Week 2:- BiW Fixture Basics Challenge

Master's Certification in BIW Fixture & Plastic Design

(Automotive BIW Fixture Design)

REPORT

Assignment-2

By Ravi Ahuja

Q1.

Process of project execution activities can be like this flow chart

In this process first of all customers present their requirements like time duration, cost etc. Then we would reply back with the possible changes according to the feasibility of the timeline of the process which is sent to the customer and after agreement of both the sides the process of designing the product starts.Each of these processes are explained in detail below.

1. RFQ:A request for quotation (RFQ) is a business process in which a company or public entity requests a quote from the supplier for the purchase of specific products or service.

2. 1^stspec discussion meeting: After RFQ the commercial offer, the technical offer, the timeline of the project etc., and will be discussed and prepared from outside. During this time required for the 3d concept design and simulation, quality check, 2d drawing release, bought outs, manufacturing, assembly, installation and commissioning will be discussed and prepared in the technical offer.

Fig.:An example of technical offer for manual welding.

3. Offer submission: After the finalizing everything in the meeting the offer is submitted to the customer. Generally, after comparing from other similar orders from different suppliers on the basis of Technical, cost, quantity, standard and name in the industries the customer will finalize the offer.

4. LOI/PO Receipt: After offer has been finalized customer will release the LOI/PO(Purchase order).Once PO is released work has to start.

5. Schedule preparation: After PO release schedule is prepared which has to meet the timeline in the technical offer. Schedule preparation is the process of providing time limits with start and finish date to the activities like design data study, DAP, simulation, quality check, 2D detailing, drawing check, release of BOM, Manufacturing, bought outs, assembly of fixture, paint, trial run out, installation and commissioning etc.

Fig.:Schedule preparation chart

6. BOM Preparation: Bill of materials like cylinders, motors, etc., which is required for the project are prepared.

7. Concept design preparation: To make a concept design we have to first study the data given by customer according to the requirement of the customer. During this process we make rough sketches of the required design to get the flow of the concept and mental image of the product and its surroundings. Concept preparation process includes the process like load act on panels, clamping process, which spot should be welded first.In concept design preparation the design of layout are prepared at very initial level which gives the information of placements of robots n fixtures.

8. Customer approval: It is also know as design approval process(DAP). After concept design is completed customer review the concept design and suggest some changes, corrections or any reduction in cost during a meeting with the supplier. After the agreement of the customer design is approved to proceed for further operations.
9. Detailing and drawing release: After design is approved the detailing of the fixture parts which are to be manufactured is 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 drawings before releasing the drawing to the manufacturing team.

10. Manufacturing/BOP ordering: The mechanical and electrical parts like sensors, cyinders,etc., which are needed to be ordered as per design specifications.

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

12. Quality Inspection: After the assembly again the quality check is done. In this all dimensions, positional accuracy, coordinates are checked using CMM.

13. Internal Trial: After quality inspection internal trials are done o check the operation of the fixtures. It takes place in-house and are assembled to check if seating is correct or clamping is sufficient.

14. Online trial: This is done automatically though a control panel to check if fixtures work like they are designed.

15. Packaging: To avoid damaging the product while transportation which can affect the aesthetic look and proper function of the fixture. After QC confirmation packaging is done as per certain standards. Different companies follow different standards but one should always go for the standards specified by the customers.

16. Dispatch: After packaging it is dispatched from the supplier’s premises.

17. Installation as per layout: Layout design has to be prepared to place the robots and fixtures at very initial level during concept design phase.

18. Trials and training at customers: Production trials will be taken place and the specifications presented during the technical offer like no of assemblies in a certain time is shown to confirm the operation of the fixtures.

19. Buy off meeting: After trials and training at the customer end, buy off meeting takes place. In this meeting customer finalizes the fixtures and if there are some changes needed they are expressed in the meeting.

20. Final Handover: The fixtures and the documents supporting fixtures/production will be submitted to the customer. Documents like Clamp validation documents, ergo sheets, BOM, Charts are prepared and submitted to the customer. Every automobile industry follow some standards to maintain documents as per ISO, IATF. IATF-The international automotive task force is a group of automotive manufacturers which aim to provide improved quality products to automotive customer worldwide.

Q2.

Joining process:Joining consists of large number of processes used to assemble individual parts into a larger and more complex assemblies.

Joints transmit forces during service from one part to another.

Types of joining processes: Performance of an assembly depends upon individual components and strength of the joints between them.

There are three types of joining processes:

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

Metallurgical joining

Welding can be broadly classified into 3 types which are:

1. Fusion welding
2. Pressure welding
3. Brazing/Soldering

Fusion welding melts the base materials and a welding rod used for joining the base material i.e., filler material. Pressure welding melts base mechanically through friction, pressure or electric current. Brazing/Soldering uses a filler material(brazing paste) applied on joints.

Fusion welding: One or both of the base materials are melted. Arc welding is the common example of fusion. Laser welding is also used but using robot arms. In complicated product assembly lines, such as for automobile parts, robot and human welding are used depending on the characteristics or conditions of the process.

Classification of fusion welding:

1. Arc welding
2. Gas welding
3. Thermit welding
4. Arc welding:

• Arc welding is one if the most used welding processes used in the industries.
• There are many varieties of arc welding processes according to the material and quality of the weld. Like gas shielded arc welding in which a gas is used to protect the weld from the atmosphere such as TIG, MIG and MAG.
• Arc welding including gas shielded arc welding is divided into two types: Electrode consumable type & Non electrode consumable type

Non- consumable (non-fusible) electrode type	l Tig welding l Plasma welding
Consumable (fusible) electrodetype	l Shielding metal arc welding l MAG welding l MIG welding l Electro gas arc welding(EGW)

Fig.: Classification of arc welding

Types of arc welding:

• MIG
• TIG
• Shielded metal arc welding
• Plasma arc welding
• Submerged arc welding
• Electro slag arc welding
• Atomic Hydrogen welding

MIG: It is and arc welding technique in which an inert gas is used to protect the weld from the atmosphere and is released from the nozzle with welding gases.It is a consumable electrode type welding process.

TIG: Tungsten inert gas welding uses a non consumable tungsten electrode while everything else is same as MIG welding. Hence it is a non consumable process.

