Spot Welding Is A Process Engineering Essay

Topographic point welding is a procedure when acquiring in touch with metal surface are truly joined up with by the heat obtained from opposition to electricity current flow. Work-pieces take topographic point together under force per unit area exerted by electrode. Normally the sheet come into the 0.5 to 3 millimeters thickness figure. The procedure uses non one but two forms copper metal electrodes to concentrate welding current as a little ispoti and to boot to at the same time clamp the sheet together. Pushing a large current through the topographic point will run the metal and to boot organize the dyer's rocket. The sum of energy is picked to accommodate the sheetis stuff qualities, it thickness, and to boot sort of electrode. Applying besides small energy wonit melt the steel or can do a hapless dyer's rocket. Applying besides much energy can run excessively much steel and besides do a hole alternatively of a dyer's rocket [ 1 ] . Topographic point welding involves three phases ; the 1st phase that involves the electrodes being brought to the texture of the metal and besides using a minor sum of force per unit area level.The current from the electrodes is so used rapidly. Soon after the current is removed, the electrodes stay put in topographic point to let the stuff to chill. Weld times vary from 0.01 sec to 0.63 sec harmonizing to the thickness of the metal, the electrode force plus the size of the electrodes. The equipment found in the topographic point welding procedure is made up of tool holders and to boot electrodes. The tool holders work since a scheme to keep the electrodes strongly put in topographic point and in add-on support optional H2O hosieries that cool the electrodes during the class of welding. The electrodes by and large are truly manufactured a low opposition metal, normally Cu and are structured in many different types and dimensions this depends on the application needed. Design of experiments ( DOE ) is a techniques which allow a interior decorators to find at the same clip a synergistic effects of the factors which effected the green goods any design. Design of experiments ( DOE ) will assist to find the delicate parts and besides sensitive countries within a characteristics. The interior decorator are so able to rectify these troubles and besides acquire the finest parametric quantity of design. Response surface methodological analysis ( RSM ) explores the committedness between explanatory variables and response variable in statistic. Response surface methodological analysis ( RSM ) is a sequence of design of experiments ( DOE ) to acquire some kind of optimum response. It is equal to find that explanatory variables have some sort of consequence on the involvement of reaction variables. 1.2 Problem Statement Resistance topographic point welding ( RSW ) is easy the most effectual procedure for fall ining both tantamount and to boot dissimilar metals. Resistance topographic point welding is systematically utilized in the vehicle industries for organic structure assembly production lines. The major benefits associated with topographic point welding are effectual energy utilized, and to boot high production velocities. To maximise the power and besides high quality of welding, the welding parametric quantity will be investigated. A small alteration of the parametric quantity can act upon all of the some other parametric quantities. The primary parametric quantity for topographic point welding is welding current, welding clip, push, and hold clip. These yearss, the full universe faces of energy crisis and environmental issues, energy economy and besides wellbeing have become the most of import issues for auto devising industry. To obtain these aims, weight loss is the most effectual to do the fast development and application of advanced high strength steels. In this research, DP600 is decidedly an Advanced High Strength Steel ( AHSS ) have been picked to obtain the optimal parametric quantities for the topographic point welding to finding the criterion of the dyer's rocket nugget development given that character of the stuff like light organic structure weight, low ratio of output power to tensile strength, high work solidifying capacity and besides good energy soaking up. The great formability of DP600 permits the users to better the strength of the constituents. Subsequently, the merchandises can be made stronger and to boot less unsafe under burden. Resistance topographic point welding is a cardinal engineering in vehicle assembly industries that the attack is fast and besides easy weld tonss of stuff combination which are difficult to fall in by some other welding procedure. The weld ability of different stuffs such as advanced high strength steel DP600 and to boot low C metal is to look into the quality of the nugget development because of the creative activity of hardness, tensile strength. This surveies will be to research the impact of opposition topographic point welding ( RSW ) parameters this sort of as welding current, welding clip, force and hold clip sing the development of nugget formation, focused on top of weld nugget and Heat Affected Zone ( HAZ ) . 1.3 Objective Of Study The chief intent of this survey: I. To happen the optimal parametric quantity to optimise the size of dyer's rocket nugget and Heat Affected Zone ( HAZ ) in order to obtain a good quality of Resistance Spot Welding utilizing Factorial Design and Response Surface Methodology ( RSM ) . II. To developed a mathematical theoretical account to foretell the size of dyer's rocket nugget and Heat Affected Zone ( HAZ ) utilizing Response Surface Methodology ( RSM ) 1.4 Significance of the Undertaking The development mathematical theoretical accounts can be efficaciously used to foretell the size of dyer's rocket zone which can better the welding quality and public presentation in Response Surface Methodology ( RSM ) . 1.5 Scope of Study The range of research will be study with the opposition topographic point welding procedure utilizing Factorial Design and Response Surface Methodology ( RSM ) to happen the optimal parametric quantities to optimise the size of dyer's rocket nugget and Heat Affected Zone. The stuff used is DP600 advanced high strength steel 1.0mm thickness combined with low C steel 1.0mm thickness. The machine used is C- guns type diameter 6mm. The electrode Cu alloys item as below: Alloy RWMA Class Hard Elec. Cond & A ; Desc Use To Weld CMW 3 2 83B 85 % CU + CHROMIUM CRS & A ; GENERAL WELDING The microscope used is LEICA DM 6000 which is the compound light microscope. It normally binocular ( two oculars ) . The compound light microscope combines the power of lenses and visible radiation to enlarge the topic being viewed. The ocular allows for 10x or 15x magnification and when combined with three or four aim lenses which can be rotated into the field of position and bring forth higher magnification to a upper limit of around 1000x by and large. In the lab of stuff, microscope is used to watch and catch the image of size dyer's rocket nugget and Heat Affected Zone ( HAZ ) utilizing IMAPS package that connected to the computer.. Chapter II LITERATURE REVIEW 2.0 Introduction of Resistance Spot Welding ( RSW ) Resistance Spot Welding is a procedure when steel surface are truly joined up with extremely used inside the automotive constructive application for many working old ages for the fiction of sheet metal assemblies. The attack can be used for fall ining sheet stuffs and besides takes advantage of molded Cu metal electrodes to do usage of force per unit area