Spot Welding Involves Three Stages

federal agency dyers rocket Involves Three StagesSpot conjoin is a mould in which contacting scratch surface are joined by the light up obtained from metro to electric received f let loose. Work-pieces are held to evolveher at a lower frame pressure exerted by electrode. Typically the sheet are in the 0.5 to 3 mm thickness range. The attend uses two shapes copper alloy electrodes to slenderize conjoin flow rate into a small do and to simultaneously clamp the sheet together. Forcing a large rate of flow through the key ordain flux the coat and form the dyers mignonette.The substance of verve is chosen to pock the sheets stuff properties, it thickness, and type of electrode. Applying likewise little zipper wont melt the admixture or bequeath commence a poor dyers rocket. Applying similarly much get-up-and-go leave alone melt too much metal and make a hole kind of than a dyers rocket 1.Spot join involves three point in condemnations the firs t-year stage which involves the electrodes macrocosm brought to the surface of the metal and applying a slight amount of pressure. The new from the electrodes is therefore use briefly. later on the menstruation is removed, the electrodes remain in place in order for the stuff to cool. Weld measures range from 0.01 arcsecond to 0.63 sec depending on the thickness of the metal, the electrode cart and the diam of the electrodes.The equipment utilise in the strike intercourse conjoin process consists of tool holders and electrodes. The tool holders function as a mechanism to hold the electrodes firmly in place and similarly support optional water hoses which cool the electrodes during conjoin. The electrodes generally are make of a low electric resistance alloy, usually copper, and are nameed in many different shapes and surfaces depending on the masking needed. fancy of samples ( get-up-and-go) is a techniques that change a inclinationers to conciliate simultane ously a interactive exits of a performers that effected the entrust in any rule. Design of experiments (DOE) helps to pinpoint the graduate(prenominal) uply sensitive splits and sensitive areas in a designs. The designer are then capable to fix these problems and get the optimum parameter of design. receipt surface methodological analysis (RSM) explores the relationship betwixt explanatory variables and reaction variable in statistic. solvent surface methodology (RSM) is a sequence of design of experiments (DOE) to obtain an optimum rejoinder. It is sufficient to determine which explanatory variables have an impact on the use up of retort variables.1.2 Problem Statement ohmic resistance location dyers mignonette (RSW) is the most effective process for joinning both(prenominal) similar and dissimilar metals. enemy berth dyers rocketing is commonly utilize in the automotive industries for body convention production lines. The major advantages of speckle welding is efficient energy apply, and high production rates. To improve the bearing and good note of welding the welding parameter is to be investigated. A small change of the parameter willing effect all the former(a) parameters. The main parameter for spot welding is welding current, welding clock time, pierce, and hold time.Nowadays, the world faces of energy crisis and environmetal problems, energy miserliness and safety have become the most important issuses for auto qualification industry. To achieve these goals, clog reduction is the most effective to leads to the fast ontogenesis and application of advanced high authorisation steels. In this research, DP600 is an Advanced exalted expertness Steel (AHSS) have been chosen to perplex the optimum parameters for the spot welding to determining the quality of a weld nugget ripening be vitrine the characteria of the material such as light weight, low ratio of yield faculty to tensile strength, high work hardening capacity and good energy absorption. The good formability of DP600 allows the users to increase the strength of the components. Therefore, the products can be made stronger and safer downstairs load.Resistance spot welding is a key technology in automotive assembly industries that the process is fast and easily weld many different material combination that are difficult to join by other welding process. The weldability of different materials such as advanced high strength steel DP600 and low carbon steel is to investigated quality of a nugget ripening due to the formation of inclemency, tensile strength. This research is to muse the solve of resistance spot welding (RSW) parameters such as welding current, welding time, pressure and speed on the development of nugget formation, focused on weld nugget and change touch regulate (HAZ).1.3 Objective Of StudyThe main determination of this study I. To find the optimum parameter to optimize the size of weld nugget and Heat Affected Zone (HAZ) in order to obtain a good quality of Resistance Spot Welding utilise factorial Design and answer Surface methodology (RSM).II. To developed a numerical circle to predict the size of weld nugget and Heat Affected Zone (HAZ) using Response Surface Methodology (RSM).1.4 Significance of the inventThe development mathematical sit arounds can be effectively used to predict the size of weld zone which can improve the welding quality and capital punishment in Response Surface Methodology (RSM).1.5 Scope of StudyThe electron orbit of study is to investigate on the resistance spot welding process using Factorial Design and Response Surface Methodology (RSM) to find the optimum parameters to optimize the size of weld nugget and Heat Affected Zone. The material used is DP600 advanced high strength steel 0.8mm thickness feature with low carbon steel 1.0mm thickness. The tool used is OBARA guns type diameter 6mm. The electrode copper alloys detail as under every(prenominal)oy RW MA Class backbreaking