INTRODUCTION TO HINDUSTAN AERONAUTICS LIMITED The beginning of HAL can be traced to the year 1940 when a far sighted industrialist, the late Seth Walchand Hirachand, set up a compa company ny calle called d Hindus Hindustan tan Aircr Aircraft aft Lim Limite ited d at Bangal Bangalore ore with with the object object of establis establishing hing an aviatio aviation n industry industry that can manufac manufacture ture,, assemble and overhaul aircraft. Initially aircraft like Curtiss Hawk, Vultee Bomber and Harlow Trainer was taken up for manufacture and and over overha haul ul in colla ollabo bora rati tion on with with Inte Interr Cont Contin inen enta tall Ai Airc rcra raft ft Company of the USA. With the escalation of the Second World War, the government of India took over the management of the company in 1942 and handed it over to US Air force for repair and overhaul of various aircraft. The main activity for the next few years after the war was reconditioning and conversion of war surplus aircraft for the use of IAF and Civil Operators. To fulfill the fresh mandate of the post independent India and to meet the challenges challenges of open market economy of recent times the mission of the company has been redefined as: “To become a globally competitive aerospace industry while work workin ing g as inst instru rume ment nt for for achi achiev evin ing g sel self reli relian ance ce in desi design gn,, manufacture manufacture and maintenance maintenance of aerospace defense equipment and diversifying to related areas, managing the business on commercial lines in a climate of growing professional competence.” In the six decades, HAL has spread its wings to cover various activ activiti ities es in the the areas areas of design design,, devel develop opmen ment, t, manufa manufact cture ure and maintenance. Today HAL has 14 production divisions spread over at Bangalore, Nasik, Koraput, Kanpur, Lucknow, Korwa, Hyderabad and Barrackpore. These divisions are fully backed by 9 design centers, which are co-located with the productive divisions. These centers are engag engaged ed in the design design and and devel develop opmen mentt of comba combatt aircr aircraft aft,, helicopter, aero engine, engine test beds, aircraft communication and naviga navigatio tion n syste systems ms and access accessori ories es of mech mechani anica call and fuel fuel systems and instruments.
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The current program include production of Dhruv an Advanced Light Light Helic Helicopt opter, er, Jagua Jaguar, r, LCA, LCA, Su-30, Su-30, MkI MkI and upgra upgrades des of MiGs, MiGs, Jaguar and Avro HS-748.
HAL ENGINE DIVISION, KORAPUT An agreement was signed in August, 1962 with the Soviet Union for manufacture of MiG-21 E7FL Air craft under license the Aero engine Factory at Koraput (ORISSA), the Air frame Factory at Nasik (Maharashtra), and the Avionics Factory at Hyderabad (Andhra Pradesh) have been set up to meet this requirement on the name of Aeronautics India Limited which was formed on April 1964 and new compa company ny under under the name name of Hindus Hindustan tan Aeron Aeronaut autic ics s Lim Limite ited d was formed. The government sanction for the first phase of construct of the aero engine factory at Sunabeda (Koraput) was accorded March 1964 1964 and and the the fact factor ory y star starte ted d manu manufa fact ctur ure e of R11F R11F22-Se Seri ries es-I -III II engines for fitment on MIG-21FL Aircraft from 1969 onwards. The first engines of imported category manufactured in December 1968 and and vari variou ous s categ ategor orie ies s of engi engine nes s were were prod produc uced ed duri during ng the the subsequent years. The first raw material engine was produced in February 1971. The The prod produc ucti tion on prog progra rams ms for for the the fact factor ory y also also incl includ ude e manufa manufact cture ure of forgin forging g and and casti casting ng requir required ed for MiG-A MiG-Airc ircraf raft. t. To meet meet the the Ai Airr forc force e requ requir irem emen entt for for im impr prov oved ed figh fightt inte interc rcep epto torr aircr aircraft aft,, an agree agreemen mentt was signe signed d with with US USSR SR in Augus August19 t1976 76 for manufacturing MiG-21BIS Aircraft. The power plant of this aircraft is the R25 turbojet engine. The government approval for setting up capital facilities was accorded in October 1977. The first engine of imported category delivered to HAL Nasik Division in the year 197879.The FI raw material engine was delivered during January1983. With signing of the inter governmental agreement for manufacture of MiG 27M Aircraft on 19 th March 1982, this Division would be involved in the manufacture of R-29B series of engine from the year 1984-85. In order to attain self-sufficiency and to avoid difficulties regarding supply of Raw Material & other layout items from USSR, it was decided to provide indigenous supply of spares manufacturing for Overhaul/maintenance Overhaul/maintenance of the fleet. The Government approval for undertaking the task received during 1977-78 and the indigenization plan was formed to tackle,
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ARS and first moving spares. Metallic material. Non-metallic material. Ready-made Ready-made articles.
The activities towards these are being progressed as per approved time frame. The various departments present in this division are: 1. Forge 2. Foundry 3. Tool room 4. Small parts and fuel 5. Sheet metal and welding 6. Blades 7. Electroplating Electroplating 8. Heat treatment 9. Compressor 10. Turbine 11. CNC 12. Assembly 13. Overhaul 14. Gear 15. Test house 16. Maintenance
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MIG 21 (R-25 Engine)
MIG 27 (R-29
B)
NON-TRADITIONAL MACHINING INTRODUCTION From some time past engineering industries have witnessed a rapid growth in the development of harder and difficult to machine materials such as hastalloy, nitralloy, nitralloy, waspalloy, nimonics, carbides, stainless steel, heat resisting steels and many other high strength temp temper erat atur ure e resi resist stan ant( t(HS HSTR TR)) allo alloys ys.. Thes These e mate materi rial als s find find wide wide application in aerospace, nuclear engineering and other industries owing owing to their their high high streng strength th to weight weight ratio ratio,, hardne hardness ss and heat heat resisting qualities. For such materials the conventional edged tool machining is highly uneconomical and the degree of accuracy and surface finish are poor. Besides, machining of these materials in to comp comple lex x shap shapes es is diff diffic icul ult, t, time time cons consum umin ing g and and some someti time mes s impossible. Cons Consid ider erin ing g the the seri seriou ousn snes ess s of the the prob proble lem, m, Merc Mercha hant nts s in 1960’s emphasized the need for the development development of newer concepts in metal metal mach machini ining. ng. Conseq Consequen uently tly,, non-t non-trad raditi ition onal al machin machining ing proc proces esse ses s have have emer emerge ged d to over overco come me thes these e diff diffic icul ulti ties es.. Thes These e proce processe sses s are non-co non-conve nventi ntiona onall or non-t non-tra radit dition ional al (NTM) (NTM) in the sense that they do not employ a conventional or traditional tool for metal removal, instead they directly utilize some from of energy for machining.
Characteristics Characteristics of non-traditional machining Non Conventional Machining Processes are characterized as follows:
Material removal may occur with chip formation or even no chip formation may take place. For example in AJM, chips
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are are of mi micr cros osco copi pic c size size and and in case case of Elec Electr troc oche hemi mica call machining material removal occurs due to electrochemical dissolution at atomic level.
In NTM, NTM, ther there e may may not not be a phys physic ical al tool tool pres presen ent. t. For For example in laser jet machining, machining is carried out by laser beam. However in Electrochemical Machining there is a physical tool that is very much required for machining.
