Week 1:- Introduction to BiW and Fixtures Challenge

Answer

Q.1.

BIW which is briefly known as Body in White, is welded sheet metal components which forms the Vehicle Structure to which other components will be assembled. In short, whatever sheet metal components visible in exterior of vehicle body would be known as BIW.

Talking about parts of BIW, these are divided in 5 parts,

1. Body side :-

Following are different entities includes in body side

a. A Pillar - It is front part which supports the roof

b. B Pillar - It is supporting unit to A pillar

c. Ring Panel- It is intermediate panel which connect the front and rear side of vehicle.

2. Under Body :-

Following are different entities includes in Under Body.

a. Dash Panel - It is intermediate portion between Engine and cabin.

b. Front end under frame - It is frontier portion of vehicle.

c. Rear end under frame - It is rear portion of vehicle.

3. Closure :-

Following are different entities includes in Closure

a. Front Door - The doors of front seats.

b. Rear Door - The doors of rear seats.

c. Hood - A portion which covers the engine compartment.

d. Deck lid - A portion which covers the Deck.

4. Roof :-

Following are different entities includes in Roof

a. Roof Inner - Inner side of roof.

b. Roof Outer - Outer side of roof.

5. Fender :-

It is the middle member between hood and wheel of car as shown in figure below. It measurely covers the wheel as well as side portion of the engine.

Q.2.

• Nomenclature is basically choosing name for things.
• BIW have numbers of parts in it.
• We know that automotive field has spreaded through entire world. Every country has its wide base.
• Similarly Every country has different language. So some part of BIW have different names in its region.
  
  Following are some descriptions which will guide us about BIW Nomenclature

UK Description	US Description
Inner Wing Panel	Motor compartment side panel
Upper wing member	Motor compartment upper rail
Suspension tower	Shock Tower
Upper A pillar	Windshield pillar
Windscreen header rail	Windshield header
Roof stiffener	Roof bow
Rear parcel tray	Package shelf
Cantrail	Side roof rail
Backlight frame	Backlight header
C pillar	C pillar
D pillar	D pillar
Rear quarter panel	Rear quarter panel
Boot floor panel	Rear compartment panel
Rear seatback ring	Rear seatback opening frame
Boot floor panel	Rear compartment panel
Rear seatback ring	Rear seatback opening frame
Rear seat panel	Rear seatback panel
B pillar	B pillar
Floor panel	Floor panel
Sill	Rocker
Lower A pillar	Front body hinge pillar
Dash Panel	Dash Panel
Engine Rail	Motor compartment lower rail
Front bumper	Front bumper
Spare wheel well	Spare tyre well
Centre tunnel	Tunnel
Rear seat cross beam	4 crossbar
Rear suspension support beam	5 crossbar

Q.3

A fixture is a device which holds the workpiece to be processed 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.

Following are some requirements if BIW Fixture,

• It should prevent distortion in workpiece during welding operation.
• The clamping need to be light but firm means the clamping force should be able to maintain the part at its required position without damaging the part.
• Placement of clamping need to be clear of welding area.
• Fixture need to be quite stable & rigid to withstand to welding stresses.
• The fixture should maintain its consistancy to do defect free operations.

Types of BIW Fixtures :-

1.Production Fixtures :-

• This fixtures are used for Mass Production purpose.
• Requires high consistancy through its operations to maintain the geometry.
• Quality of maintaining diamensions & tolerances are also checked in it.
• The time requires for assembly & disassembly should be low as possible which saves the cycle time.

2. Preproduction Operation Fixture :-

• 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.
• Could be considered as base fixtures which helps to set the benchmark.
• It helps us to detect the error.
• In this, Many manual operations are involved, for which many engineers and quality related people required.
• It has large cycle time as compare to production fixture.
• Its production time and cost is more.

3. Checking Fixture :-

• As name suggests, these are used for checking purpose.
• No operations like welding, gluing etc are carried out in this fixture.
• The gauges are used in these fixtures to get the diamensions & tolerances
• The data is compared with the designed dimensions to check whether the part is ok or not.
• The geometry of welded parts is also checked in this fixtures to ensure the parts maintain the required dimensions and geometry.

Q.4

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

6 translational degrees of freedom : +X, -X, +Y, -Y, +Z, -Z

And 6 rotational degrees of freedom,

• Clockwise around X axis
• Anti clockwise around X axis
• Clockwise around Y axis
• Anti clockwise around Y axis
• Clockwise around Z axis
• Anti clockwise around Z axis

• To make sure the proper fixing of the part we need to restrict all 12 degrees of freedom of the workpiece.
• The major portion of time of BIW fixture designer is spent to deciding how to fix these all degrees of freedom
• Hence the 3-2-1 method is the fundamental principle for all types of fixture design.

