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Chapter 1

Introduction

Wire-cut electro discharge machining ( WEDM ) is one of the applications of Electro Discharge Machine ( EDM ) . WEDM procedure, with a thin wire as the electrode transforms electrical energy to thermal energy for cutting stuffs. WEDM is capable of bring forthing complex forms such as tapers, involutes, parabolas and eclipsiss. This non-traditional is widely used in fabrication of dies, molds, preciseness fabrication and contour film editing. Furthermore, WEDM is capable of green goods a all right film editing, precise, corrosion opposition and wear opposition surface ( Liao et al. , 2004 ) .

The WEDM is a preciseness machining procedure for micro machining of micro-structures such as high facet ratio micro holes, slots and molds. The basic features of the WEDM procedure is similar to that of the EDM procedure with the chief different being in size of the tools used, the power supply of discharge energy and the declaration of the X, Y, and Z axes motion ( Rao and Sarcar, 2009 ) . Therefore, to better the procedure control and quality surface unity, it is really of import to understand the machining parametric quantities involved in the stuff remotion mechanism.

Wire cut electro discharge machine ( WEDM ) is an version of the basic EDM procedure, which can be used for cutting complex two and three dimensional forms through electrically carry oning stuffs. WEDM is a widespread technique used in industry for high preciseness machining of all types of conductive stuffs such as metals, metallic metals, black lead, or even some nonconducting stuffs of any hardness ( Singh and Garg, 2009 ) . WEDM applied a thin wire continuously traveling as an electrode. The electrode is a thin wires that diameter runing between 0.05 to 0.3 millimeter ( Zakaria et al. , 2005 ) .

The wire electrode is drawn from a supply reel and collected on a take-up reel at top of machine. The wire is guided by sapphire or diamonds ushers and kept straight by high tenseness. The wire tenseness detector ever kept touching the wire during the cutting procedure. Tension is of import to avoid tapering or unsmooth of the cut surface. During the cutting procedure, high frequence DC ( direct current ) pulsation delivered to wire and workpiece. The WEDM procedure used electrical flickers between a thin, going wire electrode and the workpiece to gnaw the work stuff and bring forth the coveted form ( Miller et al. , 2004 ) . The WEDM cutting procedure is shown in Figure 1.1.

Figure 1.1: Conventional position of Wire Cut EDM Cutting Procedure

The pulsation delivered will doing a flicker discharges in the narrow spread between the two. The wire workpiece spread normally ranges from 0.025 to 0.05 millimeter and is invariably maintained by a computing machine controlled placement system. The power supply for WEDM fundamentally same as for conventional EDM, except the current carrying capacity of the wire limits currents to less than 20A, with 10A or less being most normal. The flicker frequences are higher, up to 1MHz to give a all right surface on the workpiece ( Hassan et al. , 2009 ) .

Many WEDM machines have adopted the pulse bring forthing circuit utilizing low power for ignition and high power for machining. But, it is non suited for completing procedure since the energy generated by the high electromotive force bomber circuit is excessively high to obtain a coveted all right surface ( Singh and Garg, 2009 ) . WEDM is capable of bring forthing any complex form merely generated with high class of truth and surface coating utilizing computing machine numerical control ( CNC ) .

1.1 Problem Statement

WEDM is a non-traditional machining method that widely used to model tools for die fabrication industry, but the job occurs on the surface unity after machining because in fabrication procedure industries, the assortment, preciseness and truth has become the indispensable portion ( Parashar et al. , 2009 ) . The job happened when the machining parametric quantities tabular arraies provided by machine makers frequently do non run into the operator demands and sometimes do non supply efficient guidelines to fabricating applied scientists. From that state of affairs, they make some accommodations to run into their demands, which may set up in hapless quality and non make the criterion of the concluding merchandise.

WEDM procedure is used to accomplish high truth, all right surface coating, high remotion rate and increased productiveness. However there are some jobs that might happen when machining the work-piece in WEDM procedure such as bad surface coating, micro-cracks, undercut and others. The job still happened even the skilled operator is used. It is hard to accomplish the optimum public presentation machining. These jobs made the merchandise have bad surface coating, low mechanical strength and other jobs.

