Ch09 ME 406 Grinding and NTM With Problems(2)

8/13/2019 Ch09 ME 406 Grinding and NTM With Problems(2)

1/44

Manufacturing Processes for Engineering Materials, 5th ed.

Kalpakjian Schmid

2008, Pearson EducationISBN No. 0-13-227271-7

Grinding Wheel


Kalpakjian Schmid


FIGURE 9.1 Schematic illustration of a physical model of a grinding wheel, showing its structure and

grain wear and fracture patterns.

TABLE 9.1 Knoop hardness range for

various materials and abrasives.


2/44


3/44


Kalpakjian Schmid


Superabrasive Wheels

FIGURE 9.3 Examples of superabrasive wheel configurations. The rim consists of superabrasives

and the wheel itself (core) is generally made of metal or composites. Note that the basic numberingof wheel types (such as 1, 2, and 11) is the same as that shown in Fig. 9.2. The bonding materials

for the superabrasives are: (a), (d), and (e) resinoid, metal, or vitrified; (b) metal; (c) vitrified; and (f)

resinoid.


4/44


Kalpakjian Schmid


Grinding Wheel Marking System

FIGURE 9.4 Standard marking system for aluminum-oxide and silicon-carbide bonded abrasives.


5/44


Kalpakjian Schmid


Diamond and cBN Marking System

FIGURE 9.5 Standard marking system for diamond and cubic-boron-nitride bonded abrasives.


6/44


Kalpakjian Schmid


Abrasive Grains

FIGURE 9.6 The grinding surface of an

abrasive wheel (A46-J8V), showing grains,

porosity, wear flats on grains (see also Fig.

9.7b), and metal chips from the workpiece

adhering to the grains. Note the randomdistribution and shape of the abrasive

grains.

FIGURE 9.7 (a) Grinding chip being produced by a single

abrasive grain. Note the large negative rake angle of the grain.

Source: After M.E. Merchant. (b) Schematic illustration of chip

formation by an abrasive grain. Note the negative rake angle,the small shear angle, and the wear flat on the grain.


7/44


Kalpakjian Schmid


Grinding Variables

FIGURE 9.8 Basic variables in surface

grinding. In actual grinding operations, the

wheel depth of cut, d, and contact length, l,

are much smaller than the wheel diameter,

D. The dimension tis called the grain depthof cut.

Chip length, external grinding

Chip length, internal grinding

Chip length, surface grinding


8/44


Kalpakjian Schmid


Grinding Parameters

FIGURE 9.9 Chip formation and plowing

(plastic deformation without chip removal)

of the workpiece surface by an abrasive

grain.

TABLE 9.2 Typical ranges of speeds and feeds for abrasive

processes.


9/44


Kalpakjian Schmid


Specific Energy in Grinding

TABLE 9.3 Approximate Specific-Energy Requirements for Surface

Grinding.

Temperature rise:


10/44


Kalpakjian Schmid


Residual Stresses

FIGURE 9.10 Residual stresses developed on the workpiece surface in grinding tungsten: (a) effect of wheel

speed and (b) effect of type of grinding fluid. Tensile residual stresses on a surface are detrimental to the

fatigue life of ground components. The variables in grinding can be controlled to minimize residual stresses, a

process known as low-stress grinding. Source:After N. Zlatin.


11/44


Kalpakjian Schmid


Dressing

FIGURE 9.11 (a) Methods of grinding wheel

dressing. (b) Shaping the grinding face of awheel by dressing it with computer-controlled

shaping features. Note that the diamond

dressing tool is normal to the wheel surface

at point of contact. Source:OKUMA America

Corporation.


12/44


Kalpakjian Schmid


Surface Grinding

FIGURE 9.12 Schematic illustrations of surface-grinding operations. (a) Traverse grinding with a horizontal-spindle surface grinder. (b) Plunge grinding with a horizontal-spindle surface grinder, producing a groove in the

workpiece. (c) Vertical-spindle rotary-table grinder (also known as the Blanchard-typegrinder).

FIGURE 9.12 Schematic illustration of a

horizontal-spindle surface grinder.


13/44


Kalpakjian Schmid


Thread and Internal Grinding

FIGURE 9.14 Threads produced by (a)

traverse and (b) plunge grinding.

FIGURE 9.15 Schematic illustrations of internal-grinding operations.


14/44


Kalpakjian Schmid


Centerless Grinding

FIGURE 9.16 (a-c) Schematic illustrations

of centerless-grinding operations. (d) Acomputer-numerical-control centerless

grinding machine. Source: Cincinnati

Milacron, Inc.


