Week 1:- Introduction to BiW and Fixtures Challenge

1. What is BIW & define its parts ?

• The Body In White is a manufacturing stage at which the cars body is joined/welded together. This excludes moving parts (doors, hood, rear door,etc), trims (glass, seat,etc) and any other chassis sub-assemblies. The BIW can be a monocoque design, where all the members carry load and chassis is in-built or a body-on-frame, where the ladder farme is the load carrying member. It is designed to provide saftey to the passengers in the vehicles during crash.
• Parts of BIW

Bodyside:

• bodyside inner-The inner supporting panels of the car, this panels provide strength to the outer panels
• bodyside outer-The outer skin of the car.

Underboy:

• Front end underframe-On which the engine will be mounted;
• Main floor-The floor on ehich the seats are attached;
• Rear end underframe.

Closure:

• Doors-All the main doors of the car;
• Rear door-Rear storage compartment door of the car;
• Hood-Part to cover the engine.

Roof:

• Roof outer-The outer skin of the roof;
• Roof inner-Inner support rails and bow roofs.

Fender: The part above the front wheel/to cove front wheel.

2. What do you undersatnd by BIW nomenclature ?

• The terms used for the BIW parts is known as the BIW nomenclature. In the picture below different sections of the BIW is reffered by different terms. There is US description and UK description.

3. What is fixture & its types ?

• A fixture is a device which holds/supports the workpiece which is to be processed.
• The fixture are fixed to the floor or workbench. Frequent checking, positioning and marking is elimintaed by using fixtures. A fixture is used used for assemblies, to stop the workpiece. A fixture contains locator and clamps. The locator, locates the workpiece on the fixture and the clamp holds the workpiece sceurly.
• Types of fixture:
• Production fixture: This fixture is used for mass production purpose.
• Pre production operation fixture: This fixture is used for initial batch production to study the feasibility.
• Checking fixture: This fixture is used for inspection.

4. What is the basic priciple of fixture design ?

• The fixture is designed based on how the workpiece is fixed on the fixture. All the Degrees of Freedom of the workpiece are to be constraint.
• The 3-2-1 principle is used.
• The workpiece has twelve Degree of Freedom. six transitional DOF and 6 rotational DOF.

• Transistional: X, -X, Y, -Y, Z, -Z.
• Rotational: Clockwise around X axis (CROT-X); Anticlockwise around X axis (ACROT-X); Clockwise around Y axis (CROT-Y); Anticlockwise around Y axis (ACROT-Y); Clockwise around Z axis (CROT-Z); Anticlockwise around Z axis (ACROT-Z).
• The rotational DOF have to be constraint.
• Using 3-2-1 priciple.
• First the workpiece is constraint by 3 pins on below surface. This lock the Y DOF, Clockwise around X axis (CROT-X); Anticlockwise around X axis (ACROT-X) the Clockwise around Z axis (CROT-Z); Anticlockwise around Z axis (ACROT-Z).
• Then another side perpendicular to the below surface is constraint by 2 pins. This locks -Z and +Z DOF and Clockwise around Y axis (CROT-Y); Anticlockwise around Y axis (ACROT-Y).
• Then any one side perpendicular to both the below and the other 2 side of the workpiece is constaraint by 1 pin. This locks X DOF.
• The part is now fully constraint and cannot move
• The 3 points are used as 3 points define a plane. Four points cannot be used due to irregularity of the surface in real world.

5. Elaborate types of BIW Stations?

Tool station: This contains various tools used for machining the workpiece.

• Geo-tools: This tools are used for accurately defining the geometry of a car panel.
• Re-spot tools: In this fixture weld spots are welded, which were bnot welded in Geo-tool.
• Marriage tools: This tools are use for marriage of parts of the car together.

Gripper: This is used for grabbing the workpiece. This is usually attached to the end of the robot arm.

• Material Handling Gripper: This gripper is use for handling the material.
• Process gripper: The workpiece undergoes a process while being gripped.
• Dual Gripper: This gripper grabs the workpiece from both side.

Stand: This is were the tools/grippers/robots/fixyures are mounted.

• Gluing and sealer stand: This where the gluing of the workpiece is done. The gluing gun is fixed on a stand on the floor.
• Date stamp stand: For engraving the date on the product.
• Pedestal gun stand: A weld gun mounted on a stand.

1. Gauge type station: A station where workpiece is on hold and various gauges are used for measurement.
2. Fixed type checking station: Here the worlpiece is fixed on the fixture and a CMM Machine is used for checking the workpiece.
3. Automated checking station: Here the checking is done automaticall.

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

• Car panel- Referes to the car skin such as hood, door, etc
• spot welding- Resistant welding.
• Takt time- Avg. time needed to meet the customer demand.
• cycle time- Time required to excute a task.
• 2 metal spot- spot welding to join 2 sheets.
• 3 metal spot- spot welding to join 3 sheets.
• Car lines- The designer needs to know the lines.
• Rest Block- Block for resting the work piece.
• Clamp block- Block for holding the component.
• Location Round Pin- Pin used to location BIW sheet metal parts