Week 2:- BiW Fixture Basics Challenge

OBJECTIVE :

• To explain about the process of project execution activity.
• To state the types of joining processes.
• To eleborate on Resistance Welding & its application in the automotive sector.
• To elaborate on Fusion welding & types of fusion welding with its application in the automotive sector.
• To discuss about the 3-2-1 principle.
• To define Body coodrinate system.
• To elaborate Body plane system & its essentials.

1. To explain about the process of project execution activity.

• Project Execution Activity is the initial phase in every project.
• It describes the sequence of activities which has to be followed during a process.
• The various processes involved are mentioned below

RFQ

• Request for Quotation shortly known as RFQ is received from the customer end.
• It has all the requirements of the customer as per which the manufacturing has to be performed.
• It consists of the technical asspects, commercial aspects, project completion time.

First Spec Discussion Meeting

• Once the RFQ is received, a discussion will be carried out regading the customer inputs.
• Feasibility of the project, completion time, technical aspect will discussed.
• Based on the technical aspects a commercial offer will be finalized.

Offer Submission

• Once the discussion over all the aspects discussed are summarized.
• These aspects are finally offered to the customer end.
• Customer will get offers from various other sources as well.
• Based on the comparison, an optimum offer will be finalized.

LOI/PO receipt

• Once the offer is finalized , the customer will release the LOI/PO which is the purchase order.
• This is an indication for the process to start from the manufacturer end.

Schedule Preparation

• Once the LOI/PO is received, scheduling starts.
• Scheduling defines how this project is going to be processed further.
• It provides a proper sequence in which the activities are to be followed to achieve maximum output.
• This schedule must be able to match paramaters which was offered to the customer durint offer submission.

BOM Preparation

• Billi of Material is prepared once the scheduling is done.
• A BOM is a structured, comprehensive list of the materials, components and parts required to manufacture or repair a product, as well as the quantities in which the materials are needed and their names, descriptions and costs.
• A BOM also includes instructions for procuring and using these materials.

Design Concept Preparation

• Here the Data is first received as input from the customer in form of 3D data or 2D drawings.
• These data will be studied initially inorder to proceed further.
• After examining it properly, the design concepts are further created to meet the customer requirements.

Customer Approval

• The created design concepts will be sent to the customer to review them.
• The customer checks if it is in line with all the technical aspects which was proposed earlier.
• If any changes requried will be made.
• Once the customer is satisfied with the results the process will be carried on further.

Detailing and Drawing Release

• Once all the necessary changes are made, a detailed drawing is made fromm the manufacturer end using GD & T.
• GD&T is an acronym that stands for Geometric Dimensioning and Tolerancing. It is a symbolic language used by designers to communicate manufacturing constraints and tolerances clearly.

Manufacturing/BOP ordering

• The Mechanical and Electrical parts which are required for the manufacturing process of the component will be ordered.

Mechanical / Electrical Assembly

• After receiving all the required parts, the parts will be initially checked for quality.
• Upon clearing the quality check, these parts will be assembled to produce the final component.

Quality Inspection

• Once the assembly is done, another Quality check is done on the finished component.
• The dimensions, roughness, tolerances and accuracy are checked.

Internal Trial testing

• After the Quality check is done, internal trials are performed with the component.
• These trials are performed inorder to check for theproper functioning of the component.

Online Trial

• Online trial is performed automatically through control pannel.
• It also checks the feasibility of the assembly in an automated way.
• It is sent to the customer for approval.

Packaging

• Once the customer approves the assembly, a component is sent to the customer for trial.
• This packaging is done as per the packaging standars followed in industries.

Dispatch

• Once proper packaging is done, it is dispatched to the customer.

Installation as per layout

• An initial installation will be done as per the layout.
• This ensures the mounting position of the component.
• This layout is done as per the customr requirements.

Trials and Training at customer

• After the installation , trials will be performed at the customer end.
• These trials are to ensure that the number of components are produced as stated in the offer submission.
• The quality of the components are also checked to make sure they are up to the standards as proposed.

Buy off meeting

• This is the pen ultimate stage of this project activity which occurs after the trial and training at customer end.
• All the components are reviewed by the customer, any necessary changes are made.

Final Handover

• Once all the reviews are over, if the customer is satisfied then the product will be handed over to the customer
• This marks the end of the Project Execution Activity.

