Challenge

Week 3:- BiW Fixture Design Methodologies Challenges

MManthan Waghaye10 Oct 2023

1)What is Design Methodology?

Design methodology - It is nothing but the steps followed during the Concept designing stages of fixture design.

Design methodology is divided into the following sub parts: -

1.Purchase Order:

A purchase order is the order from the customer end for the starting of the work. A purchase order (PO) is a commercial document and first official offer issued by a buyer to a seller indicating types, quantities, and agreed prices for products or services. It is used to control the purchasing of products and services from external suppliers. Purchase orders can be an essential part of enterprise resource planning system orders.
A purchase order does not constitute a contract in and of itself. If there is no prior contract, the seller's acceptance of the order constitutes a contract between the buyer and the seller. Bought out item (Purchased parts) standards like pneumatic items, toggle clamp, bearing, screw, dowel etc. company information.

2.Inputs from Customer

Inputs from customer:

For BIW fixture designing the customer demands some requirements to be fulfilled in it viz., functional requirements, preferred standard components, car products, layout, ergo data, weld study, standard detailing templates.

Functional requirements:
The purpose of the function of the fixture will be given as input from the customers like what are the function the fixture is going to do i.e., Welding, riveting, gluing, or whether it is a checking fixture, etc.

Preferred standards:
As we know different companies follow different standards. we will be following the standards, followed by the customers. By following the standards in the time of designing and manufacturing of parts we will be saving the time and cost which will be automatically minimizing the time of the projects. As per the standard parts, it can be easily replaced from the used fixture to the new fixture which reduces cost.

Car products:
The inputs we get from car products are GD&T, parts list, CAD files of car part, Clamp plan, Produce assembly process sheet.

Layout:
Layout shows the entire assembly plan to understand the process. Layout provides information of flow of parts, station pitch, robot stations, accessories like tool changes and tip dressers, sub assembly links, platform height, loading and unloading sequence heights.

Ergo data:
As same as preferred standards, different companies for the different standards of ergo data. We have to follow the customary standards of ergo data. The inputs of Ergo data will be given by the customer mostly in case of manually operated fixtures. The Ergo data is mainly used to make the operator comfortable which may lead to improve the efficiency in cycle time and production. Data provides inputs like platform height, maximum and minimum treat from operator to fixture, maximum and minimum height of the fixture, whether the child parts or assemblies are visible while clamping for loading and unloading. Also provides information like loading height, working safety zone of operator, etc.

Weld study:
Weld Study is the important inputs given by the customer. It gives details about the study of particular gun that we use for welding. Also like the number of welds, weld position of the components will be given. In short weld study includes welding gun details, weld Matrix and weld points.

Standard detailing templates:
These inputs include the detailing templates of 2D cad drawing as per the customer standards. So, we have to follow the detailing templates as per the customer standards.

3. Percentage completion criteria:

Percentage completion criteria is followed in the designing stages and dispatch stages of the welding fixtures.

0-25% - Input and concept design

25-40% - Concept approval and simulation check

40-85% - Design freezing and detailing

85-100% - Check and final dispatch

The above-mentioned percentage of the percentages of state wise completion criteria of the projects.

4. Design output:
The output is 3D models and 2D drawings of the tools. The are two types of tools:

Design Output consist of lots of data like 3D and 2D documents, VMC IGS files, STEP files, gas-cut or laser-cut files in drawing format and BOM, etc.

1. Unitized tools: (multiple units on a common base) requires two types of drawing sheets.

Key sheet: An index of units and their placements on the tool base.

Layout sheet: A detailed drawing of individual units to include all of their components.

2. Non unitized tools: Tools that can stand alone and can be completely detailed in a layout sheet.

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

To start designing a fixture the following are the inputs required for designing a fixture.

· Functional requirements

· Preferred Standard Components

· Car Product’s

· Layout

· Ergo Data

· Weld Study

· Standard detailing Templates.

