FORMAT FOR SEMINAR REPORT

Acknowledgment

I wish to express my profound sense of deepest gratitude to my guide and motivator Prof. MANOJ KUMAR, Mechanical Engineering Department, Jodhpur Institute of Engineering and Technology, for his valuable guidance, sympathy and cooperation and finally help for providing necessary facilities and sources during the entire period of this project. I wish to convey my sincere gratitude to all the faculties of Mechanical Engineering Department who have enlightened me during my studies. The facilities and co-operation received from the technical staff of Mechanical Engineering Dept. is thankfully acknowledged.

Last, but not least, I would like to thank the authors of various research articles and book that referred to.

AbstractElectron beam machining is a thermal nontraditional process, uses electrical energy to generate thermal energy for removing material. A pulsating stream of high-speed electrons produced by a generator is focused by electrostatic and electromagnetic fields to concentrate energy on a very small area of work. High-power beams are used with electron velocities exceeding half the speed of light. As the electrons impinge on the work, their kinetic energy is transformed into thermal energy and melts or evaporates the material locally.The electron beam machining process is used in a variety of industries. Applications range from fully automated, high productivity and low cost automotive in-line part production to single part batch processes in the high-cost aircraft engine industry at the other end of the industrial spectrum. For those manufacturers and many others not specifically mentioned here, machining processes have to meet increasingly stringent standards that have become more prevalent over the years. In this regard, the electro beam machining process is well-positioned to provide industries with the highest quality welds and machine designs that have proven to be adaptable to specific machining tasks and production environments.CHAPTER 1INTRODUCTION

Electron beam machining (EBM) is one of several industrial processes that use electron beams. Electron beam machining uses a high-velocity stream of electrons focused on the work piece surface to remove material by melting and vaporization. A schematic of the EBM process is illustrated in the figure:

An electron beam gun generates a continuous stream of electrons that are focused through an electromagnetic lens on the work surface. The electrons are accelerated with voltages of approx. 150,000 V to create velocities over 200,000 km/s. The lens is capable of reducing the area of the beam to a diameter as small as 0.025 mm. On impinging the surface, the kinetic energy of the electrons is converted into thermal energy of extremely high density, which vaporizes the material in a very localized area. EBM must be carried out in a vacuum chamber to eliminate collision of the electrons with gas molecules.

Electron beam machining is used for a variety of high-precision cutting applications on any known material. Applications include drilling of extremely small diameter holes, down to 0.05 mm diameter, drilling of holes with very high depth-to-diameter ratios, more than 100:1, and cutting of slots that are only about 0.025 mm wide. Besides machining, other applications of the technology include heat treating and welding.

The process is generally limited to thin parts in the range from 0.2 to 6 mm thick. Other limitations of EBM are the need to perform the process in a vacuum, the high energy required, and the expensive equipment.

1.1 HISTORYElectron beam machining (EBM) is a thermal material removal process that utilizes a focused beam of high-velocity electrons to perform high-speed drilling and cutting. Just as in electron beam welding, material-heating action is achieved when high-velocity electrons strike the work piece. Upon impact, the kinetic energy of the electrons is converted into the heat necessary for the rapid melting and vaporization of any material.

1952 is seen as the dawn of electron beam technology. The physicist Dr. h.c. Karl-Heinz Steigerwald built the first electron beam processing machine. Much of what is now taken for granted first had to be painstakingly worked out all those years ago.

The history of electron beam technology began with the experiments by physicists Hittorf and Crookes, who first tried to generate cathode rays in gases (1869) and to melt metals (1879).

These cathode rays were an interesting physical phenomenon and lead to the discovery of a particular type of ray by Rntgen (1895), Thompson (1897) and Millikan (1905), which were described as fast moving electrons.

The heat created by electrons colliding was considered rather to have a damaging effect at the time of those experiments and attempts were made to prevent this by means of cooling.