Elec. Cond Desc Use To WeldCMW 3 2 83B 85% CU + chromium CRS GENERAL WELDINGThe microscope used is the compound light microscope. It commonly binocular (two eyepieces). The compound light microscope combines the power of lenses and light to enlarge the subject being viewed. The eyepiece allows for 10x or 15x magnification and when combined with three or tetrad object lens lenses which can be rotated into the field of view and commence higher magnification to a maximum of around hundred0x generally. In the research laboratory of material, microscope is used to watch and catch the picture of size weld nugget and Heat Affected Zone (HAZ).CHAPTER IILITERATURE REVIEW2.0 Introduction of Resistance Spot Welding (RSW)Resistance Spot Welding is a process in which metal surface are joined widely used in the automotive structural application for many years for the dissimulation of sheet metal assemblies. The process is used for joining sheet materials and uses sh aped copper alloy electrodes to apply pressure and convey the galvanising current through the work piece. Heat is developed mainly at the port among two sheets, eventually causing the material being welded to melt, forming a molten pool, the weld nugget. The molten pool is contained by the pressure utilize by the electrode tip and the surrounding solid metal. The resistance spot welding has the advantage which is high speed and suitability for automation. material body 1 Resistance Spot Welding Machine with Work 3The size and shape of the for individually one formed welds are limited primarily by the size and delineate of the electrode faces. The weld nugget forms at the laying surfaces, as shown in watch 1, entirely does non extend completely to the outer surfaces. In section, the nugget in a properly formed spot weld is round or rounded in shape. Spacing betwixt adjacent spot welds or rows of spot welds must be enough to prevent shunting or to limit it to an unobject ionable amount.In Resistance Spot Welding (RSW), methodology is development to determine the optimum welding conditions that maximize the strength of joints. Response Surface Methodology (RSM) utilized to develop an effective model to predict weld strength by incorporating parameters such as pressure, weld time and the others 7. In this guinea pig study from journal that conducted as per central composite face revolve about design for spot welding of 0.2 and 0.3mm thick copper and brass speciments. Response surface model interfaced with the Genetic Algorithm to optimize the welding conditions for coveted weld strength. The welding process of copper and brass produced large raise up affected zone (HAZ) and fusion zone (FZ). epitome 2 ceremonious oppose 7 parry 1 Variables for joining of Cu- brass specimens 7In response surface method the important is design of experiments. Identified the factors which have a significant influence on weld strength. It is weld pressure, weld ti me, and bountifulness of vibration of horn. For 0.2 and 0.3 mm thick copper-brass speciments to determine maximum and minimum place of welding parameters large material bodys of trial runs. From the trial runs the most fitted parameters were identified in table 1 above.Response surface model for weld strength is a collecting of mathematical and statistical techniques efficacious for the modeling and analysis of problems in response of interest is influenced by variables and the objective is to optimize thsi response 7. Then developed mathematical models to predict the weld strength. For the experiments the equation isWhere yi is the the response of weld strength, xi is pressure, weld time and amplitude, 0, j, jj and ij represent the constant, analogue, quadratic and interaction terms. For the spot welding equations like below After 20 experiments are conducted at different levels of parameters the value of weld strength obtained from experiments and those predicted from respons e surface model along the design matrix.Table 2 Weld strength and RSM 7Figure 3 subject of amplitude and weld time on weld strength 7Figure 4 Effect of pressure and weld time of weld strength 7Figure 5 Effect of amplitude and pressure on weld strength 7And for some other experiments that used Response Surface methodoogy (RSM) by spot welding that used atomic number 13 as a specimen 8. They investigated effect between aluminium coruscate and the metal spot-welded colum. Based on their experiment. Numerical simulation and analytical models was developed to partition the energy absorption quantitatively into the foam get across component and the hat section component and the relative contri yetion of each component to the interactive effect.Figure 6 schematic drawing of the spot welding-welded used in the experiment 8Response Surface Methodology (RSM) is a method to understanding the correlation between multiple enter variables and issue variable.Figure 7 Comparison of the experiment and numerical top 8Figure 8 Response surface of sea for the foam filled spot welded column 8Figure 9 Response surface of peak make for the foam filled spot welded column 8Table 3 optimal foam filled square column 8From the Response Face methodology (RSM) they get the optimum value of the t = thickness, a = thickness, density, pressure and SEA.2.1 Electrothermal operate of WeldingIn resistance welding, the heat are required to frame the coherence is generated by applying an electric current through the stack- up of sheets between the electrodes. So, the formation of a welded joint, including the nugget diameter and the heat- affected zone (HAZ), are definitely depends on the electrical and thermal properties of the sheets and coating materials. The general expression of heat generated in an electric circuit can be expressed asQ= I Rt (modification of the Ohms Law) 3where Q is heat (Joule), I is current (Ampere) , R is electrical resistance of the circuit (ohm,O) a nd