Week 1:- Introduction to BiW and Fixtures Challenge

1. BIW: BIW stands for Body in White. It is a sheet metal welded structure of a Car body in which all other components like Engine, Underbody, Doors, etc. are married. The name is white because This structure is a greyish tone structure that is ready for painting after assembly.

Parts of BIW are as follows:

• BODY SIDES includes the inner and outer sides.
• UNDERBODY includes the engine compartment, rear compartment, and main floor
• CLOSURES includes the Hood, Doors, Decklid
• ROOF includes the inner and outer roofs.
• FENDER

2. BIW Nomenclature: It defines the name of all the components of a BIW structure which are identified by some label. Which is shown in the attached ppt.

3. FIXTURES: A fixture is a device that is used to hold a part or component so that operations such as welding, hemming, etc. can be performed over it. For example, if we consider a welding fixture that is used where welding operations on a part are performed. In this fixture, the part is held on the fixture component which holds it firm but rigid with help of clamping arrangement or guide type arrangement to ensure that the part has zero DOF once it is held.

TYPES OF FIXTURES:

• Production fixture: This type of fixture is used in mass production.
• Pre-Production Fixture: This type of fixture is used for the initial production batch(pilot production)
• Checking fixture: This type of fixture is only used for feasibility check

4. PRINCIPLE OF FIXTURE DESIGN: The basic principle of fixture design is to prevent the part from moving by using the 3-2-1 principle.

As we know, any solid part is having 12 Degree of Freedom which comprises 6 Translations and 6 rotational along three axes i.e "x", "y", "z". These Degrees of Freedom are named as follows:

• +X, -X, +Y, -Y, +Z, -Z (6 Translations)
• Anti-clockwise rotation (+x, +y, +z)- 3 rotation
• Clockwise rotation (-x, -y, -z)- 3 rotation

While designing a fixture we need to make sure that all the above-mentioned DOFs should be constrained such that the part which is being held on the fixture is having "0" DOF.

5. TYPES OF BIW STATIONS:

(i) Tools Station:- A fixture station where different types of units are used to hold the part

• Geo Tools: In this type of tooling station the geometry of car panels and their components are welded together. The panel or part is held over the fixture with help of positioning pins for which holes are defined on the part. The tolerance level for pins is "-0.15". eg: If the Hole size on the part is 20 mm then the pin of the tool should be 19.85mm in diameter.
• Re-spot Tools: In this type of tooling station the coordinates where welding is left on the component or panel is done at the re-spot tooling station. The tolerance for the pin here is "-0.28". eg: If the Hole on the component is 20mm diameter then the pin diameter on the tool should be 19.72mm
• Marriage or Hemming Tools: In this station, the marrying or components which are to be placed on the BIW panel are married together using Hemming or Marrying tools.

(ii) Checking Station:- Fixture which is used to inspect or check the Automotive part or Assembly for coordinates, geometry, repeatability, dimensions using checking fixture of gauge type, clamp type, or fix type.

• Fix-type checking tool: In this, the Part or component is fixed using clamp or pins and a CMM is used to measure coordinates of points.
• Gauge-type checking tool: In this, the part or component is held and various types of gauges are used for dimension and repeatability.

(iii) Grippers: It is a device or fixture where the part or panel is held and fixed at the manipulating end or robot or end effector. It is also known as EOAT- End Of Arm Tooling

• Material Handling Gripper: It is designed for handling car panels or parts from one end to the other end
• Process Gripper: It is used for handling the car panel as well as processing the pedestal stand welding, pedestal rivetting, pedestal gluing at the other end of the station.
• Combo Gripper: It is used for handling the car panels on one hand and welding gun, on the other hand, to perform multiple tasks when required.
• Dual Gripper: It is a two-sided gripper that is used in mass production.

(iv) Stands:

• Glue stand: A glue gun or Sealing gun is fixed to a stand that is grouted to the ground.
• Docking stand: It is used to increase the payload capacity of a robot to help in performing multiple tasks.
• Date stamp stand: It is used to emboss dates on Car Panels
• Pedestal gun stand
• Take out Trolley

6. Basic Terminologies are defined in the Attached file