2. Gas welding:

• Gas welding is the process in which edges of the metallic pieces are melted together to form a weld and join them together.
• Pressure is applied only during pressure gas welding.
• Flame is produced at the tip of the torch. Gases mainly used are acetylene, hydrogen, propane and butane.
• Metal 2mm to 50mm thick can be welded together.

There are 3 types of Gas welding processes that are used commonly:

1. Oxy-acetylene welding
2. Oxy-hydrogen welding
3. Air-acetylene welding

4. Thermit welding: Thermit welding is the process of joining by heat released from an exothermic reaction called thermit reaction. It consists of Aluminium powder and mixture of a metal oxide. The molten metal during the reaction works as a filler material and joins the workpieces after solidification.

Thermit mainly consists of 78% iron oxide and 22% aluminium powder during welding of steel workpieces.

The proportion of 78 and 22 is determined by chemical reaction of combustion of aluminium.

8Al + Fe₃O₄ = 9Fe + 4Al₂O₃

The reaction products are heated upto 4500 degrees farenheit. Liquid iron fills the sand mold built around the welded parts, the slag(aluminium oxide), floating up, is then removed from the weld surface.

Fig.: Thermit welding

Pressure Welding:

Pressure welding uses a collision or blast to burn part of the welding part of metal equipment and welding them under pressure. The process is also called solid-state welding. Pressure welding is a common term for welding methods that weld working pieces using machine pressure in the welding part (weld joint).

The use of mechanical pressure allows for price control of the process. Pressure welding has been widely used in FA (factory automation).

Major methods include gas pressure welding, friction welding, resistance welding, diffusion welding, ultrasonic welding, and explosion welding. Friction stir welding (FSW), a variant of friction welding, is becoming increasingly popular. This process can improve the combined efficiency by using a rotating tool to raise the basics with a rotating collision while applying strong pressure to the joining phase.

Types of pressure welding:

1. Resistance welding
2. Diffusion welding(DFW)
3. Friction welding(FRW)
4. Ultrasonic welding(USW)
5. Cold pressure welding
6. Forge welding
7. Explosion welding(EXW)

Fig.: Types of Pressure welding

1. Resistance welding: Resistance welding, sometimes called electric resistance welding (ERW), is a process in which metals can be assembled by applying pressure and conducting a powerful electric current using a combination of steel to heat welding and dissolving metals, combined.

There are, as shown in the figure, 8 types of resistance welding processes. But generally only some of them are used i.e.,

1. Resistance spot welding
2. Projection welding
3. Resistance seam welding
4. Butt welding
5. Flash butt welding

Some of them will be discussed here.

1. Resistance Spot welding: Resistance spot welding has been used extensively in the automotive industry for the joining of steel and in the aerospace industry for air-frame components made from aluminium alloys. It is one of the oldest and simplest forms of resistance welding, in which a weld nugget is produced by passing an electric current between the two metal components whilst they are held together between electrodes, typically made from copper-based alloys due to its superior conductive properties.

Fig.:Resistance spot welding

2. Resistance seam welding: Resistance seam welding is a variation of the standard welding form, however instead of a single nugget, a series of scattered nuggets are produced. This is usually done by replacing the normal welding electrode with the wheels, turning as the components are fed between them. Thus the process produces a continuous welded seam instead of a single layer. Seam welding is often used in the production of small sheets, non-leaky containers such as fuel tanks, and is generally unsuitable for welding aluminum.

3. Projection welding: Resistance projection welding is a type of resistance welding where electricity, power, and welding time are based on the proposed 'guess' of the universe. Projection welding is usually used for welds using thicker materials than thin metal pieces where welding is usually required, and usually not metals. It is mainly used in the electronics, automotive and construction industries.

4. Butt welding: Resistance butt welding is a process in which two parts of the same cross section can be joined together in a single operation that occurs simultaneously in each affected area, rather than just in small areas. Butt welding is usually on ropes and cords with small diameter dimensions, usually up to 16mm in diameter.

5. Flash Butt welding: Flash butt welding is the same, but in this case the power transmission is provided primarily by the heat resistance from the components themselves. This is the fastest form of resistance welding when the welder joins the parts by applying a certain pressure, and then transfers the heavy current to the joint which heats up the misalignment of the area. After the weld has produced sufficient heat, the components are connected by applying heat and pressure simultaneously. This produces a forge butt weld with no molten metal left in the joint.

2. Diffusion welding:

• Diffusion-welding is a solid state-controlled system, which generates heat between the target members through long-term application of high pressure at high temperatures.
• The characteristic features of this process are that they do not introduce macroscopic modification or related movements in any welded parts and that it does not melt the basic metals.
• In order to keep the bonded surfaces clean they are kept under vaccu conditions to prevent contamination.
• We can also weld dissimilar metals like steel to tungsten, steel to niobium etc.

Fig.: Diffusion welding

3. Friction welding: Friction welding (FRW) is a phase of solid welding processes, in which heat is produced by mechanical friction between the moving part and the vertical, and at the same time the lateral forces called 'irritation' are applied to the parts, to remove the plastic and mix the material.

4. Ultrasonic welding: Ultrasonic welding uses ultrasonic energy at high frequencies (20-40 kHz) to generate low amplitude (1-25 µm) mechanical vibrations. The vibrations generate heat at the joint interface of the parts being welded, resulting in the melting of the thermoplastic material and the formation of a weld after cooling. Ultrasonic welding is the fastest known welding technique, with weld times typically between 0.1 and 1.0 seconds.

5. Cold welding:

• Cold welding is a solid-state welding process that requires little or no heat to join two or more metals together. Instead, the energy used to bond the materials together comes in the form of pressure. During the cold welding process, no metal is liquefied or even heated to a remarkable degree.
• Under normal conditions almost all metals have some kind of oxide layer, even though that is not visible to the eye. These metal oxides form a barrier that prevents the metal atoms on the material from pressing together and bonding with each other. However, once the oxide layer is removed, the metal atoms are able to bond with each other with sufficient pressure.
• To remove the oxide layer, various mechanical and chemical methods are used. Wire brushing, degreasing and other techniques are used to ensure that the metal surface is free of oxides. Metals also need to be somewhat ductile. Industrial machinery is used to create the sufficient amount of pressure required to form a metallurgical bond.

