Week 2:- BiW Fixture Basics Challenge

1. What is the process of project execution activity?

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PROCESS OF PROJECT EXECUTION ACTIVITY:

• The above figure shows the process involved in process execution activities. It is a general activity that is involved in BIW fixture & Tooling.
• It is the starting phase of every project.
• It starts with the basic requirements/RFQ we received from the customer.
• As shown in the figure there are various steps involved in project activities, They will be explained in detail below

1. RFQ:

• RFQ – Request for Quotation.
• In this where the customer gives the requirement/specifications in detail for the given projects in the form of data or documents.
• Also, the customer specifies its technical offer, commercial offer, etc, how the project will be executed & the timeline of the project also will be mentioned.

2. FIRST SPEC: DISCUSSION MEETING:

• After RFQ received, Technical offer, commercial offer, a timeline of the project, etc, will be discussed and prepared from outside.
• In this time required for data study, 3D design concept, simulation validation, quality check, 2d drawing release, bought-outs, manufacturing, assembly, installation & commissioning will be discussed and prepared in the technical offer.
• Based on the technical offer, the commercial offer will be finalized.

 

3. OFFER SUBMISSION:

• After the finalization in the meeting, the offers will be submitted to the customer end. The customer will arrange to get an offer from other suppliers too.
• Based on the technical, cost, quality, standard, and name in the industries, the customer will be finalizing the offer.

4. LOI/PO RECEIPT:

• After an offer has been finalized customer will be releasing the LOI/PO (Purchase Order). Once PO is released, we have to start the work.
• After getting the PO from the customer, we have to prepare the schedule.

 

5. SCHEDULE PREPARATION:

• Once the PO released from the customer, we will be working on the preparation of the schedule which should be matched our planned commitment in the technical offer/customer required time.
• Schedule preparation is nothing but dividing the different activities like kick-off meeting, design data study, DAP, simulate, Quality check 2D detailing, drawing check, Release of BOM, Manufacturing, bought outs of electrical & mechanical components, Assembly of the fixture, paint, trial run out, installation and commissioning at the customer end, etc.
• These activities will be traced in the schedule preparation chart.
• The date-wise schedule should be matched the committed date. Otherwise have to revise the schedule and prepare accordingly by discussing it in the meetings.

6. BOM PREPARATION:

7. DESIGN CONCEPT PREPARATION:

 

• Before design concept, we have to study the data of consumer requirements thoroughly which is carried out in design data study activities.
• During the design data study, we will proceed with rough sketches to get a flow while designing concepts.
• The concept preparation would include the process like load act on panels, clamping process, which spot should be welded first, travel of the gun.
• In this concept preparation, we should conceptualize the basic data like spot plan, cycle time, etc,                                                                                               
• The weld gun should not collapse while traveling, so by considering this have to make a concept preparation.
• To avoid collapses of weld guns or robots during traveling, a spot plan will be done at the initial stage.
• In design concept preparation, the design of the layout is been prepared at a very initial level which gives the information of placements of robots and fixtures.

8. CUSTOMER APPROVAL:

• It is also known as the Design Approval Process (DAP).
• After design concepts, the customer will review the design concepts.
• If the design needs to be made simple or some other correction needs to be done in concept design will be discussed and after meeting the requirement of the customer, they will give approval to the design to go on with further activities.

9. DETAILING & DRAWING RELEASE:

• Once the customer approved the process, the detailing of the fixture parts which is to be manufactured has been done by giving appropriate dimensions and GD&T symbols.
• All the dimensions which are necessary for manufacturing should be included with GD&T in the drawing before releasing the drawing to the manufacturing team.

10. MANUFACTURING/BOP ORDERING:

• The mechanical & electrical parts like sensors, cylinders, etc, which needs for a fixture are ordered as per design specifications

11. MECHANICAL / ELECTRICAL ASSEMBLY:

 

• After the materials ordered received to our end. The quality will check the working conditions and technical specs, which meets our requirement.
• After the quality check, the mechanical & electrical parts are assembled as per design.

12. QUALITY INSPECTION:

 

• After the assembly again the quality check is done.
• In all dimensions, positional accuracy, coordinates are checked using CMM.

13. INTERNAL TRIAL:

• After QC check, internal trials are made to check the operation of the fixture.
• It is the first trial taken in-house, so we will see by putting the assembly in the fixture whether the seating of assembly/panel suited correctly, whether the clamping operation is done properly, also whether the pins are getting into the 

14. ONLINE TRIAL:

 

• The trail will be done automatically made through the control panel. The process sequence of operation is checked as by the designed way.

15. PACKAGING:

• To avoid damage, occur in the fixture while transportation which may also lead to affect the Aesthetic look & proper function of fixture packaging has been done.
• After the trials taken have to get the QC confirmation whether the panels met the standards/specs, given by the customer also whether the fixture meets the customer standards.
• After approval of QC, the packaging is been done as per standards. Certain companies follow certain packaging standards, So the packaging should be one as per customer standards.

