CAR BODY

CAR BODY 

Cars can come in a large variety of different body styles. Some are still in production,while others are of historical interest only. These styles are largely (though not completely) independent of a car's classification in terms of price, size and intended broad market; the same car model might be available in multiple body styles (or model ranges).

For some of the following terms, especially relating to four-wheel drive / SUV models and minivan / MPV models, the distinction between body style and classification is particularly narrow. Please note that while each body style has a historical and technical definition, in common usage such definitions are often blurred. Over time, the common usage of each term evolves. For example, people often call 4-passenger sport coupes a "sports car", while purists will insist that a sports car by definition is limited to two-place vehicles. For instance, if a car is for a family of more than 5 people then it demands a large car. A car to do the home to office and back, 5 times a week in city traffic might need a smaller sized car. Car body styles is a broad subject to deal with and the names given also vary from country to country.The names are given depending upon design, utility, technology used and customization.So its important to select the car body type which you are going to buy.

Classifications of car body:

   1.Sedan or saloon

           i.Notchback

          ii.Fast back

          iii.Hatchback

          iv.4 door saloon

          v. 2 door saloon and pillar less saloon

   2. Coupe

   3. Sports coupe

   4. Limousine

   5. Estate car

   6. Convertibles

   7. MUV or MPV

   8.SUV

1.SEDAN or SALOON:

  A sedan car or saloon car is a passenger car with two rows of seats and adequate

passenger space in the rear compartment for adult passengers. The vehicle usually has a
separate rear trunk for luggage, although some manufacturers such as Chevrolet, Tatra,
and Volkswagen have made rear-engined models. It is one of the most common body
styles for modern automobiles, and is often marketed at families under the rubric of
family sedan.

i) NOTCHBACK: 

A notchback  is a three‐box sedan, where the passenger volume is clearly distinct from the trunk volume of the vehicle (when seen from the side). The roof is on one plane, generally parallel to the ground, the rear window at a sharp angle to the roof, and the trunk lid is also parallel to the ground.

 Ex: ford mustang,fiat 124,ford LTD

         ii) FASTBACK:

Ex: Volkswagen beetle, Plymouth barracuda

                                                                                      

       iii) HATCHBACK:

•  Hatchback containing a passenger cabin with an integrated cargo space, accessed from behind the vehicle by a single, top‐hinged tailgate or large flip‐up window.
•  The vehicle commonly has two rows of seats, with the rear seat able to fold down to increase cargo space.entire of the back lifts up using a hatch.
• have 4 doors and one rear lift gate
• Also called as four door hatchback or 5 door saloon.

Ex: Hyundai i20, i10,eon, Ford figo, Ford Fiesta, Volkswagen polo   

       iv) 4 DOOR SALOON:


                             

      This is the most common passenger car.

•  Passenger comforts such as well designed seats, ease of entry and exit,

•  good heating and ventilation system and better styling are the features of this model.

•  Drag coefficient of this model is about 0.35 to 0.50.

Ex: Honda city, Amaze, Skoda Rapid, Maruti Suzuki Ciaz, Audi A4  

Drag coefficient :

It  is a common measure in automotive design as it pertains to aerodynamics. Drag is a force that acts parallel and in the same direction as the airflow. The drag coefficient of an automobile impacts the way the automobile passes through the surrounding air. When automobile companies design a new vehicle they take into consideration the automobile drag coefficient in addition to the other performance characteristics. Aerodynamic drag increases with the square of speed; therefore it becomes critically important at higher speeds. Reducing the drag coefficient in an automobile improves the performance of the vehicle as it pertains to speed and fuel efficiency.

   iv) 2 DOOR SALON AND PILLAR LESS SALOON:

 

•  The features of two door saloon and pillar less saloon are the same as that of four door saloon.However in pillar less saloon there will not be a center pillar.