t is time (second) which is allowed to flow in the circuit. For resistance welding, the heat generation at all location in a weldment is more than relevant than, rather than the total heat generated, as warmth is not and should not be uniform in the weldment. That means, consideration should more on the heat rate than the total heat, as it will determines the temperature history, and, in turn, the microstructure 3. For example, considering an aluminum welding, melting may not be happen if the welding current applied is low, due to the low electrical resistivity of aluminum. In general, the electric and thermal process should be considered together in welding.2.2 Spot Welds Parameter2.2.1 The parameter1. Electrode ForceThe electrode force is required to squeeze the metal sheets to be weld and joint together. This requires a large electrode force be execute the weld quality would not be good enough. However, the force must not be too large as it might cause other problems. When the electrode force is change magnitude the heat energy will decrease. So, the higher electrode force needed a higher weld current. When weld current becomes too high, spatter will occur between electrodes and sheets. This will cause the electrodes to get stuck to the sheet.2. Squeeze ageSqueeze Time is the time interval between the initial application of the electrode force on the work and the first application of current. Squeeze time is necessary to delay the weld current until the electrode force has attained the desired level 3.3. Weld or Heat TimeWeld time is the time during which welding current is applied to the metal sheets. The weld time is measured and accommodateed in rungs of line potentiality as with all timing functions. As the weld time is, more or less, related to what is required for the weld spot, it is difficult to retrovert an take on value of the optimum weld time. For instance Weld time should be as gyp as possible. The weld parameters should be chosen to give as little wearing of the electrodes as possible. (short weld time.). The weld time shall cause the nugget diameter to be big when welding thick sheets. The weld time might have to be adjusted to fit the welding equipment in case it does not fulfil the requirements for the weld current and the electrode force. (A yearlong weld time might be needed.). The weld time shall cause the indentation due to the electrode to be as small as possible. (a short weld time.). The weld time shall be adjusted to welding with reflexive tip-dressing, where the size of the electrode contact surface can be kept at a constant value. (a shorter welding time.) 3.4. Hold TimeHold time is the time, after the welding and occurred when the electrodes are still applied to the sheet to quiver the weld (time that pressure is maintained after weld is made.). Hold time is necessary to allow the weld nugget to solidify before releasing the welded parts, but it must not be to long as this may cause the hea t in the weld spot to spread to the electrode and heat it. The electrode will then get more exposed to wear. Further, if the hold time is too long and the carbon content of the material is high (more than 0.1%), there is a risk the weld will become brittle. 35. Weld CurrentThe weld current is used during welding is being made. The amount of weld current is potencyled by two things first, the setting of the transformer tap switch determines the maximum amount of weld current available second the percentage of current control determines the percentage of the available current to be used for making the weld. humbled percentage of current settings is not normally recommended because it might affect the quality of the weld. Proper welding current can be obtained with the percentage current set between seventy and ninety percent by adjust the tap switch. The weld current should be kept as low as possible. When determining the current to be used, the current is gradually increased until weld spatter occurs between the metal sheets. This indicates that the correct weld current has been reached. Weld current also influences the value of nugget diameter. Different value of current, it will produce different dimension of the nugget diameter 3.Figure 10 Welding CycleThe welding processes in resistance spot welding have 5 circle process as shown in the Figure 10. The first cycle is the squeeze time, where pressure from the electrode force is applied to the workpiece. The second cycle is weld time, this process where the current is on and the welding current is applied in the metal sheets to melt the sheet metal for the welding process. Then, postheat time, the current delay at the low level. The fourth cycle is cool time. This cycle allow the melt nugget diameter to solidify before the releasing the welded parts and lastly the off time cycle, the electrode force applied on the sheets metal is released the welding process is done.2.3 Material properties2.3.1 Introduction of Advanced high gear Strength Steel (AHSS)DP600 is one of the Advanced High Strength Steel (AHSS) for the automotive industry that have enhanced ductility and formability 4. DP600 usually used in the manufacture of passenger car and commercial vehicle wheels. It is to reduce weight and increasing service life and made of the typical properties of theese materials for maximum used.2.3.2 underlying Properties2.3.2.1 Mechanical PropertiesTable 4 mechanical properties for DP600 42.3.2.2 Chemical CompositionTable 5 Chemical Compostion for DP600 42.3.2.3 DimensionTable 6 Dimension for DP600 42.3.3 Advantages of High Strength Steel (DP600)High strength steel (DP600) are prodominantly used in automotive industries because of many advantages such as below 4 I. junior-grade ratio of yield strength to tensile stength .II. Work-hardening capacity is high.III. Good energy absorption characteristic to provide crash public presentation in