16. DESPATCH:

• After the fixture has been packed for delivery as per standards. It’s been despatched to the customer.

 

 

 

Q2. What are the types of joining processes?

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Joining processes:

 

• JOINING COMPRISES a large number of processes used to assemble individual parts into a larger, more complex component or assembly.
• The individual parts of a component meet at the joints.
• Joints transmit or distribute forces generated during service from one part to the other parts of the assembly.

 

 

TYPES OF JOINING PROCESS:

 

• The durability & performance of any structure largely depends on the quality & the design of the component joints.
• The whole structure cannot be made in one piece.
• Two fundamental options for joining materials & components are,

 

1. Metallurgical joining
2. Mechanical joining
3. Chemical joining

1. METALLURGICAL JOINING:

• Metallurgical joining are classified into,

 

• Welding.
• Brazing.
• soldering.

i. WELDING:

 

• The process of joining similar metals by the application of heat is called Welding can be obtained with or without application of pressure and with or without the addition of filler metal, which is known as an electrode. During welding, the edges of these metal pieces are either melted or brought to plastic condition. The welding process is used for making permanent joints, which is obtained by a homogeneous mixture of two materials.

ii. Brazing:

Brazing is a metal-joining process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the adjoining metal.

Brazing differs from welding in that it does not involve melting the work pieces and from soldering in using higher temperatures for a similar process, while also requiring much more closely fitted parts than when soldering. The filler metal flows into the gap between close-fitting parts by the capillary. The filler metal is brought slightly above its melting temperature while protected by a suitable atmosphere, usually a flux. It then flows over the base metal (known as wetting) and is then cooled to join the workpieces together. A major advantage of brazing is the ability to join the same or different metals with considerable strength.

There are different methods/techniques in brazing. They are:

• Torch Brazing: In this method, acetylene, natural gas & butane, or propane are combined with air, or oxygen is used to supply the required heat to melt the filler rod and diffuse the base It is not used for mass production, and flues are used in the form of paste or powder.
• Furnace Brazing: In this process, the heat is supplied by gas or electric heating The furnace can be either box type or continuous type. The preformed shape of filler metal is placed on the parts to be joined before entering the furnace. The use of flux can be avoided if an inert atmosphere is maintained in the furnace. It is used for mass production and the flux is used in the form of a paste.
• Induction Brazing: In this process also, the filler metal is used in the form of preformed The parts are heated by placing within the field of a high-frequency induction coil. The electric and magnetic resistances of the changing induction field are used to produce the eddy current. This eddy current is used to heat the metal. It is also used for mass production and the flux is used in the form of a paste. 
• Dip Brazing: The dip brazing is of two They are: i) Chemical dip brazing: In chemical dip brazing, the parts with preformed filler metal are placed into a molten bath of flux. This method is mainly used for joining large parts. ii) Molten metal bath process: In this process, the assembled parts are first prefixed & then immersed into a molten bath or filler metal. It is used only for joining smaller parts.
• Resistance Brazing: In this process, the filler metal is placed in the joint, Rapid heating minimizes oxidation and the heat-affected zone is
• Laser Brazing & Electron Beam Brazing: The laser & electron beam brazing methods are costly In laser brazing, the laser beam is used to join the metal and the beam produced by the heat source is used to join the metals in electron beam brazing. It is used only in precision work of high value & relating high-temperature materials.

 

iii. Soldering:

Soldering is a process in which two or more items are joined together by melting and putting a filler metal (solder) into the joint, the filler metal having a lower melting point than the adjoining metal. Unlike welding, soldering does not involve melting the workpieces. In brazing, the workpiece metal also does not melt, but the filler metal is one that melts at a higher temperature than in soldering. In the past, nearly all solders contained lead, but environmental and health concerns have increasingly dictated the use of lead-free alloy for electronics and plumbing purposes.

 

 

 

Q3 .What is Resistance Welding & its application in the automotive sector?

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Resistance Welding:

• Resistance welding is the joining of metals by applying pressure and passing current for a length of time through the metal area which is to be joined. The key advantage of resistance welding is that no other materials are needed to create the bond, which makes this process extremely cost effective.
• There are several different forms of resistance welding (e.g. spot and seam, projection, flash, and upset welding) which differ primarily by the types and shapes of weld electrodes that are used to apply the pressure and conduct the current. The electrodes, typically manufactured from copper based alloys due to superior conductive properties, are cooled by water flowing through cavities inside the electrode and the other conductive tooling of the resistance welding machine.
• Resistance welding machines are designed and built for a wide range of automotive, aerospace and industrial applications. Through automation, the action of these machines is highly controlled and repeatable allowing manufacturers to staff production readily.