6. Forge welding: Forge welding is a process used to join two pieces of metal together by heating them to a high temperature and then joining them together. Developed in the Middle Ages, forge welding is one of the oldest methods of joining metals. Forge welding is an essential technique and an invaluable skill for a blacksmith.

This is the traditional way of making chains, swords, railroad sticks and gates in a blacksmith's shop. It is also used in making cookware and agricultural equipment. Giving the blacksmith the ability to forge a wide variety of metals in one, forge welding is a versatile and essential skill in the smithy.

Fig.: Forge welding

7. Explosive welding: Explosive welding is a solid-state welding process that has great potential for joining dissimilar material combinations with extremely different physical properties, such as aluminum to copper, aluminum to carbon steel and aluminum to stainless steel.

In explosive welding, a compressive force produced by the explosion of explosives is used to connect sheets of overlapping metal. The parts to be joined are arranged at an angle of 1–15° towards each other, depending on the material and method, and are prepared with a layer of explosives on top. After ignition the joining areas are moved against each other at high speed. Connecting to the local plastic deformation of the contact area is constantly.

Brazing/Soldering

Brazing: Brazing is a joining process that differs from other joining processes such as welding because it does not melt the base metal during joining. Although brazing is classified into types of soldering, it uses a high temperature to join. It also requires very closely fitted parts. The filler metal flows through the capillary action into closely spaced pars.

Types of brazing:

• Torch brazing
• Furnace brazing
• Induction brazing
• Dip brazing
• Resistance brazing
• Infrared brazing
• Blanket brazing
• Electron beam and laser brazing
• Braze welding

Some of them are discussed here

• Furnace brazing: uses furnaces to heat the work piece.
• Vacuum brazing: furnace brazing performed in vacuum.
• Induction brazing: utilizes alternative EM field to heat the work pieces and flux and filler material is placed at the joint.
• Resistance brazing: Uses heat generated by electric current passing through work piece.
• Infrared brazing: Uses heat generated by high powered infrared lamp.

Soldering: Soldering is a joining process used to join different types of metals together by melting solder. Solder is a metal alloy usually composed of tin and lead that is melted using a hot iron. Iron is heated to temperatures above 600 degrees Fahrenheit which then cools down to form a strong electrical bond.

1. Soft Soldering

The main important feature of soft soldering is that the temperature they require is less than 400 oC. The filler metals used in soft solder are alloys consisting mostly of lead with a melting point below 350 oC. In soft soldering, the filler material is melted by applying heat to the parts to be joined, and this heat is also useful for firmly bonding the workpiece. In soft soldering, capillary action occurs when the workpieces are too close to each other. Soft lead is the basic requirement of this type of soldering process and hence it is called soft soldering.

2. Hard Soldering

This is also sometimes called "silver soldering". This type of soldering process produces stronger joints than soft soldering. Hard soldering is mostly used to join metals like silver, gold, copper. According to the temperature at which the solder melts, the filler metals are described as easy, medium or hard. The extra hard solder used in this process has a silver content of up to 80% and a melting point of up to 740 oC. A flux made of boric acid and alcohol is used to keep the metal and solder clean. Hard soldering or silver soldering is used by jewelers and plumbers because they require strong joints.

3. Brazing

Brazing gives us the strongest joints but at the same time requires the hottest temperatures. In brazing, a torch or high heat source is mostly needed to meet this large temperature requirement. This process is mostly used in the repair of wrought-iron furniture etc. Brazing does not involve melting of the base metal, so it gives a clean joint without the need for any kind of finishing process.

• brazing torch
• brazing furnace
• silver brazing
• vacuum brazing
• dip brazing

Fig.: Soldering

Mechanical joining: Mechanical joining includes bolting, riveting, caulking, shrink fitting and folding, all of which use mechanical energy to join work pieces.

1. Riveting: A rivet is a mechanical fastener composed of a head at one end and a cylindrical stem (called a tail) at the other that has the appearance of a metal pin.

When installed the rivet is either drilled, placed or punched into a hole, subsequently deforming the tail, holding the rivet in place.

The rivet deforms by pounding or breaking the tail, making the material flatter and usually causing the tail to expand to one and a half times the size of the original diameter of the stem.

The tail at the ends has a dumbbell shaped appearance that complements the riveted joint.

Riveting can form either lap or butt joints with a variety of different rivet configurations including single, double and zig-zag structures.

Fig.:Riveting

2. Caulking: Caulk is a flexible material used to seal air leaks through cracks, gaps or joints between stationary building components and materials less than 1 quarter inch wide. For components that move – doors and operable windows, for example – weatherstripping is the appropriate material.

Fig.:Caulking

3. Bolting: Bolted joints are one of the most common elements in construction and machine design. They consist of fasteners that capture and join other parts and are secured with the mating of screw threads.

There are two main types of bolt joint designs: stress joints and shear joints.

In a tension joint, the bolted and clamped components of the joint are designed to transfer an applied stress load through the joint to the clamped components by design of an appropriate balance of joint and bolt stiffness. The joint must be designed in such a way that the clamp load is never overcome by external tension forces acting to pull the joint apart. If the external tension forces exceed the clamp load (bolt preload), the clamped joint components will separate, leading to relative motion of the components.

The second type of bolt joint transfers the applied load to the shear of the bolt shank and depends on the shear strength of the bolt. The stress load on such a joint is only incidental. A preload is still applied but the consideration of joint flexibility is not as important as in the case where the load is transmitted through the joint under stress. Other shear joints like this do not impose a preload on the bolt as they are designed to allow rotation of the joint about the bolt but use other methods of maintaining bolt/joint integrity. Joints that allow rotation include clevis linkages, and rely on a locking mechanism (such as lock washers, thread adhesives and lock nuts).

Fig.: bolted joints

4. Shrink fitting: Shrink-fitting is a technique in which an interference fit is achieved by a relative size change after assembly. This is typically achieved by heating or cooling a component prior to assembly and allowing it to return to ambient temperature after assembly, employing the phenomenon of thermal expansion to form the joint. For example, the thermal expansion of a piece of metal drainpipe allows a builder to fit a cooler piece. As the fused pieces reach the same temperature, the joint becomes tense and strong.

