Week 1:- Introduction to BiW and Fixtures Challenge

1. What is BIW and define its parts.

Biw :

• Body-in-white (BiW) is the name given to a car body’s sheet when all its components—barring moving parts (e.g., hoods, fenders, etc.), trims (e.g., glass, seats, etc.), or chassis sub assemblies—have been welded together.
• Usually, BiW constitutes about 27% of a car’s curb weight , and remains the key determinant of how the car will perform.
• BiW can be made into two structures: the more common monocoque structure where all body members are carrying load with chassis in-built with BiW and are integrated with each other, and the body-on-frame structure where the frame is the main load-carrying member.
• During the painting process initially body is immersed in premier which after curing looks like grayish white in color because of this it is knows as Body-in-white.
• BiW is expected to possess a number of significant properties. It must have high tensile strength as well as high stiffness, bending, torsional, static, and dynamic.
• It must also provide good quality safety both to the car body and to its occupants against crashes of all kinds—front, rear, side, or even rollover, meeting the Federal Motor Vehicle Safety Standard No. 208

The parts of the BIW structure

• Body sides Structure
• Under-body Structure
• Closures
• Roof
• Fender

Body Side Structure :

• A Pillar - Front most support to the roof.A- pillar are the most stylistically interesting for a car fans Other notable aspects of the A-pillar
• B Pillar - Second support to the roof. B - pillar plays a key role providing strength to a mid section to a vehicle.
• C Pillar - C is rear most support to the roof in case of two row seating system, it will be third one. C-Pillar is often the most heavily leveraged pillar from a styling perspective. BMW has made the C - PILLAR their own distinctive curved C - pillar called the Hoffmeister kick that appears in some format in all of their cars. Coupes also rely heavily on the C-pillar to create streamlines shape.one of the most iconic is from Ford Mustang.
• D Pillar - D is the fourth support usually rear side of quarter panel. D pillar is really the end of the line in many ways this pillar is designed for the necessity to house the rear door in a wagon or SUV.
• Ring Panel - A structure panel connecting the rear & front portion.
• Quarter Panel - Rear most panel of a body side structure.
• Drip rails / Gutters - An exposed channel applied to the roof over the side windows to direct water away from the windows.

Under Body Structure:

• Dash panel - Provides partition between Engine & the driver cabin.
• FRT Floor - Provides base for the seats.
• Raiser - Connects front floor to Rear floorby providing level difference.
• Rear Floor - Floor on the rear of the car & provides partition from ground and base for the rear seats.
• Rear wheel house

Closures:

• All Doors
• Hoods / Bonnets - A hinged panel providing access to the engine compartment.

Roof:

• roofs
• Headers - Structural member above the wind shield at juncture with the forward edge of the roof panel.
• bows

Fender:

• Fender and plastic components

2. What do you understand by BIW nomenclature?

Definition of Nomenclature:

• The devising or choosing of names for things, especially in a science or other discipline.
• In formal, the term or terms applied to someone or something.

BIW Nomenclature:

• Hence from the definition of nomenclature we came to know that the terms/names applied to the BIW COMPONENTS is known as BIW NOMENCLATURE.
• The terms are standard but they differ in some countries.
• As automotive industries spread world wide, the terms and standards will be different for similar components.
• For example, One component of BIW is known as inner wing pannel in UK description otherside the same component of BIW is known as Motor compartment side panel in US description.

Above I have been attached some common terms of BIW which differs from UK to US descriptions

3. What is fixture & its types?

Fixture:

• A fixture is a tool which firmly grips a work piece on the machine bed accurately at the desired location.
• The fixture also reduces the loading, unloading, and fixing the time of the work piece, which significantly reduces the non-productive hours.

• Welding fixtures are used to hold the parts in the required shape and is used from smaller parts to larger parts of a plane. Before welding the parts are placed and positioned for the required shape. After clamping the parts by means of clamping unit welding work will be carried out.

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

Fixture Design Criteria:

The criteria for designing the fixture are,

• Design specifications.
• Factory standard.
• Ease of use & safety.
• Economy.

Types of fixtures:

• Production Fixtures
• Pre production operation fixtures(PPO)
• Checking fixtures

Production Fixture:

• This type of fixture are used for Mass production purpose.
• The production fixtures must be easy for maintainance purpose.
• It should be easy to assemble and dis-assemble the parts from the fixtures to minimize the time consumption

Pre production operation fixture:

• These fixtures are designed as the prototype fixture to check & study the feasibility of initial batch production.
• This type of fixtures are used to take the trial and errors from the components.While in trial and error, the errors are absorbed and corrections are made
• till the part/components attains its requirement as per the drawings.
• we have to maintain the cost ofthe car as low as possible.since, Pre- production fixtures tooks more cycle time & lots of time & cost we directly move
• towards the Production fixture by considering standards & checklist to ensure the free production.

