BiW Fixture Design Methodologies

Design Methodology:

The Design methodology is nothing but the steps followed during the concept designing stage of fixture design. Below are the steps followed during the design methodology.

Purchase order: A purchase order is basically confirmation from the customer side that we are ready to start work. A purchase order (PO) is a commercial document and the 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. Indent is a purchase order often placed through an agent (indent agent) under specified conditions of sale. The issue of a purchase order does not itself form a contract. If no prior contract exists, then it is the acceptance of the order by the seller that forms a contract between the buyer and seller.

Input from customer:

Inputs from customers are major inputs that we get from customers. We study those inputs to what kind of information get out of it.

• First, understand the scope of the work. This means what is expected by the customer. Every customer has its specific requirements and it may have its own raw material, electric, pneumatic, cad, design standards. Every customer also gives different inputs and expects output e.g 2d drawing, process sheet in Xls, pdf, CAD format of design, layout format, OLP.
• Bill of material (BOM) of the components to be welded- spot welding.
• CAD panel data or at least 2D drawing of assembly and individual panel data.
• Sheet metal panel thickness plays a major role to decide 2 metal or 3 metal welds.
• Spot Detail information like total no of spots and spacing between the spots.
• Weld information clarity from drawing like 2 metal or 3 metal welding.
• PLP (Principle location scheme) of the individual panel and total assembly.
• Cycle time if calculated or can be found out as per manual or robotic welding process
• Process sheet if Process engineering is done - where loading sequence, no of clamp data, and gun data is mentioned.
• All clamping cylinder and fixtures standards.
• CAD -Software guidelines.
• Raw material standards.
• Design guidelines
• Bought out item (Purchased parts) standards like pneumatic items, toggle clamp, bearing, screw, dowel etc company information

Percentage completion Criteria:

• It consists planning of the completion of the total project. How many days the project will take to complete.
• It is followed in the designing stages & dispatch stages of the welding fixture.
• It ensures that how many tasks that we have decided to complete within the stipulated time is complete or not & how much of it is rest to complete & whether it is going to be complete or not in a given time

Design Output:

• The output consists of 3D models, a 2D drawing which is the detailing part, BOM & other related documents.
• There are some tools which are multiple units on a common base are called unitized tools ex: a fixture which includes no. of units on the same base.
• They required two types of drawing sheets as follows,
  • 1. Key sheet- It shows the index of the unit & its placement on the tool base.
  • 2. Layout sheet- It is the detailed drawing of an individual unit to include all its components. Non unitized tools which can be completely detailed on the layout sheet

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

The following are the inputs we required from the customer to start the fixture design work

Functional requirements: This is basically what kinds of function that fixture design has e.g. welding, gluing, fastening, riveting. This kind of information will be given to us in functional requirements i.e. it serves a basic or main purpose like it is used for welding, gluing, or checking fixtures. so from that design concept generate.

Preferred standard: Every industry has its own standard & they follow that standard. In this requirement, the preferred standard component is basically what kind of standard component the customer already has. An input actually saves lots of time, cost & effort. Because don’t need to design that component. It is purchased from outside from that make.
Standard like ABB, NAAMS, FAUNC, FESTO, TUNKERS, ZYTRAN, DESTACO, Siemens, etc. is used for robot, pneumatic parts, motor & gearbox, electric parts.
Standard parts like riser, L-block, retainer, pins many other companies actually manufacture this.
Some components like clamp, cylinder, slides, switches, sensors.

Car Products:

Car Products gives the information regarding the Geometric dimensioning and Tolerances and Part list which types of Cad files of car parts also provides the info about the Clamp plan and Product assembly Process sheet.

Layout: Layout provides information about Flow of parts, Station pitch, Robot stations, and accessories like tool changers, Tip dressers, Platform height, Subassembly links & loading/Unloading sequence.

Ergo data: This data is given when any manual operation involves. Ergonomics refers to the study of human behavior & movements during the assembly work. It provides data regarding loading height, working safety zone of the operator, etc as per the standarad that the company follows.

Weld study: It includes information on weld gun detail, weld matrix & weld points. There are two types of weld points geo weld point & respot weld point. Geo weld points define the geometry of part & respot do all other remaining weld points also add strength to geo weld points.

Standard detailing template: Detailing is a 2D representation of a 3D part. The customer has a standard detailing template. These detailing formats are used for the drafting of parts.

