Production technology Ch26

7/31/2019 Production technology Ch26

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Kalpakjian SchmidManufacturing Engineering and Technology 2001 Prentice-Hall Page 26-1

CHAPTER 26

Advanced Machining Processes andNanofabrication


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Examples of Parts Made by AdvancedMachining Processes

Figure 26.1 Examples of parts made by advanced machining processes. These parts are made byadvanced machining processes and would be difficult or uneconomical to manufacture by conventionalprocesses. (a) Cutting sheet metal with a laser beam. Courtesy of Rofin-Sinar, Inc., and ManufacturingEngineering Magazine, Society of Manufacturing Engineers. (b) Microscopic gear with a diameter onthe order of 100 m, made by a special etching process. Courtesy of Wisconsin Center for AppliedMicroelectronics, University of Wisconsin-Madison.

(a) (b)


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GeneralCharacteristicsof AdvancedMachining

Processes

TABLE 26. 1

Process Characteristics

Process parameters and

typical material removal

rate or cutting speedChemical machining (CM) Shallow removal (up to 12 mm) on large flat or

curved surfaces; blanking of thin sheets; low tooling

and cost; suitable for low production runs.

0.00250.1 mm/min.

Electrochemical machining

(ECM)

Complex shapes with deep cavities; highest rate of

material removal among nontraditional processes;

expensive tooling and equipment; high power

consumption; medium to high production quantity.

V: 525 dc; A: 1.58 A/mm2

;

2.512 mm/min, depending

on current density.

Electrochemical grinding

(ECG)

Cutting off and sharpening hard materials, such as

tungsten-carbide tools; also used as a honing process;

higher removal rate than grinding.

A: 13 A/mm2

; Typically 25

mm3

/s per 1000 A.

Electrical-discharge

machining (EDM)

Shaping and cutting complex parts made of hard

materials; some surface damage may result; also used

as a grinding and cutting process; expensive tooling

and equipment.

V: 50380; A: 0.1500;

Typically 300 mm3

/min.

Wire EDM Contour cutting of flat or curved surfaces; expensive

equipment.

Varies with material and

thickness.

Laser-beam machining

(LBM)

Cutting and holemaking on thin materials; heat-

affected zone; does not require a vacuum; expensive

equipment; consumes much energy.

0.507.5 m/min.

Electron-beam machining

(EBM)

Cutting and holemaking on thin materials; very small

holes and slots; heat-affected zone; requires a vacuum;

expensive equipment.

12 mm3

/min.

Water-jet machining (WJM) Cutting all types of nonmetallic materials to 25 mm

and greater in thickness; suitable for contour cutting

of flexible materials; no thermal damage; noisy.

Varies considerably with

material.

Abrasive water-jet machining(AWJM) Single or multilayer cutting of metallic andnonmetallic materials. Up to 7.5 m/min.

Abrasive-jet machining

(AJM)

Cutting, slotting, deburring, deflashing, etching, and

cleaning of metallic and nonmetallic materials;

manually controlled; tends to round off sharp edges;

hazardous.

Varies considerably with

material.


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Chemical Milling

Figure 26.2 (a) Missile skin-panel section contoured by chemical milling to improve the stiffness-to-weight ratio of the part. (b) Weight reduction of space launch vehicles by chemical millingaluminum-alloy plates. These panels are chemically milled after the plates have first been formedinto shape by processes such as roll forming or stretch forming. The design of the chemicallymachined rib patterns can be modified readily at minimal cost. Source:Advanced Materials andProcesses, December 1990. ASM International.


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Chemical Machining

Figure 26.3 (a) Schematic illustration of the chemical machining process. Note that no forces

or machine tools are involved in this process. (b) Stages in producing a profiled cavity bychemical machining; note the undercut.


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Range of Surface Roughnesses and

Tolerances

Figure 26.4 Surfaceroughness andtolerances obtainedin various machiningprocesses. Note thewide range withineach process (see

also Fig. 22.13).Source:MachiningData Handbook, 3rded. Copyright1980. Used bypermission ofMetcut ResearchAssociates, Inc.


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Chemical Blanking and ElectrochemicalMachining

Figure 26.6 Schematic illustration of the electrochemical-machining process. This process is the reverse ofelectroplating, described in Section 33.8.

