BUS BODY-BUILDING

INTRODUCTION

Automobiles body building units generally specialize in a few types of vehicles. For example, a body building workshop of small capacity can under take either trucks or buses of standard design or mini buses or delivery vans or similar other vehicles used for commercial transportation of goods & passengers. But, sufficiently big auto-body building factories can under take a range of chassises for constructing and mounting body on them.

Auto-body building involves a lot of structural designs, wood & metal working processes, fastening techniques surface protection measures, arranging various accessories and instruments electrical and safety devices at proper places. Such a factory requires to be fully equipped with full-range of wood/metal working machines and tools, treating and testing equipments, high level of productivity and quality oriented team and much more facilities indeed.

Body building is a labour-oriented work where all calibres of personnels and hard working labourers are treated as assets.

The important departments of an auto-body building factory can be as under:-

1.      Design and Development

2.      Wood working

3.      Sheet metal pressed components and panels

4.      Iron & steel structures

5.      Mechanical fittings and fabrication

6.      Electrical

7.      Quality control

8.      Paint shop along with pre & post treatments

9.      Initial cost estimation

10.  Liaison/purchase/sales/stores control departments.

11.  Departmental & overall administration

12.  After sales services

13.  Tool room & machine shop, etc.

Thus, over a dozen potential departments and members of all these departments work in a team-spirit in order to run an auto body building factory successfully specially, when the factory undertakes heavy commercial vehicles like trucks and buses for new body to replace the old one on the chassis, it becomes more important to create a coherent atmosphere in the factory. It is so the because the owners of an individual truck or fleet of trucks and buses, authorize robust and hardly type of persons to supervise such works who are very shrewed as well as rough in behaviour, but they know the quality of work being offered by the body builders. Thus, if not convinced, they can create a scene. It requires a most tactful handling of such customers and also a quality work. It is possible only when fool-proof systems have been developed in the factory.

The personnels and technicians heading their respective departments, must be hard working, apt in decision making, swift if delivering their duties in a commercial spirit, and dedicated to give the best of their capabilities. Along with many marketing strategies that a factory can adopt to attract customers, a high level of work satisfaction to the dealt customers is very much significant. In truck bodies, wood works and steel structures are in abundance while in bus bodies sheet metal work, piping work, and many other specialty works find a proportionate place along with wood and steel structural works.

Painting is necessary for both trucks and buses, but the method of painting, pre and post treatments, etc. differ enormously. In a truck most of the painting is done on wooden surfaces, mainly for decorative purpose while in bus bodies, the painted surfaces are usually metallic and paint/primers are applied in coats mainly for protective purpose and also for decorative purposes. Instructions, markings and warnings on suitable places are done by painted displays. The main fabrication activities in practice are :- (i) oxy-acetylene gas flame cutting and welding, (ii) Electric Arc welding and cutting.

Different members of body structures and sub-structures are fastened together by either welding or bolt/screw, or riveting or male-female joint fixing, or bracket mounting, or adhesive pasting/pressing methods, depending on deservability of a technique in terms of mechanical properties and environmental friendliness.

Buses and trucks are subjected to several types of jerks and impacts arising from road conditions, influences of vehicles's speed on structures used, wind speeds and directions environments and many more factors.

All external and internal destabilizing forces must be with stood by the body designed and constructed for the truck or bus. The body must be mechanically well balanced, provided with safety devices, good looking, and highly indicating important slogans, symbols and signs, leading to road safety observed by safe driving by other drivers around it. Work man ship and imagination both are valuable for good body of a bus or trucks besides good design and proper methods/materials/equipments/tools.

The automobile industry was at its boom during most parts of 1980s. But, suddenly it saw a recession for over two years at the start of 1990s. However, it has once again freed itself of recessionary situations. It is believed that this new energy, with which automobile industry has emerged, will remain stable for over a decade.

Road transportation is gradually going into the hands of private sector fleet operators. This means that quality and economy both will be the deciding criteria for future auto body builders. A bus or truck owner wishes that the body once but lasts for as long as possible Modern auto body builders, therefore, need to be quite large in capacity for taking the benefits of scale, in order to keep the unit in highest repute and yet economical. This in turn, calls for active R & D, potential survey team (to give a useful feed back to the manufacturing and quality control departments) and people of expertise all around. Above all these requirements, the fabrication unit must maintain strict schedules and see to it that customers at large feel satisfied with builder's performances, commitments and mannerisons. In nut & shell, modern auto body builders must be perfect professionals with distinctions.