  

 

Types of Resistance Welding Application:

• Resistance Spot Welding, like all Resistance Welding Processes, creates welds using heat generated by resistance to the flow of welding current between the faying surfaces, as well as force to push the workpieces together, applied over a defined period of time. Resistance Spot Welding uses the face geometries of the welding electrodes themselves to focus the welding current at the desired weld location, as well as to apply force to the workpieces.
• Once sufficient resistance is generated, the materials set down and combine, and a weld nugget is formed. Resistance Seam Welding is a subset of Resistance Spot Welding using wheel-shaped electrodes to deliver force and welding current to the parts. The difference is that the workpiece rolls between the wheel-shaped electrodes while weld current is applied. Depending on the particular weld current and weld time settings, the welds created may be overlapping, forming a complete welded seam, or may simply be individual spot welds at defined intervals.

Projection Welding:

Flash Welding:

 

Upset Welding:

  

 

 

 

Q4.What is fusion welding & types of fusion welding with its application in the automotive sector?

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Fusion Welding

Fusion welding processes are all those welding processes where faying surfaces of parent part as well as filler material meltdown during welding for weld bead formation. So heat is always associated with these processes. External application of pressure is not required for these processes, except for the resistance welding group where substantial contact pressure needs to be maintained during welding for sound joining. The filler material may or may not be applied.

A typical fusion weld has got few zones like (i) fusion zone, (ii) weld interface,

 

• Fusion zone: It consists of a mixture of filler metal and base metal that have completely melted. A high degree of homogeneity is present among the component metals that have been melted during welding. Infusion zone, the solidification occurs by epitaxial grain growth, in which the atoms in the molten metal solidify at the preexisting lattice sites in the unaffected base material. Moreover, the grain structure in the fusion zone has got preferred orientation and they are oriented roughly perpendicular to the weld interface. This results in a coarse columnar grains infusion zone. R. Ganesh Narayanan, IITG The grain structure depends on various factors namely welding technique, metals being welded like similar metals and dissimilar metals welded, usage of filler metal, and the traverse speed at which welding is done.
• Weld interface: It is a narrow boundary that separates the fusion zone from the heat-affected zone. This zone consists of a thin band of base metal that was partially melted during the welding process but immediately solidified without mixing with the metal in the fusion zone. Its chemical composition is generally the same as that of the base metal. Heat affected zone: This zone is between the weld interface and base material. This experience temperatures below the melting point, but sufficient enough to change the microstructure and hence the mechanical properties. The mechanical properties are such that most of the failures occur in this region.

Advantages of Fusion Welding

• The filler material can be applied easily. So a large lacuna can be filled.
• No need to apply external pressure, so primary shape of the components does not matter (a suitable shape is required to uniformly apply pressure).
• Joint design and edge preparation are not crucial as these parameters affect only achievable penetration.
• More than two components can easily be welded at a step.

Disadvantages of Fusion Welding

• The process is associated with distortion and residual stress generation as it involves melting and solidification.
• A palpable heat-affected zone (HAZ) exists in the welded components. HAZ is always considered as the weak portion of is welded assembly.
• Mechanical properties of parent materials are also severely affected by intense heating.
• Joining dissimilar metals by fusion welding is a challenging task, especially if the metals have a substantially different melting point and coefficient of thermal expansion.
• There are so many types of Fusion welding. Let us discuss some of the fusion welding processes below:

i. Shielded Metal Arc Welding (SMAW):

 

• Shielded metal arc welding (SMAW), also known as manual metal arc welding (MMA or MMAW), flux shielded arc welding, or informally as stick welding, is a manual arc welding process that uses a consumable electrode covered with a flux to lay the weld.
• An electric current, in the form of either AC or DC from a welding power supply, is used to form an electric arc between the electrode and the metals to be joined The workpiece and the electrode melts forming a pool of molten metal (the weld pool) that cools to form a joint. As the weld is laid, the flux coating of the electrode disintegrates, giving off vapors that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination.
• Because of the versatility of the process and the simplicity of its equipment and operation, shielded metal arc welding is one of the world's first and most popular welding processes. It dominates other welding processes in the maintenance and repair industry, and though flux coat arc welding is growing in popularity, SMAW continues to be used extensively in the construction of heavy steel structures and in industrial fabrication. The process is used primarily to weld iron and steel but aluminum nickel and copper alloys can also be welded with this method.

ii. Gas metal arc welding (GMAW):

Electro-Gas Welding (EGW):

 

 

 

 

Q5.What is the 3-2-1 principle?