Functional requirements:
The purpose of the function of the fixture will be given as input from the customers like what are the function the fixture is going to do i.e. Welding, riveting, gluing, or whether it is a checking fixture, etc.

1. Standards like ABB, NAAMS, DESTACO, ZYTRAN.

2. Standard parts like L-blocks, risers, retainers, pins.

3. Components like slides, clamps, cylinders, switches, sensors, weld gun, tip dressers, tool changers.

Car products:
The inputs we get from car products are GD&T, parts list, CAD files of car part, Clamp plan, Produce assembly process sheet.

1.GD&T of the parts.

2. Part list.

3. CAD files of car parts.

4. Clamp plan.

5. Product assembly process sheet.

Ergo data:

As same as preferred standards, different companies for the different standards of ergo data. We have to follow the customary standards of ergo data. The inputs of Ergo data will be given by the customer mostly in case of manually operated fixtures. The Ergo data is mainly used to make the operator comfortable which may lead to improve the efficiency in cycle time and production. Data provides inputs like platform height, maximum and minimum treat from operator to fixture, maximum and minimum height of the fixture, whether the child parts or assemblies are visible while clamping for loading and unloading. Also provides information like loading height, working safety zone of operator, etc.

Weld study:
Weld Study is the important inputs given by the customer. It gives details about the study of particular gun that we use for welding. Also like the number of weld, weld position of the components will be given. In short weld study includes welding gun details, weld Matrix and weld points.

GD&T:
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.

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

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 customer.

3D cad file: The 3D model of the car part will be given the 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).

Product assembly process sheet: It gives the information of stage wise assembly process like how the parts move from one assembly process to other after the completion of joining process.

3)What is the input we get from "Car Products"?

Inputs we get from car products include:

GD&T

Parts lists.

3D cad file.

Clamp plan.

Product assembly process sheet.

Geometry Dimension and Tolerancing:
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.

Part List:
Part list gives thee information of parts in a unit.it consists of part number, part name which helps to identify the part easily, number of parts required and its thickness. This list helps to check all the parts and its dimensions and required number of quantities. Parts to be assembled in fixture i.e. the part no., part name, revision of the part, part thickness.

CAD files of the car part:
CAD files of car parts gives the simulations of those 3D models and their analysis. It is also used throughout the engineering process from conceptual design and layout of products through strength and dynamic analysis of assemblies to definition of manufacturing methods of components.

Clamp plan:

This is the clamping plan while doing the operation. We cannot complain without permission of the customer. It is very important input from the customer. It provides location of pins, rest, clamps, dumps, etc.

Product Assembly Process Sheet:
It gives detail process of the completion of the part from scratch to the finished product of the assembly.
Product assembly process sheet gives complete assembly of a unit. Different parts in a unit are assembled by geo weld first. Then the weld parts are assembled by re-spot welding. Similarly, every small parts of a product or unit is assembled first and these small parts are welded together to get a final product.

4. What is the clamp plan?

Clamp holds the car part firmly and prevent the part from distortion while carrying out the operation.
Clamp plan describes the location of pins, rest, clamp, dumps etc. to be placed on car part during assembly.
Clamp plan shouldn't be changed without the consent from the customer.

It gives the details of the exact X, Y and Z coordinates on which the clamps, rest, pins, dumps etc of the fixture are to be placed upon the part as shown in the image below.
We can't move the clamp location without the permission of the customer, so we must first obtain permission from the customer. Clamp plans also show where the pins, rest, clamps, and dumps are located.

5.What is the purpose of a 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 swept area of the particular robot is shown by the circle surrounding the robot, which indicates the robots' reachability, notably with the confine circle.
Parts flow, station pitch, robot stations, accessories such as tool changers and tip dressers, sub assembly links, plat form height, and loading/unloading sequence/height are all provided by layout.