Bus & truck body builders use a host of steel, aluminium, brass and other sections and parts. Wood, glass, plastics boards and hardwares are the materials which are procured in standard forms from the market and used with some essential tailor-made machining operations. But, metal sections need special machining and forming techniques before use. However, all the raw materials and consumables machineries and tools, testing and measuring equipments, jigs and fixtures, and fixtures, and instruments, are fully available indigenously. But, if necessary can also be imported. High level technology has already been developed in India to assure weight balanced and aerodynamically balanced truck and bus bodies.

Thus, from every view point the auto body building industry has bright prospects and can expect gracious harvesting of profits if established on a reasonably large scale. This project proposes to carry out all the activities for processing major raw materials within the plant.

USES AND APPLICATIONS

In this age of development, the demand of Bus, Trucks, Tempo and other automobile vehicle are growing day by day. The thousands of chassis are come to the different body builders for body building. the registration list is become large to every manufacturer.

By the growing population of our country, the new passengers are coming daily on road in lacks. So the Government had to establish a new organization for introducing chassis and body of bus/truck/mini buses etc.

A truck is used for transportation of goods, such as eatable goods industrial goods, coke, iron, Animals etc. And a bus is used to carry the passengers. So both of the vehicles have the same importance in our daily life.

State and Central Government allots a lot of money for transportation only Delhi Transport Corporation reserved twenty crore rupees for purchasing new buses. Haryana and Punjab where the main source of income is transport (Roadways) for Government, is going to improve its road lines. Punjab and other state are also investing a lot of money on these projects.

B.I.S. SPECIFICATIONS

MARKET SURVEY

The Indian automotive industry had started an uneventful course until the Eighties. The number of manufacturers was small, production levels were low and the technology employed was years behind the times.

Many seem to think that the history of motor cars in India is the history of Premer Automobiles and Hindustan Motors. This impression is probably due to the fact that automobiles from these two companies have been on Indian roads right from the late Forties. During British rule, however, international giants like Ford and General Motors used to assemble cars then in India. As many as 61 different models of such cars were available even in 1950. And still less known is the fact that during the first then years of operations, the two Indian manufacturers were compelled to work at a loss. By the mix-Sixties, the stringency of the foreign exchange caused by conflicts with China and Pakistan had compelled the Indian automobile industry to indigenise its vehicles almost fully.

Whatever cabin part has already been built by vehicle supplier, leaving that all over body pars are constructed by the customer. This service is offered by auto body builders.

PROCESS OF MANUFACTURE

All metal bodies fall into two main categories:

1.      Those which are used in conjuction with a separate chassis frame and

2.      Those which are of the type known as monocoque or unit construction.

A basic consideration, therefore, in deciding whether to use a separate chassis and body or a monocoque unit must be the anticipated quantity which is to be produced. Because of the great capital outlay involved and the time taken to produce press tools, the use of unit construction can only be applied to a design where the quantity ultimately produced will be sufficient to spread over the original outlay to achieve a reasonable cost per unit.

On the other hand, where a relatively small production is anticipated the separate chassis and body will be a more economic proposition, because less press-tools will be required.

A properly designed integral body and chassis unit will provide a structure of the utmost rigidity and this is, of course, a most desirable feature in current practice where independent rent suspension is the order of the day. Moreover, provided that sufficient volume of production is to occur, the unit-construction principle will ultimately overtake the separate chassis and body in progressive reduction of cost per unit.

The principal component of these bodies in the timber, frame work reinforced at vital points by forged steel plates. The skin of the modern bodies is of aluminum or steel sheet pinned or screwed to the timber or steel frame work.

MATERIALS

Wood:

Teak is used almost exclusively for the framing of bodies. For the more expensive types, timber should be naturally seasoned by stacking in open sheds where air may circulate freely. The stack is kept up by careful forward buying against the time of timber will be used in production and to allow time for natural seasoning.

Artificial seasoning is more general today provided the drying is properly supervised. The timber so prepared can almost equal the quality of that seasoned in the natural way. Plywood is used for panels, casings and floor. But where exposed to the weather the resin-bonded variety board should be used. Metal- faced plywood can be used for flat panels where a smooth clean finish is required.

