Week 1:- Introduction to BiW and Fixtures Challenge

1.What is BIW & define its parts?

Body in White (BIW) refers to the welded sheet metal components which form the vehicles structure to which the other components (like engine, chasis, exterior & interior trims) will be married or assembled

BIW Parts:

there are 5 majors parts in BIW as mentioned below

1. Body sides

1. Body side outer
2. Body side inner

2. Under Body

1. Front end under frame ( Enigine compartment )
2. Main frame
3. Rear end under frame ( Rear Compartment )

3. Closures

1. Front door
2. Rear door
3. Hood
4. Deck lid

4. Roof

1. Inner roof
2. Outer roof

5. Fender

2.What do you understand by BIW nomenclature?

3.What is fixture & its types?

Fixture is a device whichh hold the work piece to be processed (Welded) by using 3-2-1 principle.

In general, a welding fixture (tool) consist of no. 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 (workpieces) to be welded. It is necessary to support them in a proper location which is capable of preventing distortions in a workpiece during welding. For this the locating elements need to be carefully placed, 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 be quite stable and rigid to withstand the welding stresses.

Types of fixtures

1. Production fixtures - These fixtures are used during the time of mass production. Before mass production all the difficulties in manufacturing and errors in the results are noted for the initial batch production and based upon it the fixture is modified to obtain defect free parts during the time of mass production.
2. Pre production fixtures - These fixtures are used for initial batch production to study the feasibilty.
3. Checking fixtures - These fixtures are used for the car panel geometric inspection purpose.

4.What is the basic principle of fixture design?

The design intent of the fixture is considered on locating the work piece in a proper orientation and fixing it on the fixture to perform the desired operation on the work piece.

A free body possess 12 Degrees of freedom.

Six transational which are +X, -X, +Y, -Y, +Z,-Z

Six rotational which are Clockwise (CW) X, Anticlockwise (ACW) X, CW Y, ACW Y, CW Z, ACW Z.

So the 12 DOF should be restricted for the workpiece in a fixture.

5.Elaborate types of BIW Stations?

The BIW assembly line is divided into sevral zones where different types of panels are joined together in each zone. Each zone has several stations which are :

1.Tool station : A tool is a fixture which consists of no. of units together to hold a car part in general.

Types of Tool station:

a. Geo tool fixture : A geo tool is a fixture in which the geometry of the panels which are welded together is defined accurately. Teh pin tolerance for a geo pin will be of closer tolerance i.e. 0.15 in general.

For ex; Consider panel hole size 20mm, the pin diameter should be 19.85mm.

b. Respot tool fixture : A respot 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 respot pin will be of tolerance with -0.28 in general.

For ex; Consider panel hole size 20mm, the pin diameter should be of 19.72 mm.

c. Marriage tool : A marriage or hemming tool is a fixture in which the inner panel assembly and outer panel assembly are joined together fixture. These are done by welding or hemming in case of closure panels. In a marriage tool fixture the side bodies, under body, front body and rear body are joined together.

d. Framer tool fixture : A framer tool fixture is a fixture in which a roof is joined with output achieved from the marriage tool fixture.

e. Checking station Tool: 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 gauge type, fixed type and automated checking type.

2.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 known as EOAT - End of arm tooling.

Types of grippers:

a. Material handling grippers: Material handling grippers are designed for handling the car panel from one tool (station) to other tool (station)

b. Process grippers : Process gripper are designed for handling the car panel from one tool (station) to other tool (station) and in addition to that it undergoes processes like pedestal welding, pedestal riveting, gluing sealing etc.

c. Combo gripper : Combo gripper are designed for handling the car panel from one tool (station) to other tool (station) , Also with a combination of weld gun at another side of the gripper for welding.

d. Dual gripper : Dual gripper are designed for handling the car panel from one tool (station) to other tool (station), with two sided gripper.

3.Stands stations :

a. Gluing and sealer stand : Gluing gun or sealer gun is fixed to a welded or standard stand which is grouted to the floor.

b. Docking stand : When robots are selected for multitasking like material handling and welding, which cannot carry both due to some limitations (pay load capacity of the robot or space constraint) the robot will drop and pick the gripper or gun after completing the respective operation with the help of docking stand.

c. Date stamping stand : The panel will get the date embossed on it,with the help of date stamping device mounted on the date stamp stand

d. Pedestal 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.

4. Miscellaneous stations :

a. Curing : Curing stations holds the workpiece for curing after gluing or welding is done on the workpieces so that the glue or weld undergoes curing.

b. Buffer stand : Buffer stand is used to store the workpieces so that the flow of the assembly line is maintained during the process with no short of workpiece.

c. Conveyers : Conveyers are the rotating belts which carry the workpiece from one tool (station) to other tool (station).

d. Take out trolleys : Take out trolley is used to take the car panel out from the robotic working cell between the cycle for inspection purpose.

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

1. Fingers / Mylars / NC

2.PLP - Principle locating point

3.Blade

4.Risers

5.Shims

6.Rough locator

7.Hardwares

8.CMM - Co-Ordinate measuring machine

9.Units

10.Number plates

11.Co-Ordinate plates

12.Name plate

13.Clamp arm

14.Pivot

15.Class A surface

16.Reed Switches

17.Sensors