Week 3:- BiW Fixture Design Methodologies Challenges

Q 1 . WHAT IS DESIGN METHDOLOGY ?

 

 

In this methodology we learn about three design processes, we're going to study how do we proceed while doing a design. And one of the things that we take care of structuring or design tree so we'll be learning how to structure the design tree, and how to name the particular component or particular assembly, or the part of an assembly, which is very easy to read and very easy to understand.

Design methodologies is nothing but the steps followed during the concept designing stages of fixture design. The various stages of design methodologies are,

1. Purchase order.
2. Inputs from customer.
3. Percentage of completion criteria.
4. Design outputs.

 

Q 2 . WHAT ARE THE INPUTS REQUIRED FROM THE CUSTOMERS TO START DESIGNING FIXTURE ?

The inputs required from the customer to start designing a fixture:

1. Fundamental requirements.
2. Preferred standard components.
3. Car products.
4. Layout.
5. Ergo – data.
6. Weld study.
7. Standard detailing templates.

 

 

Q 3. WHAT IS TH E INPUT WE GET " CAR PRODUCT " ?

 

Inputs we get from car products includes;

1. GD&T.
2. Part lists.
3. 3D cad file.
4. Clamp plan.
5. Product assembly process sheet.

1. GD&T:

GD&T – Geometric Dimensioning & Tolerance.

It provides information of locating pins, rest, clamp, damp & slide unit information of each station. Also includes the information of sequence of openings of clamps, dumps & slide stroke information.

2. Part lists:

It gives the lists of parts which are going to assembled in the fixture. The list contains the information of part number, part name, revision of fixture, part thickness, etc.

3. 3D cad files:

The 3D model of the car part will be given from customer. From that 3D model we will be developing our fixture design process.

The 3D cad file will be in the format of step file (stp.) or IGES file (igs.) or sometimes it may be in part file (prt.).

4. Clamp plan:

Clamp plan provides the information of location of pins, rest units, clamp unit, dump, etc.

It is the important input from customer. The clamp plan/position should not be changed without the knowledge of customers.

It gives the detail of the exact position of the clamping units.

 

 

 

Q 4. WHAT IS CLAMP PLAN ?

 

Clamp:

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.

Essential requirements of clamps:

All clamps must fulfill four essential requirements. They are,

1. The work piece must be held rigid while undergoing operations.
2. The time required for loading / unloading the tool must be as short as possible, which means the clamping device must be quick acting.
3. when subjected to vibration, chattered, heavy pressure the clamping must be positive.
4. The clamp must not damage the work piece.

 

 

Q 5. WHAT IS THE PURPOSE OF THE LAYOUT ?

 

THE PURPOSE OF THE LAYOUT:

The purpose of the layout is to understand the information about where the fixture & 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.

The circle around the robot is the swept area of the particular robot which shows the reachability of the robots particularly with the confine circle.

Layout provides the information of flow of parts, station pitch, robot stations, accessories like tool changers & tip dressers, sub assembly links, plat form height, loading/unloading sequence/height.

Layout sheet will give you information about all the fixtures are placed, the robots are going to work on it.

In layout sheet the circle around the robot is called Trapped Area of that particular robot.

So, this is basically the reachebility of the robot which is confined to the particular circle.

Flow of parts: It shows the flow of the parts/panel in the assembly line or shop floor like how component move from one station to other station after the completion of process.

 

 

Q 6.  WHAT IS ERGO DATA ?

 

ERGO DATA:

Ergo data is nothing but the data or inputs which gives the human factors engineering data, between the operator & his working environment. Before detailing about ergo data we should know about ergonomics in detail.

ERGONOMICS:

Ergonomics also known as human engineering & human factors engineering is the scientific study of the relationship between man and his working environments.

 

 

Q 7. WHAT DO YOU UNDERSTAND BY  WELD STUDY ?

 

WELD STUDY:

Weld study is the important inputs from the customer.

It gives the study of particular gun that we use for weld, No. of spots to be welded, sequence of weld, position of weld in the components.

In short, weld study includes weld gun details, weld matrix & weld points.

Generally the weld points will be given in spheres.

Red sphere represents the Geo spot weld points whereas Green sphere represents the Respot weld points.

The weld points are classified as,

1. Geo weld points:

The Geo weld points are which is planned in the Geo fixture.

These weld will determine the position of the panels as per the given data in drawing.

The geo weld points are represents in red sphere in the weld study inputs given by the customers.

2. Respot weld points:

The respot weld points are planned in the respot tool.

These weld will determine the strength/stiffness of the panel/components.

The Respot weld points are represent in green spheres in the weld study inputs given by the customers.

 

 

 

Q 8 . WHAT ARE THE CRITERIA OF PERCENTAGE COMPLETION IN DESIGN STAGE ?