( Rao and Sarcar, 2009 ) stated that in the field of dies and molds doing, preciseness fabrication and contour film editing has a many challenges due to accomplish a high truth and preciseness coating. This composite ‘s form can be generated easy with higher truth and surface coating utilizing the WEDM. Besides, ( Zakaria et al. , 2004 ) stated that there are several jobs on the production of die-making, preciseness machining, cutting of sheet stuffs and for the fabrication of paradigms. The jobs besides occur to bring forth the complex two and three dimensional forms.

Additionally, to bring forth a complex forms such as tapers, involutes, parabolas and eclipsiss particularly in the tool doing field has a several challengings ( Hassan et al. , 2009 ) . Furthermore, the increasing applications of WEDM need the higher demands of preciseness and accurately machining procedures. Some parts need accurately machining procedure with changing hardness or complex forms that are really hard to be machined by conventional machine ( Singh and Garg, 2009 ) .

The demand for high public presentation stuffs machining of complex forms is another challenge. Attach toing the development of mechanical industry, the demands for metal stuffs holding high hardness, stamina and impact opposition are increasing ( Liao and Huang, 2003 ) . The unsmooth film editing operation is besides treated as a ambitious issue in WEDM fabrication procedure ( Mahapatra and Patnaik, 2006 ) . Therefore, utilizing the full factorial method as a tool to look into the machining parametric quantities due to accomplish the optimum public presentation feature for aluminium metal ( Al ) 5052 stuff in WEDM procedure.

1.2 Research Question

The research inquiries are:

What is the most optimization parametric quantity influenced on stuff remotion rate and surface raggedness for machining of Al 5052 metal in WEDM procedure?

How the parametric quantities affect the machining procedure in WEDM?

What are the optimal machining parametric quantity that can increase the material remotion rate and surface raggedness in WEDM procedure utilizing the mathematical theoretical account?

Research Objective

The research aims are as follows:

To look into the most optimum parametric quantity influenced on stuff remotion rate and surface raggedness for machining of Al 5052 metal in WEDM procedure.

To place the effects of parametric quantities to machining procedure in WEDM.

To look into the optimal machining parametric quantity that can increase the material remotion rate and surface raggedness in WEDM procedure utilizing the mathematical theoretical account.

1.4 Research Significance

The research significance such as:

To assist the operator to better the machining public presentation in WEDM fabrication procedure for bring forthing the high quality coating, accurate and precise work.

To put the optimisation of machining parametric quantities for machining procedure in WEDM.

1.5 Research Scope

The range of the research is:

To look into the public presentation features of WEDM machining procedure for material remotion rate ( MRR ) and surface raggedness ( SR ) .

The machining parametric quantities to be investigated include pulsate off clip ( TOFF ) , peak current ( IP ) , wire provender ( WF ) , and servo electromotive force ( SV ) .

The stuff of the survey is utilizing the Al 5052 metal as a specimen of experiment.

To use the full factorial method in the appellation of experiment.

Chapter 2

LITERATURE REVIEW

2.1 Wire-Electro Discharge Machine ( WEDM )

Wire-electro discharge machining is a procedure of stuff remotion of electrically conductive stuffs by the thermo-electric beginning of energy. The stuff remotion by controlled eroding through a series of insistent flickers between work-piece and electrode. ( Rhoney, 2001 ) states that the WEDM, as shown in Figure 1.2 ( a ) , uses a going brass wire, runing from 0.02 to 0.40 millimeters in diameter, as the electrode. Continuous electrical flickers, Figure 1.2 ( B ) , are generated between the wire and work-piece for stuff remotion. By utilizing computing machine numerical control, the thin wire is guided in the X and Y waies to cut a precise form in the work-piece.

Figure 2.1: ( a ) WEDM Cutting Operation Process,

( B ) Enlarged position of the Wire and Work-piece

In the WEDM procedure there is no comparative contact between the tool and work stuff, therefore the work stuff hardness is non a confining factor for machining stuffs by this procedure. In this operation the stuff remotion occurs from any electrically conductive stuff by the induction of rapid and insistent flicker discharges between the spread of the work and tool electrode connected in an electrical circuit and the liquid dielectric medium is continuously supplied to present the scoured atoms and to supply the chilling consequence.

