BASICS OF BIW FIXTURES - part 1

Question No.1 - What is the process of project execuion activity?

PROCESS OF PROJECT EXECUTION ACTIVITY:

Figure1. Project Activities

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

1. RFQ:

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

2. FIRST SPEC. DISCUSSION MEETING:

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

Figure 2. Basic example of technical offer for Manual welding fixture

Figure 3. Technical Offer for design & manufacturing of a Robotic Cell

3. OFFER SUBMISSION:

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

4. LOI/PO RECEIPT:

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

5. SCHEDULE PREPARATION:

• Once the PO released from customer we will be working on Preparation of schedule which should be matched our palnned committment in the technical offer/customer required time.
• Schedule preparation is nothig but dividing the different activities like Kick offmeeting, design data study,DAP,Simulate,Quality check.2D detailing,Drawing check,Release of BOM, Manufacturing,Bought outs of electrical & mechanical components,Assembly of fixture,paint,trial run out,installation and comissioning at customer end etc.,
• Thses activities will be traced in the schedule preparation chart.
• The date wise schedule should be matched the committed date. Otherwise have to revised the schedule and prepare accordingly by discussing in the meetings.

Figure 4. Example of Schedule preparation chart

6. BOM PREPARATION:

• Bill of materials like cylinders,motors,etc.,which is required for the project are prepared.

7. DESIGN CONCEPT PREPARATION:

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

Figure 5. Spot Plan

The red spot marks are the area to be welded & R1 & R2 are the robots

• Spot plan should be take in consider during concept design preparation.
• Spot plan clears us that how much robots are to be used and the sequence of the spot will be decided along with which robot will be cover certain spot places.
• Also cycle time should be considered while preparing concept design.
• To calculate the cycle time we should go to cycle time study.
• Cycle time study includes : Min. per shifts,No.of shifts,No.of days per year,No. of component per year,Total number of minutes,Efficiency,Total no. of seconds,Takt time seconds,Avg. time per spot,total no.of spot,no.of robots placed.
• From the cycle time study we can get time taken per spot,Time taken for single component,Efficiency of producion.
• If the efficiency is not satisfied we have to do some reconsideration in the design.

8. CUSTOMER APPROVAL:

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

9. DETAILING & DRAWING RELEASE:

• Once the customer approved the process, the detailing of the fixture parts which is to be manufactured has been done with giving appropriate dimensions and GD&T symbols.
• All the dimensions which is necessity 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 & electrical parts like sensors,cylinders,etc.,which needs for fixture are ordered as per design specifications.

11. MECHANICAL / ELECTRICAL ASSEMBLY:

• After the materials ordered received to our end.The quality will check the working conditions and technical specs. which meets our requirement.
• After the quality check the mechanical & the 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 QC check internal trials are made to check the operation of the fixture.
• It is a first trial taken inhouse,So we will see by putting the assembly in the fixture whether the seating of assembly/panel suited correctly,whether the clamping operation are done properly,also whether the pins are getting intothe holes,etc,.

14. ONLINE TRIAL:

• The trail will done in automatic made through control panel.
• The process sequence of operations is checked as by the designed way.

15. PACKAGING:

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

16. DESPATCH:

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

17. INSTALLATION AS PER LAYOUT:

• As we discussed in design concept preparation, the design of the layout are been prepared at very initial level which gives the information of placements of robots and fixtures.
• According to the design the installation & commissioning team will install the fixtures.

18. TRAILS & TRAINING AT CUSTOMER:

• Production trials will be taken at customer end.
• During technical offer we will be confirmed that n-number of assemblies will be produced within 8hrs/12hrs shifts.
• So in customer trial we have to achieve the confirmed quantity of assemblies.
• Once it is achieved,trainng will be given to the operator,staffs,engineers who involved in this process.
• The sequence of working process by the fixture will be explained in detail.
• The check points which has to be done after placing the panels into the fixture will be made clear to them.

19. BUYOFF MEETING:

• After trials and training at customers end,buyoff meeting will be held.
• In this meeting customer will give reviews about the fixtures,Sometimes customer may need/feels better to do some addition work also.It will be discussed and finalize in the meeting.