Checking Fixture:

• As from name we understand this type of fixtures are used for the checking purpose of the part or assemblies.
• A checking fixture is used to check the automobile parts or assemblies, ensuring all the coordinates,relative dimensions & positions as per the tolerances
• A checking fixture can be a gauge type, fixed typed & automated checking fixture.
• A checking fixture is a tool where workpiece is hold & various measuring gauges are introduced to ensure the dimensions & repeatability.

4. what is the basic principle of fixture design?

A fixture is a device which holds the workpiece to be processed (Welded), by using 3-2-1 principle.

PRINCIPLE OF FIXTURE DESIGN:

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

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

6 translation degree of freedom

1. X+
2. X-
3. Y+
4. Y_
5. Z+
6. Z-

And 6 rotational degree of freedom

1. Clockwise around X axis (CROT -X)
2. Anticlockwise around X axis (ACROT - X)
3. Clockwise around Y axis (CROT -Y)
4. Anticlockwise around Y axis (ACROT - Y)
5. Clockwise around Z axis (CROT -Z)
6. Anticlockwise around Zaxis (ACROT - Z)

we must fix all 12 degrees of freedomin order to locate the work piece in the fixture.

so, 12 degrees of freedom of the work piece need to be fixed & thus we can achieve zero degree of freedom for the work piece.

5. Elaborate types of BIW Stations?

The BIW assembly line is where different types of panels are joined together in each specified zone like Underbody zone, Hood zone Etc.
These zones are further subdivided into stations, where various processes like welding gluing and inspection are done to the part of that particular zone before they are being assembled together. For instance, in the roof zone, various reinforcement is to be added before they are married to the side zone.

BIW Stations are classified into four parts as below

• Tools
• Grippers
• Stands
• Miscellaneous

TOOLS
A tool is a fixture that consists of a number of units to hold a car panel. there are four types of tools as follows
1. Geo Tool
2. Re spot Tool
3. Marriage Tool
4. Framer Tool
5. Checking Tool

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

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.

Marriage or Hemming Tool: A marriage or a hemming 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.

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

GRIPPERS:

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:

Material Handling Gripper (MH): Material Handling gripper are designed for handling the car panel from one tool(Station) to other tool(Station)

Process Gripper: Process gripper are designed for handling the car panel from one tool(Station) to other tool(Station), And in addition to that it undergoes process like pedestal welding, pedestal riveting, Gluing, sealing, etc.,

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

Gripper + Weld Gun

Dual Gripper: Dual gripper are designed for handling the car panel from one tool(Station) to other tool(Station), With two sided gripper.

Gripper + Gripper

STANDS

Stands are fixed and workpiece is moved according to required operation to be performed

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.

Docking stand: When robots are selected for multi tasking like material handling & welding , which cannot carry both due to some limitations

Date stamp stand: The panel will get the date embossed on to it, with the date stamping device mounted on this date stamp stand.

MISCELLANEOUS

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.

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.

What are the basic terminologies used in the BIW fixture?

The basic terminologies used in the BIW fixtures are

Nc/Mylar/fingers - mylar is a tool that holds the parts. it is also known as NC block. there are two mylars, resting and clamping mylars. every fixture should have both resting and clamping mylars.

PLP (Principle locating point ) - It is used for accurate location of part for maintaining the geometry of assembly.

Blade - It is a plate mounted on the risers.

Risers - It is a part that gives height to the assemblies. riser can be of L type, welded square to frame type, etc.

Shims - shims is a tool that is used in adjustment for the stack-up tolerance, this shim comes in various thicknesses.

Rough locators - Rough locator is used as a guide locator so that the workpiece will not be incorrectly mounted on the fixture. rough locators are used in the manual fixtures.

Hardware - Hardware is nuts, bolts, screws, washers, etc.

CMM - It is a coordinate measuring machine that is used to measure workpieces precisely .

Units - A fixture is basically formed of various components. These components are called units .there are units like clamp unit, base unit, pin unit, etc.

Number plate - It is an identification plate for the units.

Nameplate - It is an identification plate for the fixture.

Clamp arm - In the clamp assembly unit, the arm that moves is called the clamp arm.

Pivot - It is the axis around which the clamp arm will rotate.

Class A surface/ skin surface - class A surface is the styling surface. this surface is visible to the customer so no damage should be done to this surface.

Reed switches and sensors - It is an electronic device used in automated fixtures. It is used for the detection of panels and automates the opening and closing of clamps.