Journal of Sc ientifi c & Industri al Research
Yo( 61. September 2002 . pp 726-728
A Low Cost Device for Production of Country Roofing Tiles
S K Handa* and C L Verma
Environmental Sc ience and Tech nology Di vision.
Central Building Research In stitute. Roorkee 247 667
Recei ved : 13 March 2002; accepted:20 May 2002
Coun try roo fin g tile s. are extensi ve ly used in th e vi ll ages as roofing material. Th e co nve nti onal product io n technique used for
producing til es i s through pott er whee l or by manua-l moulding techniq ue. These processes y ield non-uniform . u~1 co mpact ed.
dimen siona ll y unstabl e and poor quality product s. The til es generall y depict considerab le damage or breakage du nng tran sportation or fi xin g in a roo f. In view o f thi s. a low cost moulding dev ice for producti on o f compact country roo fing til es was
designed and t~1bri cated in Cent ral Building Rese~I I'C h Institute (CBR I ). Roorkee. Extensi ve trial s have pro ve n it ' amenabi lity to
comm erciali zati on for producti on rate o f 500-600 tile s/d by a se mi -s kill ed worker. Th e detail s of the low cu >t dcv1ce for
production of co untry roo fin g tiles ha ve been delineat ed. Usc of thi s dev ice w ill certain ly generate emp loy ment in the rural areas
of Indi a and other deve lopin g cou ntri es .
Salient Design Features
Introduction
Producti on of country roofin g til es has long been
considered an art within the domain of artisans' sk ill ,
prim arily due to the intricate shapes and forms of products. Advances in industri ali zati on and agricultural technoloaies
have baenerated new avenues of em pl oy ment
b
on account of which artisans are being attracted towards
higher wages and simultaneously small sca le manufacturers of co untry roofing til es are facing the probl em of
acute scarcity of skill ed pott ers and moulders 1• Large
scale units use automatic and costl y machines to produce about I ,000-2,000 clay til es/h. Small manufacturers cannot afford such expensive machin s. However
the manual process involving semi-skilled moulders y ield
poor quality, dimensionall y unstabl e and uncom pacted
products 2 . Further there is a necessity to produce low
cost quality country roofing til es. In view of thi s a projec t
for development of a low cos t moulding device was undertaken in the laboratory to cope up wi th the demand
for the producti on of com pact and uniform size country
roofing til es, co mpri sing two unit s, i. e., "Na li a" and
" Khapra". The device developed is simpl e in nature and
can be operated even by a semi-sk ill ed worker to produce quality country roo fin g til es of des ired size and
shape, simpl y by changing the mould assembly fitted on
the ri gid wooden base or tabl e' .
The device (Figure I ) essenti all y co nsists of a
wooden or steel tabl e (4) to which metallic moulding
box(2) having projection of 5 mm above th e table top is
fix ed with nuts and bolts. Th e moulding box is endowed
with a loosely fitted movable recta ngul ar shaped plunger
(9) at its bottom. The bottom plu nger comprises four
bolts I 0 mm in diam, one at its each corner, on whi ch
res ts a f-lat bottomed mould (3), (Nal ia or Kh apra) , as
per requirement. The mould is made identica l in shape
and geometry to that of the required ti le. Th e inner size
of the mould is pred etermined taking cog ni zance of allowances for drying and firing characteristi cs of the clay
to be processed. The mould is fabricated to facilitate
easy sliding of th e plun ger along th e inner surface of the
moulding box. The bottom plunger co nsists of a vertical ej ector shaft (7) w hi ch ca n be actuated by the foo t
operated lever ( I 0) with central pivot mec han is m. An
effort is appli ed at fi·ee-2 end of the 1.. er to exert pressure. Second lever mechanism is deployed for press ing
the product whose one end is hinged, whereas at th e other
end press ure is app li ed. Load acts at the middle (4) of
th e lever, havi ng an identi ca ll y opposite profi le to that
of the bottom mould. A thin m tallic li ning is provided
in th e lower and upper pressing plu ngers to avoid wearing and sti ck ing of moist clay mass during shaping of
country roofing til es . The top plun g•::r, while press i ng,
leaves a gap of desired thi ckness i nbetween th e mouldin !:! box and the pressing plunger for maint:1ining a ttni-
HA DA & VERMA: PRODUCTIO
Fig ure 1A Low cost dev ice for produc ti on o r coun try roofin g
til es: I . Mou lding tab le. 2. M oulding bo x. 3. M ould . 4. Top plun ger.