In NTM, the tool need not be harder than the workpiece material. For example, in EDM, copper is used as the tool material to machine hardened steels.
Mostly NTM processes do not necessarily use mechanical energy energy to provi provide de materi material al remov removal. al. They They use differ different ent energy energy domai domains ns to provi provide de mach machin ining ing.. For examp example, le, in USM, US M, AJM, AJM, WJM WJM mech mechan anic ical al ener energy gy is used used to mach machin ine e mate materi rial al,, wher wherea eas s in ECM ECM elec electr troc oche hemi mica call diss dissol olut utio ion n constitutes material removal.
Classification Classification of non-traditional machining processes Classification of NTM processes is carried out depending on the nature of energy used for material removal. The broad classification is given as follows: • Mechanical Processes ⎯ Abrasive Jet Machining (AJM) ⎯ Ultrasonic Machining (USM) ⎯ Water Jet Machining (WJM) ⎯ Abrasive Water Jet Machining (AWJM) • Electrochemical Processes ⎯ Electrochemical Machining (ECM) ⎯ Electro Chemical Grinding (ECG) ⎯ Electro Jet Drilling (EJD) • Electro-Thermal Processes ⎯ Electro-discharge machining (EDM) Machining (LJM) ⎯ Laser Jet Machining ⎯ Electron Beam Machining (EBM) ⎯ Ion Beam Machining (IBM) ⎯ Plasma Arc Machining (PAM) • Chemical Processes
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⎯ Chemical Machining (CHM) ⎯ Photochemical Machining (PCM) etc
INTRODUCTION TO WIRE-CUT EDM In all the machining processes EDM is one of the important nonnon-tr trad adit itio iona nall machi achini ning ng proc proces esse ses. s. Here Here we are are main mainly ly conc concer erne ned d abou aboutt wire wire cut EDM. EDM. Wire Wire cut cut EDM EDM or Elec Electr tric ical al Discharge Machining is a technique used to slice through metal. The technique uses thin brass wire for the purpose and can create intricate profiles with the process. The EDM machine uses spark discharges that are fast, repetitive, and controlled for cutting. This process works with electrically conductive metals. The process is specially suited for contours and cavities that are not possible with other cutting tools. EDM is also known as “spark machining” as it uses repetitive electrical discharges to remove metal. The electrical discharges are passed between the metal part and the electrode. A stream of continuously flowing liquid is used to remove the metal remnants produced during the process. A set of successively deeper craters is formed till the final shape is created by the discharges.
Different types of EDM EDM:: 1. Ra Ram m EDM EDM In ram EDM, a graphite electrode is used along with traditional tools. This electrode is connected to the ram with the help of a power source and is fed into the workpiece. The whole process is carr carrie ied d out out in a flui fluid d bath bath.. The The flui fluid d help helps s to flus flush h away away the the material, serves as a coolant to reduce the heat, and acts as a conduc conductor tor for passin passing g curr current ent betwee between n the workpi workpiece ece and and the electrode.
2. Wire Wire EDM EDM In this method, a thin wire is used as an electrode. The wire is fed in the metal and the discharges are used to cut the material. The process is carried out in a bath of water. When closely observed, you can see that the wire does not touch the metal. All the cutting work is done by the electrical discharge. Computer software controls the whole operation including the path of the wire. The process can
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produce all sorts of complex shapes that are very difficult with other processes.
Principle of edm It is the most most versat versatil ile e elect electric rical al machi machinin ning g proc process ess wher where e erosion is caused due to electric spark. The rate of metal removal and the resulting resulting surface finish can be controlled controlled by proper variation in ener energy gy and and dura durati tion on of spar spark k disc discha harrge. ge. It is the the proc proces ess s of repetitive sparking cycles.
Graphical Representation: Representation:
Fig 1: Series of Electric pulses at the inter electrode gap
Fig 2: Inter electrode gap voltage waveform during sparking
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Fig 3: Inter electrode gap current waveform during sparking Where,
Ton :- Pulse on period Toff :- Pulse of period Td :- Spark ignition period
Vp :- Open gap voltage Vg :- Average gap voltage Ip :- Machining peak current A series of electrical pulse generated by the pulse generator unit is applied between the workpiece and travelling wire electrode. In the event of spark discharge, there is a flow of current across wire electrode workpiece gap. The energy contained in the tiny spark remo removes ves a fract fraction ion of workpi workpiec ece e mater material ial.. Large Large numbe numberr of such such time time spac spaced ed tiny tiny disc discha harrges ges betw betwee een n the the work workpi piec ece e and and wir wire electrode cause the electro erosion of the workpiece material.
Concep Concepts ts of 4- axes wire wire cut EDM The The wire-c wire-cut ut electr electric ic disc dischar harge ge mach machine ine is compr comprise ised d of a machine tool, a power supply unit (ELPLUS), dielectric supply and chiller unit.
1.Machine tool The ELECTRA machine tool unit comprises of a main work table (called X-Y table) on which the workpiece is clamped, an auxiliary table (called U-V table) and wire drive mechanism. The workpiece is mounted and clamped on the min work table. The main table moves along X-Y axis in the steps of 1 micrometer, by means of servo motors. U & V are parallel to X & Y axes respectively. A travelling wire which is continuously continuously fed from wire feed spool is caused travel through the workpiece and goes finally to the waste
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wir wire box. box. Al Alon ong g its its trav travel elli ling ng path path the the wir wire is supp suppor orte ted d unde underr tension between a pair of wire guide, which is supported by the U-V table. The upper wire guide can be displaced transversely along the U-V axes with respect to lower wire guide. It can also be positioned vertically along Z axis by moving the vertical arm. As the material removal removal or machining proceeds, the work table carry the workpiece is displaced transversely transversely along a predetermined predetermined path which is stored in the controller. The path specification (path programme) can be supplied to the controller by the program or directly through the controller key board. When X-Y table moves along the predetermined path, the U-V table is kept stationary as stationary cut with the predetermined pattern is formed. In order to produce taper machining the wire electrode has to be tilted. This is achieved by displacing the upper wire guide (along the U-V axes) with respect to lower wire guide. The desired taper angle is achieved by simultaneous control of the movement of X-Y table and U-V table along their respective predetermined path stored in the controller. The path information if the X-Y table and U-V table is given to the controller in terms of linear & circular elements via NC programme.
2.POWER SUPPLY The power supply unit comprises of electric pulse generator, motor drive d rive unit for X-Y, X-Y, U-V axes and controller. controller.
3.Dielectric Supply Whil While e the the mach machin inin ing g is cont contin inue ued, d, the the mach machin inin ing g zone zone is continuously flushed with chilled distilled water through the nozzle on both side of workpiece. The spark discharge across the workpiece and the wire electrode causes ionization of the water which is used as a dielectric medium. It is important to note that ionization of water leads to the increase in conductivity of water. An ion exchange resin is used in dielec dielectri tric c distr distribu ibutio tion n syste system m in order order to preve prevent nt the the incre increase ase in conductivity of water.