Other examples are the mounting of a wrought iron tire around the rim of a wooden carriage wheel by a wheelwright, or the mounting of a steel tire to the wheel of a railway engine or rolling stock. In both cases the tire will overheat and become slightly larger than the diameter of the wheel, and fit around it. After cooling, the tire shrinks, binding tightly in place. A common method used in industry is the use of induction shrink fittings which refers to the use of induction heating technology to pre-heat metal components between 150˚C and 300˚C, allowing them to expand and allow the insertion or deletion of another. Component. Other methods of shrink-fitting include compression shrink fitting, which uses a cryogen such as liquid nitrogen to cool the insert, and shape memory coupling, which is achieved through a phase transition.

Fig.: Shrink fitting

Chemical joining: Chemical joining methods for molded products include a method with the use of adhesives and a method that melts the surfaces of the molded products with the likes of an organic solvent.

Adhesive bonding: Adhesive Bonding is the process of joining two surfaces together, usually with the creation of a smooth bond. This may involve the use of glue, epoxy, or one of a wide range of plastic agents which bond either through the evaporation of a solvent or through curing via heat, time, or pressure.

Glues have tended to create relatively weak joins but with the use of new self-curing adhesives these bonds are now close to the strength of the materials themselves. As a result, gluing is now the preferred method of joining for many applications, particularly when the bond is not exposed to prolonged heat or weathering.

Fig.: adhesive bonding

Q3.

Resistance welding: Resistance welding, sometimes called electric resistance welding (ERW), is a process in which metals can be assembled by applying pressure and conducting a powerful electric current using a combination of steel to heat welding and dissolving metals, combined.

There are several different forms of resistance welding (such as spot and seam, projection, flash and upset welding) that differ primarily by the type and size of weld electrodes that are used to apply pressure and conduct current. goes. The electrodes, typically manufactured from copper-based alloys due to their superior conductive properties, are cooled by water flowing through cavities inside the electrodes and other conductive tooling of the resistance welding machine.

Resistance welding machines are designed and manufactured 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 easily produce workers.

Types of Resistance Welding Applications:

Resistance spot welding, like all resistance welding processes, creates a weld by using heat generated by the resistance to the flow of welding current between the facing surfaces, as well as force to push the workpieces together, applied over a set period of time. Resistance spot welding uses the geometry of the face of the welding electrode to focus the welding current at the desired weld location as well as to apply force to the work piece. Once sufficient resistance is generated, the material sets and joins, and a weld nugget is formed.

Working principle of resistance spot welding:

• Resistance spot welding working on the following concept:
• In a resistance spot welding process, in which two or more metal sheets are joined together through a spot weld.
• The workpiece to be welded is pressed between the tips of the copper electrodes and high current at low voltage is passed through the workpiece.
• Due to the resistance offered by the workpiece (sheet metal) to the flow of current, the temperature at the contact surfaces rises to the fusion point and the weld is formed as a nugget.
• A nugget is a weld that forms in the middle of a workpiece.
• No filler material is used in the resistive spot welding process.
• The operation is repeated 'n' numbers. several times to get the spot weld at the desired location.

Applications of Resistance Spot Welding:

Resistance spot welding is used for:

• joining vehicle body parts
• Fuel Tank
• railway tracks
• Pipes of gas oil and water pipelines
• domestic radiator
• turbine blades

The advantages of resistance spot welding are as follows.

• easy automation
• less smoke
• cost effectiveness
• No filler material is required.

The disadvantages of resistance spot welding are as follows.

• Less strength in case of discontinuous welds.
• High equipment cost.
• The thickness of the welded sheet is limited - only 6 mm.

Fig.: Resistance spot welding

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 a 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 be individual spot welds only at defined intervals.

Resistance Seam Welding (RSEW) Working Principle

Resistance seam welding (RSEW) is very similar to spot welding (RSW), but circular rotating electrodes are used here. And here we get continuous weld which is air tight (if the process is correct).

The seam-welding form of the resistance process is a series of overlapping welds. Two or more sheets of base metal are usually passed between electrode rollers, as shown in the following figure, which also transmit the current and mechanical pressure required to produce a welded seam that is normally Typically gas-tight or liquid-tight.

Applications of RSEW

• Girth welds are also possible in rectangular or square or circular shape.
• Can be welded to most metals (except copper and some high percentage copper alloys)
• Butt Welding can be done.

Advantages

• Gas tight and liquid tight joints can also be made.
• Overlap is less than spot or projection welding.
• Single seam weld and parallel seam can be produced simultaneously.

Disadvantages

• The welding process is confined to a straight line or an equally curved line.
• Metal sheets with a thickness greater than 3 mm can cause problems when welding.
• The design of the electrodes may need to be changed to weld metal sheets with obstructions.

Fig.:Resistance seam welding

Projection Welding

Like other resistance welding processes, projection welding uses the heat generated by the resistance to the flow of welding current, as well as force, to push the workpieces together, which is applied over a set period of time. Projection welding localizes the weld at predetermined points using projection, embossing or intersections, all of which concentrate heat production at the point of contact. Once the weld current generates sufficient resistance at the point of contact, the projections collapse forming the weld nugget.

Solid projections are often used when welding fasteners to parts. Embossing is often used when joining sheet or plate materials. An example of projection welding using material intersections is cross-wire welding. The intersection of the wires in this case localizes the heat generation itself, and hence the resistance. In the process the wires are set into each other to form a weld nugget.

Working Principle:

Copper electrodes are used in projection welding because copper is a very good conductor of heat and electricity.

The two pieces of metal to be joined are placed between the two electrodes and the electrodes are placed between the plates as shown in the above figure. A large pressing force is to be applied on the electrode by two platen, upper and lower platen.

After that current flows through the system. As the current passes, heat is generated due to the internal resistance of the metal workpiece.

This heat generated by the resistance is concentrated at the projections on the workpiece because when two workpieces are put together, the sheets touch only at the points of the projections. Usually two or three projections are welded at the same time.

When welding workpieces of unequal thickness to be made into thicker workpieces and welding projections to dissimilar materials with higher thermal conductivity.

When pressure is applied to the workpiece by the platens, these projections collapse and fuse to form weld nuggets at the place of projection. Therefore a quality weld is made and the two metal workpieces are successfully welded.

Advantages of Projection Welding:

1) This projection welding requires very little supply of current. As less current passes through the electrode, the life of the electrode increases. This process also requires less pressure for welding.

2) Unlike spot welding, there is no limit on the thickness of the metals to be welded.