The input we get from “Car products”

• GD & T - Geometric dimensioning & Tolerance of the part for which the fixture has to be designed. GD & T provides information about Locating pins, Rest, Clamp, Dumps & slides information of each station & Sequence & opening of clamps, Dump & slide stroke information.
• Part list: The part list is nothing but listing down all parts of an assembly. It includes information about the part name, Part number, Tooling revision, Part thickness, etc. Suppose the first assembly has gone between hood inner panels & latch which going to attach the next hinge going to attach. So there are different lists of assembly we are going to perform. So every assembly will have a different fixture unit.
• 
• CAD file: 3D file of that car product require from the customer. The 3D model file of the car part is given to the customer to study. The car part is designed by using 3D modeling software. From this, we can get some conceptual idea of the design of the fixture. The model is going to be the base of the fixture design. The below figure illustrates.
• Clamp plan: It provides information about the position of the clamp unit, pin unit, rest unit, dump unit, etc. This is major input from the customer & it should be never be changed without the permission of the customer. The clamp plan provides the exact location of pins, rest, clamp, etc. It is in more detail. It gives the exact location in X, Y & Z coordinate values to start designing.
• 
• Product assembly process sheet: Product assembly process sheet is a sheet that gives the following detail.
  • Part assembly sequence
  • Sequence of operation
  • Cycle time.
• It gives a detailed process of the completion of the part from scratch to the finished product assembly. It will give a detailed plan of components how they are welded as well as how the product is moving from one assembly to another? & this process plan should not be changed without permission of the customer. Below figure shows.
• 

What is a Clamp plan?

A clamp is a force-actuating mechanism of a fixture. The forces exerted by the clamps hold a part securely in the fixture against all other external forces. Clamping surfaces are subjected to the clamping forces for obtaining invariant location. To fix a part at a particular position, we use the 3-2-1 principle in all types of fixtures to restrict degrees of freedom. Each Panel is fixed keeping the 3-2-1 principle in mind. This principle requires us to use a minimum of 3 rests, 2 pins, and 1 clamp to fix a panel. While we receive the panel, the customer also gives us the coordinates of the panel where he wants us to rest, clamp and locate the panel. We can directly input these coordinates and start designing rests clamps and pins. The Clamp Plan document serves this purpose.

Clamp plan provides the location of pins, rest, clamp, dump, etc. It is in more detail. Clamp Plan is a document that contains the panel drawing mentioning all the places where clamps and rests are to be given. It gives the exact location in X, Y, Z co-ordinate values to start designing. We should never change the clamp position.

What is the purpose of a layout?

Plant layout is a plan of an optimum arrangement of facilities including personnel, operating equipment, storage space material handling equipment and all other supporting services along with the design of best structure to contain all these facilities. An overall objective of plant layout is to design a physical arrangement that meets the required output quality & quantity most economically. It shows all the objects of the manufacturing line like robots, Fixtures, Racks, etc. & also shows the reachability of the robot to the fixtures also called the swept area of the robot (indicated by a circle around robot). It also shows the constraint of space or the space available for the fixture that we are designing. The layout provides information about flow of parts, station pitch, robot station, accessories like tool changer & tip dresser, sub-assembly links, platform height, loading & unloading sequence.

What is Ergo Data?

• Productivity is a powerful tool to improve the standards of living of people & to enhance the quality of work-life (QWL). Ergonomics is concerned with man & his working conditions. Ergonomics aims at providing comfort & improved working conditions so as to channelize the energy, skills of workers into consecutive work. This accounts for increased productivity, safety & reduces fatigue. Ergo data is given when the manual operator is involved to do an operation, so this input is given in regards to how their standard of ergo data is. Ergo data provides information on loading height, working safety, zone of the operator, etc.
• The final assembly of an automobile involves tasks of complex nature. These processes are the least priority for automation. Manual labor is best suited for assembly operations with the aid of minimal level of automation. All the processes have to be improved continuously in order to reduce costs and increase productivity.
• The workers attain various postures; exert force and work continuously in cycle time to accomplish the assembly task. Working along automobile assembly lines is characterized by repetitiveness.
• Ergo data is studied to identify and quantify ergonomics working postures that contributed to the serious development of muscle-skeletal injuries and thus investigated possible contributory their related causes. The below figure show ergonomically correct seating position while working

Weld Study

It includes information on weld gun detail, weld matrix & weld points. There are two types of weld points geo weld point & respot weld point. Geo weld points defines the geometry of part & respot do all other remaining weld points also add strength to geo weld points. Weld study consists of spots in case of spot welding fixture that gives us the position of spot in the form of coordinates. It is most important input that we get from customers. These are the points where the panel is welded. The spots can be geo spots or respots shown in the figure.