The physicist Marcello von Pirani was the first to make use of this effect. He built a piece of apparatus for melting tantalum powder and other metals using electron beams. In the period that followed, more and more scientists occupied themselves with electron beam technology, which lead to the development of oscillographs, microscopes and the drilling of metals. The main obstacle at this time was the lack of sufficiently powerful vacuum pumps.

In 1948 a new era in material processing began with the physicist Dr. h.c. Karl-Heinz Steigerwald. At this time he was concerned with developing sources of rays to achieve higher power in order to build more powerful electron microscopes.

His experiments with the electron beam as a thermal tool for drilling watch stones and for soldering, melting and welding in a vacuum were very promising and this development gathered pace:

In 1952 he built the first electron beam processing machine. In 1958 he butt-welded 5 mm thick zircaloy together and in doing so he discovered the " deep welding effect". In 1963 he founded the company Steigerwald Strahltechnik GmbH.

Outside of Germany, work began elsewhere, particularly in France and Great Britain, on developing new equipment.

Nowadays electron beam technology is widespread in the material processing field and it is difficult to give an overall view. Even at present, new applications are constantly being developed using EB technology. 1.2 PROCESS PRINCIPAL The EBM process begins after the work piece is placed in the work chamber and a vacuum is achieved. The creation of a hole by an electron beam occurs in four stages . First, the electron beam is focused onto the work piece to a diameter that is slightly smaller than the final desired hole diameter. Power is adjusted so that the electron beam will generate a power density at the work piece in excess of 108 W/CM2 (1.5 x 107 W/in.2). A power density of that magnitude is more than sufficient to instantly melt any material regardless of thermal conductivity or melting point. Drilling is accomplished through the combination of an electron beam pulse and an organic or synthetic backing (auxiliary) material, which is applied to the exit side of the surface being drilled.

When the focused beam strikes the work piece, local heating, melting, and vaporization take place instantly.

Only about 5% of the affected material is actually vaporized. The pressure of the escaping vapor is sufficient to form and maintain a small capillary channel in the material. The beam and capillary rapidly penetrate through the work piece and a finite distance into the backing material.

Figure 1.1 The four steps that lead to material removal by electron beam drilling

(Source: courtesy, Messer Griesheim GmbH, Puchheim, W. Ger.).

The volume of backing material that is contacted by the beam is almost totally vaporized resulting in the explosive release of backing material vapor. As a result of the comparatively high pressure of the backing material vapor, the molten walls of the capillary are expelled in a shower of sparks leaving a hole in the work piece and a small cavern in the backing material.

As mentioned, a single pulse is often used to produce a single hole; however it the material is very thick, multiple pulses may be required. If the desired hole shape is not round, the beam, pulsing at rates up to 1000 pulses/sec, is deflected by computer to cut out the shape along its perimeter. Using this technique, almost any hole shape can be generated.

CHAPTER-2

EBM EQUIPMENTThe appearance of electron beam machining equipment is very similar to electron beam welding equipment. Most system subassemblies such as the vacuum system, work piece-positioning system, and vacuum chamber are essentially identical with those used for EBW. There are however significant differences between the two systems with respect to the electron beam gun and power supply. Figure 2.1 electron beam machining 2.1 Electron Beam GunThe electron beam machine consists of an electron beam gun used to produce free electrons at the cathode. The high velocity particles are moving through the small spot size. The cathode (tool) is made of tantalum or tungsten material. The cathode filaments are heated to a temperature of 2500to 3000and the heating leads to thermo ionic emission of electrons. The magnitude varies from the 25 mA to 100 mA. The solidities lies between 5 Acto 15 Ac.The emission current is influenced by the voltage that is nearly 150kV, and the current is applied between the anode and cathode to release the electrons in the direction of work piece.The function of the electron beam gun is to generate, shape, and deflect the electron beam to drill or machine the work piece. The EBM guns resemble those used for welding; however the similarities end there. For example.

the EBM gun is designed to be used exclusively for material removal applications an can be operated only in the pulsed mode.