20. FINAL HANDOVER:

• The fixture and the documents supports the fixtures/production will be haded over.
• Documents like poka yoke documents,clamp validation document,ergo sheets,BOMs,Charts will be delivered and handedover to customers.
• Documents will play a vital role in industry,We should always have a proof for our work done.The sequenec of qulaity of work will be seen through the documents.
• Every automobile industries will follow some standards to maintain documents as per ISO,IATF.
• Now every automobile Industries/vendors/suppliers are maintaining the documents as per IATF (International Automotive Task Force).
• IATF -The International Automotive Task Force is a group of automotive manufacturers which aims at providing improved quality products to automotive customers worldwide.

Hence, The process of project execution activities are detailed above.

Question NO. 2 - What are the types of joining process ?

Answer:

JOINING PROCESS:

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

Figure 1. Classification of joining process

TYPES OF JOINING PROCESS:

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

1. Metalurgical joining.
2. Mechanical joining.
3. Chemical joining.

A. METALURGICAL JOINING:

Metallurgical joining are classified into,

1. Welding.
2. Brazing.
3. Soldering.

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

Classification of Welding Process: The types of welding process classified into,

1. Fusion Welding.
2. Electric Resistance Welding.
3. Solid - state welding.

a. Fusion welding:

• In fusion welding,the metal at the joint is heated to a molten state and then it is allowed allowed to solidify.
• Pressure is not applied during the welding process and hence itis also called as 'non - pressure welding'.
• Filler materials may be required during this type of welding.
• Classification of fusion welding are,

1. Thermit welding.
2. Arc Welding.
3. Gas Welding.

Figure 2. Fusion weld joint

1.Thermit Welding:

• Welding the parts by using liquid thermit steel around the portions to be welded is called thermit welding.Since it is a fusion welding process,neither arc is produced to heat parts nor flames are used.For getting high temperature,the exothermic reaction is used.
• Welding principle is the heat of the thermit reaction used for welding in plastic state & mechanical pressure is applied for the joint.
• It is depending on the chemical reaction between iron oxide & aluminium.
• The reaction in thermit welding is 8Al + Fe₃O₄ = 9Fe + 4Al₂O₃. This reaction takes place about 30 sec only and the heat liberation temperature is about 2800 degree celcius.It is twice the melting temperature of steel.

Figure 3. Thermit welding process

2.Arc Welding:

• In arc welding process,the heat is developed by an electricarc.The arc is produced between anelectrode and the work.This is a process of joining two metal pieces by melting their edges by an electric arc.In arcwelding the electrical energy is converted into heat energy.
• The electrode & the work piece are brought nearer with similar a small air gap of 3mm approximately.Then the current is passed through the work piece and the electrode toproduce an electric arc.
• The work piece is melted by an arc,The electrode is also melted and hence both the workpieces become a single piece without applying any external pressure.The temperature of arcis about 5000°C to 6000°C.The electrode supplies additional filler metal into the joints and is deposited along the joint.A transformer or generator is used to supply a current.The depth to which the metal is melted and deposited is called depth of fussion.To obtain better depth of fussion,the electrode is kept at 70° inclination to the vertical.
• Electrode used in arc welding are generally coated with a flux.The flux is used to prevent the reaction ofthe molten metal with atmospheric air.Also it removes the impurities of the molten metal and forms a slag.This slag gets deposited over the weld metal.This slag protects the weld seam from rapid cooling.
• The molten metal is forced out of the pool by electric arc.Hence a small depression is formed in the parent metal where the molten meal is oiled up.This is known as "arc carter".The distcance between the tip of the electrode and the bottom of the arc crater is called "arc length".
• The types of arc welding are,

1. Manual Metal Arc welding.
2. MIG Welding.
3. TIG Welding.
4. Submerged Arc Welding.
5. Plasma Arc welding.
6. Atomic hydrogen arc welding.
7. Carbon Arc welding.
8. Electroslag Welding.

Here I have detailed the first three types of Arc welding.

I. Manual Metal Arc Welding:

• Manual metal arc welding (MMA or MMAW) also known as shielded metal arc welding(SMAW) orinformally known as stick welding.
• Stick welding is a process where the arc is struck between the metal rod (electrode flux coated) & work piece,both the rod & the work piece surface melt to create a weld.

Figure 4. Manual Metal Arc Welding

II. MIG Welding:

• MIG Welding - Metal Inert Gas Welding.
• It is an arc welding tecnique in which a consumable electrode is used to weld two or more work piece.
• MIG welding makes use of the following components: Consumable electrode,Inert gas supply,welding head,AC or DC Supply.