2. What are the types of joining processes?

Assembly is an important step for manufacturing solid products, especially when the shape of the product is complicated having multifarious geometrical features. It is neither feasible nor economical all the times to directly produce a product having intricate shape. In such scenario, making small simple parts and joining them together is the best possible way.

Joining consists of a large number of processes used to assemble two or more parts together, irrespective of their composition, properties, features, shapes, etc.

By definition, joining is one of the manufacturing processes by which two or more materials can be permanently or temporarily joined or assembled together with or without the application of external element in order to form a single unit

Types of Joining

Joining processes are typically divided into three categories

• Mechanical joining
• Welding
• Chemical joining

Mechanical Joining

• Mechanical joining – also called joining by forming – has become interesting for the automotive industry due to the request to reduce fuel consumption and thereby emissions.
• In order to reduce weight on the car body, the usage of lightweight materials in the body-in-white application has increased.
• This includes aluminium, high-strength steel alloys, polymers, and composites.
• Here the different type of mechanical joining becomes important.
• All mechanical joining methods are cold forming techniques.
• One general benefit for all mechanical joining methods is the mobility of the material after joining. At the same time mechanical joining offers an impressive strength.

Types of Mechanical Joining

• Riveting
• Bolting
• Hemming

Riveting

• Riveting is a forging process that may be used to join parts together by way of a metal part called a rivet.
• The rivet acts to join the parts through adjacent surfaces.
• A straight metal piece is connected through the parts. Then both ends are formed over the connection, joining the parts securely.

Bolting

• In this metal joining process, the metallic parts are joined together by means of Bolt/Screw.
• This Process is widely used in assembling of parts are to be joined temporarily or joints which require periodic maintenance.
• Two main types of loads on bolted joints - Tension Shear Bolting.

 

Hemming

• Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to achieve a tight fit.
• Normally hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges.

Welding

• Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion.
• When heated or pressurized for a certain amount of time, metal starts melting.
• By melting the adjoining sections of two materials to be joined (base material or filler material) to make them blend together to form penetration and then cooling that section, you can join materials into one piece.
• This is the basic mechanism of welding.

Types of Welding process

Chemical Joining

This type of joining comprise of Adhesive bonding.

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.

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

Resistance welding allows welders to join two metal workpieces together by employing the principle of heat generation through electric resistance.

An electric current is passed to the metal sheets through weld electrodes that apply force to the sheets.

The key advantage of resistance welding is that no other materials are needed to create the bond, which makes this process extremely cost effective.

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

The various types of resistance welding are

• Spot resistance welding.
• Seam resistance welding.
• Projection resistance welding.
• Flash resistance welding.
• Butt resistance welding

 

Spot Welding

• In this process, the parts to be joined are held firmly between two heavy electrodes, which are connected in the secondary circuit of the step-down transformers.
• he maximum resistance exists at the contact surface of the two parts being joined and high heat is developed.

• The heat developed fuses the workpiece at the electrode spot.
• At the same time pressure is applied to the workpiece through the electrodes and welding takes place.
• Current supply and amount of time must be sufficient for proper melting of interface surfaces.
• The current stopped flowing but the pressure applied by the electrode remained for a fraction of a second, while the weld cooled rapidly.
• Subsequently, the electrode is removed and brought to contact another location.
• This will form a circular nugget and its size depends on the size of the electrode.

Seam Welding

• Similar to spot welding but in this a continuous weld is produced by passing the work between rotating wheel-shaped electrodes, which exert the welding pressure and also conduct the welding current.
• Seam welding may be continuous or intermittent.

• First, the rollers are exposed to the workpiece.
• A high amount of ampere current is passed through these rollers.
• This interface surfaces will melt and form a weld joint and the rollers start rolling on the work plates.
• This will form a continuous weld joint.
• The movement time of the weld and electrode is controlled to assure that the weld overlaps and the workpiece is not too hot.
• Seam welding is used to make airtight joints.

Projection Welding

• Like other Resistance Welding Processes, Projection Welding uses heat generated by resistance to the flow of welding current, as well as force to push the workpieces together, applied over a defined period of time.
• Projection Welding localizes the welds at predetermined points by using projections, embossments or intersections, all of which focus heat generation 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.
• Embossments are often used when joining sheet or plate material.
• An example of Projection Welding using material Intersections is cross-wire welding.
• In this case the intersection of the wires themselves localizes heat generation, and therefore resistance.
• The wires set-down into one another, forming a weld nugget in the process.