A little diameter wire runing from 0.05 to 0.25 millimeter is applied as the tool electrode. The wire is continuously supplied from the supply bobbin through the work-piece, which is clamped on the tabular array by the wire grip rollers. A spread of 0.025 to 0.05 millimeter is maintained invariably between the wire and work-piece. The wires one time used can non be reused once more due to the fluctuation in dimensional truth. The dielectric fluid is continuously flashed through the spread along the wire, to the triping country to take the by merchandises formed during the eroding. Brass wire is most normally used for wire film editing, and Zn or aluminium coatings are employed for high-speed cuts ( Abdul, 2006 ) .

The WEDM has become an of import untraditional machining procedure, widely used in the aerospace, atomic and automotive industries. This is because the WEDM procedure provides an effectual solution for machining difficult stuffs with intricate forms, which are non possible by conventional machining methods. In WEDM the cost of machining is instead high due to high initial investing for the machine and cost of the wire electrode tool. The WEDM procedure is more economical, if it is used to cut hard to machine stuffs with complex, precise and accurate contours in low volume and greater assortment ( Abdul, 2006 ) .

There are many research surveies by old research worker about the WEDM machining procedure for different stuff and parametric quantity scene. ( Kern, 2007 ) stated that during the cutting procedure the high on wire tenseness is necessary to maximise truth. For the legion occupations with more relaxed tolerance such as +/- .001 ” or larger, a lower degree of wire tenseness will let the machine to cut faster. Wire tenseness combined with heat and the onslaughts of the flicker upon the wire cross-sectional country, is what finally will interrupt the wire. If we lower the wire tenseness significantly for dilutant, less accurate occupations, we can use more power to the wire without interrupting it.

Besides, there are a several myths in WEDM machining procedure like a larger wire ever gives more economical public presentation. That is non truly rectify for all cutting occupations because it is merely a anticipation. So the key to successful public presentation optimisation is methodical and little accommodation of parametric quantities. It is besides of import to let the machine to stabilise after each alteration is made and ever supervise the film editing rate and stableness during the consecutive line cut ( Kern, 2007 ) .

The choice of optimal machine puting parametric quantities plays an of import function for obtaining higher cutting velocity or good surface coating. Improperly selected parametric quantities may besides ensue in serious effects like short-circuiting of wire and wire breakage. Wire breakage imposes certain bounds on the cutting velocity that in bend reduces productiveness. As surface coating, material remotion rate and cutting velocity are most of import parametric quantities in fabrication, assorted probes have been carried out by several research workers for bettering the surface coating, material remotion rate, cutting velocity and breadth of kerfs of WEDM procedure ( Kern, 2007 ) .

However the job of choice of cutting parametric quantities in WEDM procedure is non to the full solved, even though the latest version of Computer Numerical Control ( CNC ) WEDM machine are soon available. WEDM procedure involves a figure of machine puting parametric quantities such as peak current ( IP ) , pulse on-time ( TON ) , pulse off clip ( TOFF ) , servo electromotive force ( SV ) , wire provender ( WF ) , wire tenseness ( WT ) , and dielectric force per unit area flushing ( DFP ) . The stuff of work-piece and its tallness besides influence the procedure. All these parametric quantities influence the surface coating and material remotion rate of WEDM machining procedure. ( Parashar et al. , 2009 ) stated that the strength and hardness of the work stuffs are non important factors in WEDM machining procedure.

2.2 Performance Features

2.2.1 Surface Roughness Characteristics

Harmonizing to the development of mechanical industry, the demands for metal stuffs holding high hardness, stamina and impact opposition are increasing, so a good quality coating for the workpiece have to better ( Liao et al. , 2004 ) . Therefore, good quality surface improves the weariness strength, corrosion and wear opposition of the workpiece ( Singh and Garg, 2009 ) . Normally, the scenes of machining parametric quantities ever based on the operators working experience and sometimes they refer to the machining parametric quantities tabular arraies provided by machine tool builders. An analysis of effects of assorted procedure parametric quantities for accomplishing improved machining features is required for successful use of procedure with high productiveness ( Rao and Sarcar, 2009 ) .

Therefore, the surface coating is controlled by figure of discharge per second, more frequently referred to as the frequence sparks. The greater sum of energy applied the greater sum of stuff removed. However, when greater sum of current are used, larger craters are eroded from the work, doing a rougher surface coating. To keep increased metal-removal rates and at the same clip better the surface coating, it is necessary to increase the frequence of the discharge ( Abdul, 2006 ) .

