Week 3:- BiW Fixture Design Methodologies Challenges

1.  Design Methodology

Above image is of design methodology and steps involve in it.

i. Purchase Order: We start designing after customer gives us purchase order. So, basically it is indication to start designing of particular
fixture.
il. Inputs from Customer: Customer gives us requiremements or specifications of fixture before starting actual design work. So, we have
to design fixture by considering all the points of customers.
ill. Percentage Completion Criteria: To complete design in time we have to create schedule or time plan called Percentage Completion
Criteria. In this we mention all activities related to design and time required to complete that task like concept design, final finished
design and 2D of all units in fixture ete.
iv. Design Output: Design Output consist of lots of data like 3D and 2D documents, VMC IGS files, STEP files, gas-cut or laser-cut files in
dwg format and BOM, etc. We have to give these data to our customer as design output.

2.  inputs required from the customer to start designing a Fixture

Following are the inputs from customers to start design work:
1. Functio1n Requirement: Generally, function requirement means for what purpose we are going to design fixture like welding, gluing or
riveting fixture and inspection fixture
2. Preferred Standard Components; While designing fixture we have to use standard components as much as possible to save time,
money and efforts to design, manufacture that non-standard components.
3. Car Product; It consist of 3D, read files, geometric tolerance and PLP (principle locating points) of fixture.
4. Layout; Layout is not (pg but management of space which helps to understand process or flow of work of entire assembly line.
5. Ergo data: Every company have standard ergo data and they provide it to fixture designer to design fixture considering that points Ex
height of fixture is decided according to ease while working on fixture. So, we have to design a fixture by considering safety. easy and
fool proof design.
6. Weld Study: In this input, customer specify which type of welding (spot or seam) is required to join components according to which
we have to design fixture.
7. Standard Detailing Templet; Customer gives us standard detailing templete, so we can use that to detail or diminesioning
components according to that templete

3.  input we get from "Car Products"

The inputs we get from the Car Products are as follow.
1. GD & T: GD & T stand for Geometrical Dimensioning and Tolerance. GD & T of each part is given in car product in which information
of locating pins, clamps, rest and slides are mentioned. Image provided below shows how GD & T is apply for particular part.

2. Part List: It states about the parts and assembly style. Part list consist of unique part names of each and every parts in assembly and
each part has its own part number which helps while assembly process to identify each and every part in assembly.

3. Cad Files of Car Part: 3D cad files of parts are necessary while designing fixture.
4. Clamp Plan: It is one of the important data while designing fixture because clamp plan mentions location of clamps in which components is Going to clamp

5.Product Assembly Process Sheet In product assembly process sheet, sequence or stages of assembly of components are given

4. Clamp plan

 A clamp is a fastening device used to hold or secure objects tightly together to prevent movement or separation through the application of inward pressure. In the United Kingdom the term cramp is often used instead when the tool is for temporary use for positioning components during construction and woodworking; thus a G cramp or a sash cramp but a wheel clamp or a surgical clamp.

types of clamp unit

• screew clamp
• quick release clmap
• bar clamp
• locking clamp
• algle clamp
• flooring clamp
• band clamp
• toogle clamp

5. purpose of a Layout

The purpose of the layout is to understand the information about where the fixtures & robots are been placed, working area covered by the robot, what are the fixtures assigned for the robots to do the process, etc. Layout shows the entire assembly plan to understand the process.

6. Ergo data

Ergo data provides inputs like Platform height, maximum & minimum reach from operator to fixture, maximum & minimum height of the fixture, whether the child parts/ assemblies are visible while clamping or loading & unloading. Also provides informations like Loading height, working safety zone of operator, etc.

7. Weld study

Body in White (B.I.W.) refers to the welded sheet metal components which form the vehicles structure to which the other components will be married, i.e., engine, chassis, exterior and interior trim. Services: ... Designing of prototype and series production welding fixtures.