degree and besides convey the electric power current through the work piece. Heat is developed largely during the user interface between non one but two sheets, bit by bit doing the stuff being welded to run, organizing a liquefied pool and the dyer's rocket nugget. The liquefied pool is contained by the force per unit area degree used by the electrode tip every bit good as the environment solid steel. The opposition topographic point welding contains the advantage that is high velocity and to boot suitableness for mechanization. Figure 1: Resistance Spot Welding Machine with Work [ 3 ] The size and to boot form of the personally created dyer's rockets are limited chiefly by the graduated table and besides form of the electrode brushs. The dyer's rocket nugget signifiers at merely the resting surfaces, as shown in Figure 1, but does non widen in its entireness to the exterior surfaces. In point, the nugget have oning a right created location dyer's rocket is round or possibly elliptic in profile. Spacing between next place dyer's rockets or rows of place dyer's rockets needs to be plenty to avoid shunting or to maximum it with an acceptable sum. In Resistance Spot Welding ( RSW ) , methodological analysis is development to find the maximal welding conditions which enhance the endurance of joint parts. Response Surface Methodology ( RSM ) used to construct up a strong effectual theoretical account to expect weld strength by integrating parametric quantities these as emphasis, weld clip every bit good as the others [ 7 ] . In this instance studied from diary that has conducted as per cardinal composite face centered design for topographic point welding of 0.2 and 0.3mm thick Cu and brass speciments. Response surface theoretical account interfaced with the Genetic Algorithm to optimise the welding conditions for coveted weld strength. The welding procedure of Cu and brass produced big heat affected zone ( HAZ ) and merger zone ( FZ ) . Figure 2: Conventional represent [ 7 ] Table 1: Variables for connection of Cu- brass specimens [ 7 ] In response surface method the of import is design of experiments. Identified the factors which have a important influence on dyer's rocket strength. It is weld force per unit area, weld clip, and amplitude of quiver of horn. For 0.2 and 0.3 millimeters thick copper-brass speciments to find upper limit and minimal value of welding parametric quantities big Numberss of test tallies. From the test runs the most suited parametric quantities were identified in table 1 above. Response surface theoretical account for weld strength is a collection of mathematical and statistical techniques utile for the mold and analysis of jobs in response of involvement is influenced by variables and the aim is to optimise thsi response [ 7 ] . Then developed mathematical theoretical accounts to foretell the dyer's rocket strength. For the experiments the equation is Where Lolo is the the response of weld strength, eleven is force per unit area, weld clip and amplitude, i0, ij, ijj and iij represent the invariable, additive, quadratic and interaction footings. For the topographic point welding equations like below: After 20 experiments are conducted at different degrees of parametric quantities the value of weld strength obtained from experiments and those predicted from response surface theoretical account along the design matrix. Table 2: Weld strength and RSM [ 7 ] Figure 3: Consequence of amplitude and weld clip on weld strength [ 7 ] Figure 4: Consequence of force per unit area and weld clip of weld strength [ 7 ] Figure 5: Consequence of amplitude and force per unit area on weld strength [ 7 ] And for another experiments that used Response Surface methodoogy ( RSM ) by topographic point welding that used aluminum as a specimen [ 8 ] . They investigated consequence between aluminum froth and the metal spot-welded colum. Based on their experiment. Numeric simulation and analytical theoretical accounts was developed to partition the energy soaking up quantitatively into the froth filter constituent and the chapeau subdivision constituent and the comparative part of each constituent to the synergistic consequence. Figure 6: conventional drawing of the topographic point welding-welded used in the experiment [ 8 ] Response Surface Methodology ( RSM ) is a method to understanding the correlativity between multiple input variables and end product variable. Figure 7: Comparison of the experiment and numerical consequence [ 8 ] Figure 8: Response surface of sea for the froth filled topographic point welded column [ 8 ] Figure 9: Response surface of peak force for the froth filled topographic point welded column [ 8 ] Table 3: Optimum froth filled square column [ 8 ] From the Response Face methodological analysis ( RSM ) they get the optimal value of the T = thickness, a = thickness, denseness, force per unit area and SEA. 2.1 Electrothermal Process of Welding In opposition welding, the heat are required to make the coherency is generated by using an electric current through the stack- up of sheets between the electrodes. So, the formation of a welded articulation, including the nugget diameter and the heat- affected zone ( HAZ ) , are decidedly depends on the electrical and thermic belongingss of the sheets and surfacing stuffs. The general look of heat generated in an electric circuit can be expressed as: Q= Ii Rt ( alteration of the Ohmis Law ) [ 3 ] where Q is heat ( Joule ) , I is current ( Ampere ) , R is electrical opposition of the circuit ( ohm, O ) and t is clip ( 2nd ) which is allowed to flux in the circuit. For opposition welding, the heat coevals at all location in a weldment is more relevant than, instead than the entire heat generated, as warming is non and should non be unvarying in the weldment. That means, consideration should more on the heat rate than the entire heat, as it will find the temperature history, and, in bend, the microstructure [ 3 ] . For illustration, sing an aluminium welding, runing may non be happen if the welding current applied is low, due to the low electrical electric resistance of aluminium. In general, the electric and thermic procedure should be considered together in welding. 2.2 Spot Welds Parameter 2.2.1 The parametric quantity 1. Electrode Force The electrode force is required to squash the metal sheets to be weld and joint together. This requires a big electrode force because the dyer's rocket quality would non be good plenty. However, the force must non be excessively big as it might do other jobs. When the electrode force is increased the heat energy will diminish. So, the higher electrode force needed a higher weld current. When weld current becomes excessively high, splatter will happen between electrodes and sheets. This will do the electrodes to acquire stuck to the sheet. 2. Squeeze Time Squeeze Time is the clip interval between the initial application of the electrode force on the work and the first application of current. Squeeze clip is necessary to detain the weld current until the electrode force has attained the coveted degree [ 3 ] . 