The layout information includes

1. Flow of parts: Layout explains the flow of parts from one station to another station.

2. Station pitch: The distance between two stations representing space constraints of a layout.

3. Robot stations: Robot stations and position of the robots in the space constraint.

4. Accessories like tool changer and tip dressers: The locations of accessories in the layout where the robot has to pick up and place the tool from its location.

5. Sub assembly links: Sub assembly links describes the link between subassembly fixture and the main assembly lines.

6. Loading/unloading sequence heights: The height of the platforms and its loading and unloading sequence.

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.

OBJECTIVES OF ERGONOMICS:

Two mainobjectives of ergonomics are:

· To enhance the efficiency and effectiveness with which the work is carried out so as to increase the convenience of use, reduced errors & increase in productivity

· To enhance certain desirable human values including safety, reduced stress fatigue and improved quality of life.

Ergonomics involves the design:

a. Work place suitable for the worker.

b. Machinery & controls, so as to minimize physical strain on the worker to enable the improvement in the efficiency.

c. An environment for performing a task most effectively and conducive

d. A conducive task and work organization.

Benefits of Ergonomics:

Ø Improved working condition.

Ø Reduce physical workload.

Ø Improved work postures,

Ø Reduced efforts of certain movements.

Ø Better reading instrument displays, handling of machine levers & Controls.

Ø Reduced unnecessary information recall efforts.

7)What do you understand by Weld study?

Weld study means a study of the welding technique that we are going to use, its temperature, type of current, type of gases used, type of gun used for welding and where are we going to weld etc. If we use a spot welding what kind of electrode is used for welding, number of spots etc, come under the weld study of that particular component.

Weld Study includes:

Weld gun details.

Weld matrix and weld points.

Geo weld points and respot weld points.

Weld Gun Details:

This involves the study of the gun like

· Type of weld it does

· Number of spots it can weld

· Temperature of the weld.

· Type of current used

· Approach of the gun.

Weld matrix and weld points:

Weld points are basically where the welding is going to happen at which point at which coordinates is going to happen.

8. What are the criteria for percentage completion in the designing stage? Explain it in detail.

Percentage completion criteria is followed in the designing stages and dispatch stages of the welding fixtures.

0-25% (Input and concept design) :-

The initial stage of designing fixture involves understanding the customer input describing their requirements and preparing the design concept as per the customer requirement.

25-40% (Concept approval and simulation check):-
The customer approves the design or suggests some design changes they require if any. After the design approval from the customer the fixture design will be subjected to simulation checking.

40-85% (Design freezing and detailing): -
After successfully passing the simulation checking the design concept is freeze and finalised and the detailing of the fixture assembly and its child part components is done.

85-100% (Check and final dispatch): -The fixture assembly and the components manufactured are then inspected and finally dispatched

The four stages of percentage completion criteria are as follows:

Ø Input & concept design

Ø Concept approval & simulation check

Ø Design freezing & detailing

Ø Check & final dispatch

Ø Input & concept design:

This is Initial stage of project. Input data provided by customer like functional requirement, customer standard etc. & after studying those inputs the concept of fixture design is created. After completion of this tasks about 25% of work completed

Concept approval & simulation check:
As concept of fixture design is created & simulation checked it is sending for customer approval Customer will study all simulations & gives his approval. If there are any changes required, then it has to do accordingly & again submit for approval. This concept design approval from the customer after study of simulation contributes only 15% of total design work. But with completion of this task 75-40% works completed.

Design freezing & detailing:
This phase involve design freezing after approval of concept design Freezing means finalizing concept design. Then next step is detailing as per customer standard template. With completion of this stage almost 85% of work is completed in designing stage.

Check & final dispatch:
After detailing the quality checking team starts inspection of all the date it will dispatch to the customer litis ok as per customer standard. If there is in error in drafting it will create issue or mistake in manufacturing stage. Thus, a percent completion criterion helps us to know where we are in design process.