4.Part programming
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The geometry of the profile and the motion of wire electrode tool along the profile are fed to the part programming system using keybo eyboar ard. d. The The prof profil ile e geom geomet etry ry is defi define ned d in ter terms of vari variou ous s geometrical definition of points, lines and circles as the wire tool path elements on graphical screen by using a totally menu driven software. The wire compensation (for wire diameter and machining overcuts) and taper angle can be specified for total path or for each path element separately. After the profile is fed to the computer all the numerical information information about the path is calculated automatically automatically and its print out is generated. The entered profile can be
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veri verifi fied ed on the the grap graphi hic c disp displa laye yed d scr screen een and and modi modifi fied ed if necessary. After successful profile definition, the profile is recorded by the computer on a floppy disk which can be used in the controller controller for the execution.
Work preparation 1.W 1. Workpiece material Any sli slight ght dislo disloca catio tion n in the workp workpiec iece e materi material al may resul resultt distorted job. It is important to use the material free from residual str stresse esses, s, aris arisin ing g from from vari variou ous s proc proces esse ses. s. This This may may affe affect ct the the machin machining ing accura accuracy cy to a very very large large exten extent. t. Workpie orkpiece ce mater materia iall should be
Electrically conductive (at least 0.1 micro-ohm/cm) Suitable for clamping Non-combustible Non-viol Non-violent ent chemica chemicall reactio reactions ns with water, water, oxygen oxygen and hydrogen
2.Wire electrode The The wir wire elec electr trod ode e is requi equirred to have have a suff suffic icie ient nt tens tensil ile e strength and should be of uniform diameter and free from kinks and twist. The electrode wire material should be Brass/super alloy (coated) Diameter variation within + 0.02 mm 2 Tensile strength more than 50 kgf/mm Even winding free from kinks/breaks
Wire diameter and minimum corner radius radius::
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Fig 7: Rib width The diameter of wire imposes a restriction on the minimum achievable corner radius. Minimum corner radius = (0.5*diameter) + overcut
Current carrying capacity of the wire: As a thumb rule a brass wire of 0.2 mm in diameter can easily pass current of about 0.3-0.7 amperes in air but the same wire can pass current of about 6-9 amperes in water. While machining water should always be surrounded by the water column to avoid wire strength.
Wire tension (WT): Wire ire tens tensiion det determ ermines how much the the wir wire has to be stretched between upper and lower guides. More thickness of the job more is the tension required. Improper setting of tension may result inaccuracy in the job as well as wire breakage. Following chart give gives s nomi nomina nall valu value e of the the wir wire tens tensio ion n for for diff differ eren entt sett settin ings gs.. Minimum tension (for zero setting of WT) is approximately 200 gms which can be adjusted by clutch adjustment provided on feed spool mounting rod. This should be adjusted for different weight of spool. WT 1 2 3 4 5 6
TENSION (GMS) NOMINAL VALUES 300 420 540 660 780 900
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7 8 9 10
1020 1140 1260 1380
Wire feed (WF): Due to spark erosion the travelling wire electrode becomes thin and brittle. Wire feed is the rate at which the wire electrode travels along wire guide path. It is always desirable to set the wire feed to the the maximu mum m. This wil will resul sult in less ess wire ire brea break kage, age, bett etter machining, stability and little more cutting speed. With more feed set as 8 m/min on an average of a 0.25 mm diameter brass wire spool of 5 kg will last for 24 sparking hours. Setting WF at 15 will correspond to 15 m/min (approx.).
Overcut: It is lateral distance between the wire and workpiece during the sparking. Overcut is larger if Machining gap voltage is higher Discharge energy is higher Wire tension is lower Guide span is higher Job thickness is higher Dielectric conductivity is higher Machining is unstable
Wire compensation (offset): Wire compensation = (0.5*wire diameter) + overcut Wire compensation can be to the left (G41) or right (G42) of profile depending depending upon the direction of motion and wire being inside or outside of the profile as shown:
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Fig 8: wire compensation
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Water dielectric 1.Ch .Characterization medium
&
suitability
of
wire
cut
The
use of water as dielectric dielectric permits widening of spark gap to minimize short circuit, resulting in high cutting speed. Water has good wire electrode cooing effect (than kerosene as example). It is non flammable and its vapours are non-toxic.
2.Dielectric strength Since the insulation characterization of dielectric fluid decides the overcut so it is important to keep the conductivity of dielectric water constant. constant. Conductivity Conductivity of water changes due to generation generation of metallic ions and dissolution of ambient gases. The conductivity can be decreased by passing the water through de-ionize resin. This is done automatically by the machine.
3.Flushing Flushing is important to achieve stable condition. It plays very important role as far as cutting speed concerned. Both the nozzles uppe upperr and and lowe lowerr shou should ld be just just abou aboutt 0.22 0.22 mm away away from from the the workpiece, otherwise cutting performance drops considerably. Also both the nozzles should also be checked periodically for damages, scratches or slight damage on the contact edge affect cutting speed. Purity of the water should be machined by firm displacements of filters.
Setting up and operations 1.Job mounting: Mount the job and damp by maximum possible clamp, dial the top surface of the job by dial gauge. The dial gauge can be marked on the upper flushing assembly. Provision for the same is provided. Make the wire vertical with the help of vertical block provided with the machine.
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2.Job reference point: It is always desirable to have a reference point on the workpi workpiece ece for settin setting g the work work co-ord co-ordina inate te system system (WCS) (WCS).. The The refer eferen enc ce point int can be defi define ned d by the gro ground und edge edge of the the workpiece or the centre of the bored hole on the workpiece.
a) Edge finding finding (EF): (EF): This function should be used to find the edge for the setting work co-ordinate system. Find the edge of the workpiece from a distance of 2-5 mm. After edge finding the wire system is always from the workpiece edge by a distance equal to wire radius.
Fig 11: Edge Distance
b) Center Center finding (CF): This function should be used to find the centre of the reference hole. Centre finding should be repeated at least few times to verify consistency.
Care should be taken to perform CF and EF functions. Workp orkpie iece ce surf surfac ace e shou should ld be tak taken to perf perfor orm m CF and and EF functions. Upper assembly section should not be wet. WF should be at 3 and WT at 6.
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Technology guidelines The technology chart gives guideline to the operator to set up the paramete parameterr and get optimum performanc performance e from from the machine machine.. Actual process results may differ to same extent. Generally by increasing the spark energy one can achieve the desired cutting rate. To achieve optimum results of cutting rate and the job accuracies, the machining parameter should be properly set. The parameters which control its pulse energy and ultimately its machining speed are described below:
1.
Machining parameters
Diffe fferent ent par paramete meters rs cont ontroll olling ing its pul pulse energ ergy machining conditions are given below along their setting: Ton 000
Toff 00
Ip 000
Vp 0
WP 0
WF 00
WI 00
SV 00
SF 0000
and and
T 00
Ton : Pulse on time During Duri ng this this peri perio od the the volt voltag age e (Vp) is appli pplied ed acr across oss the the electrodes. Range:- 000-031 (in step of 1) Higher is the T on setting larger the pulse on period. The single puls pulse e disc discha harrge ener energy gy incr increa ease ses s with with incr increa easi sing ng T on period, resulting in higher cutting rate. With higher values of T on surface rough oughne ness ss tend tends s to be high higher er.. The The high higher er valu values es of disc discha harg rge e energy may also cause wire breakage.
Toff : Pulse off time Voltage for the gap is absent during the period.