3) Unlike spot welding, more than one spot can be created in a single operation.

4) It is suitable for process automation.

5) No filler metals are used in this process. Therefore, clean weld joints are obtained in this process.

6) This process is also effective in welding joints at complex locations.

7) This process gives a good heat balance when welding.

Disadvantages of Projection Welding:

1) Projection manufacturing in Projection Welding is a complex process and time consuming. Only a skilled person can make projections of various required sizes like spherical projections.

2) This process is not applicable to all types of workpieces, the structure of the workpiece has to be considered when choosing this welding process.

3) It cannot be applied to some kinds of brass and copper.

4) Projections cannot be made in thin workpieces.

5) Equipments are expensive.

Applications of Projection Welding:

• Projection welding is most commonly used when special nuts, small fasteners, special bolts, studs, and similar parts are used as projection on the part to be welded.
• Projection welding is also used for welding parts of refrigerators, condensers, refrigerator racks, grills, etc.
• In addition, projection welding is used in automobile workshops, shipbuilding works, and sheet metalwork.

Fig.:Resistance projection welding

Flash welding

Like other resistance welding processes, flash welding uses heat generated by resistance to the flow of welding current, as well as force, to push the workpieces together, which is applied over a set period of time. Flash welding is a resistance welding process that produces resistance using a flashing action. This action is created by using very high current densities at very small contact points between workpieces. At a predetermined point after the flashing process begins, force is applied to the workpieces, and they are moved together at a controlled rate. The rapid upset produced by this force forces oxides and impurities out of the weld.

Working Principle:

• Initially the two halves which are to be joined are placed at some distance and facing each other.
• One part is attached to the fixed clamp and the other part is attached to the movable clamp.
• Now, air is present between the two parts and when there is a continuous flow of electricity, the electric ions start jumping from the part held in a fixed clamp to the part in the movable clamp.
• The parts to be combined complete the single turn secondary of a heavy duty transformer.
• After that, the part in the movable clamp is gradually brought closer to the part that is clamped in the fixed clamp. As it gets closer, the gas between the two parts begins to ionize.
• Hence, heat is evolved in the air present between the two joining parts. Now as the heat is developed, both the ends of both the parts get heated.
• Heat is generated at the interface and most of the molten metal is expelled as flash and the moving clamp is advanced keeping a constant gap until a suitable temperature is reached at the interface.
• Resistance arises due to the air present between the ends of the two parts and due to this resistance heat develops between the two parts.
• Since resistance is used to develop heat in this welding, this welding is the type of resistance welding.
• When the appropriate temperature is reached, using the movable clamp a very high force is applied from the part in the movable clamp towards the part in the fixed clamp and the two parts are forged together. This applied force is in an axial force.
• After applying force, the ends of both the parts which are in plastic state come in contact with each other.
• When the two ends collide, the molten metal flashes outward, and this outward movement of the metal causes the glowing effect. Because of this flashing effect, this welding is known as flash welding.
• During the flashing process, a weld is developed between the two ends. This welding process creates a neat, clean and strong joint.
• When the joint is fully formed, the AC power supply is turned off.
• The two halves are then held in clamps for some time so that they can solidify. After solidification, we get a very strong joint using this welding process.

• When preheating welding heavy parts the parts are exposed several times and then they are separated to form resistance heating but the onset of flashing is delayed.

This welding process is generally used to weld the channel section of the beam.

This welding process can be used in mass production as this welding process takes very less time

Advantages of Flash Welding:

1. I) The power required in this welding process is less.
2. ii) There is no need to prepare the weld surface.

iii) This process is very cheap.

1. iv) Metals with different melting points can be welded using this flash welding.
2. v) This process provides up to 100% strength factor.

Disadvantages of Flash Welding:

1. i) The potential for fire hazards is high.
2. ii) The welding machine is very heavy.

iii) Metal is destroyed during flashing and upsetting.

1. iv) This process is very expensive due to high consumption of electricity.
2. v) The workpiece often loses its straightness during this welding process. The straightness of the workpiece needs to be maintained.

Applications of Flash Welding Process:

1. i) It is used for fitting metal sheets, bars, rod fittings etc.
2. ii) This welding process is used for manufacturing automotive and airplanes.

iii) It is also used in manufacturing of home appliances, refrigerators and agricultural implements.

Fig.: Flash welding

Upset welding

Like other resistance welding processes, upset welding uses heat generated by resistance to the flow of welding current, as well as force to push the workpieces together, which is applied over a set period of time. Similar to flash welding, in upset welding the workpieces are already in contact with each other, so no flashing occurs. The pressure is applied before the current starts, and is maintained until the process is completed.

Fig.: Resistance upset welding

Working principle:

Pressure is applied before heating begins and is maintained throughout the heating period. The equipment used for upset welding is similar to the equipment used for flash welding. It can be used only if the parts to be welded are equal in cross-sectional area. Enclosed surfaces must be prepared very carefully to provide proper heating. The difference from flash welding is that the parts are clamped in the welding machine and force is applied to bring them tightly together. The high-amperage current is then passed through the joint, which heats the adjacent surfaces. When they are heated to the appropriate forging temperature a disturbing force is applied and the current is stopped. The high temperature and high pressure of work on adjacent surfaces cause cohesion. After cooling, the force is released and the weld is complete.

Advantages of upset Welding :

1. Upset welding is more suitable for welding many alloys that are difficult to weld using fusion welding. The metal retains the base metal characteristics because the base metal does not melt during welding.
2. The welded joint is stronger as the hot work structure is maintained.
3. The introduction of composite materials and the incorporation of secondary materials on the base metal are almost minimal.
4. Upset welding is primarily adapted to forming structures much larger than conventional resistance welding.

Applications of Upset Welding:

1. This process is mainly used for welding of small cross section non-ferrous materials such as bar, rod, wire, tube etc.
2. Upset welding is used to seal capsules, small vessels and containers,

3, It is applied in welding steel-rail.

Q4.

Fusion welding: Fusion welding joins the edges of different materials by heating them to a melting point. Sometimes, a filler material is necessary when there are gaps in the joint you are making. The material will undergo several phase transitions as the heating process creates a heat affected zone (HAZ) on the material.