9)Brief about "Output" in design?
After completion of the fixture design the output documentations should be provided to the customer. The output is 3D models and 2D drawings of the tools, user manual data, functioning of the tools, switches, sensors and cylinders. The are two types of tools :

1. Unitized tools: (multiple units on a common base) requires two types of drawing sheets.
Key sheet: An index of units and their placements on the tool base.

Layout sheet: A detailed drawing of individual units to include all of their components.

2. Non unitized tools: Tools that can stand alone and can be completely detailed in a layout sheet.

The output should compile following points:

a. Approved standard components are to be used wherever possible.

b. Design must be as simple and economical as possible.

c. Design must comply with safety and ergonomic requirements.

d. Design must provide for controlled and damaged free handling of product.

e. Adequate error proofing must be incorporated into each design by providing proximity switches, rough locators etc.

f. The weight of the moving parts must be kept to a minimum while maintaining maximum strength.

g. Frames and structures are to be kept simple and sturdy.

h. Design clearance and accessibility for routine maintenance and services.

i. Designer is responsible to validate clamps and all weld guns.

j. Motion control must be considered on any moving equipment’s.
In the fixture element design output contains detailed design of locators, detailed design of clamps, detailed design of supports positions of locators, positions of clamp, positions of supports if any type of locators, types of clamps, types of supports, clearing forces & supports.

10)What do you understand by structuring a design tree? How does it reduce errors during the design process?

structuring a design tree implies to a process where all the assemblies and parts are named in a specific standard. Different customers have different set of standards to structure a design tree.
It helps us to identify a specific part or assembly, as to which project, tool or unit it belongs to.
This helps us to avoid errors during design study, manufacturing, assembly, inspection etc.

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

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

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

Every part, every component should be named according to their procedures.

If we did a mistake or renamed the entire standard parts from the customer as a design part. Now the customer is going to manufacture the entire part again from the scratch, but he already has that product in his itinerary. But extra cost extra time and is feasible. This is also known as an error which is actually going to increase the cost of the entire assembly as well

Naming a fixture or a unit or a part gives the information as to which project zone or assembly do they belong. If we name the part properly or name the fixture properly ill actually tell which unit or which assembly or which zone or in which station it actually belongs

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

In design tree in which designed parts are at top & all standard parts are at bottom.

The blue highlighted number is PXZT9A-RSTOA-FJ5-U001-01-003
PXZT9A - The project name

RSTOA - Panel name

FJ5 - Jig no.3

U001 - unit no

01 - Part no.

003 - Component no.

Under the product there are main assemblies, sub assembled child part standard parts, etc . these all parts are provided with specific number, zone etc. to identify easily.

11)What are Units? Mention 5 types of units.

A unit is a device that forms a specified function, in a BIW fixture assembly. Multiple units are mounted together on a base unit and the combined assembly forms a BIW fixture.

A welding fixture is assembly of different types of units.

As name refers, the different units each serves with different functions and different purposes.

Units are classified into two types:

· Unitised tools

· Non unitised tools

1.UNITISED TOOLS:

Unitized tools are basically tools which are a art of multiple units or multiple tools inside of it. These are the tools which has to be represented by two formats i.e. Key Sheets and Layout Sheets. Unitized tools are basically two types:

a. Simple units:

Simple units will have a very simple design to it, then the approach of the designing and manufacturing is also very simplistic. Simple units are classified as:

Rest unit: Rest unit is basically a unit where the component is tested, there is no upper clamp to it, there is no force applied to it. There is no cylinder attached to it, usually it will have a riser, a blade and few rest mylar.

Fixed pin unit: Fixed pin unit is basically a unit which has a pin which is already fixed it cannot be moved.

Retract pin unit: Retract pin unit is opposite to fixture which can be moved up and down by using a extractable pneumatic cylinder, so it can be retraced to a certain distance.

