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Advanced Machining Advanced Machining ProcessesProcesses

Manufacturing Manufacturing ProcessesProcesses

OutlineOutline

Chemical MillingChemical MillingPhotochemical BlankingPhotochemical BlankingElectrochemical MachiningElectrochemical MachiningPulsed Electrochemical MachiningPulsed Electrochemical MachiningElectrochemical GrindingElectrochemical GrindingElectrical-Discharge MachiningElectrical-Discharge MachiningElectrical-Discharge GrindingElectrical-Discharge GrindingElectrical-Discharge Wire CuttingElectrical-Discharge Wire CuttingLaser-Beam MachiningLaser-Beam MachiningElectron Beam MachiningElectron Beam MachiningPlasma Arc CuttingPlasma Arc CuttingWater Jet MachiningWater Jet MachiningAbrasive Water Jet MachiningAbrasive Water Jet MachiningAbrasive Jet MachiningAbrasive Jet Machining

Examples of PartsExamples of Parts

Chemical MillingChemical Milling

Produces shallow cavities on a Produces shallow cavities on a workpiece, usually to reduce workpiece, usually to reduce weightweight

The area affected by the The area affected by the chemical reagent is controlled chemical reagent is controlled by masking or by partial by masking or by partial immersionimmersion


Procedure:Procedure:

1.1. Relieve residual stresses to Relieve residual stresses to prevent warpingprevent warping

2.2. Clean the material surfaceClean the material surface

3.3. Apply masking materialApply masking material

4.4. Remove the masking on regions Remove the masking on regions that require etchingthat require etching

5.5. Apply the reagentsApply the reagents

6.6. Wash the partWash the part

7.7. Remove remaining maskingRemove remaining masking

8.8. Additional finishing or chemical Additional finishing or chemical milling procedures may be usedmilling procedures may be used

Photochemical BlankingPhotochemical Blanking

Uses chemicals and Uses chemicals and photographic processes to photographic processes to remove material, usually from remove material, usually from a thin sheeta thin sheet

Can produce complex shapes on Can produce complex shapes on metals as thin as .0025 mm metals as thin as .0025 mm without forming burrswithout forming burrs

Examples of PartsExamples of Parts


Procedure:Procedure:1.1. Prepare the design at a Prepare the design at a

magnification of up to 100x; make magnification of up to 100x; make a photographic negative and a photographic negative and reduce it to the size of the partreduce it to the size of the part

2.2. Coat the blank with Coat the blank with photosensitive materialphotosensitive material

3.3. Place the negative over the part Place the negative over the part and expose it to ultraviolet light to and expose it to ultraviolet light to harden the exposed harden the exposed photosensitive coatingphotosensitive coating

4.4. Dissolve the unexposed coatingDissolve the unexposed coating5.5. Apply the chemical reagentApply the chemical reagent6.6. Remove the masking and wash Remove the masking and wash

the partthe part

Chemical MachiningChemical Machining

Design Considerations:Design Considerations:- Avoid sharp corners, deep narrow Avoid sharp corners, deep narrow

cavities, steep tapers, folded cavities, steep tapers, folded seams and porous workpiecesseams and porous workpieces

- Undercuts may developUndercuts may develop- Most of the workpiece should be Most of the workpiece should be

shaped by other processes to shaped by other processes to speed productionspeed production

- Variations may occur depending Variations may occur depending onhumidity and temperatureonhumidity and temperature

- Computerized designs must be Computerized designs must be converted to a format compatible converted to a format compatible with the photochemical artwork with the photochemical artwork equipmentequipment

Electrochemical Electrochemical MachiningMachining

Uses an electrolyte and electrical Uses an electrolyte and electrical current to ionize and remove current to ionize and remove metal atomsmetal atoms

Can machine complex cavities in Can machine complex cavities in high-strength materialshigh-strength materials

Leaves a burr-free surfaceLeaves a burr-free surface

Not affected by the strength, Not affected by the strength, hardness or toughness of the hardness or toughness of the materialmaterial


Design Considerations:Design Considerations:- The electrolyte erodes away The electrolyte erodes away

sharp profilessharp profiles- It is difficult to control It is difficult to control

electrolyte flow; irregular electrolyte flow; irregular cavities may not be formed cavities may not be formed accuratelyaccurately

- Allow for small taper in holes Allow for small taper in holes made this waymade this way

Pulsed Electrochemical Pulsed Electrochemical MachiningMachining

A form of electrochemical A form of electrochemical machining; the current is machining; the current is pulsed to eliminate the need pulsed to eliminate the need for high electrolyte flowfor high electrolyte flow

Improves fatigue life of the partImproves fatigue life of the part

Electrochemical Electrochemical GrindingGrinding

Uses a rotating cathode Uses a rotating cathode embedded with abrasive embedded with abrasive particles for applications particles for applications comparable to milling, grinding comparable to milling, grinding and sawingand sawing

Most of the metal removal is Most of the metal removal is done by the electrolyte, done by the electrolyte, resulting in very low tool wearresulting in very low tool wear

Adaptable for honingAdaptable for honing


Design Considerations:Design Considerations:

(in addition to those for (in addition to those for electrochemical machining)electrochemical machining)

- Avoid sharp inside radiiAvoid sharp inside radii- Flat surfaces to be ground Flat surfaces to be ground

should be narrower than the should be narrower than the width of the grinding wheelwidth of the grinding wheel

Electrical-Discharge Electrical-Discharge MachiningMachining

Uses a shaped electrode and Uses a shaped electrode and electric sparks to remove electric sparks to remove metal; discharges sparks at metal; discharges sparks at about 50-500 kHzabout 50-500 kHz