3. Weld or Heat Time Weld clip is the clip during which welding current is applied to the metal sheets. The weld clip is measured and adjusted in rhythms of line electromotive force as with all timing maps. As the dyer's rocket clip is, more or less, related to what is required for the dyer's rocket topographic point, it is hard to give an exact value of the optimal weld clip. For case: i Weld clip should be every bit short as possible. i The dyer's rocket parametric quantities should be chosen to give as small erosion of the electrodes as possible. ( short dyer's rocket clip. ) . i The dyer's rocket clip shall do the nugget diameter to be large when welding thick sheets. i The dyer's rocket clip might hold to be adjusted to suit the welding equipment in instance it does non carry through the demands for the dyer's rocket current and the electrode force. ( A longer weld clip might be needed. ) . i The dyer's rocket clip shall do the indenture due to the electrode to be every bit little as possible. ( a short dyer's rocket clip. ) . i The dyer's rocket clip shall be adjusted to welding with automatic tip-dressing, where the size of the electrode contact surface can be kept at a changeless value. ( a shorter welding clip. ) [ 3 ] . 4. Keep Time Hold clip is the clip, after the welding and occurred when the electrodes are still applied to the sheet to chill the dyer's rocket ( clip that force per unit area is maintained after dyer's rocket is made. ) . Hold clip is necessary to let the dyer's rocket nugget to solidify before let go ofing the welded parts, but it must non be to long as this may do the heat in the dyer's rocket topographic point to distribute to the electrode and heat it. The electrode will so acquire more open to have on. Further, if the clasp clip is excessively long and the C content of the stuff is high ( more than 0.1 % ) , there is a hazard the dyer's rocket will go brickle. [ 3 ] 5. Weld Current The dyer's rocket current is used during welding is being made. The sum of weld current is controlled by two things ; foremost, the scene of the transformer pat switch determines the maximal sum of weld current available ; back the per centum of current control determines the per centum of the available current to be used for doing the dyer's rocket. Low per centum of current scenes is non usually recommended because it might impact the quality of the dyer's rocket. Proper welding current can be obtained with the per centum current set between 70 and 90 per centum by seting the pat switch. The weld current should be kept every bit low as possible. When finding the current to be used, the current is bit by bit increased until weld splatter occurs between the metal sheets. This indicates that the right dyer's rocket current has been reached. Weld current besides influences the value of nugget diameter. Different value of current, it will bring forth different dimension of the nugget di ameter [ 3 ] . Figure 10: Welding Cycle The welding processes in opposition topographic point welding have 5 rhythm procedure as shown in the Figure 10. The first rhythm is the squeezing clip, where force per unit area from the electrode force is applied to the workpiece. The 2nd rhythm is weld clip, this procedure where the current is on and the welding current is applied in the metal sheets to run the sheet metal for the welding procedure. Then, postheat clip, the current hold at the low degree. The 4th rhythm is cool clip. This rhythm allow the thaw nugget diameter to solidify before the let go ofing the welded parts and in conclusion the off clip rhythm, the electrode force applied on the sheets metal is released the welding procedure is done. 2.3 Material belongingss 2.3.1 Introduction of Advanced High Strength Steel ( AHSS ) DP600 is one of the Advanced High Strength Steel ( AHSS ) for the automotive industry that have enhanced ductileness and formability [ 4 ] . DP600 normally used in the industry of rider auto and commercial vehicle wheels. It is to cut down weight and increasing service life and made of the typical belongingss of theese stuffs for upper limit used. 2.3.2 Basic Properties 2.3.2.1 Mechanical Properties Table 4: mechanical belongingss for DP600 [ 4 ] 2.3.2.2 Chemical Composition Table 5: Chemical Compostion for DP600 [ 4 ] 2.3.2.3 Dimension Table 6: Dimension for DP600 [ 4 ] 2.3.3 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. Low ratio of output strength to tensile stength. II. Work-hardening capacity is high. III. Good energy soaking up characteristic to supply clang public presentation in structural. IV. Product stronger and safer under burden. V. Good bake indurating responce that organizing the output strength in the formed countries is significantly increased. Chapter III RESEARCH METHODOLOGY 3.0 Methodology of The Undertaking Methodology really is a systematic research of system and besides group of process. In this survey, so there are consist of many measure. Figure 3 below shown a methodological analysis for this undertaking. 3.1 Detail of methodological analysis 3.1.1 Information Gathering In information assemblage every associated information on topographic point welding, and besides information utilized was really gathered to supply farther cognition. All of the associated information is get from all the web, diary, and library along with the some other resources. It is critical understands the theory and besides predating option. 3.1.2 Design of experiment Design of Experiment is decidedly an advancement to assist better design functional public presentation that to cut down rhythm clip for you developed procedures [ 5 ] . Design of experiment is a assortment of trial to alter the input variable ( parametric quantity ) to larn and besides identififying the end product alteration inside the production response. Then analyze the consequence of procedure to obtain the optimal value or parametric quantities which consequence to the attack. Figure 11 Figue 4 shown an case theoretical account of process that shown an sum of uncontrolled factor which are distinct, for illustration differences machine or operators and to boot similar ambient temperature or humidness. 3.1.2.1 Screening Design and Full Factorial Design Screening design is to find which factor and consequence which are of import. When have 2-4 factors and can execute a full factorial. Full factorial design in two degree. Full factorial design ia a conventional experimental design with all input factors set at two degrees each. These degrees is called ihighi and ilowi or +1 and -1. A consolidation of all the input factors is called full factorial design in two degree [ 6 ] . If there are thousand factors at 2 degrees, full factorial design has 2? tallies. Table 7: Example Number of run 2? Full Factorial Number of Factors Number of Runs 2 4 3 8 4 16 5 32 6 64 7 128 Aim of factorial design as below: 1. To place factors which important effects on the response. 2. To place interations between the factors. 3. To place which factors is the most importance effects on the response. 