The front door inner panel and side bracket of GM sedan car are to be spot welded as shown in Figure1.

The previously spot welded inner panel assembly is then welded with the cross bracket as shown in Figure 2. The work cell and modular fixture designed must be compatible for both the assemblies to be spot welded

Weld spots for each weld assembly are highlighted in Figure 1 and 2 as WP1, WP2, WP3 and so on. Weld points are the locations on which spot welding will be carried out on the automobile sheet metal components. The Weld points forms the base for fixture design, the clamping plan & locating plan are done based on the weld spot distribution. The weld spots for Front door inner panel - side bracket assembly are located as shown in Table 1 with respect to the body line of car.

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

• Percentage completion criteria are followed in the designing stage & dispatch stage of the welding fixture. The percentage completion criteria contain the current status of a task, expressed as the percentage of the task's duration that has been completed. You can enter percent complete, or you can have Project calculate it for you based on actual duration.
• It is followed in the designing stages & dispatch stages of the welding fixture.
• It ensures that how many tasks that we have decided to complete within the stipulated time is complete or not & how much of it is rest to complete &
  whether it is going to be complete or not in the given time.

0-25%- Input & concept design:
This is the initial stage of the project. Input data provided by customers like the functional requirements, customer standard, etc. & after studying those inputs the concept of fixture design is created. After completion of these tasks about 25% of the work is completed.
25-40%- Concept approval & simulation check:
As the concept of fixture design is created & simulation checked it is sent for customer approval. The customer will study all simulations & give his approval. If there are any changes required, then it has to do accordingly & again submitted for approval. This concept design approval from the customer after the study of simulation contributes only 15% of total design work. But with completion of this task 25-40% works was completed.
Design freezing & detailing- 40 to 85%:
This phase involves design freezing after approval of concept design. Freezing means finalizing concept design. The next step is detailing as per customer standard template. With the completion of this stage, almost 85% of work is completed in the designing stage.
Check & final dispatch- 85 to 100%:
After detailing the quality checking team starts inspection of all the data & it will dispatch to the customer if it is ok as per customer standard. If there is an error in drafting it will create issue or mistake in the manufacturing stage. Thus, a percent completion criterion helps us to know where we are in the design process

. Brief about “output” in design?

• It includes data to be given to customer after completion of design stage. The output is 3D models & 2D drawings of the tool.
• 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 clamp, types of supports, clamping forces & supports.

There are two types of tools in fixture design unitized tool & non unitized tool

• In a unitized tool there are multiple units on a common base for e.g. geo fixture, respot fixture, checking fixture, hemming station, etc. Unitized tools require
  two types of sheet key sheet & layout sheet.
• Non- unitized tools that can stand-alone & can be detailed completely on a layout sheet. E.g. Rack, take out
  trolleys, turntables, grippers, etc.
• Key sheet: an index of units & their placement on the tool base. The key sheet shows the placement & location of that particular unit on the tool base where exactly & exact position of the tool base. The key sheet is showing an orthogonal or isometric view of that entire component.
• 
• Layout sheet: A detailed drawing of individual units to include all of their units. Layout sheet is a detailed drawing of that particular tool where we are going to detail of component. The grid view below the figure tells that where exactly the component is located in geometry. This is also helpful in CMM inspection of fixture
• 

The output should compile the following point

a). Approved standard parts should be used wherever possible. This saves lots of time, effort & economical.
b). Design should be as simple & economical as possible. Geometry is complex then fixture design is complex but the approach is trying to design as simple as possible.
c). Design must comply with all current safety & ergonomics standard.
d). Design must provide for controlled & damage-free handling of the product. It should not damage another part.
e). Adequate error-proofing provision must be incorporated in each design by providing proximity switches, rough locators etc. Proximity switches are basically sensors which tells part is present or not in fixture. Rough locators work as poka-yoke to guide the entire panel orientation.

