Week 1:- Introduction to BiW and Fixtures Challenge

INTRODUCTION OF BIW AND FIXTURE

BIW-Body In White

1.BIW refers to the welded sheet metal components which form the structure of the vehicle to which the other components (like engine,chassis,exterior & inerior trims) will be married or assembled.

2.The stage in automative design or automobile manufacturing in which the car body sheet metal components are been assembled by welding & by another joining process.

3.The structural performance of an automobile can be determined by the performance of the body,refered to as BIW.BIW is the steel structural shell composed of generally steel panels welded together.BIW structure supports the overall other subsystems in the vehicle.

4.To achieve an efficient car design it is necessary to have the BIW design with optimized mass.BIW connected all the components in the vehicle like powertrain, driveline.

5.BIW encloses, protects the passengers & cargo. The BIW design needs to be stiff to support the mass & securely keep them all integrated. Further, it needs to resist & absorb energy during the event of a vehicle crash.

6.BIW design also needs to be light weight structure so that there can be a possibility of reduced fuel consumption & increased performance.

7.The structure is made from Steel or Aluminium panels (0.7-2.0mm thickness).The panels are stamped into shape and then the spot is welded together.

8.BIW constitutes about 27% of a car's weight.

BIW is mainly categorized as:

1.Body side

2.Under body

3.Closures

4.Roof

5.Fender

6.Reinforcements

BODY CONSISTS OF:

1.Body side outer

2.Body side inner

It generally refers to both the side of the car that is left and right side .it mounts various BIW components like A-pillar, C-pillar ,Panel side shell etc.

UNDER BODY CONSISTS OF:-

1.Front end under frame:This is the compartment are where the engine and other components of automobile like battery , radiator etc

2.Main floor :This is the compartment where the interior parts like seats info. panel etc will be mounted .

3.Rear end under frame : this compartment shapes the rear end of car.This is what provide space of mounting of rear closure parts and boot space.

CLOSURE COMPONENTS CONSIST OF:

1.Front door : Two front doors in each side .

2.Rear door : Two rear doors on each side.

3.Hood : To cover the engine compartment.

4.Trunk lid :To cover the interior and boot space.

ROOF CONSISTS OF :

1.Roof inner

2.Roof Outer

FENDER :-The component seat between side body and front end under frame.

QUE-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 sub parts 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 term are standard but they differ in same countries. As automotive industries spread worldwide the terms and standard will be different for another side the same component of BIW is known as the motor compartment side panel in the US description.

QUE-3.What is Fixture & its type ?

Fixture is holding device which hold the workpiece to be processed. In general should firmly hold the piece without causing vibration ,distortion , stress in the workpiece and also fixture should not disturb or interfere the processing of the workpiece.

TYPE OF FIXTURE :

1.Production fixtures
2.Pre- production operation fixture(PPQ)
3.Checking fixtures
1.Production fixture

This Fixture for mass production it required high consistency through its operation to maintain the geometry of the part so the material used is well tested for hardness & asthetics. Tolerances are also checked. The production fixtures need to eassy for maintenace puprose. The fixture need some maintence after completing number of opations.The time require for assembly & disassembly should be as low possible which saves lot of time.

Pre- Production operation fixture(PPO)

These fixture are designed as a prototype to check the feasibility of intial batch production & to check which things need to be improve before starting the fixture can be taken as the base fixture which sets the benchmark & criteria which helps us to rectify the error that we could get from preproduction operation fixtures. In this many manual operations are involved. Many engineers & quality-related persons are required. It has a large cycle time as compared to production time fixture. It requires lots of time & cost also. We have to maintain the cost of the car as low as pssible so we directly go the production fixture by considering standared, a checklist to maintain the error - free production .

3.Checking fixture :

As the name suggests these fixture are used for checking no operation like welding gluing or hemming are carried out in the fixtures. The guages are used in these fixure to get the dimensions & the tolerances part having & data is compared with the designed dimensions to check whether the part is ok or not. The geometry of the welded parts is also checked in these fixutre to ensure the parts maintain the required dimensions & geometry.