A typical triode EBM gun functions in a manner very similar to an EBW gun. An electron "cloud" is generated by a superheated tungsten filament, which also acts as the cathode. A combination of repewng forces from the negative cathode and the attracting forces from the positive anode causes the free electrons to be accelerated and directed toward the work piece. Before passing through the anode, the beam travels through a bias electrode, which controls the flow of electrons and acts as a switch for generating pulses.

After passing through the anode, the electron beam is diverging rapidly and traveling at approximately one-half the speed of light. A magnetic coil, which functions as a magnetic lens, repels and shapes the electron beam into a converging beam. The beam is then passed through a variable aperture which results in the removal of stray electrons from the beam's fringe areas, thus reducing the final focused spot diameter and producing a more favorable beam energy distribution for machining applications.

Beneath the aperture are three final magnetic coils that are used as the final magnetic lens, deflection coil, and stigmator. Pinpoint focusing is accomplished with the lens, and a small amount of controllable beam deflection is achieved with the deflection coil. The stigmator corrects minor beam aberrations and ensures a round beam at the work piece.

To protect the electron beam gun from metal spatter and vapor, a series of rotating slotted disks are often mounted directly beneath the gun exit opening.

The rotational rate of the disks is synchronized such that the beam pulse will pass through the slots, but the spatter is blocked.Some equipment uses are Cathode, Bias grid, anode, electromagnetic lens, electromagnetic coils, deflector coils, telescope, vacuum gauge, throttle valve, diffusion pump.2.1.1 Bias grid

It is also known as grid cup. The grid cup is a negative that is subjected with respect to the filament. So, the electrons generated with the help of the cathode will directly flow towards the anode. During the flow of the electrodes no diversions are seen. The anode attracts the electrons and gets accelerated; the electrons will gain a high velocity. The cathode controls the flow of the electrons, and the grid cup used to operate the gun in pulsed mode only.

After the anode the electron beam passing through the magnetic lens and the apertures are connected in series. The magnetic lens is used to shape the electron beam and reduce the diversion factor.

The apertures allow the convergent electrons to permit and caught the low energy divergent electrons from the fringes.

Finally the electron beam passes through the electromagnetic lens and deflection coil. Then the deflection coil sends the electron beam through the hole, to improve the shape to machine a hole.

The vacuum is created between the work piece and the electron beam gun, and there is a series of rotating disc with slots.

The disc allows the electron beam to pass over the material for machining, and it prevents from the fumes and vapors generated during the machining.

Work piece is placed on the CNC bench. Then holes of any shape are made on the work piece material. In the gun beam flection and CNC control are used to shape.

Vacuum is maintained in gun, and the vacuum ranges from Suitable vacuum is maintained because the electron as it does not lose their energy, and where the life of the cathode is obtained. By using the diffusion pump and rotary pump the vacuum is maintained.

Diffusion pump should act as an oil heater. If the oil is heated then the oil vapor rushes upwards. The nozzle changes the direction of the oil vapor and starts moving in the downward direction at high velocity. The oil vapors are reduces in the diffusion pump; this is because of the presence of the cooling water cover.

2.2 Power SupplyThe high-voltage power supply used for EBM systems generates voltages of up to 150 kv to accelerate the electrons. The most powerful electron beam machining systems are capable of delivering enough power to operate guns at average power levels of up to 12 kw. Individual pulse energy can reach 120 joules/pulse. To avoid the possibility of arcing and short circuits, the high-voltage sections of the power supply are submerged in an

insulating dielectric oil.

AB power supply variables, such as the accelerating current, focus current, pulse duration, and others, are controlled by a CNC unit or by a microcomputer. To ensure process repeatability, the process variables are monitored and compared with set-points by the power supply computer. If a discrepancy arises, the operator is alerted.

