Week 1:- Introduction to BiW and Fixtures Challenge

Week 1:- Introduction to BIW and Fixtures Challenge

1.BODY IN WHITE (BIW):-

Body In White(BIW) refers to welded sheet metal components which form the vehicle structure to which the other components will be joined i.e.engine,chassis,interior and exterior trims.Body in white refers to the stage in automotive design or automotive manufacturing in which the car body sheet metal(including doors,hoods,and deck lids) has been assembled or designed but before the components (chassis,motor)and trim (windshields,glass,door lock/handle,upholstery,electronic,etc.) have been added.

BIW is the stage in automotive design or automobile manufacturing in which the car sheet metal components are been assembled by welding or by other joining method.BIW also need to be light weight structure so that there can be a possibility of reduced fuel consumption and increased performance and efficiency.

Major factors influencing BIW fixture design:

• Number of parts
• Materials
• Internal structure reinforcement

There are two types of body structure in use:-

1.Monocoque or uniBody :-

In this type of body structure,chassis inbuilt in the BIW itself and there is no separate chassis.Wheel are directly mounted to the biw with the help of a suspension system

2.Frame mounted body Structure:-

In this type body structure,the body is mounted on the separate chassis or frame and wheels are mounted on the chassis,not to the body.

Parts in BIW:

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

Body side parts:

A-Pillar - Front most support to the A-pillar is the most stylistically interesting for a car fans Other notable aspects of the A-pillar

B Pillar - Second support to the B - pillar plays a key role in providing strength to a midsection to a vehicle.

C Pillar - C is rearmost support to the roof in case of a two-row seating system, it will be the third 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 streamlined shapes. one of the most iconic is from Ford Mustang.

Drip rails / Gutters - An exposed channel applied to the roof over the side windows to direct water away from the windows

D Pillar - D is the fourth support usually the rear side of quarter 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 structured panel connecting the rear & front

Quarter Panel - Rearmost panel of a body side

Drip rails / Gutters - An exposed channel applied to the roof over the side windows to direct water away from the windows.

Closure:

The closing parts of the BIW structures such as doors/lids parts fall into this category.

1. Front door: This refers to the parts of front door panels of the automobile.
2. Rear door: This refers to the parts of rear door panels of the automobile.
3. Hood: This refers to the closure door the hood of the automobile.
4. Deck lid: This refers to the closure lid of the deck of the automobile.

Underbody:

Front End Under Frame (Engine compartment)-

It is an engine compartment area where all possible mounts for engine and other components get fixed.

PLENUM Panel - Plenum is a chamber located between the throttle body and the runners of the intake manifold, used to distribute the intake charge evenly and enhance engine breathing.

FRT wheel house/ Fender - FRT Wheel house or Fender is an encasement around the FRT wheel.

Wing panel - Wing panel are the outer most side panel in the front.

Cowl - Cowl is the portion of the body bounded by the front fenders, the base of the windshield, and the rear edge of the hood

Upper tie bar- Upper tie bar is the upper panel in front connecting the two sides (RH/LH) of Front structure.

Lower tie bar- Lower tie bar is the lower panel in front connecting the two sides (RH/LH) of Front structure.

Main Floor-

It is an area where transmission, instrumental panel or dashboard, seats and other components will fixed.

Dash panel - Dash panel provides a partition between engine and the driver/passenger cabin inside car

FRT Floor - provides a base for seats mounting and provides partition between transmission /propeller shaft/ground and the cabin.

Riser connects Front floor to Rear Floor by providing a level difference

Rear End Under frame (Rear compartment)-

It is an area where spare wheel or stepney will be placed as well as other components and will have boot space.

Rear Floor- Rear Floor is the floor on the Rear of the car and provides a partition from ground also provide base for Rear seat mounting.

Rear wheel house

Fender:

Its primary purpose is to prevent sand, mud, rocks, liquids, and other road spray from being thrown into the air by the rotating tire.

Roof-

Inner & Outer Panel-

It covers the top of the car to protect from different weather conditions.

6.Reinforcement:

The part which is used to support and provides stiffness and strength to other components of BIW is known as the Reinforcement component. Some of the reinforcement components are shown below in the picture.

2.What do you understand by BIW nomenclature?