QUE-4.What is basic princple of fixture design ?

The fixture is designed based on how the workpiece is fixed on the fixture. All the degree of freedom of the workpiece are to be constraint.

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

• For a fixture deisgn , the major portion of design time is spent deciding how to locate the workpiece in the fixture.
• You know that any free body has a total degree of freedom as below .

6 translational degree of freedom :+x,-x,+Y,-Y,+Z,-Z And

6 rotational degree of freedom:

Clock around X- axis (CROT-X)

Anticlock 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 of the part we need restrict all 12 degree of freedom of the workpiece. The major portion of the time of BIW fixture designer is spent deciding how to fix these all DOF .

PRIMARY LOCATOR:

First the three locator or supports are placed under the workpiece. The major portion of the time of BIW fixture degree is spent deciding how to fix these all DOF.

SECONDARY LOCATOR:

The next two locator are normally placed on the secondry restrecting an addtional 3 degree of freedom .

• axial movement along the Y+ axis
• Rotaional about the Z-axis

TERTIARY LOACTOR:

This locator is positioned at the end of the part. It restricts 1 degree of freedom

• All these 6 locator will restrict a total of 9 degree of fredom. The remaining 3 degree of freedom (1,4&5) will be restricted by the clamps.
• The jig and fixture are tools used holding the workpiece in a correct loaction for mass production.Various type of fixture(like drilling fixture ,milling fixture , and welding fixture ) are used in industry. The 3-2-1 method is the fundamental principle for all type fixture design.

QUE:5. Elaborate Type of BIW Station?

Elaborate Type of BIW Station:-

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

The BIW stations are further divided into following

1.Tool stations

2.Gripper stations

3.Stand station

4.Miscellaneous stations

1.TOOL STATIONS

A) Geo fixture:-

• In BIW we consider Tack/Geo fixture tack welding for all the parts to be assembly in that fixture. The geo fixture defines the geometry of the part.
• All the part must be located with two loacting pins(Pin can be common for two or more)
• These jigs have a tigth accuracy standard. In the case of the geo fixture all the machine parts individually should be made with max tolerance of +/-0.02mm. Where as positional accuracy of the pin should be with in -0.15mm

B) Re- spot fixtures

• In BIW we consider Re - spot fixture remaining tacks are completed .
• suppose in an assembly we need 50 welds On one stations we can not complete all these opertions becouse it will take more time & another sation relative to the assembly will be in ideal condition.
• In this type of case , we carefully choose some weld tack point which will define the geometry of the part & also the assembly will not get deformed after opening the clamping or in the transport due to the welding
• Re- spot fixture also have very tight tolerance will be -0.28mm.

C)Heming fixture

• As the name suggests the marriage of different assembly is carried out
• In different zones of the assembly line ,different assembly of the part are completed like underbody side body front rear body etc.
• After this ,all the parts come to the station where all parts are gets asembled by using various joinng techniques like Welding, Gluing, Reverting this station is called a marriage tool .

D) Frame Fixture

• Frame fixture is next station after the marriage.
• In frame fixture, the roof is attached to the marriage fixture & forms like a frame hence it is called a framer

E)Checking fixture

• These are used to check the assembly of parts , tolereance , dimensions.
• It can be gauge type . fixed type of automatted checking .
• A Checking guage is a tool where the workpiece is held and different measuring guage are introduced to ensure dimensions repeatability.
• A fixed type checking fixture is used where the workpiece is fixed with clamp & pins & CMM is used which measures the coordinates of the differents point of panel or then is compares with the CAD data and gives report .

2.Grippers stations

A gripper is device that enbales the holding of an objects to be manupulated . the easier way to describe a gripper is to think of the human hand. Just like a hand, a gripper enables the 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 fixed automated system.