Several researches have been made in the yesteryear to analyze the influence of different procedure parametric quantities on the of import public presentation steps of the WEDM procedure by utilizing assorted job resolution tools. ( Nihat et al. , 2003 ) investigated that the consequence of the pulse continuance, unfastened circuit electromotive force, wire velocity, and dielectric flushing force per unit area on workpiece surface raggedness, it was found that the increasing pulse continuance, unfastened circuit electromotive force, and wire velocity increases the surface raggedness whereas the increasing dielectric fluid force per unit area decreases the surface raggedness. The material remotion rate ( MRR ) straight increases with addition in pulsation on clip ( TON ) and peak current ( IP ) while lessenings with addition in pulse off clip ( TOFF ) and servo electromotive force ( SV ) ( Miller et al. , 2004 ) .

( Singh and Garg, 2009 ) stated that the pulsation on clip is the most influencing machining parametric quantity for surface raggedness, comparison to the spread electromotive force, pulsate off clip and flushing force per unit area are small effects while wire provender lowest consequence to the surface raggedness. ( Hassan et al. , 2009 ) investigated that to bring forth the good surface coating such as the WEDM machining parametric quantities should be set at low pulse current and little pulsation on continuance. It is because the pulsation on continuance has major influence in specifying the WEDM surface texture as compared to the pulse current.

2.2.2 Material Removal Rate ( MRR )

The sum of stuff removed in a given unit of clip during WEDM procedure is called material remotion rate ( MRR ) . The MRR for WEDM are slower than conventional machining methods. The rate of stuff remotion is dependent on the undermentioned factors:

Sum of current of each discharge.

Frequency of the discharge.

Material of wire.

Work-piece stuff.

Cuting velocity.

Feed rate.

Dielectric blushing conditions.

The common construct for WEDM machining procedure is when the current additions, MRR besides will increase with a flicker of 1 ampere ( A ) erodes a certain sum of metal. When the current is doubled, the energy in the discharge is besides doubled and about twice the sum of metal is removed. Modern WEDM machine have power supplies capable bring forthing more than 100 A to material per hr for every 20 A of machining current. However material remotion rates will up to 245 cm3/h are possible for roughing cuts with particular power supply ( Abdul, 2006 ) .

Factors like discharge current, pulse continuance and dielectric flow rate and their interactions have been found a important function in unsmooth film editing operations for maximizations of MRR, minimisation of surface raggedness and maximization of cutting breadth ( kerf ) ( Mahapatra and Patnaik, 2006 ) . The effects of parametric quantities ( dispatch current, occupation thickness, and material composing ) were studied on machining standards such as cutting velocity, flicker spread and MRR ( Rao and Sarcar, 2009 ) . The survey has been done by different research worker on different stuff still shows the similar consequences as good.

The servo electromotive forces have signifant influence on the MRR while lower value of servo electromotive force can increased MRR and machining production rate will be increased at the same time ( Ahmad et. Al, 2010 ) . Using an unreal nervous web patterning to execute the optimum procedure parametric quantity scenes to accomplish the features for WEDM workpiece surfaces. They obtained the optimal combination of the parametric quantities, viz. pulse breadth, clip between two pulsations, wire mechanical tenseness, and wire provender infinite for maximal cutting velocity, maintaining the surface raggedness and curliness within the needed bounds ( Spedding and Wang, 1997 ) . The stuff remotion is increased but the efficiency of stuff remotion ( volume of stuff remotion per unit energy input ) is decreased with the addition of discharge on clip. Under the same machining conditions, the surface raggedness will go better when there is greater specific discharge energy ( SDE ) , and frailty versa ( Liao and Yu, 2004 ) .

The investigated on the consequence and optimisation of machining parametric quantities on the kerf ( cutting breadth ) and material remotion rate ( MRR ) in wire electrical discharge machining ( WEDM ) operations. The experimental surveies were conducted under changing pulse continuance, unfastened circuit electromotive force, wire velocity and dielectric flushing force per unit area. The scenes of machining parametric quantities were determined by utilizing Taguchi experimental design method. The fake tempering algorithm was so applied to choose optimum values of machining parametric quantities for a multi-objective job sing minimisation of kerf and maximization of MRR ( Nihat et al. , 2004 ) . The cutting public presentation end products considered in this survey were surface raggedness and cutting velocity. It is found by experimentation that increasing pulse clip, unfastened circuit electromotive force, wire velocity and dielectric fluid force per unit area increase the surface raggedness and cutting velocity ( Nihat, 2003 ) .