Figure 2.2 Computer-controlled multi axis EBM system

(Source: courtesy, Messer Griesheim GmbH, Puchheim, W. Ger.).

2.3 The Electron Beam Machining SystemsAn EBM system, as shown in Fig. 2.1, has an appearance very similar to an electron beam welding system. A vacuum chamber is required for EBM and should have a volume of at least 1 m3 to minimize the chance of spatter sticking to the chamber walls.

The time necessary to pump the chamber to an operating level of 10-2 mbar is approximately 3 min for each cubic meter of volume. Inside the chamber a positioning system is used for the controlled manipulation of the work piece. The positioning system may be as simple as a single, motor-driven rotary axis or as complex as a fully CNC, closed loop , five-axis system.

CHAPTER-3

PARAMETER AND CAPABILITIES 3.1 PROCESS PARAMETER

Beam current, pulse duration, lens current, and the beam deflection signal are the four most important parameters associated with electron beam machining. Determining the initial parameter settings for new applications usually involves some amount of trial-and-error testing. However once established, each parameter is computer controlled during processing to ensure repeatability on a day-toA day basis. Beam current is continuously adjustable from approximately 100 gamp to 1 amp. As the beam current setting is increased, the energy per pulse delivered to the work piece is also increased. Electron beam machining systems are available that can generate pulse energies in excess of 120 joules/pulse, a value that is 200400% higher than that available from industrial laser-drwing systems. The extremely high pulse energy available with EBM explains the ability of the process to rapidly drill very deep and large-diameter holes.

Pulse duration affects both the depth and the diameter of the hole. The longer the pulse duration, the wider the diameter and the deeper the drilling depth capability will be. To a degree, the amount of recast and the depth of the heat-affected zone will be governed by the pulse duration.

Shorter pulse durations will allow less interaction time for thermal affects to materialize. Typically, electron beam systems can generate pulses as short as 50 tisec or as long as 10 msec.

The lens current parameter determines the distance between the focal point and the electron beam gun (the working distance) and also determines the size of the focused spot on the work piece. The diameter of the focused electron beam spot on the work piece will, in turn, determine the diameter of the hole produced. As mentioned earlier though, to achieve a desired hole diameter, the beam power must be sufficient to generate more than 108 W/CM2; otherwise the power density will be insufficient to promote vaporization and drilling.

The depth to which the focal point is positioned beneath the work piece surface determines the axial shape of the drilled hole. By selecting different focal positions, the hole produced can be tapered, straight, inversely tapered, bell shaped, or center-bowed. A cross-sectional view of tapered electron-bearn drilled holes is shown in Fig. 3.1.

When hole shapes are required to be other than round, the beam deflection coil is programmed to sweep the beam in the pattern necessary to cut out the shape at the hole's periphery. Beam deflection is usually applicable only to shapes smaller than 6 mm (0.236 in.).

Figure 3.1 Cross-sectional view of electron-beam-drilled holes

The deflection coil can also be used to track the work piece when drilling "onthe fly." For the duration of the pulse, the inertia-less electron beam tracks the proper location on the work piece thus avoiding elongation of the hole. After the hole has been completed and before drilling the next one, the beam is directed back to its initial position, ready for the next hole. Using this technique holes can be drilled at the rate of several thousand each second without the necessity of stopping the work piece at each hole location.

An electron beam deflection coil is able to scan the electron beam a distance of 0.1 mm (0.004 in.) in 1 msec, meaning that effective tracking can be accomplished with work piece motion as fast as 100 mm/sec. (236 in./min).

We already know that the electron gun is works within the pulse mode. The bias grid is

located after the cathode. Then pulse is given to the grid cup, where the pulse duration

ranges from 50to 15 ms.

Beam current is related to the electrons that are emitted from the cathode or available in the

beam. Beam current is ranges from the 200micro amps to 1 amp. If the beam current

increases, simultaneously there is also an increase in the energy per pulse. High pulse energy

is used to machine thicker plates and make the holes larger.