• SAE(Society of Automobile Engineers) defines such a vehicle as any two-door model with rear accommodation greater than or equal to 33 cubic feet (0.93 m3) in volume (a calculation made by adding the legroom, shoulder room, and headroom)

Ex: Chevrolet Monte Carlo, Ferrari 612 Scaglietti

2.COUPE:

 

• A coupe is commonly understood to have a fixed roof and two doors.

• The rear seat placed further forward than in a standard sedan offering either two seats or 2+2 seating for two passengers in the front and two occasional passengers or children in the rear.

•  However several four‐door vehicles, including the Mercedes‐Benz CLS and Rover P5 Coupe, are claimed by their manufacturers to be "coupes".

Ex. Mercedes benz CLS ,Rover P5

3.SPORTS COUPE:

 

•  It is a small car with two seats.

•  Better aerodynamic shape and better acceleration are the features of this model. Styling is not important.

•  Lightness and rigidity are also the features of this model.

         Cd = 0.2 to 0.3

EX: Audi R8, Alfa romeo 4C, Porsche cayman, Lamborghini Aventador.

4.LIMOUSINE:

• It is a luxury car. It is provided with components and equipment of high quality and with better finish.
•  It is usually provided with a partition between the driver and the passengers.

•  Cushioned seats, air conditioning, cooling glasses etc are the other features of this Model.

EX: Rolls royce Phantom,Hummer H2,H3, Mercedes benz S600,Ford Excursion

5.ESTATE CAR:

 

• The luggage compartment is the continuation of passenger compartment without partition between them. Thus more luggage space and longer wheelbase are the speciality of this model.

•  The other names of this model are Universal, Kombi,Station wagon, Camping Van and Break van.
• Body style similar to sedan but incorporating a full size back cargo compartment.

Ex:Mercedes estate 200t , Mercedes-Benz E-Class Estate,Tata estate

6.CONVERTIBLES:

 

• These models are provided with wind‐up windows and folding roof.
• A convertible is a type of automobile in which the roof can retract and fold away, converting it from an enclosed to an open-air vehicle.

•  Roofs are affixed to the body of the vehicle and are usually not detachable. Instead the roof is hinged and folds away, either into a recess behind the rear seats or into the boot or trunk of the vehicle. 
• The roof may operate either manually or automatically via hydraulic or electrical actuators, the roof itself may be constructed of soft or rigid material.
•  Soft-tops are made of vinyl, canvas or other textile material; hard-top convertibles have roofs made from steel, aluminum, carbon fiber or plastic materials.

Convertibles offer the flexibility of an open top in trade for:

     ⦁ potentially reduced safety
     ⦁ poor break-in protection
     ⦁ deterioration and shrinkage of the sun-exposed textile fabric over time
     ⦁ diminished rear visibility, from a large roof structure, small rear window, or
        obstructed rear window —or all of these: e.g., MINI convertible.
     ⦁ generally poor structural rigidity. Contemporary engineering goes to great length
        to counteract the effects of removal of a car's roof.

Ex: Jaguar XK8, Audi R8, Lamborghini Aventador

7.SUV:

• A sports utility vehicle, or suburban utility vehicle (SUV), is a vehicle similar to a station wagon, estate car, or van usually equipped with four-wheel drive for on-road or off-road ability. Some SUV's include the towing capacity of a pickup truck with the passenger-carrying space of a minivan or large sedan.

• It is known in some countries as an "off-road vehicle" or "four-wheel drive.

EX: Mahindra Scorpio, Toyota Fortuner, Maruti Grand Vitara, Tata Safari.



8.MUV or MPV:

• A minivan, multi-purpose vehicle (abbreviated MPV), people-carrier, people-mover or Multi-Utility Vehicle (shortened MUV) is a type of automobile similar in shape to a van that is designed for personal use. 
• more seating capacity and most of the models are designed with folded rear seats, and the area that is left can be used for some extra luggage space. A multi utility car can accommodate many passengers and also carry more luggages at a time.