4. To make up one's mind whether farther probe of a factoris consequence is set up. 5. To look into the functional assurance of a response on multiple factors at the same time. 3.1.2.2 Response Surface Methodology Response surface Methodology ( RSM ) investigated relationships between critical variables and response variables. Objective of RSM is to utilize a patterned advance of designed experiments to obtain an optimum response. Below is illustration of RSM: Figure 12: Response surface iPeaki Figure 13: Response surface iHillsidei Figure 14: Response surface iRising ridgei Figure 15: Response surface isaddlei 3.1.2.3 Mathematical Method The mathematical theoretical account interact procedure parametric quantities and their interations with response parametric quantity will be refined harmonizing to the experimental consequence. These theoretical account will be used to expect the size of dyer's rocket zone which can better the welding quality and public presentation in Resistance Spot Welding. The most common theoretical accounts accommodate to the experimental informations take either a additive equation. A additive theoretical account with two factors X1 and X2 such as below: Y = i0 + i1X1 + i2X2 + i12X1X2 + experimental mistake Yttrium is the response for given degrees of the chief consequence X1 and X2 and X1X2 is included for undetermined interation consequence between X1 and x2. Constant i0 is the response of Yttrium when both chief consequence are 0 [ 6 ] . The progress of utilizing DOE is that can provides an accession organized which it possible to dissertation both simple and recognize experimental job. The experiment is to choose convenient aim, and so execute a set of experiment. That DOE can obtain more utile and more precise information about the surveies system. The joint influence of all factors is estimated [ 5 ] 3.1.3 Experiment procedure The experiment is concentrate to find the radius of liquefied zone or dyer's rocket nugget and Heat Affected Zone ( HAZ ) . The diameter of dyer's rocket nugget and Heat Affected Zone ( HAZ ) is measured by captured the image of the specimen by the microscope. All the parametric quantity such as welding clip, the diameter of tips, weld current, and force will be varied in the experiment. All the consequence with different parametric quantity will be record to look into nugget development focused on dyer's rocket nugget and Heat Affected Zone ( HAZ ) . The process for this experiment to fix the sample of specimen are: a ) Film editing. B ) Molding. degree Celsius ) Grinding. vitamin D ) Polishing. vitamin E ) Etching. degree Fahrenheit ) Invetigate weld nugget and HAZ size utilizing microscope. 3.1.4 Decision After acquire the optimal consequence, the hardness and strength has to be verification by tensile trial, and hardness trial, the decision from this undertaking is verify and the undertaking is 100 % complete. 3.1.5 Thesis authorship After the decision reached, thesis authorship is needed to finish the undertaking. All the procedure and information from this undertaking from the start util the terminal is to be record and roll up together as a book. Chapter IV BASIC CONCEPT AND ANALYTICAL SOLUTION 4.0 Introduction Resistance topographic point welding ( RSW ) is a procedure when metal surface was approached are joined by the heat obtained from opposition to electrical current flow. Work-pieces take topographic point together under force per unit area degree exerted by electrodes. The attack was applied non one but two shaped mineral metal electrodes to concentrate welding current as a small â€Å" topographic point † and to boot to clamp the sheets together. Pushing a large current through the topographic point will run the metal and to boot organize the dyer's rocket. The redundancy of location welding is a batch of energy can experience delivered to the topographic point in a really short period of clip. Particularly, the parametric quantities play a powerful significance character of topographic point welding in finding the high quality of dyer's rocket nugget and to boot Heat Affected Zone ( HAZ ) . Any individual parametric quantities will hold to be preferred with the work done. 4.1 Variables in welding procedure There are legion factors involves in topographic point welding that are categorized since a procedure variables. The parametric quantities of procedure variables are as follow: Weld current Squeeze clip Weld clip Hold clip Electrode force 4.1.1 Weld current A current of 10000 As had been non readily available from any standard electric power mercantile establishment. 32 As is the maximal current available from common domestic and besides workplace mercantile establishments. 200 As are typical of the current available from electric entry circuits inside the industries really in mills big degrees of electric energy are utilized. Subsequently, in mill peculiarly utilised opposition welding to acquire 10000 As, some device demands to be ever option the current up from all the moderately low grade available from the energy business [ 9 ] . The merchandise that normally utilized is a transformer. Transformers can step current up or possibly down. A transformer has a twosome of spirals of wire, called the primary and besides secondary, injure around a strong Fe nucleus. The power is transferred from primary to secondary via the magnetic properties of the Fe [ 9 ] . The current is stepped up or possibly down will be to about equal the ratio between the Numberss of bend of the wire within the spiral [ 9 ] . 4.1.2 Squeeze clip Squeeze clip is the clip interval amongst the initial application of the electrode force sing the work along with the first application of current. The control of the squeezing clip is the clip interval stuck between sequence inductions and to boot originating of weld current. It is required to wait the weld current until electrode thrust has got accrued to the desired degree [ 9 ] . 4.1.3 Weld clip Weld clip is the clip during the class of the current is application to the work in doing a dyer's rocket. Weld clip calculated in rhythms of line electromotive force as are truly all of the timing characteristics. One rhythm is 1/60 of the 2nd in a 60 Hz power system [ 9 ] . 4.1.4 Hold clip Hold clip is whenever electrode force is maintained in the work after the concluding urge of welding current. Hold clip are truly required to allow the dyer's rocket nugget to indurate prior to let go ofing the welded parts [ 9 ] . 4.1.5 Electrode force Electrode force is the consequence of air force per unit area used to the air Piston linked straight to the caput. The sum of electrode force depends on top of the effectual air force per unit area, weight of caput, and Piston diameter. The expression to measure the electrode force is as below: Electrode force = 0.78 x D2 x P or p ten D2/4 x P D is the Piston Diameter in millimeter P is the air force per unit area in kilogram per millimeter square Electrode Force is in N ( Newton ) The does non let for dead weights and to boot clash. It might likely be needed when altering electrode demand from a value to some other greatly different value to re-adjust the velocity control valves. Too slow the attack wastes clip and to boot may necessitate a batch longer squeeze clip. Too fast an attack influences the electrodes and to boot shortens their being, and besides can besides damage the electrode holders or possibly caput. When projection welding, high impacts will damage the projection prior to welding and to boot give you hapless projection dyer's rockets even if every one of the different scenes is right [ 9 ] . 4.2 Electrodes The opposition topographic point welding machine typically utilised Cu metal electrodes. There are two electrodes in each location welding machine that are upper electrode and besides lower electrode. In this analysis the size of the electrodes utilized is 6mm. The electrode have three chief map. The map of electrodes as follow: To run current to the work pieces being welded To reassign the right force per unit area degree or possibly force to the work pieces to bring forth a good dyer's rocket To assist disperse temperature from all the part being welded. 4.2.1 Conducting Current The primary map of electrodes will be fire weld current through the work piece. By taking into history the committedness among current, electromotive force and to boot opposition, it turns out to be a good of import thing to pay out attending to the type of electrodes utilised. The electrodes are truly produced wholly from high opposition stuff causes they receives so hot because they had melt before the current even had a opportunity to flux right through the work piece. It is critical to vouch that the electrodes used are suited sizes that are match to the application required. The appropriate size of electrode is wholly depends with the sum of demand being induced to the work piece. 