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Range : - 00-63 (in step of 1) Higher the Toff setting larger is the pulse off period. With the lower value of T off there is more number of discharges in a given time resul esulti ting ng in incr increa ease se in the the spar sparki king ng effi effici cien ency cy;; as a resul esultt the the cutting rate also increases. Using very low value of T off period may cause wire breakage which reduces the cutting efficiency. When the discharge and its ions become unstable one can increase the T off period. This will allow lower pulse duty factor and will reduce the average gap current.
Ip : Peak current (A) This is for selection of pulse peak current. Range : 010-230 (in step of 10) Higher is the I p setting larger the peak current value. Increase in Ip value value will will incre increase ase the the pulse pulse discha discharrge energ energy y which which can impr im prov ove e the the cutt cuttin ing g rate rate furt furthe herr. For high higher er valu value e of I p gap conditions may become unstable with improper combination of T on , Toff , SV and and SF valu value e sett settin ings gs.. When When the the disc discha harg rge e cond condit itio ions ns become unstable one must reduce the I p value (and/or increase the Toff period).
Vp : Pulse peak voltage This is for selection of open gap voltage. Range : 1 or 2 Increase in Vp value will increase the pulse discharge energy which can improve the cutting rate. Normally it is always ‘2’.
WP : Flushing pressure of water dielectric This is selection of flushing input pressure. Range : 0 or 1 (0-low pressure, 1-high pressure). High input pressure of water dielectric is necessary for cutting with with high higher er valu values es of puls pulse e powe powerr and and also also cutt cuttin ing g the the jobs jobs of higher thickness. Lower input pressure used for thin jobs and in trim cuts.
WF : Wire feed rate setting
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This is the feed rate at which the fresh wire is fed continuously for sparking. Range :- 01 – 15 (in step of 1) High Higher er valu values es of wir wire feed feed rate rate (abo (above ve 6) are are requ requir ired ed for for working with higher pulse power (where job cutting rate are higher)
WT : Wire tension setting This is a gram equivalent load with the continuously continuously fed wire is kept under under tensio tension n so that that it remai remains ns strai straight ght betwee between n the the wire wire guides. Range :- 01-15 (in step of 1) Whil While e the the wir wire is bein being g fed fed cont contin inuo uous usly ly appr approp opri riat ate e wir wire tension tension avoids avoids the unintent unintentiona ionall wire wire deflecti deflection on from from its straight straight path (between the wire guides). The wire deflection is caused due to spark induced reaction forces and water pressure.
SV : Spark gap set voltage This is the reference voltage for the actual (gap voltage). Range :- 00-99 (in step of 1) volt
SF : Servo feed setting This parameters decides the servo speed, the servo speed at the set value of SF, can vary in proportion with the gap voltage (normal feed mode) or can be kept constant while machining (with constant feed mode). Range : 0000-0990 (for normal feed) 1000-1999 (for constant feed) In constant feed mode, the 3 least significant digit of SF define the feed rate in 10 th of mm/min. 1050 will give 5mm/min constant feed. Here SF can be vary from 000-990 in normal feed mode and 000-999 in constant feed mode by pressing up or down arrow keys or by page up or down, where as selection of first digit 0 or 1 can be done by pressing numeric key 0 or 1.
T : Threshold setting Threshold setting (in percent of SV) is for correcting action in abnormal discharge condition.
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Range : 0-99 (%)
Guidelines parameters Apart from these parameters, the technology guideline charts also also incl includ udes es foll follow owin ing g two two para parame mete ters rs for for proc proces ess s moni monito tori ring ng purpose:
Ig : Average gap current (A) This is the actual value of gap current read on ammeter. The value of average machining current given in the guideline chart is indicative.
Vg : Average gap voltage (volt) This is the actual value of gap voltage read on yellow voltage bar on the screen. It depends on set values of SV & SF. For stable machining, SF should be set such a way that Vg is higher is higher than SV by 3 – 9 volt.
2.
Guideline charts
The technology charts are prepared to support the wire EDM user ser and and pro provide vide some ome gui guideli delin nes. es. Every ery tec technol hnolog ogy y char chartt com compris prises es of a set set of guid guide e pert pertai aini ning ng to a spec specif ific ic wir wire job job thickness combination. Technology guidelines are available for the following wire and workpiece material:
WIRE : Material: ELECTRA DURACUT Diameter: 0.25 mm
JOB :
Material: Steel Hardness: 48 – 50 RC
Prior to machining, job materials were properly stress relieved.
CONDUCTIVITY :
The guide refers to the de-ionized water as a dielectric with conductivity value of 20 units.
20
PRESSURE :
The The maxi maximu mum m wate waterr inle inlett pres pressu surre is 15
kg/cm2.
FLOW TOP : This is the flow rate of water dielectric in liters/min (LPM) through the top wire guide nozzle.
FLOW BOT : This is the flow rate of water dielectric in liters/min (LPM) through bottom wire guide nozzle.
C- FEED : This is job cutting rate displayed on the screen as the job is being cut in units of mm/min. Guideline chart provides the cutt cuttin ing g feed feed valu values es foun found d unde underr the the test test cond condit itio ions ns (wit (with h all all requi equirred mac machini hining ng para parame mete ters rs prob probab ably ly set set as give given n in the the guideline chart for a selected job and wire thickness).
OFFSET : This is guideline value for wire offset (in mm). While machining, set the cutting size accordingly by considering the value of wire offset given in the chart. Guideline chart provides the wire offset values found under the test conditions.
3. Important notes I.
PRO ROPE PER R TEM TEMPE PERA RATU TUR RE CO CONTR TRO OL
a) Room temperatu temperature re control control : To achieve better machining accuracies, it is recom ecomme mend nded ed that that the the mach machin ine e be inst instal alle led d in cont contrrolle olled d 0 atmosphere with room temperature of 20 C (+ 1).
b) Water dielectric dielectric temperatur temperature: e: The The dielec dielectri tric c water water tempe temperat ratur ure e must must be mainta maintain ined ed 0 within the 1 C below the machine tool temperature (approx. same as room temperature). Set the temperature difference -10 C on temperature controller of dielectric cooling system. Before starting any job alignment or machining operation, the room temperature, machine tool temperature and the job temp temper erat atur ure e mu must st be stab stabil iliz ized ed by keepi eeping ng the the room oom air air conditioner, machine power and the dielectric cooling system
21
power on for at least half an hour. The dielectric water should also be kept splashing on the job and in the work area.
II.
Proper heat treatment
Proper oper heat heat trea treatm tmen entt of the the job mate materi rial al is nece necess ssar ary y machining. This is to reduce the residual stresses to a minimum (quite often the cause of instability and inaccuracies).
III.
Conduc ductivity of of wa water
Con Conduc ductivi tivity ty of wate ater (S) (S) shou shoulld be main aintai tained duri durin ng machinin machining g and be checke checked d periodic periodically ally.. Replace eplace paper paper filters filters and resins periodically. periodically.
IV.
Proper flushing Rate of dielectric flow adjustment.