structural.IV. harvest-festival stronger and safe r under load.V. Good bake hardening responce that forming the yield strength in the formed areas is significantly increased.CHAPTER IIIRESEARCH METHODOLOGY3.0 Methodology of The ProjectMethodology actually is a systematic study of method and set of procedur. In this study, there are consist of several phase. Figue 3 below shown a methodology for this job.3.1 Detail of methodology3.1.1 Information GatheringIn cultivation gathering all related schooling about spot welding, and material used was collected to provide futher understanding. All the related information is obtain from the internet, journal, library and the other resources. It is important o nderstand the theory and former step.3.1.2 Design of experimentDesign of Experiment is an advance to improve design performance which to reduce cycle time to developed processes 5. Design of experiment is a series of test to change the input variable (parameter) to study and identififying the output change in the output response. The n analyze the result of process to find the optimum value or parameters that effect to the process.Figure 11Figue 4 shown an example model of process that shown a number of uncontrolled factor that are discrete, such as difference machine or operators and such as ambient temperature or humidity.3.1.2.1 Screening Design and Full Factorial DesignScreening design is to identify which factor and effect that are important. When have 2-4 factors and can perform a all-encompassing factorial. Full factorial design in two level. Full factorial design ia a common experimental design with all input factors set at two levels each. These levels is called high and low or +1 and -1. A combination of all the input factors is called full factorial design in two level 6. If there are k factors at 2 levels, full factorial design has 2? runs.Table 7 make sense of run 2? Full FactorialNumber of Factors Number of Runs2 43 84 165 326 647 128Objective of factorial design as below 1. To identify factors with significant effects on the response .2. To identify interations among factors .3. To identify which factors have the most importance effects on the response .4. To decide whether further investigation of a factors effect is justified .5. To investigate the functional dependence of a response on multiple factors simultaneously (if and only if you test many levels of each factor) .3.1.2.2 Response Surface MethodologyResponse surface Methodology (RSM) investigates relationships between explanatory variables and response variables. Objective of RSM is to use a sequence of designed experiments to obtain an optimal response. Below is example of RSM Figure 12 Response surface Peak Figure 13 Response surface HillsideFigure 14 Response surface Rising ridge Figure 15 Response surface saddle3.1.2.3 Mathematical MethodThe mathematical model correlating process parameters and their interations with response parameter will be developed gibe to the experimental result. These model will be used to predict the size of weld zone which can improve the welding quality and performance in Resistance Spot Welding.The most common models fit to the experimental data take either a linear equation. A linear model with two factors X1 and X2 such as below Y = 0 + 1X1 + 2X2 + 12X1X2 + experimental errorY is the response for given levels of the main effect X1 and X2 and X1X2 is ncluded for possible interation effect between X1 and x2. Constant 0 is the response of Y when both main effect are 0 6.The advance of using DOE is that can provides an approach organized which it possible to address both simple and tricky experimental problem. The experiment is to select appropriate objective, and then guide and perform a set of experiment. That can conclude DOE can obtain more useful and more precise information about the studies system. The joint influence of all factors is assessed 53.1.3 Experiment processThe experiment is focused to get the radius of molten zone or weld nugget and He at Affected Zone (HAZ). The diameter of weld nugget and Heat Affected Zone (HAZ) is measured by capture the image of the speciment by the microscope. All the parameter such as welding time, the diameter of tips, weld current , and force will be varied in the experiment.All the result with different parameter will be record to investigate nugget development focused on weld nugget and Heat Affected Zone (HAZ).The agency for this experiment to prepare the sample of specimen are a) Cutting.b) Molding.c) Grinding.d) Polishing.e) Etching.f) Invetigate weld nugget and HAZ size using microscope.3.1.4 ConclusionAfter get the optimum result and the insensibility and strength have be confirmation by tensile test, hardness test and bending test, the conclusion from this project is verify and the project is 100% complete.3.1.5 Thesis writingAfter get the conclusion, to complete this project thesis writing is needed to complete the project. All the process and data from this project from the s tart util the end is to be record and compile as a book.REFERENCES1. US Patent 4456810, Adaptive Schedule Selective Weld Control, June 1984. The weld process is stopped before the melt exceeds the electrode diameter. Otherwise, an impressive but all in all undesired shower of sparks and hot metal will issue from the weld spot.2. 1995-2012 CMW inc.3. Effect of welding nugget diameter on the tensile strength of the resistance spot welding joints of same sheets metal walther jenis Faculty of Mechanical plan University Malaysia Pahang may 2009.4. www.corusgroup.com.5. A. Fauzi. Effect of cutting parameters on the hole diameter and surface roughness for dry drilling of aluminum Alloy 6061 2009.6. Engineering Statistic enchiridion 2009.7. International Journal of Advanced Engineering Research and Studies 2009.8. Optimization of foam filled spot-welded column for the crashworthiness 2010.