Metal:

Mild steel angle channel and Tea section are used as body-stiffening plates and brackets and some times for wind screen and body pillars, where it is required to reduced the bulk of framing to provided the minimum obstruction profusion or where a sounder structural job to be made by the use of a metal pillar.

Forged-steel plates made in the coach smithy are used where special shapes and contours are encountered. There are of half round section when on the surface of the framing, or square edged flat plates where sunk flush into boxings in the framing. Flat body plates of special contour can be produced from mild steel plate by the use of the flame cutting process.

Aluminium is more widely used than steel for the panels of coach built bodies.

Automobile Paints:

Automobile paints and lacquers can be divided into:

1.      Wood lacquers and

2.      metal lacquers.

This classification, again, may often overlap and may be further sub-divided. Generally speaking, wood lacquers are characterizes by comparatively high solid contents, while metal lacquers have high toughness and adhesion properties. The earlier used shellac-based varnishes have largely been replaced by more effective lacquers.

The wood surface to be painted, is first coated one coat with primer under coat, followed by sanding. Then, sealer putty is used and consequently sanded within one hour with dry sand paper. Now, the surface is ready for two lacquer coats.

Low viscosity nitrocellulose based lacquer sanding sealers (½ second grade) or medium viscosity (26 second grade) or a high viscosity lacquer sanding sealer can be used according to conditions prevailing.

Gloss wood lacquer of low viscosity (½ second) or high viscosity (25 sec.) gloss wood lacquers are further advised for finish coats.

Anti-Corrosion

On completion of the timber frame work, the whole is given two or three coats of lead primer but if the vehicle is for tropical service then, it is advisable that the components are dipped, before assembly in one of the chemical preparations available which immunise them against the conditions delegerations to timber in that climate.

Generally, steel parts are treated with a protective primer before fitting. Aluminium components and the reverse side of any aluminium panelling, are treated with aluminium primer.

Where aluminium and steel are in contact di-electric point should be applied to the components before assembly. Every manufacturer of body building, except they very small ones who put the workout, required wood working machineries and all well equipped mills should include the following machineries.

1.      Circular Saw: For general sawing, ripping, cross-cutting bevelling, rebating, tonguling and graving.

2.      Band Saw: For cutting on the sweep or barel and for straight work.

3.      Planning and thickenssing; M/cs for proving parallel to the true surface and at the exact distance required from it another planed surface.

4.      Spindle machine for planning truly and circular or irregular outline, as well as for forming any groove or rebate and, with shaped knives, any desired profile or molding. May be used for straight work and thickness with suitable fences.

Farming

When the body is being 'Framed up' it is stood on low treat carefully checked to ensure an absolutely flat foundation. In some cases the body is built directly upon the chassis.

Where a considerable number of bodies is being built for, are particular model of chassis, the trestle is built up in the form of the chassis so that the body can be subsequently mounted without fitting adjustment. The lap or help lap joint is the one most commonly used where the two pieces to be joined are more or less at right single. The scrap or splica is used for joining two pieces in the same direction and for joining curved members.

Bottom Frame

The bottom sides or runners being the foundation of the body are produced first usually a separate extension of the bottom sides is required owing to the rise of chasis frame over the rear axle. This is spliced on to the main runner and shaped on the under side to the contour of the chassis rise. This inner edges of the runners or bottom sides are rebated out to receive the floor board. The cross-bars tying the two sides are lapped into the runners and should, if, possible be fitted opposite the feet of the standing pillers so that a continuous steel body plate may be screwed to the pillers and bolted to the cross-bar the plate being sunk flusk into a boxing in the latter. All joints are made with glue or white lead and secured by steel counter sunk wood screws.

Side Pillers

On completion of the bottom frame, the side pillers are created. The standing pillers having been barelled to suit the described by the swing the door, are lapped into the bottom side.

A tenen is cut at the top of each standing piller to receive the cant-rails. The elbow rails are lapped or tenoned into the rear standing pillers and a special joint made with the backrail at the rear corners. Laps or tenon are not carried right through the door pillers or door in open. Although this is not important when the metal penelling is carried round and over the door 'Shuts'. Wheel cut with the grain running as much in the direction of the arch as possible. The arch is lapped or teenoned into the framing at the front and halved into the bottom side at back.

