Advanced Machining Processes

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Chapter 27Advanced Machining Processes


Parts Made by Advanced Machining Processes

Figure 27.1 Examples of parts produced by advanced machining processes. (a)Samples of parts produced from waterjet cutting. (b) Turbine blade, produced byplunge EDM, in a fixture to produce the holes by EDM. Source: (a) Courtesy ofOmax Corporation. (b) Courtesy of Hi-TEK Mfg., Inc.

(a)(b)


GeneralCharacteristicsof AdvancedMachiningProcesses


Chemical Milling

Figure 27.2 (a) Missile skin-panel section contoured by chemical milling to improve thestiffness-to-weight ratio of the part. (b) Weight reduction of space-launch vehicles by thechemical milling of aluminum-alloy plates. These panels are chemically milled after theplates first have been formed into shape by a process such as roll forming or stretch forming.The design of the chemically machined rib patterns can be modified readily at minimal cost.


Chemical-Machining

Figure 27.3 (a) Schematic illustration of the chemical-machining process. Note that noforces or machine tools are involved in this process. (b) Stages in producing a profiledcavity by chemical machining; note the undercut.


SurfaceRoughness

andTolerances

inMachining

Figure 27.4 Surface roughness and tolerances obtained in various machining processes. Notethe wide range within each process (see also Fig. 23.13). Source: Machining Data Handbook,3rd ed. Copyright © 1980. Used by permission of Metcut Research Associates, Inc.


Parts Made by Chemical Blanking

Figure 27.5 Various parts made by chemical blanking. Note thefine detail. Source: Courtesy of Buckbee-Mears, St. Paul.


Electrochemical Machining

Figure 27.6 Schematic illustration of the electrochemical machining process.


Parts Made by Electrochemical Machining

Figure 27.7 Typical parts made by electrochemical machining. (a) Turbine blademade of nickel alloy of 360 HB. Note the shape of the electrode on the right. (b) Thinslots on a 4340-steel roller-bearing cage. (c) Integral airfoils on a compressor disk.


Knee Implants

Figure 27.8 (a) Two total knee replacement systems showing metal implants(top pieces) with an ultra-high molecular-weight polyethylene insert (bottompieces). (b) Cross-section of the ECM process as applies to the metal implant.Source: Courtesy of Biomet, Inc.


Electrochemical-Grinding Process

Figure 27.9 (a) Schematic illustration of the electrochemical-grinding process.(b) Thin slot produced on a round nickel-alloy tube by this process.


Electrical-Discharge Machining Process

Figure 27.10 (a) Schematic illustration of the electrical-discharge machining process. This is one of themost widely used machining processes, particularly for die-sinking applications. (b) Examples of cavitiesproduced by the electrical-discharge machining process, using shaped electrodes. Two round parts (rear)are the set of dies for extruding the aluminum piece shown in front (see also Fig. 19.9b). (c) A spiral cavityproduced by EDM using a slowly rotating electrode similar to a screw thread. (d) Holes in a fuel-injectionnozzle made by EDM; the material is heat-treated steel. Source: (b) Courtesy of AGIE USA Ltd.


Stepped Cavities Produced by EDM Process

Figure 27.11 Stepped cavities produced with a square electrode by the EDMprocess. The workpiece moves in the two principle horizontal directions (x – y), andits motion is synchronized with the downward movement of the electrode to producethese cavities. Also shown is a round electrode capable of producing round orelliptical cavities. Source: Courtesy of AGIE USA Ltd.


The Wire EDM Process

Figure 27.12 Schematic illustration of thewire EDM process. As many as 50 hours ofmachining can be performed with one reel ofwire, which is then discarded.

!

Metal removal rate :

MRR = 4 "104ITw

#1.23

where

I = current in amperes

Tw = melting temperature of workpiece, °C


Wire EDM

(a) (b)

Figure 27.13 (a) Cutting a thick plate with wire EDM. (b) A computer-controlled wire EDM machine. Source: Courtesy of AGIE USA Ltd.


Laser-BeamMachining (LBM)

Figure 27.14 (a) Schematicillustration of the laser-beammachining process. (b) and (c)Examples of holes produced innonmetallic parts by LBM. (d)Cutting sheet metal with a laserbeam. Source: (d) Courtesy ofRofin-Sinar, Inc.


General Applications of Lasers in Manufacturing


Electron-Beam Machining Process

Figure 27.15 Schematic illustration of the electron-beammachining process. Unlike LBM, this process requires a vacuum,so workpiece size is limited to the size of the vacuum chamber.


Water-JetCuttingProcess

Figure 27.16 (a) Schematic illustration of the water-jet machining process. (b) Acomputer-controlled water-jet cutting machine cutting a granite plate. (c) Examples ofvarious nonmetallic parts produced by the water-jet cutting process. (Enlarged on nextslide). Source: Courtesy of Possis Corporation


Nonmetallic Parts Made by Water-Jet Cutting

Enlargement of Fig. 27.16c. Examples of various nonmetallic parts produced bythe water-jet cutting process. Source: Courtesy of Possis Corporation


Abrasive-Jet Machining

Figure 27.17 (a) Schematic illustration of the abrasive-jet machining process. (b)Examples of parts produced through abrasive-jet machining, produced in 50-mm (2-in.)thick 304 stainless steel. Source: Courtesy of OMAX Corporation.

(b)


Case Study: Stent Manufacture

Figure 27.18 The Guidant MULTI-LINKTETRATM coronary stent system.

Figure 27.19 Detail of the 3-3-3MULTI-LINK TETRATM pattern.

Figure 27.20 Evolution ofthe stent surface. (a)MULTI-LINK TETRATM afterlasing. Note that a metalslug is still attached. (b)After removal of slag. (c)After electropolishing.

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Advanced Machining Processes