Q.5

BIW Station is part of BIW assembly line.

The BIW stations are divided into following,

1. Tool Stations

2. Gripper stations

3. Stand stations

4. Miscellaneous stations

1. Tool stations :-

A) Geo Fixtures -

• In Geo fixtures, tack welding done for all the parts to be assembled in that fixture.
• This fixture defines the geometry of the part.
• All the parts must be located with two locating clamp
• In this fixtures, spot welding done in such sequence that after taking out from the fixture it achieves the required accuracy.

B) Re-Spot fixtures -

• In this fixture, Remaing work is carried out left after geo fixture.
• Suppose in a assembly 50 weld tacks. On one station we cannot complete all these operation because it will take more time & another station relative to the assembly will be in ideal condition.
• In this case, we carefully choose some weld tack points which will define the geometry of the part & also the assembly will not get deformed after opening the clamping due to the welding stresses.
• The remaining weld tacks will be completed in Re-spot fixture as per needed. By performing this kind of operation no station will be ideal hence we use Re-spot fixture.
• These have very tight positional accuracy. Re spot jig pin tolerance will be -0.28.

C) Marriage Fixture -

• As name suggest, the marriage of different assemblies is carried out in this fixture.
• In different zones of assembly line, differet assemblies are completed like under body, side body, front body, rear body etc.

D) Framer Fixture :-

• Framer Fixture is next station after marriange fixture.
• It can be of guard type, Fixed type automated checking fixture.

2. Grippers :-

Gripper is a device which enables the holding of an object to be manupulated.

Different grippers used in BIW as follows,

A) Material handling gripper :-

• These grippers are used for material handling.
• These can pick assemblies from one station & will drop the assemblies to another station.

B) Process Grippeer :-

• These are used to carry out some specific process like gluing, welding, in addition with material handling.

C) Combo Gripper :-

• These are the one which can carry out multiple task like it can do material handling and also carry out some process like gluing, welding etc.

D) Dual Gripper :-

• These are two sided grippers .
• In case when we want one LH & one RH part, these grippers are used

3. Stands :-

Stands are used to hold part when not in use.

Different stands are used in BIW as follows,

A) Pedestal Stand :-

• Weld gun is mounted on the fixed stand which is mounted to the floor permanently

B) Gluing & Sealer stand :-

• Gluing / Sealer gun is fixed to a welded or a standard stand which is grounded to the floor permanently.

C) Docking Stand :-

• The robots have some limitations,it cant do multitasking
• So in this case we add docking stand to put some equipment which is not in use for current operation but will require for next operation.

D) Dale stamp stand :-

• This stand is used for embossing or engraving the data on the job.

4. Miscellaneous Stand :-

A) Curing - After gluing, it need some time to coold down, so we put assemblies on belt & it will take panel to another station & meanwhile gluing will cool down.

B) Buffer stand - After some operation we can put the number of assemblies in this stand

C) Take Out trolleys - Used to take out some panels of inspection to rectify the process is going right or not.

D) Conveyor - It is the rotating path which transport the parts to the next station

Q.6

The Following terminologies are used in BIW

A) NC/Mylars/Fingers - Mylar is the component which holds the panel while operation.

B) Principle locating point (PLP) - These are points which are used for the accurate location of the part to maintain the geometry of the assembly.

C) Risers - Risers of the different types like L-type riser, square tube riser etc.

D) Blade - Blades are plates mounted on the riser. Other parts like cylider,arms are mounted on blade.

E) Shims - Shims are the small parts which come with thickness of 0.1mm, 0.5mm etc.

F) Rough locators - The operator can place the part in wrong orientation mistakenly. The rough locator will work as guide whicle placing the part in the fixture.

G) Hardwares - Hardwares are like the Hex head bolt , allen bolt , hex nut etc

H) CMM - Stands for coordinate measuring machine. a device that measures geometry of phisical objectby sensing the points.

I) Unit - The fixture is the assembly of different assembly of different types of unit of form a fixture.

J) Number plate - It is alluminum embossed plate placed on each unit for easy recognisation.

K) Name Plate - The data like manufacturing company name, fixture type, is embossed on plate.

L) Clamp arm - It is part of clamp unit which moves over the axis

M) Pivot - It is a axis about which clamp arm will rotates.

N) Skin surface - The outer panel of the car like hood, door, backdoor, fendor, roof are visible to customer. So outer panel should be asthetically very good.While designing the fixture to the skin surface the clamping material should be soft.

O) Reed switches & sensors - These are electric components used in automated fixtures . The reed switch is electric switch operated by an applied magnetic field .