f). The weight of the moving part must be kept to a minimum while maintaining maximum strength. Weight of moving component kept as minimum as possible but it shouldn’t compromise on strength. There is a balance between these two things.
g). Frames & structures are to be simple & sturdy.
h). Design clearance & accessibility for routine maintenance & service. The fixture needs to maintain after a certain period of time so it is easily accessible for maintenance.
i) Motion control must be considered on any moving component. Adequate to control the motion of components like slider, clamp arm so that it does not give any vibration & stays on particular limit by use of hard stopper, shock absorber.
j). Designer is responsible to validate all clamps & weld guns. So that all clams & guns should perform their function without fail

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

• Structuring a design tree implies a process where all the assemblies & parts are named in a specific manner. Different customers have a different set of standards like how to structure a design tree? So they will be give a standard template based on that design tree-structure, which helps us to identify a specific part of an assembly. It specifies the Project number, station number, unit number; part number of each component so that it is easy to identify the parts.
• It is an important process that helps us to identify a specific part or assembly as to which project, tool or unit, it belongs to. This helps us to avoid error during design study, manufacturing, assembly, inspection, etc.
• If parts or assemblies are not named properly or the design tree is not structured properly, it will create confusion to understand & create major possibilities of making an error.
• Naming of a fixture, a unit or a part gives the information as to which project or zone or assembly they do belong.
• It can help us to identify quantity of items of same type or different types that are being used in assembly for e.g. bolt. It actually tells you how many bolts are particularly required in that assembly or unit. Below figure shows design tree structure properly & component shown in key sheet. Each unit has a separate name.
• Structuring the tree is important as it is easier to differentiate the manufacturing parts from standards, bought outs and hardware’s. Order of tree from top to bottom is: designed or manufacturing parts, after those standards parts from customer, bought outs parts are at bottom as shown in below figure. Every design tree base unit is first unit.
• 
• As shown in the above figure naming is done as
  H1L-T9A: Project name.
  RRFRA: Panel name rear panel.
  JG3-: Jig no.3
  00-00: Unit no, part no respectively.
  0R: Right side panel.

. What are units? Mention 5 types of units.

• Welding line fixtures support, clamp & locate two or more panels of a car body in the welding process so that they will get welded accurately at the desired position.
• A Fixture may comprise a single or more units where the product will be placed for holding or clamping or locating in order to perform operations like welding or clinching
• 

A unit, which may have NC block (Mylar), Locating pin, Shim sets, Blade (Dolly Plate), Power clamp, Air cylinder, Riser, Rough locator, Weld gun, Frame etc. to hold or clamp or locate or weld the product at the specified location. According to the 3-2-1 principle of fixture design the units are designed to locate & clamp the car panel to its specified position in fixture while operation is going on.
Ex. Clamping unit, Locator unit, Locating pin unit, Rest unit, Weld gun unit, Base frame unit.

Types of Units:

Unitized tool- Unitized tool is basically tool which is part of multiple units or multiple parts inside it. These are represented by a key sheet. Unitized tools have two types as simple unit & complex unit. The simple unit has a simple design & the approach for manufacturing is also simple, whereas the complex unit has a complex design.
Non-unitized tools: Non-unitized tools are basically one unit. It doesn’t have any processing functionality in it. It has the function to keep components stable. Example of non unitized tools are stands, takeout trolleys, conveyor, turntables etc. where we don’t need key sheet for that only layout sheet is enough to tell orientation as well as position

Rest unit- Rest unit is a unit designed to support car panels using Mylar/ NC block/ rest. The component is rested only, no upper clamp or force applied there.
Fixed pin unit- It is a unit designed to locate car panels using pins. It is unit pin is already fixed it cannot be moved.
Retractable pin unit- It is opposite of a fixed pin unit which can be moved up & down. It can be retracted to certain distance. A retractable pin unit is designed to locate the car panel using pins, but the entire pin package parts will be mounted on the retractable pneumatic cylinder. Each pneumatic cylinder will receive air through valve. When air is given to cylinder it is extended in forward motion & if air is given out it is retracted. Now day’s pneumatic cylinders come with a locking mechanism in forward motion. Below are parts in general.

Rough locator unit- It roughly guides the operator for locating the part.
Sensor unit- It is designed to sense car panel using electrical sensor.
Base unit- It is the unit on which all other units are mounted. It supports all other units

Describe fixed pin units & their purpose?

It is unit designed to locate car panel using pins. It is unit pin is already fixed it cannot move & below are different parts of the unit in general. Fixed pin unit basically have pin, pin retainer, shims/ spacers, block, blade or adaptor plate. Pin retainer support that pin.