Fig.: Fusion welding and its types

Working principle:

Fusion welding occurs when a molten base material is joined with a molten filler. The heat that melts the material can be applied to the joining area or developed externally to the intended weld point. For example, the electrical contact between the edges of the material you are welding can pass current through resistance to develop the heat you need.

It is important to understand the different types of fusion welding processes when discussing fusion welding. On the basis of heat source, fusion welding processes can be classified as follows:

1. Arc Welding Process

Arc welding is one of the better methods of fusion welding process. True to propagation, arc welding joins two parts (or more) using an electric arc. This is because electric arcs generate heat levels that reach up to 6,000 degrees Fahrenheit, making them ideal for fusing hard metals and materials. Additionally, arc welding is also suitable for offshore applications where you can perform fusion welding under water. Typically, arc welding processes include:

• Shielded Metal Arc Welding (SMAW): Commonly used for welding of non-ferrous and ferrous materials in almost all conditions.In this process Weld is protected by some inert gas from the atmosphere to prevent contamination.

Fig.:Shielded metal arc welding

• Metal Gas Arc Welding: An electric arc is forming between the material and the consumable wire electrode, causing them to melt and fuse. The shielding gas is used for MIG welding to avoid airborne contaminants and oxidation.

Fig.:Metal gas arc welding

• Tungsten Inert Gas Welding: Non-consumable tungsten is used to form an arc between the basal plate and the electrode. To avoid oxidation and atmospheric pollution, an inert shielding gas is used.

Fig.:Tungsten inert gas welding

• Plasma Arc Welding (PAW): In this arc an electric arc is formed between the torch nozzle and the electrode. Argon gas (plasma), usually in the chamber, is ionized by an electric arc.

Fig.:Plasma arc welding

• Submerged Arc Welding (SAW): It uses a continuously fed consumable electrode with a flux. The flux prevents splatters and sparks and becomes conductive in the molten state, so the current provides the electrode and material path.

Fig.:Submerged arc welding

• Flux Cored Arc Welding (FCAW): In this process the consumable electrodes are continuously inserted along with the flux; Hence it acts as an alternative to SMAW.

Fig.:Flux cored arc welding

Advantages of Arc Welding

• Arc welding has high speed as well as welding efficiency
• It includes a simple welding apparatus.
• It is simply moveable.
• Arc welding forms the physically powerful bond between the welded metals.
• It provides reliable welding quality
• Arc welding offers a superior welding atmosphere.
• The power source of this welding is not costly.
• This welding is a quick and consistent process.
• The welder can utilize ordinary domestic current.

Disadvantages of Arc Welding

• A high expert operator is necessary to perform arc welding.
• The rate of deposition can be incomplete as the electrode covering tends to burn and decrease
• The length of the electrode is 35mm and needs electrode changing for the entire production rate.
• These are not clean for reactive metals such as titanium & aluminum

Applications

• Used in the weldings of sheet metals
• For welding thin, ferrous & non-ferrous metals
• Used to design pressure & pressure vessels
• The developments of piping in industries
• Used in the domains of automotive and home furnishing
• Industries of Shipbuilding
• Used in the manufacturer of aircraft & aerospace
• Auto body restorations
• Railroads
• Industries like construction, automotive, mechanical, etc
• Gas Tungsten Arc Welding is used in aerospace industries to connect many areas like sheet metals
• These weldings are used for repairing dies, tools, and mostly on metals that are made with magnesium & aluminum.
• Most of the fabrication industries use GTAW to weld thin workpieces, particularly nonferrous metals.
• GTAW weldings are used where extreme resistance to corrosion as well as cracking over a long period of qualities are required.
• It is used in space vehicles manufacturing
• Used to weld small-diameter parts, thin wall tubing, making it applicable in bicycle industries

2. Laser Beam Welding (LBW)

As the name suggests, it is a fusion welding process that uses a focused laser beam as its energy heat source. Higher heat levels have useful precision rates for joining metals and polymers. It is a rapid and automated process that uses light to generate heat.

Unlike electron beam fusion welding processes, you can do LBW in air instead of vacuum.

Fig.:Laser beam welding

Advantages:

• Easily automated process.
• Controllable process parameters.
• Very narrow welds can be obtained.
• High quality of weld structure.
• Very small heat affected area.
• Different materials can be welded.
• Very small delicate workpieces can be welded.
• Vacuum is not required.
• Less deformation of the workpiece.

Disadvantages:

• The initial cost is high. The cost of equipment installed in LBW is high.
• The maintenance cost of LBM is high.
• Fractures can occur in some metals due to rapid cooling.
• Highly skilled workers are required to do LBW.
• The welding thickness is limited to 19 mm.
• The energy conversion efficiency in LBW is extremely low. It is usually less than 10%.

Applications of Laser Beam Welding Process

• It is a staple in the automotive industry. Therefore, it is used in the area where large quantities of production are required.
• It is employed for high precision welds. Since it does not use any electrodes, the final weld will be lighter but stronger.
• Laser welding is also often used in jewelry making.
• However, laser beam welding is used in the medical industries to hold metals together on a smaller scale.

3. High Energy Welding Processes

It is a fusion welding process that produces heat through light irradiation. To fuse different materials, you blast radiated light onto the surface of the material, causing them to heat up and begin to melt. The workpieces will later merge as they cool slowly.

Advantages of electron beam welding

1) Clean process to be done in vacuum chamber:EBW is free from potential gas contamination because welding is performed in a vacuum chamber, resulting in a high quality weld with no oxidation.

2) Good for fragile assemblies:Since EBW uses localized heating (small heat affected zone, or HAZ) and has minimal heat input, the surrounding material remains cool. This allows welding of delicate products and close proximity to heat sensitive areas such as populated electronics enclosures. EBW has the same HAZ as laser beam welding, which is less than 5% of similar TIG welds.

3) High quality and integrity from machine-controlled automation:EBW has high power with minimal distortion or damage. In addition, it requires very little post-weld machining due to its accuracy, making it suitable for welding precision parts. Since the machine is programmable, it is possible to have a custom weld-profile. Our quality is ensured through AS9100 Rev D, AS9104 and NADCAP certifications as well as bespoke OEM approvals.

4) Repeatable accuracy and quality control:Precise parameters can be machine-programmed to reproduce large quantities of welds while maintaining accuracy.