15/44


Kalpakjian Schmid


Creep-Feed Grinding

FIGURE 9.17 (a) Schematic illustration of the creep-feed grinding process. Note the large wheel

depth of cut. (b) A groove produced on a flat surface in one pass by creep-feed grinding using a

shaped wheel. Groove depth can be on the order of a few mm. (c) An example of creep-feed

grinding with a shaped wheel. Source: Courtesy of Blohm, Inc. and Society of Manufacturing

Engineers.


16/44


Kalpakjian Schmid


Finishing Operations

FIGURE 9.18 Schematic illustration of the structure ofa coated abrasive. Sandpaper, developed in the 16th

century, and emery cloth are common examples of

coated abrasives.

FIGURE 9.19 Schematic illustration of a honing tool to

improve the surface finish of bored or ground holes.

FIGURE 9.20 Schematic illustration of thesuperfinishing process for a cylindrical part: (a)

cylindrical microhoning; (b) centerless microhoning.


17/44


Kalpakjian Schmid


Lapping

FIGURE 9.21 (a) Schematic illustration of the lapping process. (b)

Production lapping on flat surfaces. (c) Production lapping on cylindricalsurfaces.


18/44


Kalpakjian Schmid


Chemical-Mechanical Polishing

FIGURE 9.22 Schematic illustration of the chemical-mechanical polishing process. This

process is widely used in the manufacture of silicon wafers and integrated circuits, where it

is known as chemical-mechanical planarization. Additional carriers and more disks percarrier also are possible.


19/44


Kalpakjian Schmid


Polishing Using Magnetic Fields

FIGURE 9.23 Schematic illustration of the use of magnetic fields to polish balls and rollers: (a)

magnetic float polishing of ceramic balls and (b) magnetic-field-assisted polishing of rollers.Source:After R. Komanduri, M. Doc, and M. Fox.


20/44


Kalpakjian Schmid


chip dimensions in grinding operations


21/44


Kalpakjian Schmid


material removal rate in surface grinding

9.61 (Textbook

) Derive a formula for the materialremoval rate in surface grinding in terms of

process parameters. Use the same terminology as

in the text.

The Metal Removal Rate is

MRR = Volume of material removed/time

In surface grinding, the situation is similar to the metal removal rate in slab milling

(see Section 8.10.1). Therefore,

MRR = lwd / t = vwd

where w is the width of the grinding wheel.


22/44


Kalpakjian Schmid


workpiece strength and impact on depth of cut

9.59(Textbook) If the workpiece strength in grinding is in-

creased by 50%, what should be the percentagedecreases in the wheel depth of cut, d, in order to

maintain the same grain force, all other variables being

the same?

From Section 9.4.1, it is apparent that if the workpiece-materialstrength is doubled, the grain force will be doubled. Since the grain

force is dependent on the square root of the depth of cut, the new

depth of cut would be one-fourth the original depth of cut. Thus, the

reduction in the wheel depth of cut would be 75%.


23/44


Kalpakjian Schmid


Temperature increase in surface-grinding


24/44


Kalpakjian Schmid


power dissipated in surface grinding


25/44


Kalpakjian Schmid


Ultrasonic Machining

FIGURE 9.24 (a) Schematic illustration of the ultrasonic-machining process; material is removed

through microchipping and erosion. (b) and (c) Typical examples of cavities produced by ultrasonic

machining. Note the dimensions of cut and the types of workpiece materials.

Contact time:Contact force:


26/44


Kalpakjian Schmid



27/44


Kalpakjian Schmid



28/44


Kalpakjian Schmid


d

Machinin

gProcesse

s

TABLE 9.4 General

characteristics of advanced

machining processes.


29/44


Kalpakjian Schmid


Chemical Milling

FIGURE 9.25 (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

milling of aluminum-alloy plates. These panels are chemically milled after the plates have first

been formed into shape, such as by roll forming or stretch forming. Source:ASM International.


30/44


Kalpakjian Schmid


Chemical Machining

FIGURE 9.26 (a) Schematic illustration of the chemical machining process. Note that no forces are

involved in this process. (b) Stages in producing a profiled cavity by chemical machining.


31/44


Kalpakjian Schmid


Roughness and Tolerance

Capabilities

FIGURE 9.27 Surface roughness and dimensional tolerance capabilities of various machining processes. Note the wide

range within each process. (See also Fig. 8.26.) Source: Machining Data Handbook, 3rd ed., 1980. Used by permission

of Metcut Research Associates, Inc.