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3-2-1 principle is used for the design of the fixtures

• For a fixture designer, the major portion of design time is spent deciding how to locate the workpiece in the fixture.
• You know that any free body has a total of twelve degrees of freedom as below:
• 6 translational degrees of freedom: +X, -X, +Y, -Y, +Z, -Z  And
• 6 rotational degrees of freedom:

 

• Clockwise around X-axis (CROT-X)
• Anticlockwise around X-axis (ACROT-X)
• Clockwise around Y-axis (CROT-Y)
• Anticlockwise around Y-axis (ACROT-Y)
• Clockwise around Z-axis (CROT-Z)
• Anticlockwise around Z-axis (ACROT-Z)

 

PRIMARY LOCATOR:

First, the three locators or supports are placed under the workpiece. It will be positioned on the primary locating surface also known as a datum. It will restrict 5 degrees of freedom.

 

SECONDARY LOCATOR:

The next two locators are normally placed on the secondary surface, restricting an additional 3 degrees of freedom.

 

TERTIARY LOCATOR:

This locator is positioned at the end of the part. It restricts 1 degree of freedom

 

 

 

 

Q6, Define Body coordinate system?

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Body Co-ordinate System:

• The body coordinate system has been widely used in the automotive industry for drawing of body parts, product & process design. A coordinate system is a reference system consisting of a set of points, lines & surfaces, used to define the positions of points in space in either two or three dimensions. In general, BCS is also called as car line & body line.
• Car lines are the (grid lines) shown on the fixture, which virtually represent the same location in BIW. All the car line on fixture displays the coordinate at corner for reference. With these lines one can easily relate the location in BIW.
• Sometimes single coordinate hole is given in fixture that also represents the car line coordinates, from that reference point fixture is made & can be inspected. Body coordinate are mentioned near hole. Below figure show car line on fixture.

• Automotive sheet metal components are designed in CAD (Computer aided Design) software e.g. CATIAv4-v5, UG, ProE, Ideas, In any cad tool, there is a default axis system X, Y, Z.
• Lets us consider if every designer starts the design of the BIW Door Assembly part a default axis system, then it will be difficult to assembly or position the part with respect to each other.
• Due to avoid this issue, BIW car panels are designed with reference to car axis means at their Original position of the final car built.
• Reference axis system of the software is used for the design of the various features of the parts (e.g. hole, fillet, threads,) To correlate the position of all the automotive components during the final assembly the axis system of the vehicle is used. Most of the time vehicle axis system and software axis system is the same. e.g. In most of European OEM, The X-axis represents the length of the vehicle Y-axis represents the width of the vehicle Z-axis presents the height of the vehicle. Y-axis is considered to be located at the front axle. All BIW welding fixtures are designed with reference to the car line
• These datum schemes provide a reference system for all part surfaces and features using body coordinates. Figure below illustrates a typical body coordinate system. This system replaces the traditional X, Y, and Z directional designations with fore/aft (X), in/out (Y), and up/down or high/low (Z). The 0,0,0 point of the car is the front, lower, and center position.

• VEHICLE ORIENTATION:

 

• All vehicle product drawings are identified numerically relative to three vehicle planes described and shown below.
• X= longitudinal direction (fore & after-F/A) or (Front O line-FOL). Y= transverse direction (Cross car-C/C) or (Centre O line-COL).
• Z= Vertical direction (Up & down- U/D) or (Bottom O Line-BOL).
• The origin of the body coordinate system (OX) is defined at the front centre of a vehicle. It indicates a length of car & the coordinate system (OZ) is below its underbody indicates height of car & the coordinate system (OY) its starting point is the centre of car body indicates width of car.
• Maintaining X,Y & Z coordinates in fixture is very important factor.
• We should try that the coordinates of locating & clamping points should not be in three decimal (e.g. X=100.124, Y=245.127, Z=450.458)
• They should be in the whole nos or max upto 1 decimal. Once these coordinate are maintained automatically the BIW base structure is mainteined.

 

 

 

 

Q7. Elaborate Body plane system & its essentials.

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BODY PLANE SYSTEM:

• Body planes are the reference plane in an automotive car. These planes are used to define the GD & T of all car parts in a automotive domain.
• Body planes are three mutually perpendicular imaginary planes. These are generally considered to be present at the driver position or sometimes at the engine location or at the front end of the car depending on the customer.
• The measurements from the body planes to the parts are called as body line dimension.
• These body planes are called as
• FOL Front “O” line.
• COL Centre “O” line
• BOL Body “O’ line
• The measurement along FOL or X-axis is called as F/A Frontaft.
• The measurement along COL or Y-axis is called as C/C Cross car.
• The measurement along BOL or Z-axis is called as U/DUP down.

 

• In below figure origin is somewhere below driving sheet as it depends or changes from customer to customer. But axis system is commonly same.

• It defines the exact position of each product in the vehicle w.r.t. a fixed origin.
• It ensures flawless design for assembly.
• While designing lines, all the designs are carried out relative to the bodyline, viz, fixture, turn table etc.
• It assists in easy location of different parts in a vehicle.
• It aims in creating a standardized system.
• It assists in quality checks.