Week 1:- Introduction to BiW and Fixtures Challenge

1.What is BIW & define its parts?

Ans. BIW stands for the body in white. Body in white (BIW) is the stage in automobile manufacturing in which a car body frame has been joined together, that is before painting and before the motor, chassis sub-assemblies have been integrated into the structure.

BIW is sub-divided into five categories

1. Body sides

2.Under body

3. Closures

4. Roof

5. Fender

BODY SIDE:

The bodyside includes an inner and outer panel which consists of A-pillar, B-pillar and C-pillar. The side doors are mounted and functioned according to the pillar attached.

UNDERBODY:

The underbody of the car consists of the front end underframe(engine component), main floor and rear end under the frame. The underbody coating is usually done to overcome the corrosion problems.

CLOSURES:

The hood, deck lid, front door and back door comes under this category because these frames have to be opened and closed eventually. Hinge and latch are used in the case of hood and tailgate.

ROOF:

The roof consists of different parts as front roof rail, bow roofs, center bow roof and rear roof rail. Depending on the curvature the bow roofs are designed.

FENDER:

The fender of the car is used to protect the side walkers from the stones not to fall on them.

2.What do you understand by BIW nomenclature?

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 HOUSEFRONT 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

•ROOF
•HEADERS
•BOWS

3.What is the fixture & its tyPE?

FIXTURE: A fixture is a device which holds the workpiece to be processed (welded, glued, fastening), by using the 3-2-1- principle.

1. Fixtures have to maintain a minimum amount of distortion (in aspect to design, dimensions.)

2. Clamping has to be light but firm.

3. Welding area should be clear up and need not have any interceptions.

4. Fixture should be so rigid & stable to withstand the welding stresses, vibrations.

TYPES OF FIXTURE:

Fixtures are mainly divided into three types:

1. Production fixture: Mainly for mass production. For car body assemblies. Hardness, static load condition, quality, maintenance of fixture is needed.

2. Pre-production operation fixture (PPO): For initial batch production to study the feasibility (Prototype).

3. Checking Fixtures: For car panel geometric inspection purposes (gauges).

4.What is the basic principle of fixture design?

The fixture works on the 3-2-1 principle. The datums such as primary must restrict three DOF, secondary must restrict two DOF and tertiary must restrict one DOF.

There are 12 DOF in the space.

6 are translational: +x, -x, +y, -y, +z,-z

6 are rotational: CW X, CCW X, CW Y, CCW Y, CW Z, CCW Z

The fixtures need to restrict all the 12 DOF.

5.Elaborate types of BIW Stations?

The assembly line in the BIW fixtures is divided into stations.

1. Tools

2. Grippers

3.Stands

4. Miscellaneous

1.TOOLS:

A tool is a fixture that consists of a number of units together with a car part in general.

1.Geo tool: The geometry of the panels which are welded together is defined accurately.

the pin tolerance must be 0.15.

2.Re-spot tool: Remaining weld spots that are not achieved in the geo tool are welded for the pre-welded panel from the geo tool.

The pin tolerance must be 0.28 mm.

3.Marriage or hemming tool: Inner panel assembly and outer panel assembly are joined together.

4. Checking station: Check the automotive parts or assemblies ensuring all coordinates, relative dimensions and positions as per the tolerances.

2.GRIPPER:

Fixtures that hold the car panel and is fixed to the manipulating end of a robot or an end effector.

TYPES OF GRIPPER:

Material Handling gripper: Handling the car panel from one tool station to another tool station.

Process gripper: Pedestal welding, pedestal riveting, gluing, stealing.

Combo gripper: Gripper + weld gun

Dual gripper: two-sided gripper.

3.STANDS:

Gluing and sealer stand.

Docking stand

Date stamp stand.

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

1. A class panel-Generally exterior sheet metal components is having A-class surfaces. A class surface plays important role in the overall styling of automobiles. A, B class surface depends on the degree of the curves. Most of the product designer works with various styling software e.g.ICSM Surf, Alias to design free form design panels. A class panels eg. LH/RH bodyside, Doors, Tail gate, Bonnet, Fenders and Roof
2. Spot Welding- It's a type of resistance welding .2/3 sheet metals are joined together
3. 2 Metal Spot- Resistance spot welding to join sheet 2 metal parts
4. 3 Metal Spot- Resistance spot welding to join sheet 3 metal parts
5. Carlines- All the BIW product design and BIW fixture/ tool designer, BIW process planner and BIW simulation Engineer has to know car lines. To represent the position of biw car parts,welding fixture and its unit assemblies with its individual parts (e.g.mylars) in 2D drawings, their respective positions are shown with reference to (X=0,Y=0,Z=0)positions. In short its shows in 2D XY, YZ or XZ coordinate position of BIW welding fixture parts or assemblies with reference to origin X=0,Y=0,Z=0
6. Mylar: Called as Rest or Clamp block which is used for holding 2/3 BIW sheet metal parts.Mylars are also called NC blocks. In German language Mylar is called as counter stein. Mylars plays important role in the BIW welded assembly geometrical accuracy. Mylars are made of steel or in plastic material.
7. Rest Block : As per the 3-2-1 principle to rest any part/ assembly 3 points are required. Generally rest block are provided and given adjustment by providing shims.
8. Clamp block : Generally as per the 3-2-1 principle for holding the component the clamp block are moved via toggle clamp against the rest block PLP- Principle Location point
9. RPS- Reference Punkt System. Same as PLP
10. Location Round Pin- Pin used to location BIW sheet metal parts.Also called 4way pin.
11. Diamond Pin- Pin having diamond shape in top view.Used to restrict only 2 direction.Mostly referred as 2 way pin.
12. Shim solid- Generally for the Mylar and Locating pin adjustment solid plate of 5 mm thk with various size is used. Generally solid shim of 2 slot, 3 slot or 4 slot.
13. Shim Pack - Generally for the Mylar and Locating pin adjustment solid shim pack is used. 5 mm thk shim pack has various option of 0.5mm x2, 1mmx2, 2mmx1 makes shim pack. Shim is of 2 slot/ hole, 3 slot/hole or 4 slot/hole