5. Handle. 6. Hi nges. 7. Ej ec tor. 8. Foot pedal. 9. Botto m plunger.
I 0. Foo t lever. II . Bow cutter. 12. Country ti lc ( ali a)
form thi ckn ess of the prod uct. The spec ial features of
thi s moulding tab le w hi ch distinguish it from some of
the co nventi onal presses are: (i) Top press ing, and (ii )
foot operated ejection sys tem.
Operational Technique
Initi all y, plastic clay is wetted w ith water and
kept for about 24-48 h for homogenization and uniform
distribution of moisture w ithin the clay mass . It is then
kneaded properl y, either manually or through small capacity pug ;nil! , before being cha rged into th e mould in
th e fo rm of clay bats. The ba ts are moulded manuall y
inro rectangular shape of requi site thi ckness and overall
vo lume. These are sli ghtl y larger th an that of the actu al
table mould size. M oulding of the clay bats is separately done we ll in advance on the level ground or tabl e
itself, over wh ich fine sa nd is sprinkl ed so as to avoid
sticking with each other.
The clay bat is rested on the mould and th e top
plunger is operated for pressing th e clay by a handl e provided at the end of pressing lever ( 4 ). For accurate
press ing, one semi -c ircul ar shaped projected wooden
piece is nail edlo the top plunger and an identical shaped
grooved wooden piece is fixed to the plunger ju st below
the upper projecti on. Afte r pressing the top piunger is
OF COU NTRY ROOFING TILES
727
w ire bow handle ( II ) for rem oval from the mould . For
ej ecti on th e foot operated peda l is pressed dow nward
wh ich pu shes the mould up to its top leve l. The operator pi cks up the mould along w ith the pressed til e (Nali a/
Kh apra) and turns on a wooden pallet for its remova l.
Th e pedal is th en rel eased w hi ch brings th e bottom
plunger down w hich rests on four corner supports of the
moulding box. Afte r releas in g th e prepared til e the
wooden mould is withdrawn and returned to the mould
box. This makes th e mould ready for subsequent operations. Th e lining of th e mould may require appli cation
of waste oil after the shaping of 4-5 til es to avoid sticking or clay with the top plunger and the mould. A lternati ve ly, fine sand or fine sand y clay, screened coa l ash/
nya. h passing I 00 mesh screen co uld also be used as
dusting material to faci I itate easy demouldi ng of til es
from the mould box assembly. The produced tiles are
shifted to pl ain ground surface or on floor for drying in
an enclosed shed.
Commercial Production
Ex tensive trials were conducted in th e Institute
for production of country roofi ng tiles by this low co t
moulding device and it was observed that about 500600 til es could be produced per day when a semi -skilled
worke r is trained for 3-4 d. For commercial producti on
of Nalia/khapra, one skill ed worker/moulder and two
s:;ompani on labourers are req uired. The quality of the
product obt:1ined is superi or to the one made by the
moulder, either in a mould or on potter 's wheel. The
til es prepared are not di sturbed till suffi cient handling
strength has been obtained. The top compaction renders higher strength to the til e which is found to be more
dimensionally stable than the conventional roofing til es.
Therefore, probability of damage during handling and
warpin g in firin g is substanti all y reduced.
Concluding Remarks
Produced til es when fired at 900 ± 20 "C, show
Breaking load strength as 40-60 kg with water absorpti on o f I 5-20 per cent. The detailed design drawings of
th e pressing and ej ec ti on system of low cost produ ction
device are available in the In stitute. The es timated cos t
of the table fitted w ith the mould, pressing arrangements,
and accessories is projected at Rs 5,000/- approx. This
low cost technology for production of country roofing
til es is ready for co mmercial ex pl oitati on on co mmercial scale, holding potential for employ ment generation
728
J SCIIND RES VOL 6 1 SEPTEMBER 2002
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