INTRODUCTION TO BIW & FIXTURE CHALLANGE

1.WHAT IS BIW ,DEFINE ITS PARTS ?

Body in white (BIW) is the stage in 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 have been integrated into the structure using one or a combination of different techniques: welding (spot, MIG/MAG), riveting, clinching, bonding, laser brazing etc. BIW is termed before painting and before the motor, chassis sub­ assemblies, or trim (glass, door locks/handles, seats, upholstery, electronics, etc.) have been assembled in the frame structure.

FIG:-Shows welded BIW component which forms vehicle structure

BIW parts are categorized as below

1.Body sides structures

2.Under body

3.Closures

4.Roof

5.Fender

• Bodyside Structure:-

A- pillar - front most support to the roof

B- pillar - second support to the roof

C/D pillar - c- is rear most support to roof in case of two row seat ing system,it will be third one.

D- is the fourth support usually rear side of quarter panel.

Ring panel - a structure panel connecting the rear and 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.

• AnUnder Body Structure :-

1.Dash panel-provides partition b/w engine and the driver cabin.

2.FRT floor - provides base for seats.

3.Raiser - connects front floor to rear floor by providing level difference.

4.Rear floor - floor on the rear of the car and provides partition from ground and base for rear seats

Rear wheel house

• Closures:-

all door

1. Hoods/Bonnet -ahinged panel providing access to the engine

compartment.

• RoofStructure:­

Roof

Headers - structural member above the windshield at juncture

with the forward edge of the roof panel.

Bows

2. what do you understand by BIW nomenclature ?

• Nomenclatureis basically choosing of names for things.BIW have no. of parts in i All parts have different names.
• Asthe Automotive industry is spread worldwide. Every nation has its own languag So the same part of the BIW have different names in its region.
• Forexample, The one component of the BIW is called suspension tower in UK & the same component is called shock tower in US

2. what is fixture & its types?

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

In BIW fixture, the fixtures are designed to hold no. of parts during welding. It is necessary to hold the parts at proper location to avoid the distortions & to maintain the required geometry of the parts.

Fig- shows BIW fixture BIW fixture requirements

• Itshould prevent distortions in work piece duringweldingoperation
• Theclamping need to be light but f irm means the clamping force should be able to maintain the part at its required position without damagingthe
• Placementof clamping need to be clear of welding area.
• Fixtureneed to be quite stable & rigid to withstand the welding stresses.
• Thefixture should maintain its consistancy to do defect free operations.

Biw fixture types

1. Productionfixtures- This fixtures are used for mass production purpose. It requires high consistancy through its operation to maintain the geometry of the parts so the materialused are well tested for the hardness & asthetics. The

quality for maintaining the dimensions & tolerances are also checked. The

production fixtures needs to easy for mainatainace purpose.The fixture needs some maintainance after completing no.of operations.The time requires for assembly & dis-assembly should be as low as possible which saves lots of time.

2. Preproductionoperation fixtures(PPO)- These fixtures are design as a

prototype fixture to check the feasibility of initial batch production & to check which things need to be improved before starting the production.These fixtures can be taken as the base f fixtures which sets the benchmark & criteria which help

us to rectify the errors that we could get from preproduction operation fixtures. In this many manual operations are involved, many engineers & quality related persons are required.It has the large cycle time as compare to production

fixture.It requireslots of time & cost also.We have to maintain the cost of the car

as low as possible so we direct y go to the production fixture by considering standards, checklist to maintain the error free production.

3. Checkingfixtures- As name suggests these f ixtures are used for the checking

purpose.No operations like welding gluing or hemming are carried out in this fixtures.Tha gauges are used in these fixtures to get the dimensions & the

tolerances part having & the data is compared with the designed dimensions to check wheather the part is ok or not. The geometry of the welded parts is also checked in this f ixtures to ensure the parts maintain the required dimensions & geometry.

4) What is the basic principle of fixture design?