Case 1. For rough finishing To
achiev achieve e maxim maximum um cutti cutting ng rate rate in case case when when both both guide guide nozzle can be closely connected with both the sides of work surface (0.1-0.2 mm away from workpiece) keep under and lower flushing valves fully open. Adjust the position of upper flushing nozzle so as to achieve the required flow rate as per the technology guidelines. In case when upper guide nozzle can’t be closely connected with the work surface. Keep the lower flushing valve fully open. Adjust the flow through the upper flushing valve in such away that the flushing flow from upper guide suppresses the flushing flow of the lower guide. In case when neither of the guide nozzle (upper or lower) be closely connected with the work surface, select low pressure (WP =0) for dielectric flushing.
Case 2. For finishing machining a) With die machining (without taper cut) cut)
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For
job thickness less than 30 mm keep lower flushing valve fully close and upper flushing flow at about 1.2 liters/min. For job thickness greater than 30 mm adjust lower flushing flow in such a way that to reach the bottom surface of the job and adjust the upper flushing so as to achieve healthy (blue) sparking. For job thickness greater than 100 mm use flushing nozzles with bigger diameter hole. b) With taper taper cut machining machining For cutting job taper profiles proceed as… Keep Keep the clearance clearance of 0.5-1 mm between upper flushing nozzle and top surface of the job. Specify the Z height (quill position) in the program (new height = job thickness + 1 mm). Apply flushing condition as for die machining. The cutting speed for taper cut should be lower (by 20-40 %) than straight cut machining.
c) With With punch punch machinin machining g Adjust
the lower flushing flow in such a way so as to reach the bottom surface of the job and adjust the upper flushing to 2-3 liters/min.
d) With complex complex profile machining machining (different profile at top top & bottom) For cutting job with complex profiles proceed as… Keep
the clearance of 2-5 mm between upper flushing nozzle and the top surface of the job. Specify Z height (quill position) and top and bottom height in the program. i.e. Z height = job thickness + 2-5 mm Top height = workpiece thickness Bottom height = 0 (normally) Apply the flushing condition as with die machining. The cutting speed for the complex profile should be lower (3040 %) than that of straight cut machining.
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e) The data for wire upset value given in the technical guidelines, guidelines, is
obtained (with tolerance of +5 mm) for cutting square punches. However for cutting the job profiles of other shape and size may require some correction for offset values. Before cutting actual job a test cut must be taken for every workpiece material to asce ascert rtai ain n wir wire offs offset et (com (compe pens nsat atio ion) n) valu value e accu accura rate tely ly.. The The mach machin inin ing g para parame mete ters rs (inc (inclu ludi ding ng wate waterr cond conduc ucti tivi vity ty and and flushing) selected for test cut must be maintained exactly same during actual job cutting to maintain same overcut values.
f) Apply Apply technolog technology y guidelin guidelines es The
selected pulse on time (Ton), the machining gap voltage (SV), (SV), peak peak curr current ent (Ip) and and servo servo feed feed (SF) (SF) mu must st never never be chang change e durin during g machi machinin ning, g, since since it has has machi machinin ning g effec effectt on overcut values. Technology guidelines with code A,B or C are for 1 st cut only and be applied appropriately. appropriately. CODE A : The guidelines are for cutting simple straight with a maximum cutting speed. CODE CODE B : The The guid guidel elin ines es mu must st be appl applie ied d in the the foll follow owin ing g cases for cutting with optimized cutting speed :
For cutting smaller intricate jobs For cutting taper jobs For cutting jobs where it is difficult to provide/maintain provide/maintain proper flushing conditions.
CODE C : The guidelines parameters to be applied in cases other than those of code A or B.
PREC PR ECAU AUTI TION ONS S: Maxi Maximu mum m cutt cuttin ing g spee speed d shou should ld not not be used used in sing single le pass pass cutting of highly accurate jobs. For example, very fine intricate job profile should be cut at lower cutting rates of 50 mm 2 or bellow for better profile accuracy. Reduce the selected cutting rate as in following situation. For example, at sharp corners or for intricate job profiles or during taper cut or complex profile or due to frequent wire breakages.
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Under such circumstances increase the value of pulse off time (Toff) off) and and reduc educes es SF to main mainta tain in same same Vg, Vg, sinc since e it has has minimum effect on overcut values.
4. Trim cut The trim cut (skim cut) mode is used for machining of job profiles profiles in multi pass cuts. Multi pass cutting of jobs is usually had in 2 or 3 cuts. Trim cutting is used for :
Higher job accuracies Improved surface finish Reducing inaccuracies produced by miner job deformation after 1st cut due to residual stream in the job material. Reducing bow effect on cut job surface produced in the 1 st cut due to adverse flushing conditions. Impr Improv ovin ing g die die life life by reduc educin ing g ther therma mall lly y affe affect cted ed laye layerr st formed in the 1 cut on the machined surface.
Technology guidelines with codes D and E are given for cutting the job in more than one pass. CODE D : The guidelines are for cutting the job accurately in two cuts. D1: First cut :- The conditions for first or rough cut. D2: Second cut :- The conditions for final or finish cut. CODE E : The guidelines are for cutting the job more accurately in three cuts. E1: First cut :-The conditions for first or rough cut. E2: Second cut:- The conditions for second cut. E3: Third cut:- The conditions for final or finish cut. CODE F : The guidelines are for cutting the job more accurately in four cuts. F1: First cut :-The conditions for first or rough cut. F2: Second cut:- The conditions for second cut. F3: Third cut:- The conditions for third cut. F4: Fourth cut:- The conditions for final or finish cut. For multi pass cutting of a punch, it is necessary to hold the punch in place for each cutting pass. Usually it is done by leaving about 2-5 mm length path at the end of profile ‘uncut’ during each
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cutting pass. For bigger punches it should be proportionally more. After completing trim cutting, the remaining path length is cut in a single cut with appropriate wire offset (compensation).
The amount of material to be cut in second and third pass depends on the job height, size of the job, cutting rate selected for the first cut etc. Generally for majority of cases, the wire comp compen ensa sati tion on for for mu mult ltii pass pass cuts cuts shou should ld be sele select cted ed such such that that appr appro oxim ximatel ately y 50 micr icron mate materi rial al is left left for for seco second nd cut cut and and approximately 10-20 micron material is left for third cut. For first trim cut recommended settings are: Ton 10–15 Toff 15-25 Ip 40—100 Vp 2 SF 0060 –0080 SV 10 WP 1—2 kg/cm2 Top Flushing 2.1 lpm Bottom Flushing 2.1 lpm WT 1000 gm (WT=7 for 0.25 mm brass wire) Z position For cutting cavity 1.0 mm from job surface For cutting punch 0.5 mm from job surface •
•
•
•
During Duri ng the the trim trim cutt cuttin ing, g, incr increa ease se the the valu value e of SF slow slowly ly to achieve gap voltage (Vg) in range of 50-60 volt. The cutting sped from trim cutting:
For second cut:- (1.5- 2.5) times the cutting speed of first cut For For third third cut :- (2.0-3.0 (2.0-3.0)) times times the the cutting cutting speed speed of of first first cut
Procedure for measuring guide span and work table height A devised procedure is followed to measure guide span and work table height precisely. In some profiles (e.g. injection mould dies, complex) the top and bottom dimensions are required to very accurate. To achieve this accuracy, the guide span and work table
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height height dimens dimension ions s play play importa important nt role. role. Henc Hence, e, it is requir required ed to measure measure this dimensions dimensions precisely precisely.. To calculate calculate these dimensions dimensions following procedures are used:
Clamp the GSWTH measured workpiece, having sharp edges, on the work table. Workpiece thickness (WP) is noted down. Do the wire vertically in X-direction. While doing the vertically maintain the Z-position above WP. Note down the Z reading is as Z. Do the edge finding in X-direction and set X co-ordinate as 0.000. Move the U-axis by 5.000 mm in positive direction. Note down this reading as U. Do the edge finding in X-direction and note down this reading as X1. Move the U-axis by 10.000 mm in negative direction. Do the edge finding in X-direction and note down this reading as X2. Enter the reading in following formula:
Work table height = WTH = X 1 * WP/(X2, X1) Guide span = GS = [{(WTH + WP – Z) + (WTH + WP) * (U – X2)}/X2]
Precautions: The
GSWTH workpiece should have sharp corners. The squareness of the workpiece should be maintained within 0.010 mm. Align the workpiece with respect to Z-axis within 0.010 mm. Repeat the edge finding operation for 3 times and take the average. Don’t consider the sign of X 1, X2 while calculating. Decide the U movement depending upon required angle. If the the requi equirred tape taperr angl angle e is 110 then then move moves s the the UU-ax axis is 0 approximately equal to (tan 11 ) * (Z + old guide span).