EX: Toyota Innova, Nissan Datsun GO Plus, Maruti Ertiga, Mahindra Xylo

WINDOW LOCK MECHANISM:

The car door window glass can be opened by these methods


     MECHANICALLY OPERATED :

 

• In the above method the window is opened or closed manually.
• If the handle inside the door is rotated it will rotate the pinion.
• The power from the pinion to circular rack is transmitted.
• There is a linkage attach the lifter to the rack.so if the pinion rotates the circular rack and rack , gets the up and down movement depending upon the direction of rotation of the rack.
• There is another linkage which is used to support the lifter in up and down movement.
• The window glass is attached to the lifter and gets the movement to open and close.

There will be enough friction between pinion and rack, this friction helps to hold the lifter at any position.so we can adjust the window at any position depending upon our convenience.

    

  SCISSOR TYPE:

 

 

 

• In the scissor type same as above method the pinion is connected to the circular rack.
• There is a scissor type of linkage is attached to the rack.and both the linkages are hinged at the mid point where they meet.
• When the passenger rotates the lever from inside the door the rotation power transmitted to the rack and the scissor gets a scissor cutting motion.
• In the other end of the linkage there  is space provided for move forth and back of the linkage.
• so this movement will lift the glass through the lift channels which is attached below the glass.
• The glass will move up and down in the tracks by the sliders.
  

DOOR UNLOCKING MECHANISMS:

 

Here are some of the ways that you can unlock car doors:

• With a key
• By pressing the unlock button inside the car
• By using the combination lock on the outside of the door
• By pulling up the knob on the inside of the door
• With a key less-entry remote control
• By a signal from a control center

In some cars that have power door locks, the lock/unlock switch actually sends power to the actuators that unlock the door. 

 

 

This actuator can move the metal hook shown in this photo to the left or right. When mounted in the car, it is vertical, so the hook can move up or down. It mimics your motions when you pull the knob up or push it down.

• The power-door-lock actuator is positioned below the latch. A rod con­nects the actuator to the latch, and another rod connects the latch to the knob that sticks up out of the top of the door.

• When the actuator moves the latch up, it connects the outside door handle to the opening mechanism. When the latch is down, the outside door handle is disconnected from the mechanism so that it cannot be opened.
• To unlock the door, the body controller supplies power to the door-lock actuator for a timed interval.

Inside the Actuator

• ­­­This system is quite simple. A small electric motor turns a series of spur gears that serve as a gear reduction. The last gear drives a rack-and-pinion gear set that is connected to the actuator rod. The rack converts the rotational motion of the motor into the linear motion needed to move the lock.

• One interesting thing about this mechanism is that while the motor can turn the gears and move the latch, if you move the latch it will not turn the motor. This is accomplished by a neat centrifugal clutch that is connected to the gear and engaged by the motor.

• When the motor spins the gear, the clutch swings out and locks the small metal gear to the larger plastic gear, allowing the motor to drive the door latch. If you move the door latch yourself, all of the gears will turn except for the plastic gear with the clutch on it.

  

centrifugal clutch

 

SEAT ADJUSTMENT MECHANISM:

These are the adjustment can be made 

• Back rest angle,cushion edge,Fore & after position, headrest level, lumbar position, seat depth,seat height.

  

  
  

  

   

 

• The function of the radial spring is to bring back the seat to original position after the lever is released .When we move the lever upside the contact between tooth are released ,so the seat will be brought back to original position.If we push the seat backside and push the lever down , the tooth will be locked with each other again.The linear spring is to hold the lever in the lower position as well as in the upper position.So whichever the position the driver wants he can adjust the lever.
  
  

DRIVER'S VISIBILITY:

 

• In transport, driver visibility is the maximum distance at which the driver of a vehicle can see and identify prominent objects around the vehicle. Visibility is primarily determined by weather conditions and by a vehicle's design.
•  The parts of a vehicle that influence visibility include the windshield, the dashboard and the pillars.Good driver visibility is essential to safe road traffic.Blind spots may occur in the front of the driver when the A-pillar (also called the windshield pillar), side-view mirror, and interior rear-view mirror block a driver's view of the road. Behind the driver, there are additional pillars, headrests, passengers, and cargo,that may reduce visibility.
• A blind spot in a vehicle are areas around the vehicle that cannot be directly observed
  under existing circumstances. Blind spots exist in a wide range of vehicles: cars,
  trucks, motorboats and aircraft. 