32/44


Kalpakjian Schmid


Chemical Blanking

FIGURE 9.28 Typical parts made by chemical blanking; note the fine detail.

Source:Courtesy of Buckabee-Mears St. Paul.


33/44


Kalpakjian Schmid


Electrochemical Machining

FIGURE 9.29 Schematic illustration of the

electrochemical-machining process. This processis the reverse of electroplating, described in

Section 4.5.1.

FIGURE 9.30 Typical parts made by electrochemical

machining. (a) Turbine blade made of a nickel alloy,360 HB; the part on the right is the shaped electrode.

Source:ASM International. (b) Thin slots on a 4340-

steel roller-bearing cage. (c) Integral airfoils on a

compressor disk.


34/44


Kalpakjian Schmid


Electrochemical Grinding

FIGURE 9.31 (a) Schematic illustration of the electrochemical grinding process. (b) Thin slotproduced on a round nickel-alloy tube by this process.


35/44


Kalpakjian Schmid


Electrical Discharge Machining

FIGURE 9.32 Schematic illustration of the electrical-discharge-machining process.


36/44


Kalpakjian Schmid


EDM Examples

FIGURE 9.33 (a) Examples of shapes produced by the electrical-

discharge machining process, using shaped electrodes. The two

round parts in the rear are a set of dies for extruding the aluminum

piece shown in front; see also Section 6.4. Source:Courtesy of AGIE

USA Ltd. (b) A spiral cavity produced using a shaped rotating

electrode. Source: American Machinist. (c) Holes in a fuel-injection

nozzle produced by electrical-discharge machining.

FIGURE 9.34 Stepped cavities

produced with a square electrode

by EDM. In this operation, the

workpiece moves in the two

principal horizontal directions, and

its motion is synchronized with the

downward movement of the

electrode to produce thesecavities. Also shown is a round

electrode capable of producing

round or elliptical cavities. Source:

Courtesy of AGIE USA Ltd.


37/44


Kalpakjian Schmid


Wire EDM

FIGURE 9.35 Schematic illustration of the wire EDM process. As much as 50 hours of machining

can be performed with one reel of wire, which is then recycled.


38/44


Kalpakjian Schmid


Laser Machining

FIGURE 9.36 (a) Schematic illustration of the

laser-beam machining process. (b) Cutting

sheet metal with a laser beam. Source: (b)

Courtesy of Rofin-Sinat, Inc.

TABLE 9.5 General applications of lasers in

manufacturing.


39/44


Kalpakjian Schmid


Electron-Beam Machining

FIGURE 9.37 Schematic illustration of the electron-beam machining process. Unlike LBM,

this process requires a vacuum, and hence workpiece size is limited by the chamber size.


40/44


Kalpakjian Schmid


Water-Jet Machining

FIGURE 9.38 (a) Schematic

illustration of water-jet machining.

(b) A computer-controlled water-jet

cutting machine. (c) Examples of

various nonmetallic parts machined

by the water-jet cutting process.Source: Courtesy of OMAX

Corporation.


41/44


Kalpakjian Schmid


Abrasive-Jet Machining

FIGURE 9.39 (a) Schematic illustration of the abrasive-jet machining process. (b) Examples of

parts produced by abrasive-jet machining; the parts are 50 mm (2 in.) thick and are made of 304

stainless steel. Source:Courtesy of OMAX Corporation.


42/44


Kalpakjian Schmid


Design Considerations

FIGURE 9.40 Design guidelines for internal features, especially as applied to holes. (a) Guidelines for

grinding the internal surfaces of holes. These guidelines generally hold for honing as well. (b) The use of a

backing plate for producing high-quality through-holes by ultrasonic machining. Source:After J. Bralla.


43/44


Kalpakjian Schmid


Economic Considerations

FIGURE 9.41 Increase in the cost of machining and finishing operations as a function of the surface finish

required. Note the rapid increase associated with finishing operations.


44/44


Kalpakjian Schmid

Case Study: Stent Manufacture

FIGURE 9.42 The Guidant MULTI-LINK TETRATM

coronary stent system.

FIGURE 9.43 Detail of

the 3-3-3 MULTI-LINKTETRATM pattern.

FIGURE 9.44 Evolution of the stent surface. (a)

MULTI-LINK TETRATM after lasing. Note that a

metal slug is still attached. (b) After removal of

slug. (c) After electropolishing.

Date post:	04-Jun-2018
Category:	Documents
Upload:	khaled-hassan
View:	218 times
Download:	0 times

Ch09 ME 406 Grinding and NTM With Problems(2)

Documents