Different gripper are used in BIW as follows

A) Material handling gripper

• As the name suggest these gripper are used for material
• These gripper can pick assembly from one station & will drop the assembly at another

B)Process grippers

These gripper are used to carry out some specific like it can do material handling .
The gripper will go under gluing stand in case of gluing process & will goes under the pedestal weld stand in case of the welding process.
C)Combo Gripper:-

Combo gripper are the one which can carry out multiple tasks like it can do material handling & also it can carry out some specific process like gluing . welding as well
Weld gun + Gripper
D) Stands Station
stands are used to hold the part when not in use or also it to mount some parts or bodies on it .

a)Pedestal stand
Weld gun is mounted on the fixed stand which is mounted to the floor the gripper can carry the panel under the stand to do the operation.

B)Gluing & sealer
Gluing gun or sealer gun is fixed to a welded or a standard stand which is grouted to the floor.

c) Docking Stand
The robert have some limitation such as the payload capacity of the robot and due to lack of .
when we select the robot for multitasking it can't do both the task simultaneously .
In this kind of case , we add a docking stand put some equipment that is use for the curent operation but will be rquired for next
Hence the robot can drop or gun & pick the next operation equipment to complete the task from the docking

D)Data stamp stand
Every Mnaufactruing product has some data to stamped or to be embossed on it like serial no , batch no date for some future reference , or for data collection .

4)Miscellaneous stand
A)Curing
After gluing it needs some time to cool down , so we put the assembly on some belts and it will takes the panel to another station & mean while gluing will cool down.

B) Buffer stand
After some operation we can put the no. of assembly in this stand which is buffer stock & it can be transported to another station in easy they are used to store the inventory
while the machine is under going some maintence

c) Take out trollys
It used to take out some panels for inspection to rectify the process is going in the rigth or not between the cycle
d)conveyor
the converyor is the rotating path that transport the parts to the next station which are kept over it
QUE:-6.What are the Basic terminologies used in the BIW Fixture?
The following terminolgies are used in BIW
A)NC / Mylars / finger
Myler are the components that hold the panel while these are placed from topside & from the bottom side also . the top side mylars called clamping myler & the bottom side mylars called resting mylars . every clamping mylars have resting mylars . it doesnt allow deformation of the part due to welding stresses

B) Principle locating point(PLP)
These are the point that are used for the accurate loacation 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 defines in the drawing . the positional dimensions or relative dimensions are very precise in stamping & fixture also

C)Risers

Riser are of different type like L- type riser . Square tube 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 mounted on the blade .
E) Shims

• shims are the small parts that comes the thickness of 0.1mm ,0.2mm,0.5mm etc
  these will compensate for the stackup tolerance which reflects at the panel holding part called we gives down from their defines position .
• if the mylars lift up then there will be a distorosion due to welding stress . to adjust the mylars at its define position we use shims so the panel wont be deformed & also dont get any impression on it

F) Rough Locators
The operator can place the part in the wrong orientation . the rough locator will works as a guide while placing the part will be loaded in the desired orintation .
it is part of foolproofing .

G)Hardware

Hardware is like the hex hand bolts Allen bolts , Hex nuts , spring washers , self - locating nuts

H)CMM

• CMM Stands for assembly measuring machine . it is a device that measure the geometry of physical object by sensing discrete point on the surface of the object with a probe . it gernerate a report by comparing the data with the CAD file data.
• I)Unit
  .The fixture is the assembly of different type of units there are different unit 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 recongnizing
  K)Nameplate
  . The data like manufactruing company name , fixture weight is embossed on the plate & joined to the fixture.
  L) Class A surface /skin surface
  The outer panel of the car like a hood , door , backdoor , 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.

M)Clamp Arm

• The clamp arm is the part of the clamp unit which moves an over clamp arm the mylars are mounted.

N) Pivot

• It is an axis about which the clamp arm will rotate

O) Read switches & sensors
.There are the electric compponents used in automated the read switch is an electrical switch operated by an appied magnetic field . the detects the panel is loaded or not done by sensor.