4.2.2 Transmitting Force The different work of the electrodes is by suggested of mechanized. The sum of force had to do a good dyer's rocket is different, depends with the sort of metal being welded every bit good as other facets. As electrodes are truly normally with the small side, therefore it is important to choose electrodes which are able to defy with the forces had to bring forth a good dyer's rocket nugget. The forces used are inversely relative to the opposition. It signifies which more forces will outcome less opposition and to boot more opposition can ensue less forces needed. Force even allows you to do the dyer's rocket in good status because it is being created. As the current creates temperature, the steel of work piece starts to melt. When metal thaws, it can drip to anyplace and to boot exploded from the work piece. The appropriate dyer's rocket push is needed to avoid this first-class state of affairss being gone incorrect. The forces can do the molten metal to stay put, hence can solidified and to boot cool to organize weld nugget. 4.2.3 Cooling the Workpiece Electrodes can acquire rather a spot hot with 10-20 KA or possibly more continuously fluxing under 100s of force. Presently, most welders have some kind of internally H2O chilling system which empowers H2O to go around through the tips of the electrodes while dyer's rockets are being created. But the trouble is a doomed, wrecked or improperly size air conditioning H2O pipe. Without anything to chill down the tips, heat can fleetly construct to the point where the electrodes could bit by bit weld to the work pieces. To rectify this issue, H2O pipe must be put in the electrodes so that the inbound cold H2O can strikes the finest facet of the electrode foremost [ 10 ] . 4.3 Full Factorial Design A factorial design is regarded as the common option to larn the terminal consequence of a twosome or more private variables, though the focal point on characteristics which have entirely non one but two separate factors for simpleness. In a factorial design, all of the degrees of each private variable are truly matched with every one of the sums of the assorted other separate factors to bring forth all of the possibility fortunes. In a factorial design, two degrees of the first independent variable would be combined with two degrees of the 2nd to bring forth four distinguishable conditions. In this research it would be called a 2Ãâ€"4 factorial design because there are four independent variables, each of these has two degrees. In a 2Ãâ€"4 design, there might hold eight distinguishable conditions [ 16 ] . A full factorial experiment can be analyzed utilizing ANOVA or arrested development analysis. It is comparatively easy to gauge the chief consequence for a factor. To calculate out the chief consequence of a factors. Assorted other utile explorative analysis tools for factorial experiments consist of chief effects secret plans, interaction secret plans, and a normal chance secret plan of the estimated effects. At two-level factorial designs assume that the effects are linearIf in instance a quadratic influence is expected for a factor, a more ambitious experiment must be utilised, like a cardinal blend design. Optimization of factors which possibly have quadratic effects is the chief end of reaction surface methodological analysis. 4.4 Responce Surface Methadology Response surface methods ( RSM ) provide statistical tools for design and analysis of experiments anticipated at procedure optimisation. At the concluding phases of procedure development, RSM illustrated the sweet topographic point where high output of in peculiar merchandises can be achieved. It produces statistically validated premonition theoretical accounts and, with the counsel of specialised package, response surface maps that point the manner to apogee of procedure public presentation. Before manipulate Response surface methodological analysis ( RSM ) , should take full advantage of a far simpler tool for design of experiment two-level factorials, which can be really impressive for testing the cardinal few factors included interactions from the insignificant that have no important impact [ 17 ] . Response surface methodological analysis ( RSM ) inspect the relationships beween analytical variables and one more response variables. Response Surface methodological analysis is a patterned advance of factorial design to obtain an optimum response. The first degree manner to gauge the theoretical account is utilizing a factorial experiment or a fractional factorial designs. This method is acceptable to find which analytical variables have an impact on the response variables. After estimated that, the peculiar important explanatory factors are truly left, so estimated the 2nd grade theoretical account. Then, optimise a response on the 2nd grade theoretical account [ 16 ] . 4.5 Analytic Solution Analytic option is a method which utilize mathematic as a chief component so as to work out the issue. There are many sorts of analytic option by signifies of structural, electrothermal, electromagnetic, computational fluid kineticss and so on. Every of these methods are utilised to work out the moral force and besides physical job of any building. These solutions even use to work out the trouble that involved the complex portion in organic structure construction. 4.5.1 Heat Generation The entire heat coevals rate, Qg can be described as: – [ 12 ] Where R = Rw + Rc + Re Rw: workpiece majority opposition Rc: entire contact opposition Rhenium: electrode opposition I: welding current Welding clip The heat of merger required for nugget formation, hafnium is [ 13 ] Where Hydrogen: heat of merger per unit volume : Nugget volume ( ) The entire heat loss can be described in three different parts with lumped measures. The entire heat loss: [ 11 ] Where = denseness = specific heat = volume = temperature rise n = in nugget s = in environing vitamin E = in electrodes Therefore, the entire heat balance including the entire heat loss rate, through the theoretical account boundaries can be written as follows: – The above equation can be rearranged as By pretermiting the heat loss and temperature rise in the electrodes and the temperature rise in the surrounding, the equation becomes 4.5.2 Effect of Geometry and Heat Loss By sing the entire heat loss, the old equation alterations to changeless The entire heat loss rate of the nugget, is the amount of the axial heat loss rate through the electrodes, and the radial heat loss through the workpiece. Then, the axial loss rate [ 11 ] Where: thermic conduction : thaw temperature : interface temperature at workpiece : distance from runing interface to electrode contact surface : nugget radius. The heat required for temperature rise in environing nugget stuff is determined by the heat flux out of the nugget and the heat coevals in environing stuff itself. The temperature distribution in this part is assumed to be determined by when the nugget growing to sufficient size. If the heat loss through the workpiece is assumed to be relative to the country of the nugget side wall, so Where: characteristic surrounding temperature : feature heat diffusion length The thermic conduction includes in the heat loss equation alterations with temperature while the interface temperature is besides affected by geometry and interfacial feature. This is besides affected by heat coevals due to the