1. Forward visibility:

A-pillar blind spot 

This diagram shows the blocked view in a horizontal-plane in front of the driver. The
front-end blind spots caused by this can create problems in traffic situations, such as in
roundabouts, intersections, and road crossings. Front-end blind spots are influenced by the following design criteria:

⦁ Distance between the driver and the pillar
⦁ Thickness of the pillar
⦁ The angle of the pillar in a vertical plane side view
⦁ The angle of the pillar in a vertical plane front view
⦁ the form of the pillar straight or arc-form
⦁ Angle of the windshield
⦁ Height of the driver in relation to the dashboard
⦁ Speed of the opposite car

1.Effects of A-pillar angle on visibility :

• Most passenger cars have a diagonal pillar as shown in this side view. The angle between the horizon and A-pillar is approximately 40 degrees with a straight pillar that is not too thick. This gives the car a strong, aerodynamic body with an adequately-sized front door.
•  vertical A-pillar having small blind spots
  
  

  

  
  

  40° angle A-pillar bar blind spots

  
  

  
  

      1.1 Panoramic windshield:

 The sides of a panoramic windshield are curved, which makes it possible to design vertical A-pillars that give the driver maximum forward visibility. However, it is impossible to design an aerodynamic small car with a vertical A-pillar because the more vertical the A-pillar is, the less space the door opening has, and the greater frontal area and coefficient of drag the vehicle will have.

Examples of cars with an almost vertical A-pillar:
⦁ Honda Step Bus Concept
⦁ Saab 900
⦁ School bus
⦁ Almost all Cadillacs from 1954-1959

    

•  Some modern car designs have an extremely flat A-pillar angle with the horizon. For example, the Pontiac Firebird and Chevrolet Camaro from 1993-2002 had a windshield angle of 68° with the vertical, which equals just 22° with the horizon.A flatter A-pillar's advantages include reducing the overall drag coefficient and making the car body stronger in a frontal collision, at the expense of reducing driver visibility in a 180° field of view from left to right.

    1. 2 Other disadvantages of a flat windshield angle
 
⦁ Other traffic can not see the driver through the reflection if the driver can see them.
⦁ The heater needs more time to heat the bigger window surface.
⦁ The flat windshield angle does not let snow slide off easily.
⦁ The driver cannot reach the whole flat window to clean it easily.


2. Height of the driver:

Turning your head reduces blind spot

• Driver height can also affect visibility. An A-pillar that is split up and haves a small triangle window (Front Quarter glass) can give a short driver visibility problems. 

• Some cars the windshield is fillet with the roofline with a big radius. A fillet round A-pillar can give a tall driver visibility problems.Also sometimes the A-pillar can block the driver from seeing  motorcyclists.

• Also the B-pillar (car) can block the vision of a tall driver in small 4 door cars.

• A driver may reduce the size of a blind spot or eliminate it completely by turning their head in the direction of the obstruction. This allows the driver to see better around the obstruction and allows the driver better depth perception.

3. Visibility in a convertible:

Because there is no roof connection between the A- and B- pillar The A-pillars of a convertible automobile have to be stronger and even thicker, However, with the top down there are no B or C pillars, improving driver visibility behind the driver.

4. Windshield reflections:

Sunlight dashboard reflection

     
      4. 1. Dashboard reflection

• It is best if the dashboard has a non-reflecting dark colored surface.  

• A small dashboard gives some reflection on the lower part of the windshield.

• A big dashboard can give reflection on eye height.

      4. 2. A-pillar reflection

• It is best if the inside of the A-pillar has a non-reflecting dark colored surface.If the side of the window is curved there is less A-pillar reflection.

      4. 3. Light through roof reflection

Some new model cars have a very big roof-window. Sometimes the sunlight through the roof lights up the dashboard and gives a reflection in the windshield.

