Week 1:- Introduction to BiW and Fixtures Challenge

1. what is BIW & define its parts?

• BIW (Body in white):
• Body in white (BIW) is the stage in the automobile manufacturing in which a car body's frame has been joined together, that is before painting and before the motor, chassis sub-assemblies, or trim (glass, door locks/handles, seats, upholstery, electronics, etc.) have been integrated into the structure. Assembly involves different techniques such as welding (spot, MIG/MAG), riveting, clinching, bonding, and laser brazing.
• The structural performance of an automobile can be determined by the performance of the body, referred to as Body in White. BIW is the steel structural shell composed of generally steel panels welded together. BIW structure supports the overall other subsystems in the vehicle.
  • there are two major ways to build an Automobile

1. Unibody ( Monocoque )

2. Body on Frame

In the above picture left side indicates an automobile frame on which body comes and Right side one shows the body in white

• The term body in white is the appearance of a car body after it is dipped into a white bath of primer

• BIW parts are divided as follows

1. Underbody structure
2. Front End structure
3. Body side structure
4. Closure
5. Roof

2. what do you understand by biw nomenclature?

• The names of different parts of Biw are as shown in the Figure given below

3. What is fixture & its types?

• Fixture:- A fixture is a work-holding or support device used in the manufacturing industry. Fixtures are used to securely locate and support the work, ensuring that all parts produced using the fixture will maintain conformity and interchangeability
• fixture arrests all 6 DOF so we can able to work on the workpiece without any movement of the workpiece
• The fixtures are used in the automotive industry to hold the biw in an assembly line so robots can do different operations in the automobile body

• General types of Biw fixtures are

1. production Fixture
2. preproduction operation Fixtures(PPO)
3. checking Fixtures.

The above fixture is a checking fixture it is used to hold the workpiece if we look at the above fixture all clamps are attached to the workpiece so we can inspect the work it is one of the types of fixtures

• production fixtures are used for mass production of components these are mainly used in the assembly lines, these fixtures need to be highly accurate in shape so that work to be produced on this component will be having good geometry

• preproduction operation Fixtures(PPO) are for initial batch production to study the feasibility

• checking fixtures are used for inspection of the produced part.

4. What is the basic principle of fixture design?

• 3-2-1 principal is used for the design of the fixtures
• Any object in space has 12 degrees of freedom those are translation along x, y, z-axis that takes 6 DOF Rotation( both positive side and negative side) and Rotation with Respect to x,y, z-axis ( clockwise and Anti Clockwise Rotation) its takes 6 DOF

• By using 3-2-1 principle we can arrest 9 DOF Remaining 3 DOF are left free for Loading and unloading of the workpiece

• In the above picture 1, 2, 3 pins Restrict the motion of x-axis Rotation both clockwise and anticlockwise, the motion of workpiece along the negative y-direction and Rotation of the workpiece along the z-axis
• 4,5 pins block the motion of negative z-direction and rotation along y-direction both clock and antilock wise rotation and 6 the pin stops translation long negative x side
• so by this 9 DOF are arrested the remaining three DOF is used for movement of the workpiece to loading and unloading
• if we want the Remaining 3 DOF can be blocked by additional clamping to the workpiece

5. Elaborate types of BIW Stations?

• BIW assembly line divided into zones and zones are divided into stations

• The different types of stations are

1. Tool station
2. Gripper station
3. stand station
4. miscellaneous stations

1. Tool station: tool station Consists of a number of units together, there are different types of tools are present those are

• 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 closer tolerance i.e -0.15 in general.

• Respot tool: A Re-spot tool is a Fixture in which the 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 of respot pin will be tolerance with -0.28 in general

• Marriage fixture: A marriage or hemming tool is a fixture in which inner panel assembly and outer panel assembly are joined together. these are done by welding or by hemming in case of closure panels.

• checking station: A checking station is a Fixture which is used to check the automotive parts or assemblies, ensuring all the coordinates, Relative dimensions, and positions as per the tolerance. A checking station can be a gauge type, fixed type, and automated checking fixtures

• A checking gauge is a tool where a workpiece is hold and various measuring gauges are introduced to ensure the dimensions & Repeatability
• A Fixed type checking fixture is used where the workpiece is fixed with clamps and pins& a CMM machine is used which measures the coordinate of different points of panel or assembly. compare it with the nominal value & gives the report

Fig: the above picture shows the normal checking fixture in which clamps hold the workpiece for inspection.

2. Gripper: A Gripper is a device or a fixture that holds the car panel, and is fixed to the manipulating end of a robot or end effector. also known as EOAT ( End of arm tooling)

• Types of Grippers:

1. Material Handling gripper(MH): Material Handling gripper are designed for handling the car panel from one tool (station) to another tool (station)
2. process Gripper: process gripper is designed for handling the car panel from one tool(station) to another tool (station), and in addition to that it undergoes process like pedestal welding, pedestal Riveting, gluing, sealing, etc.

3. combo gripper: combo grippers are designed for handling the car panel from one tool(station) to another tool(station), also with the combination of weld gun at another side of the gripper for welding. (Gripper+weld gun)

4. Dual gripper: Dual Gripper are designed for handling the car panel from one tool(station) to another tool(station), with two-sided grippers (Gripper+Gripper)

3. stands: stands are used to hold the workpiece

1. Gluing and sealer stand: Gluing gun or sealer gun is fixed to a welded or standard stand which is grouted to the floor permanently.
2. docking stand: when Robots are selected for multitasking like welding & material handling, which cannot carry both due to some limitations (payload capacity of the robot or space constraint) the robot will drop and pick the gripper gun after completing the respective operation with the help of docking stands.
3. Date stamp stand: the panel will get date embossed on to it, with date stamping device mounted on this date stamp stand.
4. pedestal gun stand: weld gun is mounted to a fixed stand which grouted to the floor permanently, where process grippers carry the car panel to weld the spot with this fixed weld gun

4. miscellaneous:

1. Take out trolley: take out trolley used to take car panel out of the robotic working cell between the cycle for inspection
2. conveyor: conveyor is used to transporting parts to next station
3. curing: After gluing we will put workpiece on curing stand to settle down the glue
4. buffer stand: buffer stand has used an inventory. we will keep sub-assemblies in buffer stand while other operations are going on and we will keep the workpieces in buffer stand while the machine is undergoing some maintenance.

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

• the following terminologies are used in biw

1. Nameplate: the fixture specifications are embossed on a plate and fixed to the fixture.
2. Number plate: Number plate is an aluminum embossed plate have unit number on the plate
3. CMM: A coordinate measuring machine (CMM) is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a probe. Various types of probes are used in CMMs, including mechanical, optical, laser, and white light. Depending on the machine, the probe position may be manually controlled by an operator or it may be computer-controlled.
4. Rough locator: the rough locators will guide the workpiece to place them in the correct manner.
5. Principal locating point: these are used to accurately locate the workpiece on the fixture to process the workpiece.
6. Read switches & sensors: these are electronic components there are used to detect the workpiece is loaded on the fixture or not.