8. criteria for percentage completion in the designing stage

To complete design in time we have to create schedule or time plan called Percentage Completion Criteria. In this we mention all
activities related to design and time required to complete that task like concept design, final finished design and 2D of all units in fixture etc.
The persentage completion criteria is as below:
1. 0-25% (Input & Concept Design): In this stage of percentage completion criteria, we have to built concept design of fixture in this
stage.
11. 25-40% (Concept Approval.& Simulation); In this stage, concept design is approved by customer and gives some correction points if
any. Later we have to to give working simulation of fixture for better understanding of how fixture works.
Ill. 40-85% (Design Freezing & Detailing); If all requirements and specifications of customers are satisfied then design is freezed and
detailing work starts.
IV. 85-100% (Check & Final Dispatch): In this stage, quality checking is done using CMM (coordinate measuring machine) and then
dispatched to customers.

9. "Output" in design

Design Output consist of lots of data like 3D and 2D documents, VMC IGS files, STEP files, gas-cut or laser-cut files in dwg format and
BOM, etc. We have to give these data to our customer as design output. The basic output are 3D models and 2D drawing of fixture. Output
are classified as below:
1. Unitised Tool; This tool consist of two type of sheets, they are as follow:
i Key Sheet; Key sheet mentioned or shows the location of every units in fixture.
il. Layout Sheet: Layout sheet is detail drawing of particular unit in fixture.
2. Non-unitised Tools; This type of tools don't require key sheet. Ex. stands and tool changer. Tools that can stand alone and details in layout
sheet.

10. structuring a design tree

Structuring a design tree is very necessary while designing fixture because it help to identify all manufactured part in whole fixture.
Every customer company have there own standard. This will help us during design study, manufacturing and inspection to avoid errors.
If we ignore structuring a design tree it will crete confusion to understand design and may errors will appers in fixture.

11. Units

In general, units is a device that has a specified function, especially one forming part of a complex mechanism.
• A welding fixtures is a assembly of different types of units.
As narne refers, the different units will be only seen in the unitized tool.
• A units are classifiend into two. They are,

1. Simple unit:

in a sirple welding, fixture, the combination of these different units will be seen.
a Rest unit
b. Fined pin units.
C Retract pin units.
d. Rouph locator unit.
e Sensor unit.
1. Base unit.

2. Complex unit:

in a complex welding, fixture, in addition with some of the simple units these complex units will also seen
a Slide unit
b. Dump unit.

12. Fixed Pin units & their purpose

Fixed Pin Unit is non movable locating unit which arrest movement of component in fixture. Fig, shows an example of fixed pin unit. It
consist of pin, pin retainer, blade, two way shims or spacer which control X, Y direction adjustment, block and riser.

Purpose of Fixed Pin Unit are as below:
• Main purpose of fixed pin unit is to locate component
• This unit is used arrest 6 degrees of freedom of component
• Two pins are used to locate component. First pin restricts 4 translational motion and other one restricts 2 rotational motion.

13. different parts of a fixed unit

Fixed Pin Unit is non movable locating unit which arrest movement of component in fixture. Fig. shows an example of fixed pin unit. It consist of pin, pin retainer, blade, two way shims or spacer which control X, Y direction adjustment, block and riser.

urpose of Fixed Pin Unit are as belowr
• Main purpose of fixed pin unit is to locate component
• This unit is used arrest 6 degrees of freedom of component
• Two pins are used to locate component. First pin restricts 4 translational motion and other one restricts 2 rotational motion.
i PINE Pin are main part in this type unit because it is used to locate conponent. 2 pins are used to restrict 8 degrees of freedom. In this type of fixed pin unit, pins are fixed or non movable.

1. PIN RETAINER; Pin Retainer are used support or carry pin in it as shown in figure.
2. BLOCK; Block can be machined in any desired shape according to fixture. It may be simple square or rectangular block or it may be L shaped block as shown in figure.
3. SHIMS OR SPACER: Shims or spacer are used to compensate tolerance stack up. In pin unit we need to control two direction that are X and Y using shims or space. Shims are generally thin sized plates used in group called Shimpack and spacer are used as single plate and can be machined accordingly.
4. BLADE: As shown in figure blades are bolted on riser.
5. RISER: Riser are used to increase height of unit and these are standard parts so need not detailed it or designed it.