5. Other automobile design factors:
 

• Other design factors may prevent a manufacturer from maximizing visibility. These include safety, as narrower pillars cannot be made strong as easily as thicker pillars, and size restraints pertaining to aerodynamics, as taller, more vertical windshields create additional drag and reduce fuel efficiency.

6. Rear-view mirror blind spots:

• A vehicular blind spot is the area of the road that while driving cannot be seen when looking forward or through either the rear-view or side mirrors. Blind spots can be checked by turning one's head briefly, eliminated by reducing overlap between side and rear-view mirrors, or reduced by adding other mirrors with larger fields-of-view.

• Detection of vehicles or other objects in blind spots may also be aided by systems such as video cameras or distance sensors, though these are uncommon or expensive options in automobiles generally sold to the public.  

 VISIBILITY TESTS:

 
(1)Reversing visibility test procedure:
 
The test procedure consists of the following:

1.  a laser pointing device,
2.  a dummy to represent an average adult size,
3.  a test cylinder to represent the shoulder height of an average 2 year old child ,and
4.  a grid extended 1.8 x 15 meters to the rear of the vehicle.

• The laser is directed through the rear window of each vehicle. The position where the laser is visible on the test cylinder is noted. This procedure is repeated for all positions on the grid. The results are analysed and an overall score is given. 
• The best scores are awarded to the vehicles which have the most effective rear visibility. A low star rating car means a driver looking out the rear window is less likely to see an object of child height, compared to a car with a better star rating. The more stars the better.

(2) Visibility test by Motor Research Industry Association:

• Each of the cars was driven into the darkened lab and lights mounted in a dummy driver’s eye position were used to project shadows on to a screen which surrounded the car. The grid on the screen was marked with a scale so that the edges of the shadow could be measured in terms of their distance from the driver’s eyes.

• Three sets of measurements were taken for each car. Firstly, a single bulb was used to project the shadow of both A-pillars on to the screen. Then, the coordinates of the upper and lower corners were measured to enable the area of vision obscured by the pillars to be calculated.

• The dummy’s ‘head’ was then changed to one which had both left and right ‘eyes’ (bulbs) so that binocular vision and pillar thickness could be assessed. The edge of each pillar was measured using one bulb, then the other. In this way, we ensured that only the proportion of the pillar which was obscured to both eyes was measured.

Finally, the ‘critical vision area’ of the windscreen, which is four degrees above and four degrees below the driver’s straight-ahead eye position, was also measured and assessed.
 

Analyzing and presenting the data: 

• A car with wide pillars and a wide screen will give a better overall field of view than a vehicle with the same thickness of pillars, but a narrower screen.

• The ratio of the screen to pillar areas is the ‘critical vision area’ of the windscreen divided by the left and right pillar areas added together.The higher this value is, the better the score the car will receive.

System for improving the visibility in vehicles:

1) Laser Measuring

A system for improving the visibility in vehicles, including the following:

1. an illumination optical system (2) for continuous radiation of infrared pulsed light
2. an associated receiver optical system (3) for receiving reflected components of the radiated light; 
3. a display (4) for representing information obtained by the receiver

• optical system (3), and a device (5, 6) for determining the presence of glare in the receiver optical system (3) from a foreign vehicle illumination optical system and for changing the keying interval or duty cycle of the infrared pulsed light of the illumination optical system (2) driven with fixed keying interval in dependence upon the vehicle direction of travel in such a manner that the glare is eliminated.

• Therein the illumination optical system is driven is driven with a fixed keying interval depending upon the vehicle direction of travel or, in certain cases, the direction of illumination.

•  In an alternative embodiment, the illumination optical system (2) is operated at a wavelength which depends upon the vehicle direction of travel or, in certain cases, the direction of illumination.

2) Patent Research

• The invention concerns a device for improving the view in vehicles, in particular at night, bad weather and fog.