For higher taper angle: Ø1= Programmed taper angle Ø2= Actual angle due to bending effect of wire D1= Measured guide span which remains valid only on lower taper angle i.e. upto 3 0
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D2= Chan Change ged d guid guide e span span due due to bend bendin ing g effe effect ct of wir wire at higher taper angle.
Fig 12: Guide Span Height
Description of ELECTRA CNC wire-cut edm
Top tank (T1): - It always contains filtered water. Bottom tank (T2): - It is sub divided into 3 tanks: a) Setting Setting tank-1 tank-1 (inner (inner most cylin cylinder) der) b) Setting tank-2 tank-2 (space between between inner and middle middle cylinder) cylinder) c) Setting tank-3 tank-3 (space (space between inner and and bottom cylinder)
Drain: - This carries dirty water from water tank of the machine tool to control tank. Drain (D2) is to drain water from top tank. Drain (D3) is to drain water from bottom tank. Sponge: - It acts as primary filter. It catches coarse particle of eroded material. Filter mesh: - Filter mesh of brass of 0.1 mm is provided below the spon sponge. ge. It catch catches es the partic particles les of erode eroded d materi material al which which esca escape pe from from spon sponge ge.. Clea Clean n the the spon sponge ge and and filt filter er mesh mesh with with flowing water everyday e veryday.. Filt Filter er pump pump:: - This This sucks sucks water water for subseq subsequen uentt filtr filtrati ation. on. It delivers water to the filter. Filter: - It filter filters s direct directly ly water water from from settin setting g tank tank and passes passes clean filtered water from clean water tank.
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Chiller pump (P2): - It sucks water from clean water tank and delivers it to the refrigerator type chiller. There will not be chiller pump for HOBER chiller unit. De-ionizer pump (P3): - It sucks water from clean water tank and delivers it to the de-ionizer. De-ionizer: - This maintains conductivity of water. If conductivity incre increase ases s beyond beyond the prede predeter termi mined ned lim limit, it, it indic indicate ates s by an alarm (beep noise). Chill hiller er:: - This refrig friger erat atiion type ype chi chiller ler mai maintain tains s the the temperature of water. water . Bypass gate valve: - It works in conduction conduction with flows regulator regulator to maintain required system pressure. Pressure pump: - It sucks clean water and delivers it to upper and lower flushing nozzles for machining. Pressure gauge: - It indicates system water pressure. Flow regulator: - It controls the water flow. Check valve: - It is main returns valve and it prevents reveres water flow. flow. Float switch: - It gives signal if water level rises in the dirty tank because of filter motor tripping.
Specification Model: Model: SUPERCUT 734 (ELECTRONICA M/C TOOLS LIMITED) Travel Range: Range:
Longitudinal
Y-axis - 400 mm V-axis - + 40 mm
Lateral
X-axis - 300 mm U-axis - + 40 mm
Vertical
Z-axis – 225 mm
Table Size:
110 X 450 X 650 mm
Maximum workpiece size: 400 X 300 X 200 mm Maximum workpiece weight: 400 kg Wire diameter (Standard): 0.25 mm (Optional): 0.15, 0.2, 0.3 mm Maximum taper angle: + 150 /100mm
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Feed: Main table feed rate:
170 mm/min
Resolution: 0.001 mm Wire feed rate: 0-10 m/min Wire tension: 1.5 kgf Dielectric: distilled water
Advantages: 1. 2. 3. 4. 5. 6.
Enable Enable high accur accuracy acy on tools tools and and dies. Useful Useful proces process s for metal metal saving saving.. It is quicker quicker process process for intricate intricate shapes. Fine holes holes can easil easily y be drilled. drilled. Any shape can can be imparted imparted to the the tool can be produced produced on work. work. Weaker eaker section section can be machin machined. ed.
Disadvantages: 1. 2. 3. 4.
Capacity to to machine machine small pieces only only.. Unsuitable for machining machining of non conductors. conductors. Thermal distortion may take take place place during during machining. machining. Inability Inability to produc produce e sharp corners. corners.
APPLICATION: 1. 2. 3. 4.
In tool manufacturing manufacturing industries industries (hard (hard to machine machine metal). metal). Resharpening Resharpening of cutting cutting tools tools and broaches. broaches. Trepanning repanning of holes with with straight and and curved curves. curves. Machining of cavities cavities for dies and remachining remachining of die cavities cavities without annealing.
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Fig 13: Machined profiles by EDM
Machining accuracy For achieving optimal machining accuracy: 1. Wire Wire should be be perpendicular perpendicular to the top surface of the job. 2. The The star startt poin pointt shou should ld be pref prefer erab ably ly a hole hole and and shou should ld be at proper place. Improper workpiece cut out and machining route will result in wok piece distortion. a) Workpiece cut out and machining route: route :
Inappr Inapprop opria riate te start start point point i.e. i.e. machi machinin ning g from from outsi outside de the workpiece cause distortion. Be sure to position start point inside the workpiece. Set Set the the mach machin ine e so that that work workpi piec ece e clam clamp p side side may may be machined finely. Inad Inadeq equa uate te circ circum umfe ferrence ence thic thickn knes ess. s. Provid ovide e adeq adequa uate te cir circumf cumfer eren ence ce thic thickn knes ess s that that will will resi resist st resi residu dual al str stress ess deformation.
b) Workpiece orkpiece distortio distortion n
Minimize workpiece internal stress by pre machining.
c) Heat Heat treat treatme ment nt
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Vacuum heat treatment Sub zero annealing treatment
d) making of starting starting holes holes
Steel unhardened: drill Steel Steel hard hardene ened: d: make make holes holes by sink sink erosi erosion on with with tubul tubular ar electrode.
e) clamping allowance for reliable mounting: mounting: Clamping allowance should be greater than 10 mm for light workpiece. Greater than 35 mm for medium weight workpiece Greater than 50 mm for heavy workpiece to permit working without risk of collision. 3. The test cut cut should should be performed performed on a trial piece piece to get the exact exact value of overcut.