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

You know that any free body has a total of twelve degrees of freedom as below: 6 translational degrees of freedom:+X, -X, +Y, -Y, +Z, -Z

And 6 rotationaldegrees of freedom:

- Clockwise around X axis (CROT-X)

- Anticlockwise around X axis (ACROT-X)

- Clockwise around Y axis (CROT-Y)

- Anticlockwise around Y axis (ACROT-Y)

- Clockwise around Z axis (CROT-Z)

- Anticlockwise around Z axis (ACROT-Z)

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

The jig and fixture are tools used for holding the work piece in a correct location for mass production. Various types of fixtures (like driling fixtures, milling fixtures, and welding fixtures) are used in industry. The 3-2-1 method is the fundamentalprinciple for all types of f ixture design.

6)Elaborate types of BIW Stations?

BIW Station is the part of BIW assembly line. The BIW assembly line is divided into zones & these zones are again divided into stations.

The BIW stations are further divided into fol owing

• Toolstations
• Gripperstations
• Standstation

4) Miscel aneous stations

l)Tool stations -

A)Geo Fixtures -

• InBIW we consider Tack I Geo Fixture. In Geo fixture tack welding done tor all the parts to be assembled in that f ixture.The geo fixture defines the geometry of the par
• Alltheparts must belocated with two locating pin ( Pin can be common tor two or more parts.)
• TheseJigs have tight accuracy standard . In case of Geo fixture allthe machine parts individualy should be made with max tolerance of ± 0.02 mm .Where as positional accuracy of pin should be within -0.15

B)Re-spot Fixtures -

• InBIW we consider Re-spot Fi In Re-spot fixture remaining tacks are completed.
• Supposein a assembly we need 50 weld tacks. On one station we cannot complete allthese operation beacause it will take more time & another station relative to the assembly wilbe in idealconditio
• Inthis type of case, we careful y choose some weld tack points which wi ldefine the geometry of the part & also the assembly will not get deformed after opening the clamping or in transportation due to the weldingst
• Theremaining weld tacks wilbe comp eted in Re-spot f ixture as per By performing this kind of operation no station will be ideal Hence we use Re-spot fixtures.
• Re-spotfixtures also have very tight positional accura Re-spot jig pin tolerance will be -0.28 mm.

C) Marriage Fixture-

• Asname suggests the marriage of different assemblies is carried out in this f ixtur
• Indifferent zones of assembly line different assemblies are completed like under body, Side body, Front body, Rear body
• Afterthis all the parts comes at the station where this all parts are gets assembled by using various joining techniques like welding, Gluing, Riveting This station is called as marriage tool.

D)Framer Fixture -

• Framerf ixture is next station after the marriage
• Inframer fixture the roof is attached to the output of the marriage f ixture & it form like frame hence it is caled as framer

E) Checking Fixture -

• These are used to check the assembly of parts, Tolerance ,Dimensions &

coordinates.

• Itcan be of gauge type, Fixed type ot automated checking f ixture.
• Achecking gauge is a tool where work piece is hold & different measuring gauges are introduced to ensure dimensions & repeatabilit
• Afixed type checking fixture is used where the work piece is f ixed with clamps & pins & CMM is used which measures the c:orodinates of the different points of panel or assembl Then is compares with the CAD data & gives report.

2) Gr ippers -

A gripper is a device which enables the holding of an object to be manipulated. The easier way to describe a gripper is to think of the human hand. justlike a hand, a gripper enables holding, tightening, handling and releasing of an object. A gripper is just one component of an automated system. A gripper can be attached to a robot or it can be part of a f ixed automation system.

Different grippers are used in BIW as follows,

A)Mater ialhandling gripper -

- As the name suggest These grippers are used for material handling.

• Thesegrippers can pick assemly from one station & wil drop the assembly to another stati

B)Process grippers -

• Thesegrippers are used to carryout some specific process like gluing, welding, riveting in addition with materialhand ing.
• Thegripper wilgoes under gluing stand in case of gluing process & willgoes under the pedestalweld stand in case of welding

C)Combo Gripper -

• Combogrippers are the one which can carry out multiple tasks like it can do material handling & also it can carryout some specific process like gluing,welding as well.
• Weldgun + Gripper

D)Dual Gripper -

• Theseare two sided grippers. In case when we want one LH & one RH part,these grippers are used. It can handle the material from one station to another station
• Gripper+ Gripper

3) Stands -

Stands are used to hold part when not in use or also it is used to mount some parts or bodies on it.

Different stands are used in BIW

A) Pedestal stands -

• Weld gun is mounted on the fixed stand which is mounted to the floor permanental The gripper can carry the panel under the stand to do the operation.