 

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, applied over a defined period of time.
• Flash Welding is a Resistance Welding Process which generates resistance using flashing action.

• This action is created using very high current density at very small contact points between the workpieces.
• At a predetermined point after the flashing process has begun, force is applied to the workpiece, and they are moved together at a controlled rate.
• Rapid upset created by this force expels oxides and impurities from the weld.

Butt Welding

• The butt welding differs from flash welding, in that no arcing takes place between the surfaces being joined.
• The heat is produced solely by the electric resistance at the butting surface to the flow of current.

Advantages of Resistance welding

• No filler metal is required.
• Similar and dissimilar metals can be welded.
• High skilled labour is not needed because of the simple and fully automated process.
• It has a high production rate.
• It is an environmentally friendly process.
• This process has a high welding speed.

 

Diasdvantages of Resistance welding

• The equipment cost of resistance welding is high.
• The thickness of the workpiece is limited due to the current demand.
• It is less suitable for high conductive materials.
• It has a high electric power required.
• The weld joints have low tensile and fatigue strength.

Applications in Automotive sector

• Resistance welding has a wide range of applications in Automotive sector such as BIW features.
• It is used in the welding of metal doors.

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

Fusion welding is the welding process in which two or more materials of similar composition or melting points are joined or fused with each other by melting the materials.

In many of the fusion welding processes, the filler material is added to the molten pool of metal required but some fusion welding can be carried out without using the filler material.

The filler material is added to increase the strength of the weld joint.

The welds made without filler materials are called autogenous welds.

If the filler material used and the parent material are the same, then the weld produced in this type of welding is called homogeneous weld.

If the filler material used and the parent material are different, then it is called a heterogeneous weld.

Types of Fusion Welding

The various types of fusion welding are

• Arc Welding
• Oxy-Fuel Welding
• Laser Beam Welding
• Thermit welding
• Induction Welding

 

Arc Welding

• Arc welding refers to the group of welding processes in which the metals are heated to melting points by an electrical arc.
• In some arc welding processes pressure is also applied to the workpiece for better weld strength and quality.
• Most of the arc welding process makes use of filler material.

Arc Welding is further classified into the following types,

• Shielded Metal Arc Welding (SMAW)
• Submerged Arc Welding (SAW)
• Tungsten Inert Gas Welding (TIG)
• Metal Inert Gas Welding (MIG)
• Plasma Arc Welding (PAW)

Shielded Metal Arc Welding (SMAW) - It is also known as manual metal arc welding (MMA or MMAW), flux shielded arc welding or stick welding. Suitable for welding ferrous and non-ferrous materials in all positions.

Metal Inert Gas Welding (MIG) - It isalso known as Gas Metal Arc Welding (GMAW). MIG and MAG welding are the most common arc welding processes, in which an electric arc forms between a consumable wire electrode and the workpiece leading them to melt and join. Both use a shielding gas to protect the weld from airborne contaminants, or oxidation in the case of MIG welding.

Tungsten Inert Gas Welding (TIG) - It is also known as Gas Tungsten Arc Welding (GTAW). This arc process uses a non-consumable tungsten electrode to create the arc between the electrode and the base plate. An inert shielding gas is used to protect from oxidation or other atmospheric contamination. This process can be used autogenously on thin parts, but will require the addition of a wire, rod, or consumable to be added for thicker parts.

Plasma Arc Welding (PAW) - This process uses an electric arc created between an electrode and the torch nozzle. The electric arc ionises the gas (usually argon) in the chamber creating what is called a 'plasma.' It is then forced through a fine bore copper nozzle that constricts the arc and directs it to the workpiece, allowing the plasma arc to be separated from the shielding gas (which is usually made from a mixture of argon and hydrogen).