electrical electric resistance alteration with temperature. [ 11 ] The comparing of heat loss in axial and radial way can be determined by the growing of the nugget. The ratio of axial heat loss to the radial heat loss is given by: By presuming that the nugget size is straight relative to the geometry of the electrode and the thickness, so Where: incursion : concluding incursion to workpiece thickness ratio : electrode contact surface radius Then, the concluding ratio becomes, By presuming that the nugget front revises its place at every half rhythm or ( 1/120 sec ) in AC welding, so the ratio becomes The entire heat loss can be described as a map of: [ 11 ] 4.5.3 The Principle of Electrical Distribution The rate of heat coevals depends upon the flow of current, in amperes, through the opposition of the stuff. Other electrical factors, such as electromotive force, frequence and power factor, enter into consideration merely with regard to their uniformity. They affect merely the value of the current. Harmonizing to Ohmis Law: Where: current : electromotive force bead across the electrodes : opposition through the stuff in Ohm The entire heat in Watt-seconds is generated in the welding electrodes is expressed by Or ; Where T is clip in 2nd. [ 14 ] 4.5.4 Formulation for Electric Analysis In two dimensional jobs the regulating equation of the electric possible distribution is expressed by the Laplace equation [ 15 ] : ( ? ^2i ) / ( ? x^2 ) + ( ? ^2i ) / ( ? y^2 ) =0 Where i = i ( x, Y, T ) is the electrical potency as a map of co-ordinates and clip. The finite element transition of this equation can be formulated in the same manner as in the 3-dimensional analysis, and there are two sorts of boundary conditions to be specified in the electric analysis: i=i_0 On the boundaries in contact with the power supply with known possible i_0 and ( ? i ) / ? n=0 on the free boundaries, where N denotes the normal way of a boundary. After finding the possible distribution, the current denseness can be calculated as , J_y=-1/ ? ( ? i ) / ? Y Where J is current denseness and? is electric electric resistance. The heat coevals rate per unit volume is calculated utilizing the expression Q= ? iJ^2 4.5.5 Formulation of Thermal Analysis The regulating differential equation for planar transient heat conductivity with an internal heat beginning is: / ? ten ( k? T/ ? ten ) + ? / ? Y ( k? T/ ? Y ) +Q= ? iC? T/ ? T Where T is the temperature as a map of co-ordinates and clip, K is the thermic conduction, ? is the mass denseness, and C is the heat capacity per unit mass. The three types of boundary conditions involved are T=T0 On the boundaries with the specified temperatures, -k? T/ ? n=0 On the lines of symmetricalness, and -k? T/ ? n=h ( T-T_e ) On the free surfaces, the effectual heat exchange is taken into history. H is the convection heat transportation rate of the environing air, and Te is the ambient temperature. [ 15 ] . Chapter V STATISTICAL AND EXPERIMENTAL PROCEDURES 5.0 Introduction to MINITAB package Minitab are the package that pattern statistics bundle. Minitab sofware green goods by Minitab Inc that headquartered at Pennsylvania State university by a Barbara F.Ryan Thomas A. Ryan, Jr and brian l. Joiner in 1972. The intent of the minitab is to spreadsheet for better analysis for informations and file direction. It besides can regression analysis, power and sample size and create tabular arraies and graphs for the experiments. For many variables that is used it can multivariate analysis that include factor analysis, bunch analysis and corresponce analysis. And it besides functional to analysis the discrepancy to find the difference between the information points. In this research, practicality of minitab package is to plan of experiment and testing design or factorial design to place which factor that consequence the response variables. Factorial design is to plan the experiment where the input factors are ste at two degree each. The intent of the factorial design is to place the important consequence on the response, place the interaction of the factors, place the factors hat have most importance effects on the response, to make up one's mind for the farther probe that which factors should to be bead in causes the factor is non important. 5.1 Design of Experiment process The building of the design of experiment is carried out in MINITAB package. the measure procedures to make the desgin of experiment are provided in the sub-section as follows: 5.1.1 Launch and Creation of New File To establish the MINITAB16, open the MINITAB16 booklet and choose the MINITAB16 icon. Once file is opened the panel like figure 5.1 will look. Figure 5.1: MINITAB 16 Screen After the panel appear, create the new file by snaping on the file and choice New as shown in the figure 5.2 below. Figure 5.2: Created new file 5.1.2 Create factorial design To make factorial design, chink at start button so choice DOE, factorial so Create Factorial design as shown in figure 5.3 below: Figure 5.3: Create Factorial Design Since we haved 4 factors which are weld current, weld clip, hold clip and force select 4 figure of factors and chink at 2 degree factorial. Figure 5.4: Choice no of factors Figure 5.5: Choice no of Center Points Per Block Figure 5.6: Choice 4 factors and a6 no of tally 5.1.3 Enter the high an depression of the factors Click the factor button and the rename the factors are used and the enter the high and low value of the factors. For the dyer's rocket current the units used is kA ( Ampere ) , weld clip is rhythm, hold clip besides in rhythm and force in kN. Where the equation of rhythm to change over to 2nd is 1/Frequency ten cycles/sec = seconds. 5.7: Enter the high and low of the factors After that chink on the option button and consequence and merely snap Oklahoma. Figure 5.8: Option and Consequence 5.1.4 Table of the experiment is created After the measure is finished, in conclusion click OK button so the tabular array as shown in figure 5.9 is created. The agreements of the experiment is indiscriminately create by the package. For the experiment parametric quantities and the agreement is harmonizing to the tabular array. Figure 5.9: The Table of Eperiment 5.2 Experimental Procedure Procedures In this research all the experiment procedure all done in the workshop and stuff scientific discipline research lab. The procedure of experiment was done by utilizing all the equipment in the module. First, the natural stuff of mild steel have taken from machining workshop. And for DP600, this stuff have been order from PROTON Holdings Berhad. This sheet steel so being cut by utilizing shearing machine as ( Figure 5.10 ) in the machining workshop. The size and form of the specimen have been decided from the diary and the article to acquire the exactly consequence. Therefore, the size of the specimen that have been cut is 110mm ( length ) x 25mm ( breadth ) as shown in ( Figure 5.11 ) . Figure 5.10: Shearing Machine Figure 5.11: specimen After finished cutting procedure, the specimen will be clean by wire coppice utilizing the bomber as ( Figure 5.12 ) to take the dust or the oils. Figure 5.12: Bomber with wire coppice After the specimen is ready, it will be welded at the PROTON Holdings Berhad. The machine used is the portable welding machine C- gun type as ( Figure 5.13 ) . the power transformer capacity for portable welding machines is the primary dyer's rocket electromotive forces is 415 V/ 50 Hz, maximal input is 450 kVA for one welding transformer, and maximal welding current is 18 Ka. Figure 5.13: Welding machine After the specimen have been welded ( Figure 