The relational and signal to-noise ( S/N ) ratio analysis to show the influence of table provender and pulse-on clip on the material remotion rate. It was found that the table provender rate had a important influence on the metal remotion rate, while the spread breadth and surface raggedness were chiefly influenced by pulse-on clip. The probe on the optimisation and the consequence of machining parametric quantities on kerf and the MRR in WEDM operations has been studied ( Huang and Liao, 2003 ) .

Some research worker has developed mathematical theoretical accounts correlating the assorted WEDM machining parametric quantities ( peak current, responsibility factor, wire tenseness and H2O force per unit area ) with metal remotion rate, wear ratio and surface raggedness based on the response surface methodological analysis ( Hewidy et al. , 2005 ) . Another research worker has presented a multiple arrested development theoretical account to stand for relationship between input variables and two conflicting aims, such as cutting speed and surface coating. A multi-objective optimisation method based on a non-dominated sorting familial algorithm ( NSGA ) was so used to optimise the WEDM procedure ( Kuriakose and Shunmugam, 2005 ) . The familial algorithm, a popular radical attack, is employed to optimise the wire electrical discharge machining procedure with multiple aims.

2.3 Effected of Machining Parameter

2.3.1 Effect of Peak Current

As illustrated in Figure 2.2, increased discharge frequence can better the surface coating. Within bounds, by duplicating the amperage and frequence, the MRR will duplicate without altering the coating ( Abdul, 2006 ) .

Figure 2.2: Consequence of current and frequence on surface coating and MRR.

At high frequences, the amperage is reduced due to inductance, thereby cut downing the MRR. The economic sciences involved, hence, set a practical bound on surface coating. The relationship between current and frequence on surface coating is shown in Figure 2.3 ( Abdul, 2006 ) . The value of peak current should be high to obtain higher MRR ( Singh and Garg, 2009 ) .

Figure 2.3: Surface Finish as Related to Frequency and Current

2.3.2 Effect of Pulse Duration

As illustrated in Figure 2.4, the value of pulse off clip can be selected in such a manner to acquire the desired of MRR in machining procedure. So, when the pulsation off clip is increased the MRR will diminish. The consequence of pulse continuance in machining procedure has a signifant to the MRR ( Singh and Garg, 2009 ) . ( Rao et al. , 2010 ) investigated that the MRR addition with lessening in TOFF, this is because when TOFF addition there will be an unwanted heat loss which does non lend to MRR. This will take to drop in the temperature of the work-piece before the following flicker starts and hence MRR decreases as shows in Figure 2.4.

Figure 2.4: Pulsate off clip and MRR

During the off clip, TON, the capacitances are charged up and melted stuff is flushed from the spread between the wire electrode and work-piece. After circuit is completed, the flicker is discharged and the energy and the energy are delivered during the on clip, TON, which is the flicker on clip. This entire clip for bear downing and discharging is the spark rhythm as shows in Figure 2.5 ( Hassan, 2009 ) .

Figure 2.5: Voltage V. Duration during the WEDM film editing procedure

2.3.3 Effect of Wire Feed

The Figure 2.6 shows that the MRR remains neraly changeless with fluctuation in the wire provender. Therefore, the wire provender should be selected in a manner that there is no wastage of the wire in the machining procedure ( Singh and Garg, 2009 ) . ( Rao et al. , 2010 ) evaluated that the wire provender is signifant to MRR, when the wire provender increases the mean ( dubnium ) for MRR besides increases as shows in Figure 2.7.

Figure 2.6: Material Removal Rate ( MRR ) and Wire Feed ( WF )

Figure 2.7: Average S/N Ratios ( dubnium ) to Wire Feed Rate

2.3.4 Effect of Servo Voltage

The MRR is maximal at low servo electromotive force and lower limit at high electromotive force. Figure 2.6 show that the MRR decreases regurlarly with addition in the servo electromotive force ( Singh and Garg, 2009 ) .