5) Joining dissimilar materials:One of the biggest advantages of EBW is its ability to weld materials with different melting points from copper to stainless steel. From a cost and performance perspective, EB welding has the potential to weld high cost nickel alloys to relatively low cost stainless steels.

For example, the corrosive performance of a nickel alloy that is only required in a particular area within the product's design can be EB welded into a low-cost stainless steel that is not subjected to the same corrosive environment as nickel. is alloy. Heat-treated components can be EB welded to highly reflective metals such as platinum. Refractory metals such as titanium can also be EB welded.

6) No filler material used:Typically, no filler material is used in the EB welding process. It is the basic material that is melted to form the joining and thus the assembly.

7) Penetration Range:A variety of weld penetrations are possible from 0,005” (0,127mm) to 2” (50mm). It also has a high depth-to-width ratio (10:1 to 40:1 in many cases).

8) High welding speed:Although EBW has a longer cycle time than laser beam welding, it achieves higher welding speeds of up to 30 mm per second.

9) Cost Savings:EBW is a cost-effective method of welding, requiring only a single pass of the electron beam, unlike TIG, MIG and arc welding, which support multiple passes of the heat source.

The EBW process can also provide weight savings if the product design allows for it, which can further drive benefits such as reduced lead times and inventory costs.

Disadvantages of electron beam welding:

For a balanced overview let's look at some of the reasons why EBW may not be suitable…

1) Setup Cost:The initial outlay for the equipment is expensive. Considering these costs, a company would need a large work-flow to justify the investment. Unless you have a large amount of throughput over a long period of time, outsourcing your EBW needs is usually more cost-effective.

2) Equipment:The complex technical equipment requires expert operators. If you are starting out with a clean piece of paper, you will need to invest in professional training and hire experienced qualified welding engineers.

3) Size Limitations:The size of the components to be welded is limited by the size of the vacuum chamber at your disposal.

4) X-rays and Radiation:The safety standards are exceptionally strict as both X-rays and radiation are present during the welding process.

4. Electronic Beam Welding (EBW)

The electronic beam welding process involves high-velocity electrons to join the workpieces together. The electrons generate intense heat that enters the material causing their solid state to become molten. EBW welds are deep and thin and can only be achieved under specific atmospheric conditions.

Fig.:Electronic beam welding

Advantages of electron beam welding

1) Clean process to be done in vacuum chamber:EBW is free from potential gas contamination because welding is performed in a vacuum chamber, resulting in a high quality weld with no oxidation.

2) Good for fragile assemblies:Since EBW uses localized heating (small heat affected zone, or HAZ) and has minimal heat input, the surrounding material remains cool. This allows welding of delicate products and close proximity to heat sensitive areas such as populated electronics enclosures. EBW has the same HAZ as laser beam welding, which is less than 5% of similar TIG welds.

3) High quality and integrity from machine-controlled automation:EBW has high power with minimal distortion or damage. In addition, it requires very little post-weld machining due to its accuracy, making it suitable for welding precision parts. Since the machine is programmable, it is possible to have a custom weld-profile. Our quality is ensured through AS9100 Rev D, AS9104 and NADCAP certifications as well as bespoke OEM approvals.

4) Repeatable accuracy and quality control:Precise parameters can be machine-programmed to reproduce large quantities of welds while maintaining accuracy.

5) Joining dissimilar materials:One of the biggest advantages of EBW is its ability to weld materials with different melting points from copper to stainless steel. From a cost and performance perspective, EB welding has the potential to weld high cost nickel alloys to relatively low cost stainless steels.

For example, the corrosive performance of a nickel alloy that is only required in a particular area within the product's design can be EB welded into a low-cost stainless steel that is not subjected to the same corrosive environment as nickel. is alloy. Heat-treated components can be EB welded to highly reflective metals such as platinum. Refractory metals such as titanium can also be EB welded.

6) No filler material used:Typically, no filler material is used in the EB welding process. It is the basic material that is melted to form the joining and thus the assembly.

7) Penetration Range:A variety of weld penetrations are possible from 0,005” (0,127mm) to 2” (50mm). It also has a high depth-to-width ratio (10:1 to 40:1 in many cases).

8) High welding speed:Although EBW has a longer cycle time than laser beam welding, it achieves higher welding speeds of up to 30 mm per second.

9) Cost Savings:EBW is a cost-effective method of welding, requiring only a single pass of the electron beam, unlike TIG, MIG and arc welding, which support multiple passes of the heat source.

The EBW process can also provide weight savings if the product design allows for it, which can further drive benefits such as reduced lead times and inventory costs.

Disadvantages of electron beam welding:

For a balanced overview let's look at some of the reasons why EBW may not be suitable…

1) Setup Cost:The initial outlay for the equipment is expensive. Considering these costs, a company would need a large work-flow to justify the investment. Unless you have a large amount of throughput over a long period of time, outsourcing your EBW needs is usually more cost-effective.

2) Equipment:The complex technical equipment requires expert operators. If you are starting out with a clean piece of paper, you will need to invest in professional training and hire experienced qualified welding engineers.

3) Size Limitations:The size of the components to be welded is limited by the size of the vacuum chamber at your disposal.

4) X-rays and Radiation:The safety standards are exceptionally strict as both X-rays and radiation are present during the welding process.

5. Friction Welding

When applying friction welding technology, different materials are joined together using mechanical friction. There are many ways to perform mechanical abrasion on aluminum, steel and sometimes wood materials.

Mechanical friction is a difficult process. However, the heat you generate will soften both materials, forming a bond after mixing and subsequent cooling.

There are several ways to do friction welding, which determines the type of joints you will have. These processes include:

• Friction stir welding
• Rotary friction welding
• Friction Stir Spot Welding
• Linear Friction Welding

When applying friction welding, there is no need for shielding gas, flux or filler metals. This process is ideal for applications that are considered lightweight and for non-weldable materials such as some types of aluminum alloys.

Fig.: friction welding

Application:

• For welding tubes and shafts.
• It is mostly used in the aerospace, automobile, marine and oil industries.
• Components like gears, axle tubes, valves, drive lines, etc. are friction welded.
• It is used to replace forging or casting assembly.
• Hydraulic piston rods, truck rollers bushings, etc. are joined by friction welding.
• Used in electrical industries for welding copper and aluminum equipment.
• Used in pumps for welding pump shafts (stainless steel to carbon steels).
• The gear lever, drill bit, connecting rod etc. are welded by friction welding.