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 are come in pack of 0.1, 0.2 & 0.5 mm

Purpose of fixed pin unit: Pin is most important part of fixture & used to restrict rotational as well as translational degrees of freedom of that particular component. Purpose of fixed pin unit is to fix the panel translation motion along two axes and to prevent rotation of panel in the axis of panel.

It supposes to have exact coordinate for it to get fix. Suppose it will move by 0.1 to 0.2 mm from its original positional then entire assembly will not happen orget rejected.

What are the different parts of a fixed unit?

Fixed pin unit consist of riser, blade, block, shims or spacer, pin retainer & pin. All parts are described below.

Riser: Risers can be of L-type, welded or square tube or frame type. These are basically manufactured parts are used to give height to assembly

Blade: Blades are plates attached to riser. Other part likes cylinder, arms etc are mounted on the blade. Chamfer is given here to strengthen the blade. Two Dowel Four Hole arrangement is used to butt blade to the riser.

L-Blocks: L Block is used just to provide the necessary shimming for adjustment. In case of mounting an L block, we should check bolting access as there is already a bolt to tight the pin. Hence, clear hole should be given from L block

Shims/spacer: In fixture, we are providing tolerance to each part mostly manufactured. Those tolerances tend to stack up & reflect together. In order to avoid that we use shims so we can easily adjust after assembly so whatever stack up there we will rectify it through shims. Shims come in thicknesses of 0.1, 0.2, 0.5 etc

Pin: It is used for the location purpose of the panel. Standard Pins should be used as far as possible and the lengths of pins should be reduced to the maximum possible. Generally, pin diameter should be cylindrical grinded to maintain its dimension accurately. Usually, two locating pins are enough to properly locate the workpiece on one plane. There are dozens of styles of locating pins that can be utilized in a design. The different types of Standard Pins are as follows:
Round Pins: These can be Screw secured (PNRS) or Grub Screw secured (PNRG) or Thread secured (PNRT) for Prototype build only. One of the most common pins is a stepped pin with either small or large head.

Diamond Pins: The Diamond Shape is a critical feature that helps with machining inaccuracies and smoother locating operation. When two round head pins are installed onto one plate, the distance between two mounting holes must be extremely precise and even then, the work piece will not be placed on the base as easily as it would with the use of a diamond shape pin. These can be Screw secured (PNDS) or Grub Screw secured (PNDG) or Thread secured (PNRT) for Prototype build only

Pin retainer: Pin retainer support that pin. Pin Retainer is designed to hold the pin in its place and is also used as a rest for the pin. A counter hole is drilled on which pin is fit

What is the purpose of making a rest unit & describe its parts?

Rest unit:

Rest unit is a unit designed to support car panel using Mylar/ NC block/ rest. The 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. Because of this simplicity, the rest unit is combined with other units to reduce the cost of the overall project.

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

There is no cylinder attached to it. It has a rest Mylar, blade & riser & below is different parts of rest unit. The Rest unit is also divided into a simple support unit, multiple support units & a retractable support unit.

Mylar/ NC blocks/ Fingers:

These are parts are used to hold panel. They are globally called as Mylar. Top side Mylar is called as clamping Mylar & bottom side is called resting Mylar. Every clamping Mylar should have resting Mylar. It is jaw type. It prevents panels from deforming while welding. It is hardened to increase its wear strength.

Riser: Risers can be of L-type, welded or square tube or frame type. These are basically manufactured parts are used to give height to assembly. It is machined at mounted ends only to save cost.

Blade: These are plates mounted on the riser. Other parts like cylinder, arms etc are mounted on the blade

Shims/spacer: In fixture, we are providing tolerance to each part mostly manufactured. Those tolerances tend to stack up & reflect together. In order to avoid that we use shims so we can easily adjust after assembly so whatever stack up there we will rectify it through shims. Shims come in thickness of 0.1, 0.2, 0.5 etc

What are the basic fundamentals to design a sensor unit?

Sensor unit: It is designed to sense car panel using electrical sensor. This signal the sensor will be fed to the PLC & so next process will be executed. Sensor unit are used actually in sensing whether panel are there or not or particular component are there or not. Suppose there are 9 no’s of par require for assembly then we have that no. of sensor at least. Whenever operator manually assemble entire component they do the process like fastening, gluing. The sensor will show that particular component is there or if component is missing it will give an error.