The power and energy density is ruled by the energy per pulse and the nozzle spot size. With

the help of the electromagnetic lens the spot size is controlled. For lower spot size they

require a high energy density. The metal removal must be high; this is when compared to the

holes size where the hole must be similar.

The plane of focusing must be above or below the surface of the work piece material.

3.2 PROCESS CAPABILITIES

A wide range of materials, such as stainless steel, nickel and cobalt alloys, copper, aluminum, titanium, ceramics, leather, and plastics, can be successfully processed by EBM. Some materials are easier to process than others. For example, aluminum and titanium require less beam power to remove a given volume of material than either steel or tungsten.

Because EBM is a thermal machining process, some thermal effects remain on the machined edge after processing.

However because of the extremly high beam power density and the short duration of the beam/work piece interaction time, thermal effects are usually limited to a recast layer and the heat-affected zone, which seldom exceeds 0.025 mm (0.001 in). Typically, no burr is generated on the exit side of the hole, although, a small lip of solidified material may remain around the rim of the hole on the entrance side. Another capability of the electron beam process made possible by the high power density is the ability to drill deep, high aspect ratio holes. Aspect ratios as large as 1 5: 1 can be achieved in most materials. The hole diameters that can be drilled range from 0.1 to 1.4 mm (0.004 to 0.055 in.) in thicknesses up to 10 mm (0.390 in.). The tolerance on the hole diameter is typically 5% of the diameter or 0.03 mm

(0.001 in.), whichever is greater. The rate at which holes can be drilled is a function of the hole geometry and material thickness. Figure 3.3 is a homograph that can be used to predict drilling rates for a given hole diameter and depth or volume. To use this chart, first find the diagonal lines that correspond to the desired hole diameter and depth. After locating the intersection point of the two lines, follow the vertical line up to the center of the white band in the top chart. From that point, move left to read the corresponding drilling rate. This drilling rate is applicable when drilling materials such as steels, nickel, and cobalt alloys.

An electron beam does not apply any force to the work piece, thereby allowing brittle or fragile materials to be processed without danger of fracturing. Electrical beam machining makes a hole ranges from 100 to 2 mm.

The depth of cut must be 15 mm with a length to diameter ratio of nearly 10.

Holes can be elongated along with the barrel shape or depth.

Reverse tapper can also be performed below the surface of the work piece material.

In the electron discharge machining Cut formation is not observed

With the help of the electron discharge machining we can machine the wide range of materials like stainless steel, aluminum, steel, plastics, ceramics etc.

In EBM the heat affected zone is narrow; this is because of the short pulse occurrence. The heat affected zone is nearly 20 to 30

Compares to the steels aluminum and titanium is freely machined.

Based upon the type of the material, power density, depth of cut holes diameter, which are the reasons for the number of holes drilled per second on the material.

The EBM does not apply any cutting forces on the material.

During the process very simple investment is required for work

Holes are drilled at an angle of 20 to 30 EBM process allows machining of brittle and fragile materials.

Figure 3.2 Minimum distance between hole centerlines for EBM

(Source:courtesy, Messer Griesheim GmbH, Puchheim, W. Ger.).further benefit from the non contact nature of the process is the ability to drill holes at angles as shallow as 200 off the surface. Figure 3.2 illustrates the minimum required spacing between holes for successful electron beam drilling. The relationship is a function of hole diameter, with the minimum center line-to-center line distance being twice the hole diameter. Even with this limitation, work pieces can be perforated with small holes 2 at up to 1000 holes/cm.

Figure 3.3 An EBM drilling rate homograph

(Source: courtesy, Messer Griesheim GmbH, Puchheim, W. Ger.).

3.3 OPERATING PARAMETERS3.3.1Power

EBM operations are performed at voltage ranging from 50-150 kV. The beam current is usually between 0.1-1.0 mA. Power requirements are on the order of 0.5-60 kW. Beam intensity ranges between 1.55x105to 1.55x109W/cm2. Electron bean equipment is employed in a wide variety of production applications.By varying the power density, many different jobs can be performed using EB techniques.