Advantages:

• It is environment friendly process without generation fumes etc.
• Narrow heat affected zone so that there is no change in the properties of the heat sensitive material.
• No filler metal is required.
• Welding strength is strong in most cases.
• easily automated.
• High welding speed.
• High weld efficiency.
• Various types of metals can be welded by this process.

Disadvantages:

• It is mostly used for round bars of the same cross section.
• Non-forgivable materials cannot be welded.
• Workpiece preparation is more important
• High installation cost.
• Combined design is limited.

6. Resistance Welding Processes

This is one of the fastest fusion welding options you can apply, making it a better choice for the automotive industry. Today, there are two resistance welding processes. These are:

Resistance spot welding

It works by generating heat at two electrodes. However, the bonding process depends on the properties and thickness of the material. The process limits the welding voltage to a single location when fusing different workpieces.

Resistance seam welding

It is a form of spot welding that involves a sequence of joint-alternating nuggets. It uses transfer discs to replace spot welding electrodes to join materials together.

Fig.:Resistance welding

Applications

Today, there are many uses for fusion welding, including the construction of mega-structures such as ships, airplanes, welded pipes, bridges, automobiles, and pressure vessels. Fusion welding is also used to seal explosives, among other functions.

Since fusion welding uses a good heat source, you can fuse the thicker part of the workpiece with relative ease. The primary uses of fusion welding include:

Fusing metal

The primary difference between fusion welding and soldering or brazing is the high heat process involved. Brazing and soldering do not melt the base metal, whereas fusion welding sometimes must include a filler material.

When various parent metals are subjected to high heat intensities, the increased temperature forms a molten state where they join and form a weld bead upon cooling. The result can be a stronger joint than the original material.

Fusion Welding for Joining Wood Materials

Wood welding also uses heat that is generated from mechanical friction to join different materials. The materials are subjected to immense pressure followed by a linear friction movement to create the heat that bonds the work pieces firmly.

The process is fast and allows the joining of wood materials without using nails or adhesives within seconds. It is also a better way to preserve the wood design while strengthening the final work piece.

Advantages of Fusion Welding

• Easy use of filler material when filling a large gap when joining different workpieces.
• The initial shape of the materials does not matter. Hence there is no need for external pressure.
• No need for edge preparation or design as they will affect the heat penetration.
• Fusion welding allows more than two-parent materials to be joined firmly together.
• The fusion welding process is fast and straightforward, making it the best solution for industrial use.

Disadvantages of Fusion Welding

• It is difficult to join metals with different melting points.
• Profound heat-affected zones (HAZ) are evident on welded components. HAZ is the weakest part of a welded workpiece.
• There are cases where the mechanical properties of the workpiece materials get compromised due to intensive heating. Such instances occur when using filler materials and different metals.

Q5.

3-2-1 Principle:

Principle of Location in Jig and Fixture:

The principle of location is discussed here with the help of the most popular example which is available in any book covering jigs and fixtures. First of all it is important to understand the problem.

Any rectangular body has three axes with multiple x-axis, y-axis and z-axis. It may be greater with any of these axes or any of its movement may be left on these three axes. Also the body can rotate about these axes. So the total degree of freedom of the body with which it can move is six. It is necessary to prevent all degrees of freedom (DOF) by arranging suitable location points for the body to be processed and then clamping it in a fixed and required position. The basic principle used to locate the points is desirable below.

Detection - Principles and Methods:

3-2-1 Principle of Location Used in Jigs and Fixtures:

[1] This is also known as the six-pin or six-point location principle. In this, three adjacent positions of the blank (workpiece) are resting against pins 3, 2, and 1 respectively, which hold 9 degrees of freedom.

[2] The remaining three degrees of freedom are arrested by three external forces usually provided by direct clamping.

Fig.: 3-2-1 principle used in fixture design

3-2-1 Principle Statement:

The 3-2-1 principle states that six locators are sufficient to limit the required degrees of freedom of any workpiece. Movement is restricted by the use of clamps and locators. A three-pin base may restrict five motions and a six-pin may restrict nine motions.

Working of the 3-2-1 Principle:

For this look at the picture below;

Fig.: Example used in working

[1] The workpiece rests on three pins A, B, and C that are inserted into the base of the fixed body.

[2] The workpiece cannot rotate about the axes XX and YY and cannot move downwards.

[3] Thus the five degrees of freedom 1,2,3,4 and 5 are arrested.

[4] Two pins D and E are inserted into the fixed body in a plane perpendicular to the plane containing pins A, B and C.

[5] Now the workpiece cannot rotate about the Z-axis as well as it cannot move to the left.

[6] Therefore the addition of pins D and E restricts three more degrees of freedom, namely 6, 7, and 8.

[7] Another pin F in the second vertical face of the stationary body blocks the degrees of freedom 9.

The above method of mounting the workpiece to the fixture is called the 3-2-1 principle.

Q6.

Body Co-ordinate system in BIW:

The body co-ordinate system has been widely used in the automotive industries for drawing body parts, products and process design.

A co-ordinate system is reference system consisting of set of point, lines and surface used to define the position of points space in either two or three dimension.

In general body co-ordinate system is also called as car line and body line.

Fig.:Body coordinate system

Fig.:Reference frame

Q7.

Body Planes

Body planes are the reference plane in an automotive car. These planes are used to define the GD&T of all car parts in 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 customers.

The measurement from the body planes to the parts are called body line dimensions.

These body planes are called as,

1. FOL- Front ‘O’ line
2. COL- Centre ‘O’ line
3. BOL- Body ‘O’ line
4. The measurement along FOL or X axis is called as F/A or Front aft.
5. The measurement along COL or Y axis is called as C/C or cross car.
6. The measurement along BOL or Z axis is called as U/D or up down.

Fig.: Body planes

Essentials of body planes:

Body lines dimensions are essential for the reason stated below.

1. It defines the exact position of each product in the vehicle with respect to a fixed origin.
2. It ensures the flawless designing for assembly.
3. While designing lines, all the designs are carried out relatie to body lines, VIZ.fixtures, turn table etc.
4. It assists in easy location of different parts in a vehicle.
5. It aims in creating a standardized system.
6. It assists in quality check.