BIW (BODY IN WHITE)/BODY SHELL/BLUE BUCK
BIW is an assemblage of all welded sheet metal panels as before going for priming and painting.
There are two kinds of BIW Structures in use: 1. Monocoque Body structure
2. Frame mounted Body structure
In monocoque body, chassis is in built in the BIW itself and there is no separate chassis. Wheels are directly mounted to the BIW with the help of suspension system. In Frame mounted body, body is mounted on a separate chassis/frame and the wheels are mounted on the chassis and not to the body.
BIW structure can be divided in following substructures: UNDERBODY STRUCTURE
FRONT END STRUCTURE BODY SIDE STRUCTURE CLOSURES
ROOF
An UNDERBODY Structure consists of following major panels: • DASH PANEL
• FRT FLOOR • RISER
• REAR FLOOR
• REAR WHEEL HOUSE
FRONT END structure consists of following major panels: • PLENUM PANEL
• FRT WHEEL HOUSE/FENDER • WING PANEL
• COWL
• UPPER TIE BAR • LOWER TIE BAR
BODY SIDE structure consists of following major panels: • A-PILLAR
• B-PILLAR • C/D PILLARS
• RING PANEL
• QUARTER PANELS • DRIP RAILS/GUTTERS
CLOSURES consists of following major panels: • ALL DOORS
• HOOD/BONNET
ROOF structure consists of following major panels: • ROOF
• HEADERS
• BOWS
Dash panel provides a partition between engine and the driver/passenger cabin inside car.
FRT FLOOR provides a base for seats mounting and provides partition between transmission/propeller shaft/ground and the cabin.
Riser connects Front floor to Rear Floor by providing a level difference.
Rear Floor is the floor on the Rear of the car and provides a partition from ground also provide base for Rear seat mounting.
A floor assembly consists of Sills/bars for mtg on frame in case of frame mounted construction and in case of monocoque construction long members/cross members are welded.
Note: Where there are three row seats one more floor panel is connected to the front floor called Centre floor and the second row seat is mounted on the center floor. Plenum is a chamber located between the throttle body and the runners of the intake manifold, used to distribute the intake charge evenly and enhance engine breathing. The greater volume of gas in this enclosed area is under greater pressure than the surrounding container.
Panel below windshield connecting the dash panel to cowl, also provides base for cross car beam (CCB)/Instrument panel (IP) mounting.
Frt Wheel house or Fender is an encasement around the Frt wheel. Wing panel are the outer most side panel in the front.
Cowl is the portion of the body bounded by the front fenders, the base of the windshield, and the rear edge of the hood.
Upper tie bar is the upper panel in front connecting the two sides (RH/LH) of Front structure.
Lower tie bar is the lower panel in front connecting the two sides (RH/LH) of Front structure.
Pillars are the support to the roof, i.e. connecting panels between roof & lower body panels.
A-Pillar is the front most support to Roof.
B-Pillar is the second support to the roof and situated on the locking side of the Front door.
C-Pillar is the Rear most support to roof in case of a two row seats car, OR third support to the roof.
D-pillar is the forth support to the roof and usually on the rear side of quarter panel.
Ring panel is a structure panel connecting the rear portion of the body to front, and constitutes a big part in side structure.
Quarter panel is rear most panel of a body side structure.
Drip rails/Gutters is an exposed channel applied to the roof over the side windows to direct water away from the windows and to cover structural welding.
Header is the structural member above the windshield at the juncture with the forward edge of the roof panel.
Hood is a hinged panel providing access to the engine compartment. Some other terms used for BIW:
Backlight: The window across the rear of any automobile, regardless of body style. Some times called back window.
Beltline: The line established by the upper edge of the car lower body at the glass openings, as seen from the side.
Blind Quarter: An unusually wide “C” pillar of roof quarter, tending to enclose rear seat area.
Catwalk: A depressed surface, usually between a fender and a raised area of the hood or deck.
Convertible Boot: A covering, usually held in place with snap fasteners, over the folded-down soft top.
Convertible Stack: That part of a convertible top, which projects above the beltline of deck when the top is folded down.
Decklid: A hinged panel providing access to the luggage compartment.
Greenhouse: The upper body of an automobile; the structure above the beltline – glass, roof, and supporting members.
Hardtop: A term applied to any fixed roof with retracting window glass and no exposed “B” or middle pillar.
Lower Back Panel: Portion of body sheet metal below rear edge of deckled.
Rocker Panel: The sheet-metal surface below the door opening, running between front and rear wheel openings.
Sedan: Two-door or four-door car having stationary window frames in its doors. Tunnel: The hump in the floor pan that provides clearance for the drive shaft on rear wheel drive vehicles.
Common terms used for sheet metal technology:
Blank: Blank is the trimmed sheet to the required shape for further operations. Operation is called as blanking.
Drawing: making a cup shape is called drawing operation, material thinning takes place in the operation normally and the allowed thinning is around 15%.
Forming: this refers to bending of sheet metal to desired shape. Punching: this refers to making holes/any shape cutout in sheet metal.
Trimming: this refers to trim the outer periphery, usually after forming or drawing operation.