A nomenclature in BIW is basically naming every part of the body. These names can be said as subpart of the already categorized parts above. The nomenclature differs a little bit from region to region but the overall idea is to name individual automotive sheet metal components. Below images show the nomenclature of BIW:

The terms are standard but they differ in some countries.

As automotive industries spread worldwide, the terms and standards will be different for similar components.

For example, One component of BIW is known as inner wing panel in the UK description another side the same component of BIW is known as the Motor compartment side panel in the US description.

3.What is fixture & its types?

A Fixture is device which holds the work piece to be processed (Welded), by using 3-2-1 principle.

A fixture is a work-holding or support device used in the manufacturing industry. Fixtures are used to securely locate (position in a specific location or orientation) and support the work, ensuring that all parts produced using the fixture will maintain conformity and interchangeability.

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

Welding fixtures are normally designed to hold and support the various components (work piece) to be welded. It is necessary to support them in 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 stresses generated during welding process.

Types of Fixtures- The general types of BIW fixtures are:-

1. Production Fixture– As the name suggests, this fixture is used for mass production. It is a type of a fixture on which car body get assembled. These types of fixture require high consistency through it's operation to maintain geometry of parts. So, materialused for these types of fixture should be well tested as well as hardness level. The quality, in terms of dimension, tolerance should be met. These fixture needs to maintain after certain period of time. The assembly & disassembly should be easy as possible. So maintenance person can easily access with saving time.

BIW Welding fixtures

BIW Orientation Fixtures

2. Pre-production Fixture(PPO)- It is generally defined as prototype fixture. It is designed to study feasibility of initial batch production to check which things are need to be improving before starting production. This fixture is base of production fixture in benchmark and criteria & helps us to rectify error. In pre-production fixture there will be more involvement of manual operations, engineer, and quality person. It has larger cycle time than production fixture,but designers will not practice by designing pre-production fixture because it takes lots of time & cost. We have to maintain cost of car as low as possible so we directly go to production fixture by considering standards, checklist to maintain error free production.
3. Checking Fixture-As name suggest this fixture is used for checking assembly. Checking fixture are same as geo fixture except there are no operation done like welding, gluing or hemming. Instead of that we use different in built gauges or external gauges to check various dimension, gap, relative dimension, tolerance. These data is compared with data provided by designer or design team. The geometry of welded part also checked in this fixture to ensure the part maintains the required dimension & geometry.

4. 3-2-1 principle is used for the design of the fixtures:

For a fixture designer,the major portion of design time is spent deciding how to locate the work piece in the fixture.We know that any free body has a total of twelve degree of freedom as below:

• 6 translational degree of freedom:+X,-X,+Y,-Y,+Z,-Z
• And 6 rotational degree of freedom:

1.Clockwise around X-axis(CROT-X)

2.Anti-clockwise around X-axis (ACROT-X)

3.Clockwise around Y-axis(CROT-Y)

4.Anti-Clockwise around Y-axis (ACROT-Y)

5.Clockwise around Z-axis (CROT-Z)

6.Anti-clockwise around Z-axis(ACROT-Z)

To make sure the proper fixing of the part we need to restrict all the 12 degree of freedom of the work piece.The major portion of the time of BIW fixture designer is spent deciding how to fix these all degree of freedom.

Primary Locator:-

First,the three locator or supports are placed under the workpiece.It will be positioned on the primary locating surface also known as a datum.It will restrict 5 degree of freedom.

1.Axial Movement downward along z-axis

2.Rotational movement around X and Y axis.

Secondary Locator:-

The next two locators are normally placed on the secondary surface,restricting an additional 3 degrees of freedom.

1.Axial movement along the Y +axis

2.Rotation about the Z-axis

Tertiary Locator:-

This locator is positioned at the end of the part.it restict 1 degree of freedom.

Axial movement along the x-axis.

all these 6 locators will restrict a total of 9 degree of freedom.the remaining 3 degree of freedom (1,4 and 5)will be restricted by the clamps.To minimize the time consumption in assembly and disassembly,Have to use minimum number of pins to arrest a maximum number of degree of freedom.

5: Elaborate types of BIW Stations

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

For example:

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

2. Re-spot Tool: A re-spot tool is a fixture in which the remaining weld spot which are not achieved in geo tool are welded for the pre-welded panel from the geo tool.