B) Gluing& sealer stand -

• Gluinggunor sealer gun is fixed to a welded or a standard stand which is grouted to the floor

1. Dockingstand -

• Therobots have some limitations such as the payload capcity of the robot & also due tolack of space.
• Whenwe select the robot for multitasking it can't do both the task simultaneously due tolimitation
• Inthis kind of case,we add docking stand to put some equipment which is not in use for the current operation but will be required for next operation.
• Hencethe robot can drop a gripper or gun & pick next oparation equipment to complete the task from the docking sta

1. Datestamp stand -

• Everymanufactured product have some data to stamped or to be embossed on it like serialno, batch no, Date et for some future reference or for data col ection.
• Therequired data is stamped or embossed by using the stamping device mounted on the stand.

4)Miscellaneous stand -

A)Curing- After gluing it needs some time to cool down , so we put assemly on some belts & it will take the panelto another station& meanwhie gluing willcooldown.

B)Bufter stand- 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 way. They are also used to store the inventory while the machine is under going for some maintainence.

C)Take out trolleys - It used to take out some panels for inspection to rectify the process is going in right or not between the cycle.

1. D)Conveyor- Conveyor is the rotating path which tranport the parts to the next station which are kept over

6) What are the basic terminologies used in the BIW f ixture?

• Thefollowingterminologies are used in BIW

1. NC/Mylars/Fingers- Mylarsis the component which holds the panel while operatio These are placed from top side & from bottom side also. The top side Mylars caled as Clamping Mylars & the bottom side Mylars cal ed as Resting Mylars. Every clamping Mylars have resting Mylars. It dont alow deformation of the part due to weldingstresses.
2. Principlelocating point (PLP) - These are the points which are used for the accuratelocation of the part to maintain the geometry of the assembl There are lots of holes on the panelwhich are not accurate due to stamping operation. The PLP are defined in the drawing. The positionaldimensions or relative dimensions are very precise in stamping& in fixtures also.
3. Risers- Risers are of different type like L-typer rises, Square tube riser Riser is the manufacturing part which gives height to the assemblies.
4. Blade-Blades are plates mounted on the riser. Other parts like cylinder, arms etc are mounted on the bl

Shims - Shims are the small part which comes with the thickness of 0.1mm, 0.2mm, 0.Smm etc. These will compensate the stackup tolerance which reflects at the panel holding part called Mylars.We give tolerance to allthe parts of the fixture. Due to this tolerance the Mylars will either lift up or goes down from its defined position. If the Mylars goes down from the defined height it willmake impression or dent on the panel. If the Mylars lift up then there will be a distorsion due to welding stress. To adjust the Mylars At its defined position we use shims so the panel won't deformed & also dont get any impression on it.

1. Roughlocators- The operator can place the part in wrong orientation mistakanel The roughlocator will work as a guide whi e placing the part in the fixture & the part will beloaded in desired orientation.It is a part of fool proofing.
2. Hardwares- Hardwares arelike the Hex head bolts, Al en Bolts, Hex nuts, Spring washers, Self locking nuts e
3. CMM- CMM stands for coordinate measuring machine. It is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a It generates report my comparing the data with the CAD file data.
4. I)Unit- The fixture is the assembly of different types of units to form a fixture. There are different unitslike pin unit, base unit,clamping unit

J ) Number plates - Number plate is the aluminium embossed plate placed on the each unit for easi y recognising the unit.

I<) Name plate - The data like manufactuiring company name, fixture type, Fixture weight etc. is embossed on the plate & joined to the f ixture.

1. ClampArm - Clamp arm is the part of clamp unit which moves over a axi Over clamp arm the Mylars are mounted.
2. Pivot- It is a axis about which the clamp arm will

1. ClassA Surface/Skin surface - The outer panels of the car like hood, door, backdoor, fender.roof are visible to the customer. The outer panels should be asthetically very good.No any scratches or dent is acceptable over it. Whie designing the fixture to the skin surface the clamping materialshould be soft, so that it could not able toleft any impression or dent over skin. general y nylon or pu materialis used for clamping purpose.

0) Reed switches & sensors - These are the electric componnents used in automated fixtures.The reed switch is an electricalswitch operated by an applied magnetic field. The detects the panelis loaded or not is doine by sensors.