Submerged Arc Welding (SAW) - This frequently-used arc welding process uses a continuously-fed consumable electrode and a blanket of fusible flux which becomes conductive when molten and provides a current path between the workpiece and the electrode. The flux also prevents spatter and sparks while suppressing ultraviolet radiation and fumes

Oxy-Fuel Welding

• Oxy-fuel welding is the type of welding process in which oxygen is used as fuel to produce a flame that heats and joins two metal surfaces.
• This process is also known as oxy-acetylene welding.
• This welding process uses a combination of oxygen and a flammable gas mostly acetylene to create a hot flame to join objects.
• Oxygen and fuel are mixed in the right proportion within a handheld torch or blowpipe to produce a hot flame with a temperature of about 3200 degrees Celcius.
• As steel melts at 1500 degree Celcius, this is the only welding process which can produce such high temperature by combining oxygen and acetylene to melt steel.
• So steel can be welded using this welding process only. While other non-ferrous metals with low melting points can be welded by using a mixture of oxygen and gases like hydrogen, propane, or coal gas in the oxyfuel welding process.

Laser Beam Welding

• Laser Beam Welding is a fusion welding process in which two metal pieces are joined using a laser.
• Laser Beam Welding is done by focusing the laser beam to the cavity between the two metal parts.
• The laser beam strikes the metal parts and produces heat which melts the material of the two metals or the filler material.

After cooling of the molten metal, a weld is formed which is very strong.

Thermit welding

• Thermite welding is a welding process in which a thermite compound is used to weld two metals together.
• Thermite is a type of chemical composition of a metal powder.
• Powder normally consists of a metal and a metal oxide.
• When this powder is ignited, it undergoes an extremely exothermic redox reaction.
• Here oxide from one metal transfers to the other metal. In this welding process, a huge amount of heat is generated for a brief period.
• The most common use of thermite welding is to join rail tracks in railways.
• This process does not require any heavy machinery and is very fast.
• This process is also used to repair rail tracks as the molten metal from the reaction can be used to repair the tracks.

Induction Welding

• In Induction welding process, electromagnetic induction is used to heat the metal surfaces which are to be joined.
• An induction coil is present in the welding apparatus which is energized with a radio-frequency electric current.
• This welding process is mainly used to weld materials that are either electrically conductive or are ferromagnetic materials.
• Electrical insulators and non-magnetic materials can also be welded using this process by implanting them with ferromagnetic or metallic compounds called susceptors.

Advantages of Fusion welding

• Fusion Welding can be used to join dissimilar materials easily.
• External filler material can be added easily.
• No external pressure is needed.
• Using this process, more than two components can be welded at a step.

Disadvantages of Fusion welding

• Due to intense heating and subsequent melting, many mechanical and metallurgical properties are affected.
• Because of excessive heat input, high distortion takes place.
• Noticeable heat affected zone exists around the weld bead due to excessive heat.
• Welding two dissimilar metals is difficult specially if the metals have different melting points and coefficient of thermal expansion.

Applications in Automotive sector

• It is used to weld the parts of chassis.
• It is used in joining the wheel base.

5. What is 3-2-1 principle?

• The 3-2-1 method is a work-holding principle where three pins are located on the 1st principle plane, i.e., either XY, YZ, ZX. And two pins are located on the 2nd plane perpendicular to the 1st plane, and at last, one pin on the plane is mutually perpendicular to the 1st and 2nd planes.
• It represents the minimum requirement for the locating elements.
• The locators along with the clams which hold the part in place, provides equilibrium for all the forces.
• Stability is satisfactory if all three rest buttons are widely spaced and resultand cutting force lies within the triangular area between the buttons.
• If resultant cutting force lies outside the triangular area then it generates a moment which in turn lifts are overturns the component.

Locating Process in 3-2-1 method

We have two objectives when mounting a part in a fixture for machining

1. Accurately position the part at the desired coordinates.
2. Restrict all six degrees of freedom so that the part cannot move.

A widely used method of accomplishing these two objectives uses the 3-2-1 principle, so-called because it entails three steps that employ three, then two, then one fixed points of known location. Since that adds up to six fixed points, it’s also known as the six point method.

In the three steps of the 3-2-1 method, three mutually perpendicular planes, called datum planes, are introduced, one at each step. These three planes define the workpiece position, and together with opposing clamping forces fully constrain the part. Let’s take a look at the details of the 3-2-1 method

First Plane

Geometry tells us that three points are required to define a plane. This is the "3" in 3-2-1. So, three specific points are used to define the first plane. Fewer than three points cannot define a plane, and in the real world dimensional tolerances mean that four or more points will not be coplanar.