14. Rest unit & describe its parts

Rest Unit is one of the simplest unit in fixture used with myler. As rest unit is simple to manufacture and require low cost, hence rest
unit is combine with clamp unit and location unit. Rest unit consist of following parts:

1. RISER: Riser are used to increase height of unit and these are standard parts so need not detailed it or designed it.
2. BLADE: As shown in figure blades are bolted on riser.
3. SHIMS OR SPACER; Shims or spacer are used to compensate tolerance stack up. In pin unit we need to control two direction that are X and Y using shims or space. Shims are generally thin sized plates used in group called Shimpack and spacer are used as single plate and can be machined accordingly.
4. MYLARS; Mylars are the parts in the rest unit which are in contact with car panel or component used to give support or component.

15. Sensor unit

Sensor is a device which detect or measure a physical property. The unit which is built to sense the component or car pal
electrical sensors called Unit Sensor, The output signal of sensor is then send to PLC (Programmable Logic Control) for further
There of different types of sensors such as proximity sensors, laser sensors.

FUNDAMENTALS;
Each components which are welded in fixture should be sensed. So, we manufactured or assemble component fre
errors. Consider an example of car panel having multiple components to assemble using welding. These multiple components al sensed by sensor to assure correct component is placed at correct position.

16.  Rough locator unit

Rough Locator are the parts used to locate component correctly in fixture, basically it guide the operator while loading com,
fixture. Figure shows an example of Rough locator and different locators we can used. It may be standard part or we can design according to our component.

   

FUNDAMENTALS:

1. They are used to guide the component to load correctly in fixture and placed at the edges of components.
2. The angle in locator should be according to component.
3. Rough Locator helps component to placed in pins used in fixture to locate component.
4. Entry angle should be 30 to 45 degree and rough locator should start guiding component before 10 to 15mm to start th
   engagement.
5. For easy adjustmet rough locator mounted on base with two slots in it.
6. The direction of slots are in the directon of car panel or component.

17. Base unit and describe it's parts

 As name suggest, Base unit is used to provide base for other units such as location unit, rest unit or sliding unit in fixture. These all units
are mounted on this base unit.

1. FIbb- Plate: Plate which is used to join fixture and floor called Floor Plate.
2. Weld bars and Pedestal: Pedestal is support or base on which fixture is mounted.
3. Eyebolt: Eyebolt is used to move fixture or placed fixture on its place using cables or ropes. This threaded eyebolt is sustair
   degrees of angular forces.
4. Measuring Hole Cover; Measuring Holes are also known as Tooling hole from which other holes on base are drilled. So, mea
   holes are basically referance holes. These measuring holes are covered using measuring hole cover
5. Base Plate: The plate on which all units are mounted called base plate. Base plate is machined on both to achieve parallism.
   of base plate is too thich to sustain load of all units.
6. Valve Box & trunking Channel; Pneumatic Fixture consist of solenoid valve and these valves are placed inside valve box. Trui
   Channel protects all pressure inlet tube which are attached to pneumatic devices such as cylinders, clamps.

18. Dump Unit and what are its functions

Dump unit is used due to lack of space on fixture to built an unit. So, this is a complex unit consist of dump cylinder used for
or unclamping of car panel or component.

FUNCTION;
Due to space constrain dump unit used in fixture. It has dump cylinder having open and close position for better understanding of design. It
also has clamp cylinder used for clamping purpose hence this is too complex unit to built.

19. Slide unit

Slide Units are positioning units used to position fixture, units, weldgun and robots. This unit consist of sliding rail on which entire unit is slide in direction of rails for further operation. Sliding unit consist of open and close position. These sliding unit is commonly used in automotive industry for different similar components. Following is an example of slide unit provided for welding purpose.