The pin tolerance for the re-spot pin will be of tolerance of -0.28 in general.

For example:

Consider panel hole size is 20mm, the pin diameter should be 19.72mm.

3. 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.

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 gauge type, fixed type and automated checking fixtures.

A checking gauge is a tool where work piece is hold and various measuring gauges are introduced to ensure the dimensions and repeatability.

A fixes type checking fixture is used where the work piece is fixed with clamps and pins and a CMM machine is used which measure the coordinates of different points of the panel or assembly, compares it with the nominal values and gives a report.

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 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 other tool (station).

2. 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 under goes 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 other tool (station), also with the combination of weld gun at another side of the gripper for welding.

For example: Gripper + Weld Gun.

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

For example: Gripper + Gripper.

STANDS AND TYPES OF STANDS

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 multitasking like materialhandling 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 stands.
3. Date Stamp Stand: The panel will get the date embossed on to it, with the date stamping device mounted on this date stamp stand.
4. 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.

Miscellaneous:

1. Buffer Storage: After some operation, we can put the no. of assemblies in this stand which is buffer stock & it can be transported to another station in easy They are also used to store the inventory while the machine is undergoing some maintenance.

2. Conveyor Tools: The conveyor id the rotating paht that transports the parts to the next station which kept over it.

3. 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.

5. Curing: After gluing it needs some time to cool sown, so we put the assembly on some belts and to will take the panel to another station and meanwhile gluing will cool down.

6.Basic terminologies used in the BIW fixture

The following terminologies are used in BIWA) NC/Mylars/Fingers

Mylars are the component that holds the panel while These are placed from topside & from the bottom side also. The top side Mylars called Clamping Mylars & the bottom side Mylars called Resting Mylars. Every clamping Mylars have resting Mylars. It doesn't allow deformation of the part due to welding stresses.

B) Principle locating point (PLP)

These are the points that are used for the accurate location of the part to maintain the geometry of the There is lots of holes on the panel which are not accurate due to stamping operation. The PLP are defined in the drawing. The positional dimensions or relative dimensions are very precise in stamping & in fixtures also.

C) Risers

Risers are of different types like L-typer rises, Square tube riser Riser is the manufacturing part which gives height to the assemblies.

D) Blade

Blades are plates mounted on the Other parts like cylinder, arms, etc are mounted on the blade.

E) Shims

Shims are the small part that comes with the thickness of 0.1mm, 0.2mm, 0.5mm, etc. These will compensate for the stack-up tolerance which reflects at the panel holding part called We give tolerance to all the parts of the fixture. Due to this tolerance, the Mylars will either lift up or goes down from their defined position.

If the Mylars go down from the defined height it will make an impression or dent on the panel.

If the Mylars lift up then there will be a distortion due to welding stress. To adjust the Mylars At its defined position we use shims so the panel won't be deformed & also don't get any impression on it.

F) Rough locators

The operator can place the part in the wrong orientation The rough locator will work as a guide while placing the part in the fixture & the part will be loaded in the desired orientation. It is a part of fool proofing.

G) Hardware

Hardware is like the Hex head bolts, Allen Bolts, Hex nuts, Spring washers, Self-locking nuts

H) CMM

CMM stands for coordinate measuring It is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a probe. It generates a report by comparing the data with the CAD file data.

I) Unit

The fixture is the assembly of different types of units to form a There are different units like pin unit, base unit, clamping unit, etc.

J) Number plates

The number plate is the aluminum embossed plate placed on each unit for easily recognizing the

K) Nameplate

The data like manufacturing company name, fixture type, Fixture weight is embossed on the plate & joined to the fixture.

L) Clamp Arm

The clamp arm is the part of the clamp unit which moves an Over clamp arm the Mylars are mounted.

M) Pivot

It is an axis about which the clamp arm will

N) Class A Surface/Skin surface

The outer panels of the car like a hood, door, backdoor, fender, roof are visible to the customer.

The outer panels should be aesthetically very good. No scratches or dent is acceptable over it.

While designing the fixture to the skin surface the clamping material should be soft, so that it could not able to left any impression or dent over the skin. generally, nylon or PU material is used for clamping purposes.

O)Reed switches & sensors

These are the electric components used in automated The reed switch is an electrical switch operated by an applied magnetic field. The detects the panel is loaded or not is done by sensors.