pressure

is 3.5 to 4.0 kg/cm2. This pressure is maintaining for 10 hours. After 10 hours cool the auto

clave by releasing steam. Open the lid and remove the wares. Apply blue dye for the wares

for easy determining of fine hair line cracks. Wash the wares after applying of dye. Then see

the cracks on wares.

9. Loss on ignition:

Take the dry piece which is fully dried one and weight the piece on weighing balance is (w1).

After that sent to firing on kiln. After firing again weight the piece on weighing balance is

(w2). Apply the formula of % of L.O.I. The result of L.O.I % is noted

% of L.O.I = W1 - W2 / W1 x 100 .

10. T.D.S test for sample clay material:

Take 1000ml measuring cylinder and RO water. Take 465 gms for sample clay material and

crusher in fine powder. Take 930ml of water in measuring cylinder add 465gms of sample

clay material to the water in the measuring cylinder. Close the top of the measuring cylinder

and invert or till it for 6 times and soaked the material over night for 12hrs.

Soluble salts in clay material get dissolved in the water. And the material settle down at the

bottom and water will be at the top using meter. check the TDS of the clay material.


SUMMER INTERNSHIP

In brief the laboratory test are:

1. Clay test (Plastic materials)

1. Moisture content in clay

2. Alkali demand test

3. Residue test

4. Shrinkage test

5. Loss of ignition test(LOI)

6. Water absorption

7. Casting rate

8. MOR

9. Iron test

2. Quartz /Feldspar test (Non-plastic materials)

1. Residue test

2. Iron test

3. Moisture test

4. Cone test

3. Glaze test

1. Fired glaze color test

2. Residue test

3. Iron test

4. Slip test

1. Density/Specific Gravity

2. Flow

3. Thixotropy

4. Residue test

5. Shrinkage test

6. Warpage


SUMMER INTERNSHIP

7. MOR

8. Permeability test

5. Glaze test

1. Density/Specific Gravity

2. Viscosity

3. Drying time

4. Flow test

5. Color matching

6. Residue test

7. PSD test

6. Plaster of Paris test

1. Residue test

2. Initial and final setting time

3. MOR

4. Absorption percentage

7. Fired ware test

1. Water absorption test

2. Crazing test

3. Thermal shock resistance

4. Chemical resistance test


SUMMER INTERNSHIP

FEW DEFECTS

1. Cracks –One of the major defect found in the Sanitaryware production process.

Separation/Split of Sanitaryware surface without breaking apart.

2. Blisters – Blistering is sharp-edged burst bubble. Can be found in fired ware.

3. Crazing – Crack in glaze surface area.

4. Pinhole – Small holes in the ware.

5. Poor finish – Improperly finished ware at green stage which is found after firing.

6. Improper/Defective logo – Logo is not properly printed or positioned.

7. Iron specks –Iron speck found in Glaze surface. Defect can be found after firing.

8. Stuck – two or more wares stuck together during firing of ware.

9. Chipping – Small Broken piece from the ware.

10. Light glaze – less glaze in ware than necessary.

11. Heavy glaze – More glaze in ware than necessary.

12. Wavy glaze – Wavy ness of glaze due to improper glaze application.

13. Crawling – Small portion of the glaze separates from ware leaving the ware

exposed.

14. Leakage – Leak found in ware during water filled and flushed.

15. Poor repair – Defect due to poor repairing at various stages at process.

16. Pitting – Small pits in glaze found after firing.

17. Under fired – Improperly fired

18. Warpage – Bending in ware.

19. Sulphuring – Dull scum on glaze surface found after firing.

20. Color fading – Color disappearing after firing.

21. Bloating – Gas bubble trapped in body during firing.

22. Blown out – Impurities burns out during firing.

23. Dunting – Crack formed at silica inversion stage and the glaze filled the crack.

24. Peeling – Gaze lift away from body.


SUMMER INTERNSHIP

Sorting

In this stage of the process all wares from the kiln are inspected and sorted according to the

Defects. If ware is defects free then it will be send to packing section for packing. If ware has

minor defects like pin holes then it will be repaired by cold fill. If has light glaze or wavy or

blib then it will be sent to refire section.If there is a crack it will be rejected. This quality

check is very important to maintain standards. And also random sampling will be made for

flush test, smoke test, leak test and load test.

Refire/Rework

All repair wares will be send to rework section for minor repairs. All ware are required

according to the defect and sent to tunnel kiln. Once repaired and fired again it will be

inspected and again separated as per the grade. If quality standards are met then it will sent to

packing. If needs repairing again it will repaired in refire section. Major and un-repairable

wares will be sent to rejected area.These are normally warpage or cracked pieces.

Packing

It is the final stage of sanitary ware manufacturing/production process. All Sanitary wares

that are passed quality standards are packed and dispatched to ware house.

HSIL CD-II (1)

Documents

Transcript of HSIL CD-II (1)