3.3.2 Cut characteristics

The narrowest cut attainable with EBM operations is on the order of 0.03 mm when cutting material of 0.03 mm thickness. The maximumdepth of cut is usually about 6 mm.

3.3.3 Material removal

Material removal rates are a function of the power applied and workpiece material. Generally, penetration rates up to 0.25 mm/s have been achieved.

3.3.4 Tolerances

Elecbeam machining is capable of holding tolerances on hole size to about0.03 mm, although in special cases, tolerances of0.005 mm can be held.

3.3.5Surface characteristicsThe heat-affected zone developed by EBM is generally less than 0.25 mm deep. The heat-affected zone consists of a thin layer of recast material, which may diminish the structural integrity of work pieces, which are highly stressed. Surface roughness is usually about 1.02mm Ra,although surface roughness as low as 0.13mm Ra has been achieved.

CHAPTER-4

APPLICATIONAny known material, metal or nonmetal, which will exist in high vacuum can be cut, although experience has shown that diamonds do not cut well. Holes with depth- to-diameter ratios up to 100:1 can be cut. Limitations include high equipment costs and the need for a vacuum, which usually necessitates batch processing and restricts workpiece size. The process is generally economical only for small cuts in thin parts.

4.1 DRILLING In drilling holes, the electron beam focuses on one spot and evaporates material until it has completely penetrated the workpiece or is switched of after a specified hole depth has been reached. Hole diameter depends on beam diameter and energy density. If holes larger than the beam diameter are required, the electron beam is deflected electromagnetically in a circular path of required diameter. Varying the amplitude of the voltage generator connected to the electromagnetic deflection system can change the diameter of the circular beam path. If extremely large holes are required, the work piece can be moved off center and rotated.

In general, holes less than 0.13 mm in diameter can be drilled almost instantaneously in thickness up to 1.25 mm in any material. Hole diameters larger than0.13 mm can be drilled by deflecting or rotating the electron beam.

Circular holes are producable with electron beam drilling techniques. Hole diameters are usually between 0.03 mm and 1.02 mm. Noncircular holes can also be drilled using EBM. A multipulse technique is employed. Modern EB machines feature computer control of beam deflection coupled with CNC of work piece motion. To machine noncircular holes, the control systems are used to move the work piece and deflect the beam analog a predetermined hole contour. Electron beam drilling & machining is similar to EB-W with the added feature of Pulsed High Energy Electrons. The electron beam is focused at a targeted location and beam energy is pulsed onto the part.

The focused and pulsing EB increases the amount of concentrated thermal energy exponentially (compared to continuous beam operation used in the welding machine). As a result, the beam can create a highly sophisticated micro drill hole or machine a complex groove accurately. Figure 4.1 drilling process by EBM4.2 PERFORATION Electron beam machining is used widely to perforate many materials including heat-resistant super alloys, plastics, and textiles.

An important advantage of EB perforation is processs ability to drill relatively small holes in thick materials. The process is normally employed to produce holeswith depth-to-diameter ratios of about 10:1. This capability is employed effectively in the drilling of small holes on the trailing edges of turbine blades, for example.

Inclined holes are another advantage of EB perforation. The angle at which an electron beam can be directed at the workpiece is usually between 20- 90. Thiscapability allows the application of EB perforation to turbine blades, combustion chamber rings, mixer plates, and other gas turbine parts.