Rough Locators: A rough locator is a part designed to guide the operator, to locate the car panel on the pins accordingly. A rough locator can be of standard part or make part.

Sensor Unit: A sensor units are used in actually sensing whether the panel or a particular component is there or not. For example, if we are assembling component of 10 parts, Each part will have a sensor or multiple attached to it.

Base unit: A base unit is a unit designed to mount all other units.

b. complex units:

Complex units, like slide unit is an example of a complex unit that design itself a little complex in design.

Slide unit: The slide units are basically where the sliding mechanism is involved.

Dump Unit: Dump unit is basically like a conveyor where we assemble a component if we have a particular constraint.

2.NON UNITIZED TOOLS:

Non unitized tools are basically one unit itself, which is basically don’t have any processes functionality to it is just to keep component on it as a stable, like grippers turntable, stands, etc. Non unitized tools are:

Stands
Take out trolleys
Conveyor
Turn tables
Some gripper

12. Describe fixed pin units and their purpose?

It is designed to locate car panel using pins. It is already fixed and it cannot move up and down. Below are the different parts of pin unit in general:

Pin retainer

Shims/Spacers

Block

Blade/ plate.

Every pin unit will have two directional shims. The block is used to mount entire pin unit. Shims are used to avoid stack up tolerance while assembling entire component. Shims come in pack of 0.1,0.2 & 0.5 cm.

The purpose of fixed pin units is to restrict rotational as well as translational degrees of freedom. The fixed pin unit restricts translational motion along two axes and one rotational motion along the axis of panel.

Pin should be placed on the exact coordinate which otherwise would lead to a rejected car panel assembly.

13)What are the different parts of a fixed unit?

Different parts of a fixed unit:

The different parts of a fixed unit are:

Locating Pin

Pin retainer

Shims

Blade

Riser

Risers: Risers might be L-shaped, welded, square tube, or frame-shaped. These are manufactured pieces that are utilised to give assembly height.

Blades are plates that are fastened to the riser. Other components, such as the cylinder and arms, are mounted to the blade. The purpose of the chamfer is to reinforce the blade. To secure the blade to the riser, a two-dowel four-hole configuration is used.

L-Blocks: The L-Block is only used to provide shimming for adjustment. We should check bolting access while installing an L block because there is already a bolt to tighten the pin. As a result, the L block should provide a clear hole.

Shims/spacers: Tolerance is provided in the fixture for each part that is largely fabricated. Those tolerances tend to accumulate and reflect one another. To avoid this, we utilise shims, which we can simply change after assembly, so whatever stacks up there will be corrected with shims. Shims are available in various thicknesses, such as 0.1, 0.2, and 0.5.

Pin: The panel's placement is determined by this pin. Standard pins should be utilised as much as feasible, and pin lengths should be kept to a minimum. Pin diameters should be cylindrically ground to keep their dimensions correct. Two locating pins are usually sufficient to accurately position the work item on one plane. Locating pins come in a variety of styles that can be used in a design. We'll go over the structure and demonstrate how each style can be used. The following are the several varieties of Standard Pins:

Round Pins: For prototype builds only, these can be screwed (PNRS), grub screwed (PNRG), or threaded (PNRT). A stepped pin with a small or large head is one of the most frequent pins.

Diamond Pins: The Diamond Shape is a significant feature that aids in the reduction of machining inaccuracies and the smoother operation of the locating process. When two round head pins are inserted on one plate, the spacing between two mounting holes must be quite accurate, and even then, the work piece will not be as easily positioned on the base as if a diamond shape pin were used. For prototype builds only, these can be Screw fastened (PNDS), Grub Screw secured (PNDG), or Thread secured (PNRT).

Pin retainer: This pin is supported by a pin retainer. The Pin Retainer is utilised to keep the pin in place while also acting as a rest for the pin. A counter hole is drilled into which the pin will be inserted.

14)What is the purpose of making a Rest unit & describe its parts?