The whole arch may be braced by the fitting of the forged-steel plate screwed on the inside. Where the quantities are sufficient the wheel-arches are sometimes steamed and bent to shape. The pillers, laped into the bottom sides are temporarily held at the right distance apart by strainers screwed to them. As the top front rails and scuttle rail hold the front pillers together, these may not be assembled and filled.

Roof

The roof may be constructed for panelling entirely in metal, in which case there should be same form of insulation between the hoopstick and roof pannel such as strip felt to minimize the risk of drumming.

Some roofs are constructed with the main panel of plywood or sheet covered on top with water-proof fabric fastened with brass shank beading.

Some roofs are sometimes fitted in which the main centre portion is covered with water proof fabric structured over the padded framing. The cant rails, which form the junction of body-side and roof, are mortised to receive the tenon at top of piller and notched for the cutting of the hoopsticks.

As the side of the roof is usually reduced it is sometimes the practive to get them cant rails out of solid timber or build them up so that they can be cleaned into a good shape, the radius of the corner gradually increasing to blend with the rear dome.

The hoopsticks, which form the framing of roof and give it its shape, are cut parallel to the roof chamber and lapped into the notches provided in the cant rails. The intermediate hoopstick should represent a gradual development from minimum at front to maximum chamber at rear dome.

Pannel Battens

Pannel batten faced with felt are fitted to sides whenever the expense of pannel is considerable, and the doors to prevent 'drumming'.

Doors

The doors, comprising the bevelled 'shut' piller, the hingepiller, waist rail, garnish rail, door top and door bottom rails, are now assembled and hung. The piller having already been boxed out for the glass runs. The but things is most popular because it is easy to fit and does not cut away much Timber when fitted. The usual pattern is a parallel sided barrel shaped hinge. There is very form of concealed hinge but they have the disadvantages of cutting away much of the piller.

Elaborate concealed or semi-concealed hinges have been divided for jobs where the door line has a pronounced slope or the body side is bulbous. 'Swan-neck' of 'C' hinges are sometimes employed, because the large are described thrown the door well clear of the body and the hinge is not visible from the exterior when the door is closed. An outrigger hinge is used where a long but thins would look unsightly, as would be the case where the side 'turn-under' is considerable. Slam lock still find favour for general work, but press button types now available permit the use of partly-sunk windless.

When the door is fitted with a slam lock a double striking plate is fitted to the standing pillar to provide increased safety in that the nolt is held in the recess between the two inclined planes of the plate if the door handle has only been partly turned. Dove tails are used to register the door in its proper position.

Door stops or check straps take the form of the simple webbing strap fastened by paltes screwed to the door and standing piller or the steel band covered with leather which is secured to the body side and slides through a staple on the door hinge piller, the door being checked when fully open by a bar fastened in the other end of the strap coming into contact with the staple. Sprint steel check straps running through a slot in the body piller and connected to a flush sunk hinge in the door have the advantage of being invisible when the door is closed.

Another form is a folding steel link are end of which is fitted to the lower part of the door and secured at the other end under the bottom side, there by forming a heat and unobstructive arrangement.

Panelling

The skin are exterior panelling of the body is generally of 16, 18 or 19,500 g. aluminium sheet, although 20,500 g. steel sheet is frequently used on commercial bodies, where the weight factor is of no great importance, because of lower cost. A well fitted steel pannel, although relatively heavy, strengthens the framework considerably, but of course, is liable to rust unless great care is taken with the protective treatment prior to painting.

The high class coach Built body which is usually a one off to a special design or one of a small batch, calls for hand beaten panels because of its special shapes and contours and these must be fashioned with hand tools by expert craft man.

Mounting

This department places and fixes the body on the chassis, and fits the wings and steps, lamps, number plates and spares wheel carrier.

Fixing Body to Chassis

The method of mounting the body is usually defined by the chassis manufacture, who in many cases, provides brackets affixed to the chassis frame on which the body is mounted and bolted down, importance being attached to the accessibility of these mounting bolts.

Now-a-days flexible mounting units are widely used, being specially designed for the type and weight of the body. they incorporate rubber in their construction so that there is not metallic contact between body and chassis. Commercial bodies are often attached to the chassis.