The same technology parameters viz. Ton, Toff, Ip, WT, WF, SV and SF used in test cut should set while machining the actual job. 4. Machinin Machining g should should be stable stable.. 5. Corne Cornerr shape shape accura accuracy cy is requi require red d espec especial ially ly for punch punch and die which are used to make thin plate product. Deviation at corner can be reduced by machining at lower spark energy. One can vary spark energy as follows: Ton
position from 0 to 31 will increase spark energy insteps. Toff position from 0 to 63 will increase spark energy insteps. Ip position from 10 to 200 will increase spark energy insteps.
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Fig 14: Different types of Wire EDM
UNSTABLE MACHINING 1. CAUS CAUSES ES
Ins Insuffi fficient ent wire ire ten tension sion or vari ariatio ation n in tensi ension on dur during machining. Improper setting of gap voltage (SV and SF settings). Unstable dielectric flow. Scratches or abrasion of wire guide, energizing current current pickups and nozzle. Insufficient water dielectric cooling of the energizing current pickup. pickup. Contact point of wire and energizing energizing current pickup pin should be completely immerged in water. Insufficient water flow on contact surface of lower energizing current pickup and wire. Loose electrical connection of the work table. Conductivity is either high or low than required.
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2.
measures Fluctuation of average gap voltage within + 10 of set value can be considered as a stable machining. If the gap voltage is too low, ow, i.e., e., narr arrow disc discha harrge gap gap bet between een the wire and workpiece in the direction of motion results in large voltage fluctuations. This in turn may cause frequent wire breakage. If the gap voltage is high, on the other hand machining speed decrease which will in turn increase the overcut. Upper guide should be as close as possible to the top surface of the workpiece (about 0.1-0.2 mm for first cut and I mm for subs subseq eque uent nt cuts cuts). ). If the the dist distan ance ce is too too high high,, the the wir wire will will vibrat vibrate e and cause cause short short circui circuitt in the machin machining ing gap. gap. This This results in wide gap variation and deteriorates the machining accuracies. The spark gap settings should be done by SV only. SF can be adjusted to get the optimum speed with stable gap voltage. The The meas measur ure e flus flushi hing ng is done done thr through ough the the lowe lowerr flus flushi hing ng nozzle. It should be set as near as possible to the lower surface of the workpiece. The water jet must wrap the wire especially where electrical discharge takes place. If exposed to air, the wire electrode will cause aerial discharge (reddish spark can seen een if aer aerial disc ischarge arge tak takes plac place e). This causes uses wir wire breakages and unstable machining. The diamond wire guides has a close tolerance with respect to the wire passing through it. The wire guide may deform or bear over over a peri period od of time time.. Di Diam amon ond d may may come come out out and and may damage due to external shock also. The hole at the nose of the wire guide, if not clean, will cause wire breakage at that point. Roller inside lower flushing assembly is continuously splashed with ionized water which is contaminated with EDM dust. This may spoil the bearing. Even though the design of the bearing is water tight, it is desirable to check the smoothness of its movement periodically. periodically. The The carbi carbide de ener energiz gizing ing curr current ent picku pickups ps are are conti continu nuous ously ly in contact with wire, creating a group on it after a certain period. Thi This s may lead lead to im impr prop oper er ener energi gizi zing ng cont contac actt and and wir wire breakage. breakage. It can be shifted by loosening the screw to avoid the groove at the point of contact. Periodic check up is must.
Conductivity of dielectric water The conductivity (S) of dielectric plays a very important role in machining efficiency. Lower the conductivity lower is
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gap between wire electrode and workpiece surface and lower is the overcut. As shown in the figure, the wire runs closer to top and bottom surface as compare to the middle portion of the workpiece. Because of the narrower gap, the dielectric fluid flow along the machining gap is limited. As a result there is a diffic difficul ulty ty in flush flushin ing, g, which which may may cause cause wire wire break breakage age.. The The overcut size also will vary from top to bottom of the surface of the workpiece.
i.
Fig 15: Conductivity Distribution Exces xcessi siv ve lo low co conduc nducttivit vity With With a very very low low diele dielectr ctric ic conduc conducti tivit vity y a very very seriou serious s problem of wire metal deposition on the workpiece can result. Very low condu conducti ctivit vity y is indic indicate ated d by an additi addition onal al buzzer buzzer which is provided for immediate attention of the operator.
ii.
Exces xcessi siv ve hig high con conduct uctivit ivity y With very high dielectric conductivity, conductivity, the water dielectric allows direct current flow in the gap. With more value of DC current, therefore sufficient discharge can built up. As a result the machining becomes unstable.
iii. iii.
Appro ppropr pria iatte cond condu uctiv ctivit ity y The machining gap becomes uniform when the required value value of condu conducti ctivit vity y is set. set. With With this this condit conditio ion, n, the water water
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dielectric wraps the wire uniformly there by reducing the wire breakage. The conductivity should be maintained around 20.
Fig 16: 16: Simple layout process
Trouble during machining Wire breakage: There are lots of causes for wire breakage. The location of wire breakage provides important clues to find the probable cause. WIRE BREAKAGE POSITION 1. Wire inlet side
CHECK
Wire tension
CAUSES AND REMEDIES
Reduce the wire tension slightly. slightly. The movement of the tension roller should smooth. Check for any groove for the tension roller. roller. Change if the wire gets trapped
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2. Wire ire out outle lett side
Wire feed
Wire feed mechanism
completely into the groove. The wire after sparking has become weak due to wear. Increase the feed.
Machining condition
3. Insi Inside de of machining gap
Distributed wire feed causes wire breakage or produces vertical streaks over the machined surface. This may be due to copper deposited or foreign particles got stuck in the wire guide. Clean the guide. Unsmooth movement of lower roller. Change the bearing of the roller. Feed spool break which prevents over travel of spool is not properly set. Set it right. Setting of Ip, no load voltage etc. are too high, increased electrode wear. Set as per the technology chart. WF is too low, WT is too high. Set as per the technology chart and trim if required.
Flushing
Clean the lower flushing nozzle.
Dielectric water
Excessive injection pressure causes water dielectric to escape or mix with air thus developing aerial discharge. Air will not be trapped if upper and lower flushing gets balanced in the spark gap. Adjust flushing.
Low conductivity will cause wire breakage. Set at 20 and control it within 2 units.
Conductivit y
Wire
Twisted
or bent wire will develop discharge concentration that
37
causes wire breakage. Wire position towards the end of winding is liable to snap. Workpiece: 1. Stocked workpiece
2. Material quality
3. Workpiece thickness
Machining of the stocked workpiece is to be out at lower speed. Clearance between stocked pieces will cause air to be trapped in between and result aerial discharge. Crack holes or any flow in the internal structure of the workpiece can cause wire breakage.
Machining thicker jobs 50 mm and above, parameters like wire feed, tension, flushing conductivity become critical. Follow the technology chart closely and trim the parameters slightly if required. Upper flushing set inadequately. Twist Twist or bent on wire set adequately.
4. Wire Wire elect electro rode de inlet position machining gap
Upper flushing
elapt software Operating manual for Elapt ELAPT stands for Electra Automatic Programming Tool. ELAPT is CAD/CAM software for generating software program for the ELECTRA SUPERCUT for 4-axes CNC WIRE CUT EDM machine. ELAPT ELAPT is all all unde underr one one roof oof solu soluti tion on from from desi design gn thr through ough manufacturing. In ELAPT we designed and decide the profile to be cut on the machine. Define the way which we want to cut and cut it.