Fundamental of sensor unit design:

• Every signal loose panel which are being welded in the tool.
• Each panel should be sensed by 1 to 2 sensors depending on the size of the panel, preferred to be in diagonal opposite ends of the panel.
• Every sensor should be mounted in 3 directions adjustable ways in general.
  Some major sensor manufactures are IFM, Pepperi-Fuchs, SICK, OMRON, etc.
  
  

Types of sensors:
Proximity sensor- It has a sensing range of 5 to 6 mm. It is based on the 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 sensing range is farther away from the proximity sensor.
Photoelectric sensor: A photoelectric sensor is equipment used to discover the distance, absence, or presence of an object by using a light transmitter, often infrared, and a photoelectric receiver. They are largely used in industrial manufacturing. Below fig shows.

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

Rough locators: Rough locators are usually used in loading & unloading of particular part. It is also used to guide. Rough locator unit is apart designed to guide the operator to locate car panel on the pins accordingly. They have slot for adjustment. A rough locator can be of std. part or mate part. It is also work as pokayoke.

Fundamentals of rough locator design.

• Rough locators should be placed at the edge of car panel, which it has to guide using locating pins one can easily restrict movement of entire car panel.
• Rough locator has to be placed in the same angle of the car part edge with minimum distance of 2.5 mm from the edge of car part, so it should no damage panel.
• Rough locators should guide the panel before 10 to 15 mm. to the start of the pin engagement.
• Rough locators should guide the panel in pin arresting direction in general.
• Rough locators should be designed with two slots to mount for easy adjustment. (in general)The slot should be in the direction of car panel guiding.

What is a base unit & describe its parts?

Base Plate: Base Plate is a machined plate made of steel or Aluminum of thickness 25mm to 40mm on which the holes are drilled to mount different units like rest units, clamp units, pin units etc.

Pedestal: Pedestal is a part or an assembly (welded structure) that joins the base plate to the floor plate. The pedestal can be a standard part of a make part, depending on the size and height of the fixture. Standard pedestals are available in different heights. Pedestals are also available in different inclinations. Depending on the size of the base plate; the number of pedestals for a fixture can vary for load distribution

Valve box: Pneumatic valve box includes solenoid valve which supplies air to pneumatic cylinder & their coil. Sometimes a bunch of valves is mounted is called a valve blank.

Trunking channel: Trunking channel which is mounted on the base is used to guide all electrical cable, pneumatic pipe. Base support the entire fixture unit. Trunking Channel is a duct that carries all the electrical and pneumatic connections (wires and pipes) for units of the tool. It has a thickness of a few millimeters.

Eyebolt: They are used to lift the entire base unit, pedestal to support the base plate.

Floor plate: They are used to mount the entire unit & a leveling arrangement such as leveling bolt & pad are provided to the base unit to level the entire unit

What is a dump unit & what are its functions?

Dump unit: Dump unit is where you assemble components if you have a certain constraints. Here you will have a clamp unit, pin unit attached & panel will be assembled. So if you have certain constraints you cannot assemble in a normal way. Dump units used in a different way. It has a dump cylinder & a 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 an operation. The first cylinder dumps the assembly carrying clamp mylars, pins and then this assembly performs the required operation. In this unit, we should make sure that in the open position of the panel, we should be able to remove the panel. Below fig show dump unit.

. What is a slide unit? Mention where slide units are commonly used

Slide unit: Sliding unit consists of a sliding cylinder. It slides between open & close positions. At the end, it has a shock absorber & after that hard stopper. It has a guide rail. It uses a sliding mechanism. It also has a position locking unit for maintenance purposes that don’t allow to move entire unit & sensor unit to sense entire component reached at either side or not & stopper block to control moving. When cylinder opens position locking mechanism unlocks the panel. Then entire panel move to open position using a frictionless guide block. Guide block needs to be lubricated periodically.

Sliding units are basically used in places where you have certain constraints, space constraints. Sometimes, there are too many small panels near each other and there is not enough space as each panel requires resting, location using 2 pins, clamping, and sensing. This becomes even more difficult when a panel is at angles. To solve this problem, a slide unit mounts rest, clamp or pin unit or all of them on a slide using guide rails, guide blocks, a cylinder, locking mechanism, stop blocks and sensors. When a particular panel is to be welded, this slide moves forward, fixes the panel and on completion of operation, slide moves back and gets locked at its position. Similarly, the same is done for other panels.