5.14 ) , it will travel through a procedure to find the radius of dyer's rocket nugget. The procedure will be conducted in the stuff scientific discipline research lab. First the welded sheet steel will be cut by utilizing cutting machine ( figure 5.15 ) . This subdivision of the procedure must be done carefully and the film editings must be at the centre of dyer's rocket nugget where the centre of the dyer's rocket nugget is the maximal diameter of the dyer's rocket nugget. Figure 5.14: Welded sheet metal Figure 5.15: Stonecutter machine After the film editing procedure has been done, the little pieces of the dyer's rocket nugget has to be mounted by utilizing mounting machine ( Figure 5.16 ) . the procedure will takes about 20 proceedingss to complete one climb. ( Figure 5.17 ) shown the specimen after mounting procedure. Figure 5.16: Climb machine Figure 5.17: After mounting procedure After finished the mounting procedure, the specimens will grined utilizing swot machine ( Figure 5.18 ) . The crunching procedure must be grind by utilizing five type os sand paper. The type of sand paper are 240, 320, 400, 600, and 1200. The the specimens must be polished utilizing Polish machine ( Figure 5.19 ) in four phases. After that the specimen will be etched by utilizing ifry regenti liquid as ( Figure 5.20 ) . At this point, the welded nugget will be on position with our bare eyes. Figure 5.18: Grind machine Figure 5.19: Polish machine Figure 5.20: iFry regenti liquid Finally, the finished specimen as shown in ( Figure 5.21 ) will be taken to the microscope LEICA DM 6000 ( Figure 5.22 ) . The microscope is connected to the computing machine which used package to take the image of the specimen. The dyer's rocket nugget size and Heat Affected zone ( HAZ ) will be measured by this package. The package used is IMAPS Ver. 4.0 Professional Edition. Figure 5.21: specimen Figure 5.22: The microscope LEICA DM 6000 IMAPS is an image analyser package that functional to see and dimensional the macrostructure. The important of this package is to detect the macrostructure of stuff. 5.2 IMAPS Software Procedure First, launch IMAPS as shown in Figure 5.23 below. Figure 5.23: Image IMAPS Software After that, choose on the picture so choice prevue on as shown in Figure 5.24 below. Figure 5.24: Choice prevue On After the package is preview on, puting the fokus of the image on the microscope sunburn click the gaining control button to capture the image of the specimen as shown in Figure 5.25 below. Figure 5.25: Image captured After image is captured, snap the horizontal length button to mensurate the length of the dyer's rocket nugget and Heat Affected Zone shown on figure 5.26 below. Figure 5.26: Click Horizontal Length Button When the horizontal length button is clicked, the line would look to mensurate the length of dyer's rocket nugget and heat affected zone ( HAZ ) . The distance of the length weld nugget and heat affected zone ( HAZ ) will be calculated automatically by the package shown in Figure 5.27 below. Once the dyer's rocket nugget is measured, stamp button must be clicked to stomp the measuring and so follow up to measured heat affected zone. The radius of dyer's rocket nugget and heat affected zone so inserted into the tabular array in the MINITAB package. Figure 5.27: Measure length of dyer's rocket nugget and Heat Affected Zone ( HAZ ) Chapter VI RESULT AND DISCUSSION 6.1 PHYSICAL AND MECHANICAL PROPERTIES 6.1.1 PHYSICAL AND MECHANICAL PROPERTIES OH 1.0 MM DP 600 Mechanical belongingss give look of the elastic and inelastic behaviour of a stuff when force is applied. The intent of mechanical trial is to demo whether a stuff or portion is suited for its intended mechanical applications by mensurating snap, tensile strength and elongation. To find the mechanical belongingss of a DP 600, tensile trial in used. The intent of tensile trial of DP 600 to guarantee that the output strength of DP600 achieved the criterion. First, before get downing the tensile trial must fix the specimen. DP 600 must be cut with the criterion of 1.0 millimeter thickness steel as shown in figure below. Figure 6.1 6.1.1.1 Tensile Test Procedure 1. Put gage grade on the specimen 2. Measure the initial length, thickness and size of the specimen. Thickness is 1 millimeter, breadth is 4 millimeter and length is 35 millimeter 3. Put the velocity. Speed used is 2 mm/min 4. Maximal burden is recorded in the computing machine The consequence of the tensile trial is shown in Figure 6.2 and Figure 6.3 below. Figure 6.2: Graph of maximumm burden Figure 6.3: The Data of Tensile Test 6.2 Screening OF THE OPERATING PARAMETERS The design matrix and consequence of 24 fractional factorial design with 21 tallies included four parametric quantities which is weld current, weld clip, hold clip, and two response which is radius of dyer's rocket nugget and radius of heat affected zone are given in table 6.1. The experimental sequence which is standard order was randomized in order to minimise the unexpected variableness in the ascertained response. StdOrder RunOrder CenterPt Blocks Parameters Response weld current dyer's rocket clip force clasp clip weld nugget HAZ 17 1 0 1 8 15 2.5 3 2.827 3.444 13 2 1 1 6 10 3.5 4 2.341 3.157 2 3 1 1 10 10 1.5 2 2.815 3.415 19 4 0 1 8 15 2.5 3 2.827 3.440 11 5 1 1 6 20 1.5 4 2.242 3.252 9 6 1 1 6 10 1.5 4 2.265 3.010 16 7 1 1 10 20 3.5 4 3.205 3.552 12 8 1 1 10 20 1.5 4 3.188 3.315 3 9 1 1 6 20 1.5 2 2.364 3.237 6 10 1 1 10 10 3.5 2 3.166 3.535 10 11 1 1 10 10 1.5 4 2.821 3.414 20 12 0 1 8 15 2.5 3 2.807 3.475 5 13 1 1 6 10 3.5 2 2.308 3.157 18 14 0 1 8 15 2.5 3 2.827 3.445 1 15 1 1 6 10 1.5 2 2.255 3.072 14 16 1 1 10 10 3.5 4 3.165 3.445 4 17 1 1 10 20 1.5 2 3.195 3.325 8 18 1 1 10 20 3.5 2 3.215 3.558 7 19 1 1 6 20 3.5 2 2.355 3.380 15 20 1 1 6 20 3.5 4 2.345 3.387 21 21 0 1 8 15 2.5 3 2.807 3.445 Table 6.1 Figure 6.4 and figure 6.5 shown a normal chance secret plan of standardised effects of dyer's rocket nugget and heat affected zone ( HAZ ) at 5 % important degree utilizing Minitab package. Figure 6.4 suggest that the chief effects of weld current, weld clip and force as the interaction consequence the radius of dyer's rocket nugget. In return, figure 6.5 suggest that the chief effects of weld current, weld clip and force as the interaction consequence the radius of heat affected zone ( HAZ ) , the point that far from the line normally is a signal of of import effects. The normal chance secret plan identifited importance effects utilizing alpha 0.5. Figure 6.4 Figure 6.5 6.3 Regression Model Table 6.2 and Table 6.3 shows that the estimated coefficients ( coef ) of the variables footings in a arrested development theoretical account for radius dyer's rocket nugget and radius heat affected zone ( HAZ ) . Equation 6.3.1 and 6.3.2 shows coresponding standard divergence ( Sdcoef ) , t-statistic ( T ) and chance ( P ) values are determined at 5 % important degree. Variables footings with P & lt ; 0.05 for radius dyer's rocket nugget is A, B, C, AB, AC and BC and radius heat affected zone ( HAZ ) are A, B, C, AB and BC. These variables are considered as statically important of the responses. Consequently, all the important variables footings that correspond with the response for 2nd order multinomial theoretical account in coded are accelerated as: RADIUS WELD NUGGET: 2.70281+ 0.39344A + 0.06081B + 0.05969C + 0.04369AB + 0.03181AC – 0.04331BC ( 6.3.1 ) RADIUS HAZ: 3.32569 + 0.11919A + 0.05006B + 0.07069C – 0.05744AB + 0.02281BC ( 6.3.2 ) In the equation 6.3.1 and equation 6.3.2, the positive coefficients of the variables illustrated their mutual