In some cases, the top flanges of the chassis are bolted together; but the chassis is weakened by this method of attachment and, if adopted, the positions of the holes in the chassis frame should be approved or provided by the chassis manufacturer.

Scuttle

Flexible connection between the scuttle framing of the body and the dash-plate is essential, as the latter forms parts of the chassis and in affected by its local flexing. The scuttle framing is sometimes recessed to provided a landing for the bonnet, in which case plenty clearance is provided between the edge of the bonnet and the scuttle panel to allow for the movement of the former.

Flooring

Floor Board and the front foot-ramp, in which cut the slots for the clutch, brake and accelerator pedals, are made detachable, although where possible two or three boards may be battened together. They are made to life out by means of a flush-fittings sunk ring. In commercial and public service vehicles, the wood of about 3/4 inch to 7/4 inch thickness, and as they are not easily removable, it is important that any traps required for access is mechanical components should be provided in the follr and accurately positioned, as indicated on the body builders arrangement drawing which is supplied by the chassis manufacturer.

In order to exclude heat from the exhaust system, or from the engine where this is of the under-floor type as fitted to modern coach or mini bus chassis, it is necessary to fit as best as sheeting on the under side of the floor. Resin bonded plywood is used for the flooring of 'under floor' engined public services vehicles, since it is not so liable to shrinkage or distortion when exposed to the varying temperature conditions which obtain with this type of vehicles.

Steps

The steps of coach built commercial or passenger vehicles are made of any good wet-resisting timber and the supporting frame work reinforced with mild-steel angle plate where necessary. The trade-plate or one of the many compound or fabric-filled tread strips available to the coach builder and adged with separated aluminium or steel angle plate.

GLASING

Wind Screen: The wind screen is invariably of the single-panel type, frequently a fixture, and sometimes hinged at the top to open out wards. The screen that is curved in plan is not unusual on the latest closed bodies and greatly enhances the appearance of the Car.

The screen frame is kept as narrow as possible and is a special brass section providing a channel in which the glass is embedded in rubber and on over lapping lip which is bedded down against the panelling and sealed to ensure its being water tight. A special moulded rubber lip is fixed in the over lap of the screen frame when it is of the opening type.

FINISHING

Wood Work Interior

An important feature of the interior of the luxury coach built body is the wood work used for the waist panels organized rails and the fillets surrounding the windows.

Instrument Board

The instrument of fascia board is in effect a decorative of finishing panel surrounding the instrument plaque supplied by the chassis manufacturers.

PAINTING TECHNIQUE

Many designs of spray guns are available which atomise paint by mechanical action and avoid the expense and associated problems with compressed air spray. However, none of these spray guns give satisfactorily fine degree of atomisation. Now, two modern processes have been developed for the required results.

1.      Airless spraying using very high pressure.

2.      Electrostatic process.

The former uses hydraulic pressure. Viscosity of paint used can be reduced by raising temperature upto 1600 F in airless spraying.

The airless spray gun differs in design from the air stomization gun in many ways. Its construction is much simple. The orifice diameter may range between 0.007 inch and 0.036 inch, capable of passing approximately 250 ML/min. of liquid paint.

The paint unit is available as a complete paint spraying system; fitted with high pressure pump, stirrer and other accessories. The paint is poured into a container mounted on this compact system and lid can be opened for thinning.

The airless spraying unit can be mounted on a wheeled trolley for making it portable on the workshop floor.

The degree of excellence of painted areas largely determined by the preparation and the careful application of priming and filling coats and the rubbing down and flatting.

EQUIPMENTS SUPPLIERS

Gas Gutting Equipments:-

1. M/s. Indian Oxygen Ltd.,

P-34, Taratolla Road,

Calcutta.

 

2. M/s. Advani-Oerlikon Ltd.,

Block-D, Ground Floor, Shivsagar Eatate,

Dr. A.B. Road,

Worli,

Bombay - 400 018.

 

3. M/s. Kirloskar Electric Co. Ltd.,

Indl. Suburb, Rajaji Nagar,

Bangalore - 10.

 

4. M/s. Jaya Hind Sciaky Ltd.,

D-I, Block, Plot No. 18/1,

Chinchawad,

Poona.