Figure 2.8: Material Removal Rate ( MRR ) and Servo Voltage ( SV )

2.4 Material

The stuff will be usage in the experiment is aluminium 5052 metal. The Al 5052 metal contents with several elements such as Cu, Zn, manganese, Si, Mg and aluminum. There are two chief categorizations, viz. projecting metals and shaped metals, both of which are further subdivided into the classs heat-treatable and non-heat-treatable. About 85 % of aluminum is used for shaped merchandises, for illustration rolled home base, foils and bulges ( Degarmo et al. , 2003 ) .

Aluminum 5052 metal is one of the higher strength non-heat treatable metals ( annealed it is stronger than 1100 and 3003 ) .A Alloy 5052 has excellent features with a high weariness strength it is used for constructions which are capable to inordinate vibrations.A The Al 5052 metal besides has first-class corrosion opposition, particularly in marine ambiances and are hence normally used in boats, marine constituents, fuel and oil tube ( Degarmo et al. , 2003 ) .

The aluminum 5xxx series metals are based on Mg and are strain hardenable and non heat treatable. The major features of the 5xxx series are:

a-? Excellent corrosion opposition, stamina, weldability, moderate strength.

a-? Building and building, automotive, cryogenic, and Marine applications.

a-? Typical ultimate tensile strength scope: 18 – 51 ksi.

The aluminum Mg ( Al-Mg ) alloys of the 5xxx series are strain hardenable and have reasonably high strength, first-class corrosion opposition even in seawater, and really high stamina even at cryogenic temperatures to near absolute nothing. As a consequence, 5xxx metals find broad application in edifice and building, main roads constructions including Bridgess, storage armored combat vehicles and force per unit area vass, cryogenic tankage, and systems for temperatures every bit low as -4590F ( -2700C, near absolute nothing ) , transit, and Marine applications, including offshore boring rigs. Alloys 5052, 5086, and 5083 are the workhorses from the structural point of view, with progressively higher strength associated with the progressively higher Mg content ( Kutz, 2002 ) .

Drumhead

Therefore, from the reappraisal for the old research, to run the experiment for machining procedure in WEDM have to understand all the parametric quantities involved that influence to the public presentation features. Besides, the end product responses have to make up one’s mind in order to accomplish the optimisation public presentation machining procedure in WEDM. For this research the parametric quantities will be investigated are pulse off clip ( TOFF ) , peak current ( IP ) , wire provender ( WF ) , and servo electromotive force ( SV ) while the end product response are material remotion rate ( MRR ) and surface raggedness ( SR ) . From the reappraisal reference that the strength and hardness of the stuff non are signifant instead than the runing point of the stuff more signifant to the public presentation machining features in WEDM procedure.

The Design of Experiment ( DOE ) has to make up one’s mind in order to run the experiments besides to puting the figure of samples needed. So, in this research the full factorial design will be used to run the experiments. The figure of parametric quantities and degree for the machining procedure will be used to obtain the figure of samples that will be used in the experiment. Additionally, the analysis of the each samples from the experiments have to analyze utilizing the package as Design Expert Software to obtain all the value involved in the machining procedure. The consequences will be obtained after the information analyse in order to prosecute the optimum parametric quantities that most influence to the public presentation machining features in WEDM. From that the decision will be obtained to accomplish the research aims.

The reappraisal shows that the optimum parametric quantities puting are of import due to bring forth the high preciseness, truth and good surface coating of the stuff. The high preciseness and truth of cutting procedure can prosecute the high strength, high output and high quality merchandise. So, the parametric quantities controlled are really of import due to accomplish the aim.

Chapter 3

Methodology

3.1 Experimental Procedure

The complete processs in carry oning the experiment diagram are shows in Figure 3.1.

3.2 Machine

The WEDM machine will be used in this research was developed by FANUC, Japan and the theoretical account is ROBOCUT I±-0iD 5 axis. Assorted input parametric quantities changing during the experiments that will give effects for the work-piece every bit good. The brass wire is use for this machine which is suited to utilize and besides recommendation from the machine tools maker. The size of the wire is 0.25 millimeter which is difficult brass wire will be used for the experiments. The manufactured manual provided will be mentioning for behavior the experiments. This machine will let the operator to take the input parametric quantities harmonizing to the stuff and tallness of the work-piece. The WEDM will be used is shows in Figure 3.2.

Start

Recognition of job statements

Material remotion rate ( MRR ) and surface raggedness ( SR ) .

