Week 1:- Introduction to BiW and Fixtures Challenge

Master's Certification in BIW Fixture & Plastic Design

(Automotive BIW Fixture Design)

REPORT

Assignment-1

By Ravi Ahuja

Q1.

BIW or Body in White refers to the welded sheet components which form vehicle’s structure to which other components will be married.

Body in white has mainly 5 parts

1. Body sides- It consists of -Body side outer

-Body side inner.

2. Under Body- It consists of -Front end upper frame(Engine compartment)

-Main Floor

-Rear End Under frame

3. Closures- It consists of -Front door

-Rear door

-Hood

-Deck lid

4. Roof- It consists of -Roof inner

-Roof outer

These are the different parts of BIW assembly which together make a basic design of the car.

Q2.

BIW nomenclature refers to naming or identification given to the BIW components of the car body.

Below images show the UK & US description of the BIW parts.

Q3.

Fixture: A fixture is a device which holds the work piece to be processed (welded) by using 3-2-1 principle.

In general a welding fixture(tool) consist of number of units together to hold the car panel, and is mounted on a base unit.

Welding fixtures are normally designed to hold and support the various components(work pieces) to be welded. It is necessary to support them in a proper location which is capable of preventing distortions in work pieces during welding. For this the locating elements need to be placed carefully, clamping has to be light but firm, placement of clamping elements has to be clear of the welding area and the fixture has to be quite stable and rigid to withstand the welding stresses.

Types of fixtures:

-Production fixtures- For mass production purpose.

-Pre-production operation(PPO)- For initial batch production to study the feasibility.

-Checking fixtures- For car panel geometric purpose.

Q4.

Principle of Fixture Design:

For a fixture designer, major portion of design time is spent deciding how to locate work piece in the future.

For any free body there are 12 degrees of freedom as below:

-6 translational degrees of freedom: +x,-x,+y,-y,+z,-z

-And 6 rotational degrees of freedom

• Clockwise around X axis
• Anti-Clockwise around X axis
• Clockwise around Y axis
• Anti-Clockwise around Y axis
• Clockwise around Z axis
• Anti-Clockwise around Z axis

One must fix all degrees of freedom in order to locate the work piece in the fixture. So, 12 degrees of freedomof work piece need to be fixed & thus we can achieve 0 degrees of freedom for the work piece.

Q5.

The BIW assembly line is divided into different types of panels which are joined together in each specified zones. Each panel categories will have individual zones like under body zone,doors zone etc.

Tooling Stations: A tool is a fixture which consist of number of units together to hold a car panel in general.

Types of tools:

1. Geo tool: A geo tool is a fixture in which the geometry of panels which are welded together is defined accurately. The pin tolerance for a geo pin will be of closer tolerance i.e., 0.5 in general.
2. Re-spot tool: A re-spot tool is a fixture in which the remaining weld spots which are not achieved in geo tool are welded for the pre welded panel from the geo tool.

The pin tolerance for a re-spot pin will be tolerance with -.28 in general.

3. Marriage tool: A marriage tool is a fixture in which the inner panel assembly and outer panel assembly are joined together.

These are done by welding or by hemming in case of closure panels.

4. Checking stations: A checking station tool is a fixture which is used to check the automotive parts or assemblies, ensuring all the coordinates, relative dimensions and positions as per the tolerances. A Checking station can be a guage type, fixed type and automated checking fixtures.

Gripper Stations: A gripper is a device or a fixture which holds the car panel, and is fixed to the manipulating end of a robot or an end effector. Also know as EOAT- End of arm tooling.

Types of grippers:

1. Material handling gripper: Material handling gripper are designed for handling the car panel from one tool to another tool.
2. Process gripper: Process gripper are designed for handling the car panel from one tool to other tool, and in addition to that it under goes process like pedestal welding, pedestal riveting, gluing, sealing, etc.,
3. Combo gripper: Combo gripper are designed for handling the car panel from one tool to other tool, also with combination of weld gun at another side of gripper for welding.
4. Dual gripper:Dual gripper are designed for handling the car panel from one tool to other tool, with two sided gripper.

Stands Stations:

1. Gluing and sealer stand: gluing gun or sealer gun is fixed to a welded or a standard stand which is grouted to the floor permanently.
2. Docking stand: When robots are selected for multi tasking like material handling and welding which cannot carry both due to some limitations the robot will drop and pick the gripper or gun after completing the respective operation with the help of docking stands.
3. Date stamp stand: The panel will get the date embossed on to it with the date stamping device mounted on it.

Miscellaneous stations:

1. Pedestal gun stand: Weld gun is mounted to a fixed stand which is grouted to the floor permanently, where the process gripper carries the car panel to weld the spot with this fixed weld gun.
2. Take out trolley: Take out trolley is used to take the car panel out of the robotic working cell between the cycle for inspection purpose.

Q6.

The basic terminologies used in BIW fixtures are:

1. NC/Mylars/fingers
2. PLP(Principle locating pins)
3. Blade
4. Risers
5. Shims
6. Rough locators
7. Hardwares
8. CMM
9. Units
10. Number plate
11. Co-ordinate Plate
12. Name plate
13. Clamp arm
14. Pivot
15. Class A surface/skin surface
16. Reed switches
17. Sensors