Rest unit is unit designed to support car panel using Myler/ NC block/ rest component is rested only, no upper clamp or force applied there. It is the simplest unit to design because it has fewer parts to design & the purpose is only resting of the car panel.

It can be combined with clamp unit to clamp as well as to rest the car panel. It can be combined with locating unit to locate as well as to rest the car panel. Also locating, clamping & Test unit can be combined together in one unit to reduce cost.

The different parts of a Rest unit are:

NC blocks/Mylars

Spacers

Blade

Riser

NC blocks/Mylars:

Mylars are the part which are holding the panel from top & bottom. It is a jaw type, during welding it won’t deforms from its position. It is also known as fingers. It wont allow the deformation of the part due to welding stresses.

Mylars are of two types, they are

Clamping mylars

Resting mylars

Only resting mylars are seen in resting unit. The panel which rests on the part is known as resting mylars.

Risers:
Riser is a structure generally used to mount the toggle clamp and rest, clamp mylars and location pin.

It is not necessary to have one riser where all the parts of clamp or rest or location units are mounted.

Generally, risers are either made of plate fabrication or plate and tube welding together or from single gas cut plate.

These are generally manufactured to give height to the assembly.

Spacers/Shims:
Metal shims are used to finely adjust the location of how the fixture holds the product so that it is welded together within the dimensions set for the product to work well.
A pack of thin metal shim is placed between two components in the fixture. The first component is fixed in place and the second component is attached to the first component with the pack of shims in between. Removing one shim or adding one shim slightly adjusts the location of the second component. This is important to manufacturers who want to have their product’s parts assemble easily after being welded.

Blade:
Blades are the plates attached to the riser. Other parts like cylinder, arms etc are mounted on the blade. Chamfer is given here to strengthen the blade.

15)What are the basic fundamentals to design a Sensor unit?

Sensor unit: An electrical sensor is used to sense the automobile panel. The sensor's signal will be transmitted to the PLC, and the next procedure will begin. Sensor units are used to detect if a panel is present or not, or whether a certain component is present. If 9 pars are required for assembly, we must have at least that number of sensors. When an operator manually assembles a complete component, they perform tasks such as fastening and gluing. If a component is present, the sensor will indicate it, and if it is not, an error will be displayed.

Fundamental of sensor unit design:

Each signal has a loose panel that is being welded in the tool. Depending on the size of the panel, one to two sensors should be used to sense it, with the diagonal opposite ends of the panel being recommended. In general, each sensor should be positioned in three directions that can be adjusted. IFM, SICK, OMRON, and other significant sensor manufacturers are only a few examples.

Types of sensors used in general.

Proximity sensor - It has sensing range 5 to 6 mm. It is based on magnetic field principle. A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact.

A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal

Laser sensor: It has a longer detection range than a proximity sensor. A photoelectric sensor is a piece of equipment that uses a light transmitter, usually infrared, and a photoelectric receiver to determine the distance, absence, or presence of an object. They're commonly found in industrial settings. As shown in the diagram below.

16)What is a Rough locator unit & what are the basic fundamentals to consider while designing it?

Rough Locator:

Rough locators are elements that aid the operator to guide the car panels while loading onto the fixture and ensure a fool-proof assembly.
It is used a fool proofing method, because due to the rough locator part cannot be located in correct position. The rough locators are set according to the respective panel. Hence, art can only be loaded in defined direction and orientation.

FUNDAMENTALS OF ROUGH LOCATOR DESIGN:

Ø Rough locators should be placed at the edges of the car panel which it has to guide.

Ø Rough locator has to be placed at the same angle of the car part edge with a minimum distance of 2.5mm from the edge of the car part.

Ø Rough locator should guide the panel in the pin arresting direction,

Ø Rough locator should guide the panel before 10-15 mm to start of the pin engagement

Ø Rough locator should be designed with entry angle for the car panel. Generally it ranges between 30-45 degree.