Performance feature

Identify the parametric quantities

TOFF, IP, WF, and SV.

Design of Experiments ( DOE )

Full factorial, 24.

Weights of Samples ( before machining )

Wire – Brass ( 0.25mm ) & A ; Work-piece size ( 100 X 25 Ten 10 millimeter ) .

Run the experiments ( WEDM )

Consequence on the MRR and SR.

Weights of Samples ( after machining )

Signal to resound ( S/N ) .

Analyse Results

Analysis of variance

Conformation Trial

Obtain existent consequence.

Discussion and Decision

End

No

Figure 3.1: Flow Chart for the Experiment Procedures

Figure 3.2: FANUC ROBOCUT I±-0iD WEDM Machine

3.3 Performance Characteristic

The chief intent of this research is to analyse the effects of machining parametric quantities on public presentation features such as material remotion rate ( MRR ) and surface raggedness ( SR ) Al 5052 metal in WEDM. The machining parametric quantities will be observed such as pulse-off clip ( TOFF ) , peak current ( IP ) , wire provender ( WF ) , and servo electromotive force ( SV ) . There are the of import governable machining parametric quantities of the WEDM procedure.

( Mahapatra and Patnaik, 2006 ) investigated by experimentation the optimisation on MRR, surface coating and cutting breadth ( kerf ) of machining parametric quantities on the discharge current, pulse continuance, pulse frequence, wire velocity, wire tenseness and dielectric fluid force per unit area on the machined work-piece surface. ( Nihat et al. , 2004 ) investigated on the consequence and optimisation of machining parametric quantities of pulse continuance, unfastened circuit electromotive force, wire velocity and dielectric fluid force per unit area on kerf and MRR.

( Parashar, 2009 ) survey on optimisation of surface raggedness of machining parametric quantities of spread electromotive force, pulsation on clip, pulsate off clip, wire velocity and dielectric fluid force per unit area. ( Rao and Pawar, 2009 ) survey on modeling and optimisation of MRR on procedure parametric quantities of pulsation on clip, pulsate off clip, peak current, and servo feed puting. ( Singh and Garg, 2009 ) investigated on the consequence on MRR of procedure parametric quantities such as pulsation on clip, pulsate off clip, peak current, servo electromotive force, wire provender, and wire tenseness.

3.4 Workpiece Preparation

The specimen will be cut from a rectangular saloon of Al 5052 metal with dimension of 100 X 25 X 10 millimeter size, will be cut 10 millimeters in deepness along the longer length utilizing WEDM cutting procedure. A thin brass wire of 0.25 millimeters in diameter will be use as tool for cutting the workpiece. The experiments will be conducted in H2O by droping the workpiece to a thickness of 10 millimeter. The chemical composing and the belongingss of selected work-piece stuff are shows in Table 3.1 and Table 3.2. The workpiece stuff readying is shows in Figure 3.3.

100 millimeter

10 millimeter

25 millimeter

Figure 3.3: Work-piece Material Dimension

Table 3.1: Chemical composing of Al 5052 metal ( Kutz, 2002 )

No.

Chemical

Percentage ( % )

1

Silicon

0.45

2

Fe

0.45

3

Copper

0.10

4

Manganese

0.10

5

Milligram

2.8

6

Chromium

0.35

7

Zinc

0.10

8

Aluminum

Bal.

Table 3.2: Mechanical belongingss of Aluminium 5052 metal ( Kutz, 2002 )

Properties

Al 5052 Alloy

Output Strength ( ksi )

13

Ultimate Tensile Strength ( ksi )

28

Shear Ultimate Strength ( ksi )

18

Fatigue Strength ( ksi )

16

Elongation in 2 in ( % )

25

Brinell Hardness ( Hb )

47

Modulus of Elasticity ( 103 ksi )

10.2

3.5 Design of Experiment

Therefore, each the parametric quantities have to look into decently to accomplish the optimal public presentation of cutting procedure. The experiment will be done by the specific design of experiments ( DOE ) where is conducted to execute more accurate, less dearly-won and more efficient experiments. In this research, the experimental scheme in this experiment is using a full factorial design ( 2k ) where K is the figure of controlled variables in the experiment. There are four controlled variables investigated including pulse-off clip ( TOFF ) , peak current ( IP ) , wire provender ( WF ) , and servo electromotive force ( SV ) . Through dry tally measure, the degrees have been selected such the broad scope of value are covered. The input parametric quantities and their degree will be investigates as shows in Table 3.3.