 

Resistance Meter Wattmeter, Voltmeter, (Multimeters):-

1. M/s. MECO Instruments Pvt. Ltd.,

Bharat Indl. Estate,

T. J. Road, Sewree,

Bombay - 400 015.

 

2. M/s. Applied Electronics Ltd.,

Aplap House, A/5, Wagle Indl. Estate,

Thane - 400 604.

 

3. M/s. Agronic Instruments P. Ltd.,

204, Shiv Shakti Indl. Est. Nr Shreyas

L. B. S. Marg, Ghatkopar (W),

Bombay - 400 086.

 

4. M/s. Electronic Development Lab.,

6/3, Krti Nagar Indl. Area,

New Delhi - 110 015.

 

5. M/s. Omega Electronics,

36, Hathi Babu Ka Bagh,

Jaipur - 302 006.

 

Personnel Computer:-

1. M/s. HCL Limited (Instruments Divin.),

603, Vihal Bhavan, 95, Nehru Place,

New Delhi - 110 019.

 

2. M/s. Patni Computer System,

303/304, Ragurt Chambers,

Nairiman Point,

Bombay - 400 021.

 

3. M/s. DCM Data, Products,

4th Floor, Vikrant Towers,

4, Rajendra Place,

New Delhi - 110 008.

 

4. M/s. Sunray Computers (P) Ltd.,

44, Race Course Road,

Bangalore - 560 001.

PLANT ECONOMICS

Basis

Currency - Rs.

LAND & BUILDING

PLANT & MACHINERY

OTHER FIXED ASSETS

FIXED CAPITAL

WORKING CAPITAL REQUIREMENT/MONTH

RAW MATERIALS

1.WOOD LOGS:

2' X 1' X 10' logs (60 nos.)

= 1200 cu ft. @ Rs.1050/-per cu.ft    Rs.12,60,000.00

2.1' X 1' X 10' logs (10 nos.)

= 1000 cu.ft. @ Rs. 1200/- per cu. ft.    Rs.12,00,000.00

3. Other wood sizes 2000 cu.ft.

@ Rs.1400/- per cu. ft.   Rs.28,00,000.00

4. MS SECTIONS:200 MT.@ Rs.12,000/-per

MT(avg) Anlges,channels,rods wires,

plan/checquered plates pipes,sheets    Rs.24,00,000.00

5. ALUMINIUM & S.S. PRODUCTS :

Sheets,window frames,pipes,rods etc

25 MT @ Rs. 72,000/-per MT.    Rs.18,00,000.00

6. Hardwares,tools bits, fasteners

welding electrodes,cast brackets,

forged Hooks/Rings etc.   Rs.7,00,000.00

7. Pickling chemicals lubricants,

primers/paints, & miscellaneous

stores.   Rs.4,40,000.00

8. Plywood/Boards, sunmica sheets,

Glass sheets, cloth/rexin covered

seats etc.   Rs.52,50,000.00

9. Auto Electricals & Accessories.    Rs.11,50,000.00

TOTAL   

Rs.1,70,00,000.00

SALARY & WAGES / MONTH

UTILITIES AND OVERHEADS

Total load is 110 Kwatts

TOTAL WORKING CAPITAL/MONTH

 

COST OF PROJECT

TOTAL CAPITAL INVESTMENT

COST OF PRODUCTION/ANNUM

TURN OVER/ANNUM

PROFIT   =   RECEIPTS - COST OF PRODUCTION

   =   25,47,00,000.00 - 22,54,44,120.00

   =   2,92,55,880.00

 

PROFIT SALES RATIO   =   Profit / Sales * 100

   =   2,92,55,880.00 / 25,47,00,000.00 * 100

   =   11.49 %

RATE OF RETURN   =   Operating profit / T.C.I * 100

=2,92,55,880.00 / 7,07,81,500.00 * 100

   =   41.33 %

BREAK EVEN POINT (B.E.P)

Fixed Costs of the plant are as under -

B.E.P.   =   FIXED COSTS / FIXED COSTS + PROFIT * 100

   =   1,71,20,520.00 / 1,71,20,520.00 + 2,92,55,880.00 * 100

   =   36.92 %

LAND MAN RATIO   =   Total land / Manpower

13 : 103 :: 0 : 1

RESOURCES FOR FINANCE