Figure 5. MIG Welding

III. TIG WeLding:

• TIG Welding - Tungsten Inert Gas welding.
• It is an arc welding method that uses a non-consumeable tungsten electrode to weld two or more work pieces.
• It is very much similar to MIG Welding.
• The following components are required to perform TIG welding .They are : Power supply,Non - consumeable tungsten electrodes,Inert gas supply,Filler rod(depends on nature of work piece),welding head.

Picture 6. TIG Welding

Gas Welding:

• Gas welding is one type of welding process in which the edges of the metals to be welded are melted by using gasflame.
• No pressur is applied during welding except pressure gas welding.
• The flame is produced at the tip of the welding torch.
• The gases commonly employed for gas welding are acetylene, hydrogen, propane & butane.
• Metal 2mm to 50mm thick are welded by gas welding.
• There are three types of welding process used in industries such as,
  1. Oxy - acetylene welding.
  2. Oxy - hydrogen welding.
  3. Air - acetylene welding.

Figure 7. Gas Welding

Here I have detailed about the most commonly used gas welding

I. Oxy - acetylene welding:

• In this welding the heat is obtined by burning a mixture of oxygen & combustible gas. The gases are mixed in the required proportion in a welding torch which provides control for the welding flame. The most common form of gas welding is Oxy-acetylene welding.
• The flame only willmelt the metal. So,additional metal to the weld is supplied by the filler rod. A flux is used during weldingto prevent oxidation and to remove impurities.
• The temperature of oxy - acetylene flame in its hottest region is about 3200°C.
• The cost of acetylene is low. The gases O2,C2 & H2 can be stored at high pressure in separate steel cylinders.But the acetylene is very harmful if it is not handled carefully.
• There are two types of xy - acetylene systems employed depending upon the manner in which acetylene is supplied for welding.They are, High pressure system & Low pressure system.
• In High pressure system, both oxygen & acetylene are supplied from high pressure cylinders.
• In Low pressure system, the acetylene produced at the place of welding by interaction of calcium carbide & water in acetylene generator.

b. Electric Resistance Welding: Resistance welding is a welding technique widely used in manufacturing industry for joining metal sheets & components. This type of welding is very much used in BIW assemblies most common. The weld is made by conducting strong current through the metal combination to heat up & finally melt the metals at localized points predetermined by design of the electrodes or the work piece to be welded. A force is always applied before, during and after the application of the current to confine the contact area at the weld interfaces and in some application to forge the work piecees. Types of Resistance welding are,

1. Resistance Spot welding
2. Resistance Seam welding.
3. Resistance Projection welding.
4. Butt welding.
5. Precursion welding.

Here I will discussing about only the three important types of resistance welding in detailed.

I. Resistance spot Welding:

• The process is used for joining sheet materials & uses shaped copper - chromium or zinc conium alloy electrodes to apply pressure and convey the electrical current through the work piece.
• Heat is developed mainly at the interface between two sheets, eventually causing the material being welded to melt, forming a moltel pool, the weld nugget.
• The molten pool is contained by the pressure applied by electrode tip & the surrounding solid metal.

Figure 8. Resistance Spot Welding

II. Resistance Seam Welding:

• Seam welding is a resistance welding process for joining metal sheets in continuous,often leak tight,seam joints by directly applying opposing forces with electrodes consisting of rotary wheels.
• The current & the heat generation are localized by the peripheral shapes of electrode wheels.

Figure 9. Resistance Seam Welding

III. Resistance Projection Welding:

• Projection welding is a resistance welding process for joining metal components or sheets with embossments by directly applying opposing forces with electrodes specially designed to fit the shapes of the work pieces.
• The ccurrent & the heat generation are localized by the shape of the work piece either with their natural shapes or witth specially designed projection .
• Large deformation or collapse will occurs in the projection part of the work pieces implying high.

Figure 10. Resistance Projection Welding

c. Solid - State Welding: Solid State Welding is a welding process, in which two work pieces are joined under a pressure providing an intimate contact between them and at a temperature essentially below the melting point of the parent material. Bonding of the materials is a result of diffusion of their interface atoms.

Hence, the types of joining process are discussed in deatil.