Week 1:- Introduction to BiW and Fixtures Challenge

1. What is BIW & define its parts?

It is the stage in an automotive assembly where the car body sheet metal has been assembled like doors, hoods, and deck lids but before the component’s chassis, engine and trim. It is the plain, non-painted, steel frame components that are welded and assembled together to form the basic structure of the vehicle.

After welding and before painting that assembled sheet metal body is submerged into liquid called primer and its grey in color after drying the whole assembled structure is white in colour and that’s the reason they call Body in White (BIW)

BIW main parts

1.)Body sides

A-PILLAR

It is the front most support to Roof.

B-PILLAR

It is the second support to the roof and situated on the locking side of the Front door.

C/D PILLARS

It 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.

RINGPANEL

It is connecting panels between roof & lower body panels Ring panel is a structure panel connecting the rear portion of the body to front and constitutes a big part inside structure.

QUARTERPANELS

Quarter panel is rear most panel of a body side structure.

2.) Under body

FRT FLOOR

Front floor provides a base for seats mounting and provides partition between transmission/propeller shaft/ground and the cabin.

RISER

Riser connects Front floor to Rear Floor by providing a level difference.

REAR FLOOR

Rear Floor is the floor on the Rear of the car and provides a partition from ground also provides 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.

3.) Closures

• Front door
• Rear door
• Hood
• Deck lid

4.)Roof

• Roof inner
• Roof outer

5.)Fender

It is an encasement around the Front 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. The upper tie bar is the upper panel in front connecting the two sides (RH/LH) of Front structure

2.) What do you understand by BIW nomenclature?

BIW materials and nomenclature BODY SHELL/BODY IN WHITE is a collection of sheet metal panels that have all been welded together before being primed and painted.

The two types of BIW Structures now in use are:

1. Monocoque body composition
2. Body structure installed on a frame There is no separate chassis in a monocoque body because the chassis is integrated into the BIW itself.

3. What is fixture & its types?

1. A fixture is a device which holds, support and locate the workpiece to be processed(welded), by using 3-2-1 principle

   A welding fixture is a tool consists of number of units to hold the car parts that is mounted on a base unit, and it is necessary to locate and guide the operating tool like welding, machining and measuring etc and clamping should be carefully done to prevent the scratches of the working component and there are three types of fixtures in BIW

   1. Production fixtures
   2. Pre-production fixtures
   3. Checking fixtures

   Production fixtures – It is used for mass production purpose

   Preproduction fixture – For initial batch production to study the feasibility

   Checking fixture- For checking the car panel geometry.

2. 4. What is the basic principle of fixture design?

3. For a fixture designer, the major portion of design time is spent deciding how to locate the workpiece in the fixture and any free body has a total of 12 degrees of freedom and a fixture designer’s main objective is to make that free body to be fixed by zero degrees of freedom

   The 3-2-1 principle of location (six-point location principle) is used to constrain the movement of the workpiece along the three axes XX, YY, and ZZ.

   This is achieved by providing six locating points, 3 pins in the base plate, 2 pins in the vertical plane, and 1 pin in a plane that is perpendicular to the first two planes.

4. Geo station:

   Two components' geometry is fixed in this station. Either welding or riveting may be used. This station defines the end product's accuracy and geometry. The closest tolerance for locating pins is 0/-0.15.

   Assuming that the panel's hole diameter is 16mm, the minimum pin diameter is 15.85.

   Locating pins should have a smaller diameter than the panel hole diameter. Tolerance is therefore presented as a negative value when locating a pin.

   Respot Station:

   This station is used after the product has left the Geo Station and there are still locations that need spot welding or riveting. After that, it is transferred to Re-spot station, another station.

   The clamp plan, cycle duration, robot reach capability, or any other number of factors could be to blame for these missed areas.

   The tolerance for pins at this station is 0/-0.28.

   Marriage station:

   Inner and outer panels are joined in the marriage station. In this station, copper strips are employed between the weld tip and the A-class surface to prevent the impression on the outside panel (A-class surface).

   Gripper:

   A gripper is a device or a fixture which holds the car panel and is fixed to the manipulating end of a robot arm.

   Types of gripper:

   • Material handling gripper
   • Process gripper
   • Combo gripper

   Material handling gripper:

   It is designed for handling the car panel from one station to another station

   Process gripper:

   It is designed for handling the car panel from one station to another station and in addition to that it does process like pedestal welding, pedestal riveting, gluing, sealing etc

   Combo gripper:

   It is designed for handling the car panel from one station to other station also with combination of weld gun at another side of the gripper for welding

   Gripper + weld gun

   Dual gripper:

   It is designed for handling the car panel from one station to another station with two-sided gripper

   Gripper + Gripper

   Types of stands:

   • Gluing and sealer stand
   • Docking stand
   • Date stamp stand

   Gluing and sealer stand:

   It is fixed by using weld or a standard stand which is grounded to the floor permanently

   Docking stand:

   Some robots cannot perform multitasking like material handling and welding at the same time and has some limitations(pay load capacity and space constraint) at that time robot can perform single operation like welding and later holding the workpiece at the time second operation docking stand will helps to load the tool head

   Date stamp stand:

   It is used to emboss the date on the car parts by using stamping device mounted on the stand

   Pedestal Station:

   In this station, panels are moved manually or by a robot while a pedestal gun is installed on a tool.

   Typically, a pedestal station is a Re spot station.

   Regarding the spot station and pedestal station, they both carry out the same type of operation. However, factors like cycle time, floor space, the number of welds, clamp layout, or panel size need to be taken into account when choosing between a pedestal and a re-spot station

   Curing Station:

   In this station, products that have been sealed are left idle at room temperature to allow the sealant to dry and strengthen the bond between the panels.

   Loading Station:

   This station is used to load panels and, if necessary, to reverse their orientation for use in a subsequent station.

   When robots are unable to transfer panels from one station to another, this station may occasionally be used.

   6. What are the basic terminologies used in the BIW fixture?

   Basic terminologies

   • NC/Mylars/Fingers
   • PLP(Principle Locating Point)
   • Blade
   • Shims
   • Rough locators
   • Hardwares
   • CMM
   • Units
   • Number plate
   • Coordinate plate
   • Name plate
   • Clamp arm
   • Class A surface
   • Sensors
   • Switches

   NC/Mylars/Fingers:

   It is used to holding the car panel from top and bottom by using clamp and resting mylar

   PLP (Principle Locating Point):

   This hole needs to be precise in size and location and it acts as a reference for measuring, holding and welding operation

   Blades:

   Blades which are attached to risers(cylinder mounting) and it’s in L- shape( welded square tube frame type)

   Shims:

   To avoid distortions while assembly. We can use shims(0.2mm, 0.5mm, 1mm)

   Rough locators:

   It is used mostly in manual locators. It acts as a guide to place the panel in proper orientation

   Hardwares:

   Standard parts like bolts, nuts, fasteners and washers.

   CMM:

   It’s a Coordinate Measuring Machine and check the accuracy in micron level

   Units:

   Base unit, pin unit, clamp unit it is an assembly of different unit assembled together to form a fixture

   Number plate:

   Aluminium embossed plate is placed on each unit to recognise the item

   Coordinate plate:

   On every fixture we have tooling hole also called master hole through which all items in the fixture are to be checked in CMM( hole must be covered)

   Name plate:

   Basic information’s are marked on the name plate

   Clamp arm:

   Assembly which moves the clamp are called clamp arm

   Class A surface:

   This surface is visible to us, and that surface should be aesthetically very good.

   Sensors:

   In automatic fixture, to check the availability of part by using sensor

   Reed switches:

   To check the position of piston