•  In the process images of actual traffic scenes are recorded by a camera (2), which is sensitive outside the visible spectrum, and these images are reproduced in the visible spectrum in the vehicle via a display optic (6)

• According to the invention the type of object which is contained in a traffic scene recorded by the camera (2) is automatically classified according to type, and depending upon the type of the recognized object it is reproduced on the display optic (6) in an intensity and/or color,which corresponds to the intensity and/or color which the associated object typically has by daylight.

•  The process facilitates the recognition by the vehicle operator of images of traffic scenes recorded outside the visible spectrum.

Painting Process:

• PRE – TREATMENT PROCESS
• ELECTRO - COAT PROCESS
• SEALER PROCESS
• SPRAY BOOTH PROCESS
• WAX OPERATIONS 

1.PRE – TREATMENT PROCESS:

• Before the Pre-treatment Process , all bodies are fitted with specially designed load bars to enable the body to get loaded in Overhead conveyor and Slave tools which avoids contact damage of panels during the Paint process and enables operators to open and close panels.
• Pre-treatment provides the basis of corrosion and adhesion of Primer coat.
• It is a 11 stage automatic immersion – dip/spray process, gives full protection to all box sections.

Various stages in Pre-treatment Process :

Stage 1 : Pre wash spray rinse in which a chemical (surface active agent surfactant) is used to loosen oil and wash of contaminants on the body in white.Cleaner spray rinse – 1 where Pressurized hot water (45°C) spray loosens the oil left over in the Pre wash stage and pre-heat the car body for further processes .

Stage 2 : Cleaner spray – 2 containing a Pressurized hot solution(52°C) of Factory water and Degreasing chemical further cleans the car body .

Stage 3 : Cleaner dip containing a hot solution (50°C) of Factory water and Degreasing
chemical cleans all the interior portions and box sections of the car body thoroughly.

Stage 4 : Dip rinse – 1 in which factory water is used for removing the Degreasing chemicals used in the previous two stages.

Stage 5 : Activation dip containing Gardolene ZM solution prepares the surface of the car body for refined phosphate coating.

Stage 6 : Phosphate dip where the car body is coated with a layer of Zinc phosphate at 49°C bath temperature for 3 min.Phosphate coating prepares the basis for corrosion protection and better adhesion for Electro coat.

Stage 7 : Dip rinse – 2 cleans the excess phosphate solution using fresh DI water.

Stage 8 :Spray rinse further cleans the car body using DI water recycled from Stage 10.

Stage 9 : Passivation rinse uses a chrome free Passivation chemical for filling the gaps between the phosphate crystals and provides a smooth , uniform phosphate coating finish.

Stage 10 : DI water dip cleans the car body after passivation. 

Stage 11 : DI water spray rinse cleans the car finally before E-coat using new DI water.

2.ELECTRO - COAT PROCESS:

• Electro-coating provides comprehensive water based paint coating by Electro deposition.
• Electro-coating is a fully automatic total immersion process for maximum coverage and performance and allows uniform, run free coating for optimum quality.
• Electro-coating provides good basis for all subsequent processes.
• Electro-coat bath contains 82% DI water , 17% EC solids and 1% Solvent.
• The process time is 4 to 5 min for a car body.
• Electro-coat is the first layer of paint in a car body. The Dry Film thickness of Electro-coat thickness ranges from 16 to 23 microns.
• In the ED-system the electrically conductive car body is coated by applying DC-Voltage.
• The product acts as cathode on which the paint is deposited.
• The residual acid migrates to the anodic cells kept inside the sides of the tank through the ED solution which acts as anode system.
• The coated product passes through the subsequent ultra-filtrate and DI water rinse zones,in which the loosely adhering paint is rinsed off.