 

Answer:

The percentage completion criteria is followed in the designing stages & dispatch stages of welding fixtures.

This percentage completion criteria is followed to trace the project whether it matches the committed date given to the customer for hand over the projects to them.

Also it helps us to identify the stages in the projects like how much the project is completed and what are the further stages are in pending, to complete which helps us to complete the projects on the committed time and date.

The percentage completion criteria is divided into four stages to identify the percentage of the completion of work.

The four stages of percentage completion criteria are as follows,

1. Input & concept design.
2. Concept approval & simulation check.
3. Design freezing & detailing.
4. Check & final dispatch.

 

Q 9. BRIEF ABOUT " OUTPUT " IN DESIGN ?

 

Output In Design:

In BIW fixture design or any industry. We don't only just design a particular component and just give the CAD file to the customer, you have to give a lot of documents like 3d documents,2d documents, which is the detailing part, and as well as other factors as well like bom, bom bill of material and other documents as well about this particular component and their standards, all has to be submitted to the customer.

The output is 3D models and the 2D drawing of the tools

1.Unitized Tools

2.Non-Unitised Tools

1.Unitized Tools: 

In the unitized tools testing requires two types of drawing sheet,which is one key sheet and layout sheet.

So example of a unitized tools are fixtures,tools So where exactly multiple units are a placed.For example, the entire assembly welding fixtures,where a pin unit,clamp unit,rest unit and the panel, everything is included so that for those things.

2.Non-Unitized Tools:

Tools that can stand alone and can be detailed completely on a layouy sheet.

Non unitized tools are basically tools like Stands and tool changers is also an example of an non unitized tools where you don't need key sheet, you can actually used to layout sheet and complete the entire documentation of the particular component. So this is as known non unitized tools.

 

 

Q 10 . WHAT DO YOU UNDERSTAND BY STRUCTURING A DESIGN TREE ? HOW DOES IT REDUCE THE ERRORS IN DESIGN ..

 

 

Structuring A Design Tree:

Structuring a design tree implies to process where all the assemblies & parts are named in a specific standard. Different customers have different set of standards to structure a design tree.

It is an important process which helps us to identify a specific part or assembly as to which project, tool/unit, it belongs to.

This helps us to avoid the errors during design, manufacturing, assembly, inspection, etc.

If the parts or assemblies are not named properly or the design tree is not structured properly, it will create confusion to understand the design & may create major possibilities of making an error.

Naming of a fixture or a unit or a part, gives the information as to which project or zone or assembly do they belong.

It can help us to identify the quantity of items of same types or different types that are being used in the assembly.

While start designing a fixture, the first unit will be the base unit.

In structure tree all the manufacturing parts should be first and the standard parts should be at the last.

 

 

 

Q 11 . WHAT ARE THE UNITS ? MENTION 5 TYPES OF UNITS 

 

Units:

A unit is a device that has a specified function, especially one forming part of a complex mechanism.

A welding fixture is assembly of different types of units.

As name refers, the different units will be only seen in the unitized tool.

A units are classified into two, they are,

Simple unit: In a simple welding fixture, the combination of these different units will be seen.

1. Rest unit.
2. Fixed pin units.
3. Retract pin units.
4. Rough locator unit.
5. Sensor unit.
6. Base unit.

 

Q 12. DESCRIBE FIXED PIN UNITS & THEIR PURPOSE 

 

Fixed pin unit:

Fixed pin unit is a unit design to locate the car panel using pins.

Pin, pin retainer, shims, blocks, blade, riser are part of fixed pin unites in general.

Pin retainer is used to hold the pin firmly.

PURPOSE OF FIXED PIN UNIT:

As by 3-2-1 locating principle, the introduction of two pins helps to arrest the 6 degrees of freedom (4 axial & 2 radial movements) whereas other 6 degrees of freedom are arrested by introducing minimum three supports.

Typically, the locating pins are used to locate a body part in a position sufficiently accurate to execute a welding process a welding process.

The body part is constrained by a set of appropriately locating pin so total constraint by locating pin should be fully constrained at all times to prevent any movement.

 

 

 

Q 13 . WHAT ARE THE DIFFRENT PARTS OF FIXED PINS ?

 

 

DIFFERENT PARTS OF THE FIXED PIN UNIT:

The different parts of the fixed pin units are as follows,

1. Pin.
2. Pin retainer.
3. Shims.
4. Blade.
5. Riser.

1. Pin:

It is used for the location purpose of the panel. Typically, the locating pins are used to locate a body part in a position sufficiently accurate to execute a welding process.

The body part is constrained by a set of appropriately locating pin so total constraint by locating pin should be fully constrained at all times to prevent any movement.

There are dozens of styles of locating pins that can be utilized in a design. One of the most common pins is a stepped pin with either small or large head.