effects on the radius of dyer's rocket nugget and radius of HAZ. Meanwhile the negative coefficients illustrated their unfriendly consequence. Subsequently, the chief efect A ( weld current ) , B ( weld clip ) , and C ( force ) are the primary operating parametric quantities that influence the radius of dyer's rocket nugget. That is consequently to the diminishing significance of each variables respect to their consequence on radius dyer's rocket nugget which are A ~ B ~ C ~ AB ~ AC ~ CD ~ AD ~ D ~ BD ~ BD. For the variables term of radius HAZ, the diminishing significance variables respect to their consequence on radius HAZ is A ~ C ~ B ~ BC ~ BD ~ AC ~ CD ~ AD ~ D ~ AB. The chief variables A ( weld nugget ) , C ( force ) and B ( weld clip ) are the primary operating parametric quantities that influence radius HAZ. Table 6.2: Estimated coefficients of the arrested development theoretical account for radius of dyer's rocket nugget Term Coef SE ( Coef ) T P Changeless 2.70281 0.01407 192.10 0.000 Weld current, A 0.39344 0.01407 27.96 0.000 Weld clip, B 0.06081 0.01407 4.32 0.002 Force, C 0.05969 0.01407 4.24 0.664 Hold clip, D -0.00631 0.01407 -0.45 0.013 Weld current *weld clip, AB 0.04369 0.01407 3.10 0.050 Weld current*force, AC 0.03181 0.01407 2.26 0.740 Weld current*hold clip, AD 0.00481 0.01407 0.34 0.013 Weld time*force, BC -0.04331 0.01407 -3.08 0.404 Weld time*hold clip, BD -0.01231 0.01407 -0.88 0.592 Force*hold clip, Cadmium 0.00781 0.01407 0.56 0.003 Table 6.3: Estimated coefficients of the arrested development theoretical account for radius of HAZ Term Coef SE ( Coef ) T P Changeless 3.32569 0.007626 436.08 0.000 Weld current, A 0.11919 0.007626 15.63 0.000 Weld clip, B 0.05006 0.007626 6.56 0.000 Force, C 0.07069 0.007626 9.27 0.000 Hold clip, D -0.00919 0.007626 -1.20 0.259 Weld current *weld clip, AB -0.05744 0.007626 -7.53 0.000 Weld current*force, AC 0.00694 0.007626 0.91 0.387 Weld current*hold clip, AD -0.00419 0.007626 -0.55 0.596 Weld time*force, BC 0.02281 0.007626 2.99 0.015 Weld time*hold clip, BD 0.00994 0.007626 1.30 0.225 Force*hold clip, CD -0.00194 0.007626 -0.25 0.805 6.4 Model Competence Checking Table 6.4: Analysis of variance of the arrested development theoretical account for radius of dyer's rocket nugget Beginning DF Seq SS F P Arrested development Linear Square Interaction 6 0.08052 4.24 0.026 Residual mistake 9 0.02851 Lack of deficiency 5 0.02803 46.71 0.001 Pure error 4 0.00048 Entire 20 2.7535 S = 0.0562804 PRESS = 0.364343 R-Sq = 98.96 % R-Sq ( pred ) = 86.77 % R-Sq ( adj ) = 97.70 % Table 6.5: Analysis of variance of the arrested development theoretical account for radius of HAZ Beginning DF Seq SS F P Arrested development Linear Square Interaction 6 0.063802 11.43 0.001 Residual mistake 9 0.008375 Lack of deficiency 5 0.007564 7.46 0.037 Pure error 4 0.000811 Entire 20 0.479548 S = 0.0305052 PRESS = 0.166012 R-Sq = 98.25 % R-Sq ( pred ) = 65.38 % R-Sq ( adj ) = 96.12 % Table 6.4 shown the analysis of discrepancy ( ANOVA ) of the arrested development theoretical account for radius dyer's rocket nugget at equation 6.3.1 that obtained at 5 % important degree. Each variables which are additive, square, and interaction and the arrested development theoretical account shown P values is less than 0.05. That proved that it are statistically important. The tabular array 6.4 besides shows that the sample fluctuation of R-Sq is 98.96 % for % recovery. That is indicated to the regressors in the theoretical account merely 1.04 % of the entire variableness is non explained by the theoretical account. The value of R-Sq ( adj ) is 97.7 % at the tabular array 6.4 which contrasted 1.26 % from the value R-Sq that determined the theoretical account is extremely important. Table 6.5 is the analysis of discrepancy ( ANOVA ) of the arrested development theoretical account for radius Haz at equation 6.3.2 that besides obtained at 5 % important degree. The variables which are additive, square, and interaction and the arrested development theoretical account shown P values is less than 0.05. it besides proved that it are statistically important. The R-Sq in table 6.5 is 98.25 % for % recovery. That is indicated to the regressors in the theoretical account ony 1.8 % of the entire variableness is non explained by the theoretical account. The value R-Sq ( adj ) is 96.12 % at the tabular array 6.5 which besides contrasted 2.13 % from the value R-Sq Thai is determined the theoretical account is extremely important. The competency of theoretical account was besides examined from the normal chance secret plan of standardised remainders for dyer's rocket nugget and HAZ are shown in figure 6.6 and 6.7 below. Therefore, as shown in figure 6.6 and 6.7 all the points accumulated along a consecutive line and remainders. Figure 6.6 and 6.7 besides shows that all the fitted values are interior little magnitudes of +/- 0.06 for dyer's rocket nugget and +/- 0.04 for HAZ. These illustrate that A, B, C, AB, AC and BC for radius dyer's rocket nugget and A, B, C, AB and BC for radius HAZ are the lone important consequence and that the necessary arrested development premises are satisfied. Figure 6.6: Residual secret plan for dyer's rocket nugget Figure 6.7: Residual secret plan for HAZ Chapter VII CONCLUSION AND FUTHUR RECOMMENDATION 7.0 Decision In this survey, the consequence of the design parametric quantities which is weld current, weld clip, force and force that are affected the radius of dyer's rocket nugget and radius of heat affected zone ( HAZ ) of the topographic point welding were investigated. The multinomial theoretical accounts were developed to represent relationship between the response and its important factors. These theoretical accounts could be used to foretell public presentation of radius dyer's rocket nugget and radius of heat affected zone ( HAZ ) . The showing of assorted runing parametric quantities which is weld current, weld clip, force and hold clip of the development of radius dyer's rocket nugget and heat affected zone ( HAZ ) utilizing the 24 full fractional design were acknowledge that all the parametric quantities except hold clip were affected radius of dyer's rocket nugget and radius of heat affected zone ( HAZ ) significantly. A multinomial theoretical account for radius dyer's rocket nugget and heat affected zone ( HAZ ) as a map of the important parametric quantities were developed. And the value of R-Sq is 0.9896 and R-Sq ( adj ) is 0.9770 for dyer's rocket nugget and R-Sq is 0.985 and R-Sq ( adj ) is 0.9612 for heat affected zone ( HAZ ) . The arrested development theoretical account besides shows the high R-Sq values indicated that the theoretical account is extremely important and would be a good estimation of the response within the experimental subject studied. 7.1 Futher Recommendations Its is recommended that the probe of the topographic point welding parametric quantities to be continue with varied in other parametric quantities such as weld clip, stuffs, weld current and force. Particularly for stuffs besides can analyze for Advanced High Strength Steels ( AHSS ) such as DP780 and DP800due to their advantages which are to accomplish light burdening and improved structural public presentation. The nugget development and formation consequence is importance to calculate out systematically with the development of automotive engineering. Finally since the machine used in the machine is rather old and without a proper care, the RSW machine demands to be send to graduate once more. The electrode tip besides needs to re-align so that an optimal dyer's rocket nugget can be produce.