Advantages:

• The formation of protective films in highly recessed areas such as flanges and box sections provides critical corrosion protection.
• Use of water as practically the only carrier virtually eliminates fire hazard, materially reduces water and air pollution, and markedly reduces the cost of facilities for controlling these conditions.
• Unlike spray coating, electro-deposited paint will not sag during baking.
• Unlike dip coating, electro-deposited paint is not washed off in enclosed areas by hot vapors during curing.
• Freshly deposited paint is insoluble in water, permitting complete rinsing and recovery of dragged-out material.
• Since the process is automated, direct labor costs are markedly reduced.
• Transfer efficiencies of better than 95% result in reduced paint waste, especially when compared with spray-applied coatings.

Electro-coat curing:

• The very last stage of Electro-coat process is to cure the paint in the Electro-coat oven at a temperature of 171°C for 15 minutes. 
• This gives a smooth and resilient finish.

3.SEALER PROCESS:

Purpose of Sealers and Insulators:

• Sealers and insulators are used to eliminate water, block out fumes, reduce wind and road noise, reduce the vibration and to improve the aesthetics on clinches.

 Types of Sealers and Insulators:

• Thumbable Sealer
• Flow able Sealer or Duplex sealer
• Plugs and tapes:
• Deadner Pads
• Roof Ditch Sealer

 4.SPRAY BOOTH PROCESS;

• All industrial products have to be protected in some way or another against corrosion.
• The most common protection against corrosion is the application of paint materials.
• The paint can be applied onto the work piece by dipping or spraying.
• The spray procedure has to take place in specially designed paint spray enclosures(paint spray Booths).
• The requirements have to be met according to the paint systems (Solvent-borne paints,Water-borne paints, 2-components paints)which are very different from each other. 
• In order to make the object resistant to corrosion, and to minimize the paint spread, Gloss, etc. a certain minimum paint coat thickness is required.This coat thickness is achieved by application in 2 or 3 steps.
• For best results some basic application techniques has to be followed as per specifications for different paint types and colours.
• The Spray booth is designed for Primer, Basecoat and Clearcoat application on car bodies.
• Processing of Topcoat paint is only allowed after prior thorough cleaning of the spray booth.

There are some important aspects in Spray booth to achieve product quality:

• Filtered supply and re-circulated air
• Air conditions
• Temperature
• Humidity
• Regular air distribution
• Constant air balance
• Regular downdraft velocity
• No dust or dirt in spray booth
• Optimum lighting
• Suitable clothing for workers and visitors
• No materials containing silicone shall be used
• Keep doors of spray booth and clean room closed
• Regular cleaning of plant equipments (Flooding trays,Flooding plates, Floor grids, Spray guns, Booth walls)

Downdraft:

• The air supplied from the air supply units through filters in the spray booth with a specified velocity in a downward motion is Downdraft. 
• It controls paint over spray raised out of spray painting , increases fresh air circulation inside the spray booth and prevents accumulation of paint on the operators and structures. 

Humidity:

• The amount of water content in air is humidity. 
• The spray booth should be maintained in a specified humidity (71% +/- 6%) for preventing the solvent from drying fast.

Temperature:

• Maintaining of temperature is vital in spray booth since the evaporation of solvent rate also depends on the temperature.
• Temperature is maintained at 27+/-3 deg C inside spray booth.
• Temperature and Humidity is measured twice a day using a Digital Temperature Gauge.

Primer:

• Primer coat is applied between the E-coat and Topcoat to minimize the surface roughness problems and adhesion problems.

   Types of Primer :

1. Colour compatible Primer
2. Colour matched Primer

Basecoat: 

Basecoat gives the colouring to a car body. It is also called as color coat. Basecoat is applied after Primer coat and before Clearcoat.

Types of Basecoat :
1. Solid
2. Metallic
3. Pearlescent

Clear coat:

 Clear coat is the colourless, topmost layer of paint on a car body.Clear coat gives gloss effect and it also protects the paint layer from harmful UV rays.

Surface Preparation:

  

• Surface Preparation is a vital function of Paint shop in getting the units ready for both Primer and Topcoat.
• All traces of contaminations such as oil, dirt etc. must be removed since they will affect the final Paint finish.

Sanding:

Sanding is done for finding as well as identifying the defects.It is necessary to sand the paint surface after application of each layer.Sanding can only be done after the unit has been cured in the ovens when the paint is hardened.