A real-world, less than ideally perfect part placed on four or more reference points will, in fact, rest on only three of the points due to its less than perfect surface. Different parts may rest on different combinations of three points, resulting in variation between finished parts. A stool can be used to illustrate this concept.

A two-legged stool would certainly be unstable. A three-legged stool sits rock-solid. A four-legged stool is often found to rock. In the illustration, a three dimensional part, represented by a cube, is placed on a datum plane defined by three support points.

The part’s six degrees of freedom have now been reduced to three. It can still move along the X or Y axes, and it can still be rotated about the Z axis. The part cannot move along the Z axis because it is held against the plane by clamping force.

Second Plane

A second plane, if it is perpendicular to the first, can be defined by two points, the "2" in 3-2-1.

The part is now constrained to one degree of freedom ,movement along the Y axis.

The part cannot move along the X or Z axes because it is held against the planes by clamping force.

Third Plane

A third plane, if it is perpendicular to both of the first two planes, can be defined by one point, the "1" in 3-2-1. The part is now entirely constrained. It cannot move along or rotate about the X, Y, or Z axes. (Remember that the part is held against each of the three planes by clamping force.

Supporting

• The part is supported from "below" with reference to the Z axis. (Introduction of the first reference plane.)
• Gravity positions the part against the support locator.
• Provide adjustable auxiliary support points as needed to prevent deflection.
• Vertical location with respect to the fixture is now established
• The part is positioned horizontally, in the X-Y plane. (Introduction of the second and third reference planes.)

Holding

• The part is clamped against fixed locators. Therefore, a known and unvarying position of the part is maintained with respect to the X, Y, and Z axes.
• One strap clamp or clamp arm will restrict the workpiece in three dimensions due to friction between the workpiece and clamp. However, friction alone may not be enough to prevent the workpiece from moving during machining.
• Cutting forces will not move a properly supported and clamped part.

Summary of 3-2-1 principle

A workpiece will be completely confined when blanked against

• 3 points in one plane: The “3” in 3-2-1 refers to 3 locators (passive fixture elements) on the primary locating/datum surface.
• 2 points in another plane: The “2” in 3-2-1 refers to 2 locators on the secondary locating/datum surface.
• 1 point in a third plane: The “1” in 3-2-1 refers to 1 locator on the tertiary locating/datum surface

6. Define Body coordinate system?

Body coordinate system is used in the automotive industry for drawing of body parts and product design.

Coordinate systems are used to describe the position of an object in space.

A coordinate system is an artificial mathematical tool that we construct in order to describe the position of a real object.

It can also be knwon as Car line and Body line.

Car lines are the (Grid lines) shown on the fixture, which virtually represent the same location in the BIW. All the car line on fixture display the coordinate at corner for reference. With these lines one can easily relate the, location in BIW.

X = Longitudinal direction (Front O Line - FOL)

Y = Transverse direction (Center O Line - COL)

Z = Vertical direction (Bottom O Line - BOL)

Automotive sheet metal components are designed in CAD (Computer added Design ) software e.g.CATIAv4-v5, UG, ProE, Ideas,In any CAD tool there is default axis system X,Y,Z.Lets us consider if every designer starts design of 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 panel are designed with reference to CAR axis means at theiroriginal position of finally built car.Reference axis system of the software is used for design of the various features of the parts (e.g.hole, fillet, threads,) To correlate the position of all the automotive components during the finalassembly the axis system of the vehicle is used.

Most of the time vehicle axis system and softwareaxis system is same. e.g. In most of European OEM X axis represents length of the vehicle Y axisrepresents width of the vehicle Z axis presents height of the vehicle. Y axis is considered to belocated at front axle. All BIW welding fixtures are designed with reference to car line.

7. Elaborate Body plane system & its essentials.

Body planes are reference planes in automotive car.

These planes are used to define the GD & T of all car parts in automotive domain.

It helps in creating a standard system to work with.

It helps in locating various parts in an easy manner.

It helps in ease of access.

The measurement along FOL or X axis is known as F/A or Front Aft

The measurement along COL or X axis is known as C/C or Cross Car

The measurement along BOL or X axis is known as U/d or Up Down