The drilling of a turbine engine combustor dome made of a CrNiCoMoW steel has been performed for several years using EBM. The part has a wall thickness of 1.1 mm (0.043 in.) and is perforated with 3748 holes that are 0.9 0.05 mm (0.035 0.002 in.) in diameter. Each part is drilled in 60 min for a drilling rate of approximately one hole every second. The insulation industry relies on EBM to drill thousands of small holes in cobalt alloy fiber spinning heads that are used in the production of glass fiber and rock wool materials. A example spinning head, shown in Fig. 19.6, requires that 11,766 holes be drilled through a material thickness that varies from 4.3 to 6.3 mm (0.17 to 0.25 in.). The hole diameter requirement is 0.81 0.03 mm (0.032 0.001 in.). The EBM drilling rate of five holes per second is 100 times faster than the alternate method of EDM drilling and results in production rates of one part in 40 min (Closs, 1977).

Filters and screens used in the food-processing industry require thousands of holes to be drilled through relatively thin, formed sheet metal. Electron beam machining is a cost-effective method of producing these holes for approximately 40 cents/ 1000 holes.

Figure 4.2 drilled hole by EBM

A rather surprising use of electron beam perforation involves the clothing industry. A percentage of the shoes made today are fabricated from an artificial leather consisting of a plastic-coated textile substrate. This artificial leather is not permeable to moisture and air, thus making its level of comfort poor. A more comfortable breathing material can be produced by electron beam perforation of the plastic surface. Figure 4.3 Examples of EBM-drilling in thick sheet metal Thus treated, the material is acceptable for use in shoes, clothing, and upholstery. Electron beam machining drills these materials with 0.12-mm

(0.0047-in.) diameter holes at a rate of 5000 holes/sec.

4.3 MILLING

Applications in which EBM is employed to mill small profile-shaped holes of less than 160 mm2. The work piece is held stationary while the electronbeam is programmed to cut the pattern. CHAPTER 5

CONCLUSION

Besides their high rating in macro-range industrial manufacturing processes, beam joining methods are also increasingly gaining in importance in the micro-system technology (MST). While the industry is already using the electron beam for joining, surface modifications or for structuring with different process variations, micro-range electron beam joining is still in the laboratory stage.

A more elaborate mathematical model than the one existing before was developed for calculation of melting rate in single-wire arc machining. Additionally a mathematical model for calculation of melting rate in twin-wire arc machining not known from the literature before was developed. On the basis of variation of validity of the mathematical models developed for single-wire and twinwire arc machining it can be stated that the models are quite a true representation of the experimental results and that they are applicable to practical cases as well as to further research work.

The use of the grey-based Taguchi method to determine the SAW process parameters

with consideration of multiple performance characteristics has been reported in this paper.

Advantages of Electron beam machining There is no contact between the tool material and work piece material

Very small holes are also machined on different type of work piece materials with high accuracy

Drilling is also done on the work piece material with a diameter of nearly 0.002 inches

Drilling parameters are changed automatically during the machining

Distortions are not observed to the work piece material

This process is proficient in attaining high accuracy along with repeatability.

Compare with the other process, formation of holes is easy with the other process. No mechanical or thermal distortion

Computer-controlled parameters

Disadvantages of Electron beam machining The cost of the equipment is very high

Metal removal rate during the process is low

Small cut operations are performed on the work piece material with the help of EBM machine

Vacuum requirements boundaries the dimensions of the work piece material

Need for secondary backing materials.REFERENCES1. Closs, W. W. and Drew, J. (1977). Electron beam drilling.

2. Farrel Company Divvision, USM Corporation, Ansonia,

3. Conn.Messer Griesheim GmbH (1982).

4. EBOPULS CNC electron beam drilling machines.

5. Publication No. 47.20 1 Oe, Puchheim, W. Ger.Steigerwald, K. H.

( 1978). Electron beam machining - the process and its applications.

6. Farrel Company Division, USM Corporation, Ansonia, Conn. von

Dobeneck,

7. (1977). Drilling with electron beams. Ingenieur Dig. 16:38.

8. http://osp.mans.edu.eg/s-hazem/NTM/EBM.html9. http://www.enggdir.com/electron-beam-machining.html10. http://en.wikipedia.org/wiki/Electron_beam_machining1