      Types of sanding

1.  Scuff Sanding
2.  Detail Sanding
3.  Orbital Sanding

Scuff Sanding :
 
Scuff sanding is done on E-coat bodies for highlighting the defects.All the horizontal and upper vertical surfaces are lightly sanded in a front-to-back motion.

Detail Sanding : 

Defects found by scuff sanding are removed by detail sanding.Light, Circular motion should be used for removing the defects.

Orbital sanding :

• Orbital sanding should only be used where absolutely necessary. The Orbital sander uses self-adhesive paper discs and is powered by compressed air. Defects which cannot be removed / difficult to remove by Detail sanding are removed by Orbital sanding.

Cleaning Methods:
 
Cleaning is one of the most important ways of keeping defects to a minimum as the units progress through the Paint shop.It plays a vital part of the preparation for corrosion protection, primer and topcoat.

Tack-off:
 
Tack-off takes place before the car enters into the spray booth for Primer and Topcoat.Tack-off is a special cloth that has a slightly sticky surface.When it is used to wipe the unit, it picks up loose dirt and dust, and because it is lint-free it doesn’t leave any contamination behind.

Blow-off : 
 
Blow-off takes place after sanding operations. It is a process for removing loose dirt or dust with compressed air.Automatic blowers are fixed at the exit of Primer sanding and entry of spray booth.

Solvent wipe : 

• In some plants a process called solvent wipe is carried out. It also takes place after the sanding.Solvent wipe is used to remove Contamination on the unit before painting.
• A small amount of polishing compound is put onto the sanded area and spread around with the pad before it is started.
• The pad is used flat against the surface. A little pressure is applied for few seconds to remove the sanding scratches,Finally the Polished area is wiped with a wet scotch brite.
• Defects which cannot be removed at Polish Deck are sent to Spot repair or Major repair according to the severity.

5.WAX OPERATIONS:

Air dry Blackout:

• Air dry Blackout is a cosmetic treatment that’s applied to the rear wheel housings and certain other areas of a body. It’s a black colored paint that dries in atmospheric heat.It is usually applied after the final paint application with an airless spray gun to control overspray.
• After the blackout the wheel arch is finally visually checked to make sure there is no overspray on the exterior paint surfaces. If there is, it is removed by the approved solvent. 

 Anti-Corrosion Coating Methods:

Anti-corrosion coating is an effective way or preventing rust, and the damage it can cause, on the undercarriage of vehicles. If you are thinking of having this important protection installed on your vehicle, you should understand the various methods that are used to apply anti corrosion coatings on cars and trucks. This article will provide you with information on the most common methods use to apply the protectant coating and the benefits of each type of application.

1.Cavity Wax:

• Cavity wax, which is a paraffin wax, is applied to add further corrosion protection.
• The wax is injected into cross members and box sections of the ‘A’ Pillars , Rocker panel , Hood interiors , Deck lid interiors , Floor panel. It is also sprayed into the lower parts of the door using Wax spray gun.
• Different nozzles are used for different applications and different models.The long lance model is used to reach right to the ends of the box sections. With this type of nozzle, the trigger is pulled continuously while the lance is drawn out smoothly and evenly.
• The trigger is released just before the end of the lance reaches the opening.
• An airless spray gun with a long, slightly bent nozzle to reach the corners is used to spray paint in the door interior sections.

2.Electronic Rust Protection:

• The process involves placing anodes on the underside of the car body that are electronically charged. In theory, the anodes prevent rust between the spaces they are located by charging the anodes with a small electrical charge which polarizes them which helps to neutralize rust and corrosion cells before they form.
• While the process has been proven effective for sea vessels, the process has many critics in its application for cars. Those opposed to the process being used in cars, relate the fact that seawater is a conductor that helps to complete the electrical circuit that is needed for the process to effectively combat rust and corrosion. Many say, because there is no additional conductor available on the car (unless it is immersed in water), then the process simply does not work.