Table 3.3: Input signal parametric quantities of the scene and the degree ( Abdul, 2006 )

Control factors

Parameter

Degree 1

Degree 2

Factor A

Pulse off clip, TOFF ( Aµs )

10

30

Factor B

Peak current, IP ( A )

10

15

Factor C

Wire provender, WF ( mm/min )

10

20

Factor D

Servo electromotive force, SV ( V )

10

50

The figure of degree is 2 degrees of each factor were selected for the 24 experiment such as pulse-off times ( TOFF ) , peak current ( IP ) , wire provender ( WF ) , and servo electromotive force ( SV ) . For the DOE, there are 16 samples will be conducted for run the experiments. A common experimental design is one with all input factors set at two degrees each. These degrees are called `high ‘ and `low ‘ or `+1 ‘ and `-1 ‘ , severally. A design with all possible high or low combinations of all the input factors is called a full factorial design in two degrees.

3.5.1 Selection of Response Variable

The public presentation features steps for this experiment are material remotion rate ( MRR ) in g/min and surface raggedness ( SR ) in micrometer.

3.5.1.1 Material Removal Rate ( MRR )

After the experiments completed, each samples will be evaluate by proving machine and the specific expression to accomplish the values involved. The MRR can be expressed as the volume of work piece loss divided by machining clip. The unit for MRR is in g/min. To measure the value of MRR is measured by utilizing a digital weighing machine such as Precisa Balances series XT that merely measured the weight loss of the work-piece before and after machining procedure. The consequence of MRR will be calculated utilizing this expression:

MRR = Xb – Xa / T

Where, MRR = material remotion rate ( g/min )

Xb = Weight of specimen before cutting ( g )

Xa = Weight of specimen after cutting ( g )

T = machining clip ( min )

Figure 3.4: Precisa Balances series XT

3.5.1.2 Surface Roughness ( SR )

The surface raggedness response will be evaluated through the Taylor Hobson surface raggedness examiner to accomplish the value. It is direct transform as surface raggedness of the work-piece after machining and the unit of SR is I?m. The SR is measured by utilizing a Portable Surface Roughness Tester. The SR values are measured three times for each sample and acquire the norm. Consequence of SR can acquire direct from the machined procedure so no computation needed.

Figure 3.5: Taylor Hobson Surface Roughness Tester

3.6 Data Analysis

To happen the optimum scenes and factors for the machining of Al 5052 metal can be determine utilizing signal to resound ( S/N ) ratio and analysis of discrepancy ( ANOVA ) by utilizing the Design Expert package analyse. The parametric quantities in the machining public presentation of the WEDM procedure are identified based on experience, treatment with expert and analysis from literature. Experiments will performed by changing each input parameter maintaining others changeless. The chief ground for test experiments was to happen a scope of input parametric quantities so that it would be safe for puting parametric quantities at degrees where the trial would non stop in a failure half manner like wire breakage, no spark status or spread short.

3.6.1 Signal-to-Noise Ratio ( S/N Ratio )

The S/N will be usage to find the effects each parametric quantities has on the end product for each experiments. The norm of S/N value will be calculated for each factors and degrees to happen the scope ( R ) of the S/N for each parametric quantity. The larger the R values for parametric quantity, the larger the consequence of the parametric quantity on the machining procedure. ( Mahapatra and Patnaik, 2006 ) province that the feature that higher value represents better machining public presentation, such as MRR, is known as ‘higher is better ‘ ( HB ) . Inversely, the features that lower value represents better machining public presentation, such as SR, are known as ‘lower is better ‘ ( LB ) . Therefore, ‘HB ‘ for the MRR and ‘LB ‘ for SR was selected for obtaining the optimal machining public presentation features.

3.6.2 Analysis of Variance ( ANOVA )

The ANOVA analysis is able to place the active and inactive factors consequence to the public presentation features. The intent of ANOVA experimentation is to cut down and command the fluctuation of a procedure later, determinations can be made refering which parametric quantities affect the public presentation of the procedure. ANOVA is the statistical method used to construe experimental informations to do the necessary determinations. Through ANOVA, the parametric quantities can be categorized into important and undistinguished machining parametric quantities.

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