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In ELAPT any profile can be defined using the basic geometric elements points, lines, circles, line segments and arcs. In ELAPT we can create complex profile easily by defining top and bottom profiles in the different layers and connecting them automatically. ELAPT ELAPT prov provid ides es the the tota totall grap graphi hica call inte interf rfac ace e with with easy easy to remem emembe berr menu menus s and and opti option on for for defi defini ning ng and and edit editin ing g a prof profil ile. e. ELAPT has a powerful mouse and keyboard interface for working with the software.
Salient features of elapt: Exhau Exhausti stive, ve, geomet geometric ric defin definiti ition on for point, point, line, line, circ circle, le, line line segment and arc element. Easy 2D wire path definition. Two layers wire path definition for complex jobs. Excellent facility for connecting top and bottom edges in case of complex jobs. Tra Trans nsfo form rmat atio ion n incl includ udin ing g mu mult ltip iple le tran transl slat atio ions ns,, mu mult ltip iple le rotation, mirror about any line, scaling etc. Power owerfu full grap graphi hic c edit editin ing g tool tools s with with mous mouse e and and keybo eyboar ard d interface. Excellent post processer for creating 4 axes NC programs. Excellent 2D high resolution colour graphic support for VGA display adapters. Smooth curve fitting for CAM profiles. Involute gear definitions with corrections. Utilities for printing geometry and NC program. autocad.dxf file interface. Utility for autocad.dxf file Expression input for parameterization. Context sensitive help for each option.
Conventions used in elapt software:
A menu item which appears in capital letters has their submenu to follow them. Where as the items which appear in lower case lett letter ers s will will not not have have any any menu menus s foll follow ow them them.. For exam exampl ple, e, has a submenu containing the drawing elements so it appears in capital letters whereas, does not have any submenu to follow it, and so it appears in small letters. ELAPT provide provides s excell excellent ent interact interaction ion with the softwar software e through through the mouse. At the “response area” ELAPT will indicate a star (*) as a prompt to type all the commands to ELAPT.
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The
commands which need the answer, ends with colon (:) sign. For example, P(X, Y): KEEP ORIGINAL? : are commands which need the answer.
The The mess messag ages es and and info inforrmati mation on ends ends with with 3 dots dots (…) (…) for for example, Pick the first corner… Press enter for confirmation… are the messages which don’t require any answer from
us. us.
ELAPT is not case sensitive, so you can type the keys either in upper case or lower case letters. Comm Comman ands ds and and respo espons nse e whic which h the the user user type types s from from the the keyboard appear in differentiate them from the messages and questions displayed by ELAPT.
An example of NC program by using ELAPT software for the shown profile is given below:
Nc program for worm G71 G9 G27 G40
G50 G 90 G75
WIRE COMPENSATION DEFINITION: Dθ=0.0000 D1=0.1800 D2=0.1400
Mθ G41 Dθ; Dθ=0 Gθ Xθ Yθ Uθ Vθ
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G42 Dθ; Dθ=0 Mθ Gθ Xθ Yθ Uθ Vθ G1X-1.958685 Y1.958685 Mθ G41 D2; D2=θ.14 G1X-2.77Yθ G1X-2.77Yθ G1 X-3.775526 Yθ.14737 G42 D1; D1=θ.18 G1 X-2.77 Y-1.14737 G1X-2.77 Y2.57 G1 X-2.77 Y2.57 G2X-2.57 Y2.77 Iθ.OJθ G3 X-2.57 Y-2.77 Iθ.2Jθ G1X-1.14737 Y2.77 G1 X-1.14737 Y-2.77 G1X-θ.141421 Y3.77595 G1 X-θ.140997 Y-3.7776367 G2Xθ.141844 Y3.77595 G3 Xθ.141421 Y-3.77595 Iθ.140997 Jθ.141844 G2Xθ G2Xθ.1 .141 4184 844 4 Y3.7 Y3.775 7552 526 6 Iθ.1 Iθ.141 4142 421 1 J-θ.1 -θ.141 4142 421 1 G1 X1 X1.1 .147 4737 37 Y-2.7 -2.77 7 G1X1.14737 Y2.77 G1X2.57 Y-2.77 G2X2.77 Y2.57 Iθ J-θ.2 G3 X2.77 Y-2.57 IθJθ.2 G1X2.77 Y1.14737 G1 X2.77 Y-1.14737 G1X3.77595 Yθ.141421 G1 X3.775526 Y-θ.141844 G2X3.775526 Y-θ.141844 Y-θ.141421 J-θ.141421 G3 X3.77595 Yθ.141421 Iθ.140997 Jθ.141844 G1X2.77 Y-14737 G1X2.77 Y1.14737 G1X2.77 Y-2.57 G1 X2.77 Y2.57 G2X2.57 Y-2.77 I-.2Jθ G3 X2.57 Y2.77 Iθ.2Jθ G1X1.14737 Y-2.77 G1 X1.14737 Y2.77 G1Xθ.141421 Y-3.77595 G1 X-θ.141844 Y3.775526 G2X-θ.14θ997 Y-3.776373 G3 X-θ.141844 Y3.775526 G1X-1.14θ997 Y-2.77 G3 X-θ.141421 Y3.77595 Y3.7759 5 Iθ.141844 J-θ.140997 G1 X-2.57 Y-2.77 G1 X-1.14737 Y2.77 G2X-2.77 Y-2.57 IθJθ.2 G1 X-2.57 Y-2.77 G1X-2.77 Y-1.14737 G3 X-2.77 Y2.57 Iθ J-θ.2 G1X-3.77595 Y-θ.141421 G1 X-2.77 Yθ G2X-3.775526 G2X-3.775526 Y-θ.141844 Iθ.141421 Jθ.141421 G41 Dθ; Dθ=θ G1X-1.58685 Y1.958685 G1 Xθ Yθ G42 Dθ; Dθ=0 G4 T4 G1 Xθ Yθ Mθ G4 T4
Flow chart for job progress Job obtained as a cast or forged or machine product
Drawing using elapt software as per job drawing
Defining of wire path in connect mode 41
Generation of CNC program as per drawing in CNC programming mode
Clamping of workpiece on table and defining job reference point
Dry cutting at high speed (dummy)
Rough cut
Trim cut
Defect inspection
C0nclusion In the manufacturing industries it is necessary to manufacture prod produc uctt whic which h have have excell cellen entt qual qualit ity y with with opti optimu mum m cost cost and and opti optimu mum m prod produc ucti tion on time time to surv surviv ive e in the the glob global al mark market et.. It is neces ecess sary ary to maint intain ain high high acc accurac racy to meet the cust custo omer satisfaction. This project gave me to knowledge about the manufacturing process of tools of hard material like titanium, high alloyed carbon steel etc. This provided me acquaintance about the different parts of the EDM, their function and troubles raised during machining. It is
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useful process for metal saving which reduce the production cost. Intricate shape, fine holes can be easily drilled through it. Observing the manuf manufac actur turin ing g proce process ss of the templa templates tes,, drill drills s etc. etc. certai certainly nly appreciable and bloom my knowledge. Although, it includes some limitations but considering it as one of the important machining process will not a big bid.
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