Ø Rough locator should be designed with two slots to mount the easy adjustments

Ø The locators should be in the direction of car part guiding.

17)What is a Base unit and describe its parts?

Base unit:

A base unit is the unit designed to mount all the other units (clamp unit ,in unit, Rest unit etc) of the tool, also other parts necessary for tool pneumatic valve box, trunking cable path will also be mounted onto a base unit.

Parts of Base unit:
Parts of base unit are as follows:

Valve box

Trunking channel

Measuring hole cover

Eye bolt

Pedestal

Floor plates

A base unit primarily consists of

a. Base plate: A base plate is a structure upon which various taping and holes are machined for mounting the pin unit, rest unit, clamp units etc.

b. Pedestal: Pedestals are the parts of base unit which joins base plate to the floor plate.

c. Floor plate: A floor plate is a unit which is mounted on to the ground and upon which the entire base unit stands.

d. Valve box: A valve box is a unit which supplies pressurised air to the cylinders and also takes back as and when required.

e. Trunking channels: Trunking channels are the ducts which carries pneumatic hose pipes and electrical connections.

f. Eye bolts: Eye bolts are used to lift the entire base unit during shifting purpose.

18. What is a dump unit and what are its function?

A dump unit is used whenever there is a requirement to hold the car part in a particular geometrical constraint.
Here you will have clamp unit, pin unit attached panel will be assembled. So, if you have certain constraint you cannot assemble in normal way. Dump unit use in different way. It has dump cylinder & complex design. It consists of dump cylinder to perform the operation of clamping & unclamping car panel. A dump unit can have more than one cylinder to perform such operation.

The first cylinder dumps the assembly carrying clamp Mylar, pins and then this assembly performs the required operation in this unit, we should make sure that in the open position of panel, we should be able to remove the panel.

Functions of Dump Unit:

If you have particular constraint and you cannot assemble in a normal way to use this use it in different ways again it has same dump cylinder and it has open position and closed position and it has Clamp Cylinder Unit too.
That is why these are very complex and design.
If you have any geometrical constraints, you can use this dampener to constrain your components.

19)What are slide units? Mention where slide units are commonly used?

Sliding unit consists of a sliding cylinder which slide the entire panel along the guide rails towards the sensor unit for carrying out the operation.
It is most commonly used in situations when there is space constraints to use many units or panels to be assembled are more.

A slide unit consists of a cylinder which moves the panel to be assembled along the guide rails from the closed position to the open position where the welding operation is performed and the panel is stopped by the stopper and locked when the desired position is determined by the sensor. After finish the welding operation the panel moves back to the closed position.
Slide units may be classified into two types based on the type of guide ways. They are,

Hardened guide way.

LM guide way

Slide units may further be classified into three types based on the prime mover. They are,

Manual slides
Hydraulic/pneumatic slides.
CNC slides

It may be further classified depending on the application as

· Horizontal slide unit

· Vertical slide unit

· Angular slide unit

Basic fundamentals of slide unit design:

Ø Reverse stroke 10mm to be considered in both forward & retracted condition.

Ø Cylinder & LM guides to be validate for load & stroke.

Ø Master guide way should be constrained & the subsidiary guide way to be free.

Ø Mechanical hard stop to be considered for both extended & retracted condition.

Ø Shock absorber should be used for both extended & retracted condition to reduce impact load.

Ø Slide to be locked/clamped in the working position.

Ø Slide to be locked with a safety pin in the retracted position during transportation,

Ø The two end limits to be sensed externally by a proximity switch

Ø The design should be checked for screw accessibility, ease of assembly, machinability of parts.

Ø The LM guide & rails are integral assemblies and should not be separated at any cost.

Ø LM guide ways to be lubricated for long life.

Hence these are slide units.

Week 3:- BiW Fixture Design Methodologies Challenges

Ship work like this
in your own course.

Talk to a career counsellor

Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.