A dielectric (nonconductive) fluid A dielectric (nonconductive) fluid removes debris and acts as an removes debris and acts as an insulator until the potential insulator until the potential difference is high enoughdifference is high enough

Can be used on any material that Can be used on any material that conducts electricityconducts electricity


Design Considerations:Design Considerations:- Design parts so that the Design parts so that the

electrodes can be made electrodes can be made economicallyeconomically

- Avoid deep slots and narrow Avoid deep slots and narrow openingsopenings

- Do not require very fine Do not require very fine surface finishsurface finish

- Most of the material removal Most of the material removal should be done by other should be done by other processes to speed productionprocesses to speed production

Electrical-Discharge Electrical-Discharge GrindingGrinding

The grinding wheel lacks The grinding wheel lacks abrasives and removes abrasives and removes material by electrical material by electrical dischargesdischarges

Can be combined with Can be combined with electrochemical grindingelectrochemical grinding

Can be used for sawing, in which Can be used for sawing, in which the saw has no teeththe saw has no teeth

Electrical-Discharge Electrical-Discharge Wire CuttingWire Cutting

The wire moves through the The wire moves through the workpiece like a band saw, workpiece like a band saw, removing material by electrical removing material by electrical dischargedischarge

Dielectric fluid is applied to the Dielectric fluid is applied to the work areawork area

The wire is generally used only The wire is generally used only once; it is inexpensiveonce; it is inexpensive


Example of a wire EDM machine

Courtesy of Edison Industrial Service Center


Example of a wire used for an EDM machine

This wire has been used; the wave pattern was formed during take-up



Example of cores removed from a part using wire EDM to create the cavity in a high-pressure nozzle

Holes were drilled in the interiors so that the wire could be strung through


Laser-Beam MachiningLaser-Beam Machining

Uses a concentrated beam of Uses a concentrated beam of light to vaporize part of the light to vaporize part of the workpieceworkpiece

Usually produces a rough Usually produces a rough surface with a heat-affected surface with a heat-affected zonezone

Can cut holes as small as .005 Can cut holes as small as .005 mm with depth/diameter ratios mm with depth/diameter ratios of 50:1of 50:1


Example of a part cut by laser-beam machining

Splatter marks appear where the laser first cuts into the material


Design Considerations:Design Considerations:- Non-reflective workpiece Non-reflective workpiece

surfaces are preferablesurfaces are preferable- Sharp corners are difficult to Sharp corners are difficult to

produce; deep cuts produce produce; deep cuts produce taperstapers

- Consider the effects of high Consider the effects of high temperature on the workpiece temperature on the workpiece materialmaterial

Electron Beam Electron Beam MachiningMachining

Vaporizes material using Vaporizes material using electrons accelerated to 50-electrons accelerated to 50-80% the speed of light80% the speed of light

Produces finer surface finish and Produces finer surface finish and narrower cut width than other narrower cut width than other thermal cutting processesthermal cutting processes

Requires a vacuum; generates Requires a vacuum; generates hazardous X rayshazardous X rays


An electron beam in a very low-pressure atmosphere of helium

Plasma Arc CuttingPlasma Arc Cutting

Uses plasma (ionized gas) to Uses plasma (ionized gas) to rapidly vaporize materialrapidly vaporize material

Material removal rates are much Material removal rates are much higher than those for laser higher than those for laser beam machining and electron beam machining and electron beam machining; produces beam machining; produces good surface finish and thin cut good surface finish and thin cut widthwidth


Close-up view of a plasma arc

Electron Beam Machining Electron Beam Machining and Plasma Arc Cuttingand Plasma Arc Cutting

Design Considerations:Design Considerations:

(in addition to those for laser-(in addition to those for laser-beam machining)beam machining)

- Parts should match the size of Parts should match the size of the vacuum chamberthe vacuum chamber

- Consider manufacturing the Consider manufacturing the part as a number of smaller part as a number of smaller componentscomponents

Water Jet MachiningWater Jet Machining

A pressurized jet of water cuts a A pressurized jet of water cuts a groove in the materialgroove in the material

Effective for many nonmetallic Effective for many nonmetallic materialsmaterials

Cuts can be started at any Cuts can be started at any location; does not produce location; does not produce heat; produces very little heat; produces very little burringburring

Water Jet MachiningWater Jet Machining

Abrasive Water Jet Abrasive Water Jet MachiningMachining

The water jet contains abrasive The water jet contains abrasive particles; this increases the particles; this increases the material removal ratematerial removal rate

Can cut metallic, nonmetallic, Can cut metallic, nonmetallic, and advanced composite and advanced composite materialsmaterials

Suitable for heat-sensitive Suitable for heat-sensitive materialsmaterials

Abrasive Jet MachiningAbrasive Jet Machining

A high-speed jet of dry air, A high-speed jet of dry air, nitrogen or carbon dioxide nitrogen or carbon dioxide carries abrasive particlescarries abrasive particles

Good for cutting hard or brittle Good for cutting hard or brittle materialsmaterials

Can be used for deburring, Can be used for deburring, cleaning, or removing oxides or cleaning, or removing oxides or surface filmssurface films

Abrasive Jet MachiningAbrasive Jet Machining

SummarySummary

Advanced machining processes Advanced machining processes offer alternatives where offer alternatives where conventional procedures would conventional procedures would be insufficient or uneconomical be insufficient or uneconomical

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Download - Advanced Machining Processes Manufacturing Processes

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