Figure 26.5 Various parts made by chemical blanking.Note the fine detail. Source: Courtesy of Buckbee-MearsSt. Paul.


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Examples of Parts Made by ElectrochemicalMachining

Figure 26.7 Typical partsmade by electrochemicalmachining. (a) Turbine

blade made of a nickelalloy, 360 HB; note theshape of the electrode onthe right. Source: ASMInternational. (b) Thinslots on a 4340-steelroller-bearing cage. (c)Integral airfoils on acompressor disk.


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Biomedical Implant

(a) (b)

Figure 26.8 (a) Two total knee replacement systems showing metal implants (top pieces) with an ultrahighmolecular weight polyethylene insert (bottom pieces). (b) Cross-section of the ECM process as applied to themetal implant. Source: Biomet, Inc.


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Electrochemical Grinding

Figure 26.9 (a) Schematic illustration of the electrochemical-grinding process. (b) Thin slot producedon a round nickel-alloy tube by this process.


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Electrical-Discharge Machining

(a) (b)

Figure 26.10 (a) Schematic illustration of the electrical-discharge machining process. This is oneof the most widely used machining processes, particularly for die-sinking operations. (b)Examples of cavities produced by the electrical-discharge machining process, using shapedelectrodes. Two round parts (rear) are the set of dies for extruding the aluminum piece shown infront (see also Fig. 15.9b). Source: Courtesy of AGIE USA Ltd. (c) A spiral cavity produced byEDM using a slowly rotating electrode, similar to a screw thread. Source:American Machinist.

(c)


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Examples of EDM

Figure 26.11 Stepped cavities produced with a square electrode by theEDM process. The workpiece moves in the two principal horizontaldirections (x-y), and its motion is synchronized with the downward

movement of the electrode to produce these cavities. Also shown is around electrode capable of producing round or elliptical cavities.Source: Courtesy of AGIE USA Ltd.

Figure 26.12 Schematicillustration of producing aninner cavity by EDM, using aspecially designed electrode

with a hinged tip, which isslowly opened and rotated toproduce the large cavity.Source: Luziesa France.


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Wire EDM

Figure 26.13 (a) Schematicillustration of the wireEDM process. As much as50 hours of machining canbe performed with one reel

of wire, which is thendiscarded. (b) Cutting athick plate with wire EDM.(c) A computer-controlledwire EDM machine.Source: Courtesy of AGIEUSA Ltd.

(a)

(b) (c)


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Laser-Beam Machining

Figure 26.14 (a) Schematic illustration of the laser-beam machining process. (b) and (c) Examplesof holes produced in nonmetallic parts by LBM.


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General Applications of Lasers in Manufacturing

TABLE 26.2

Application Laser type

CuttingMetals PCO2 , CWCO2 , Nd : YAG, ruby

Plastics CWCO2

Ceramics PCO2

Drilling

Metals PCO2 , Nd : YAG, Nd : glass, ruby

Plastics Excimer

MarkingMetals PCO2 , Nd : YAG

Plastics Excimer

Ceramics Excimer

Surface treatment, metals CWCO2

Welding, metals PCO2 , CWCO2 , Nd : YAG, Nd : glass, ruby

Note: P pulsed, CW continuous wave.


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Electron-Beam Machining

Figure 26.15 Schematic illustration of the electron-beam machiningprocess. Unlike LBM, this process requires a vacuum, so workpiecesize is limited to the size of the vacuum chamber.


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Water-Jet Machining

Figure 26.16 (a) Schematic illustration of water-jet machining.(b) A computer-controlled, water-jet cutting machine cutting agranite plate. (c) Examples of various nonmetallic parts producedby the water-jet cutting process. Source: Courtesy of PossisCorporation.

(c)

(a) (b)


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Abrasive-Jet Machining

Figure 26.17 Schematic illustration of the abrasive-jet machining process.


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Nanofabrication

(a) (b)

Figure 26.18 (a) A scanning electron microscope view of a diamond-tipped(triangular piece at the right) cantilever used with the atomic force microscope.

The diamond tip is attached to the end of the cantilever with an adhesive. (b)Scratches produced on a surface by the diamond tip under different forces. Notethe extremely small size of the scratches.

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Production technology Ch26