Ch09-2008.Abrasive n Finishing -Kalpakjian-. Ina

Kalpakjian, Manufacturing Processes for Engineering Materials © 1997 Addison Wesley Page 9-1

Permesinan Abrasif dan Operasi Pengakhiran

Bab 9


Kekerasan Knoop untuk Berbagai Bahan dan Abrasif

TABLE 9.1

Common glass 350–500 Titanium nitride 2000 Flint, quartz 800–1100 Titanium carbide 1800–3200 Zirconium oxide 1000 Silicon carbide 2100–3000 Hardened steels 700–1300 Boron carbide 2800 Tungsten carbide 1800–2400 Cubic boron nitride 4000–5000 Aluminum oxide 2000–3000 Diamond 7000–8000


Batu Gerinda

Figure 9.1 Schematic illustration of a physical model of a grinding wheel, showing its structure and wear and fracture patterns.

•Type of failures


Roda gerinda yang umum

Figure 9.2 Common types of grinding wheels made with conventional abrasives. Note that each wheel has a specific grinding face; grinding on other surfaces is improper and unsafe.


Konfigurasi Roda Superabrasif

Figure 9.3 Examples of superabrasive wheel configurations. The annular regions (rim) are superabrasive grinding surfaces, and the wheel itself (core) is generally made of metal or composites. The bonding materials for the superabrasives are (a), (d), and (e) resinoid, metal, or vitrified, (b) metal, (c) vitrified, and (f) resinoid.


Contoh Abrasif Terikat

Figure extra A variety of bonded abrasives used in abrasive machining processes. Source: Courtesy of Norton Company.

•Abrasif Konvensional•Al2O3

•SiC•Superabrasif

•Cubic boron nitride (CBN)•Diamond


Sistem Penandaan untuk Abrasive diikat Aluminum-Oxide dan Silicon-Carbide

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


Sistem Penandaan Standar untuk Abrasif diikat Cubic Boron Nitride dan Diamond

Figure 9.4b Standard marking system for cubic boron nitride and diamond bonded abrasives.

Kalpakjian, Manufacturing Processes for Engineering Materials © 1997 Addison Wesley -9

Permukaan Roda Gerinda

Figure 9.5 The surface of a grinding wheel (A46-J8V) showing abrasive grains, wheel porosity, wear flats on grains, and metal chips from the workpiece adhering to the grians. Note the random distribution and shape of abrasive grains. Magnification: 50X. Source: S. Kalpakjian.


Serpih Penggerindaan

Figures 9.6 and 9.9 (a) Grinding chip being produced by a single abrasive grain. (A) chip, (B) workpiece, (C) abrasive grain. Note the large negative rake angle of the grain. The inscribed circle is 0.065 mm (0.0025 in.) in diameter. Source: M. E. Merchant. (b) Schematic illustration of chip formation by an abrasive grain with a wear flat. Note the negative rake angle of the grain and the small shear angle.

(a) (b)

D

d

VC

v•Relative

grain force•Actual force=relative grain force x strength of metal


Penggerindaan Permukaan dan PembajakanFigure 9.7 Schematic illustration of the surface grinding process, showing various process variables. The figure depicts conventional (up) grinding.

Figure 9.8 Chip formation and plowing of the workpiece surface by an abrasive grain. This action is similar to abrasive wear. (See Fig. 32.6).

Ddl D

d

VC

vt

4

C: number of cutting points per unit area of wheel surface

Dv

VCd

t

dT 4

3

•Surface temperature rise

(ploughing)


Perkiraan Energi Spesifik yang diperlukan untuk Penggerindaan Permukaan

TABLE 9.3 Specific energy Workpiece material Hardness W-s/mm

3 hp-min/in.

3

Aluminum 150 HB 7–27 2.5–10 Cast iron (class 40) 215 HB 12–60 4.5–22 Low-carbon steel (1020) 110 HB 14–68 5–25 Titanium alloy 300 HB 16–55 6–20 Tool steel (T15) 67 HRC 18–82 6.5–30

•Specific energy u = uchip + uploughing + usliding

•Much higher energy levels (~20x) than those in cutting with single-point tools Size effect: small size ( higher strength of metal); Wear flat; Chip morphology: negative rake angle ( large shear strain)

cc FDFTTorque

TMRRuPower

dwvMRR

)2)((

))(())((


Perautan Muka Menggunakan Kendali Komputer

Figure 9.11 Shaping the grinding face of a wheel by dressing it with computer control. Note that the diamond dressing tool is normal to the surface at point of contact with the wheel. Source: Okuma Machinery Works Ltd.

•Dressing: conditioning worn grains•Truing to original shape•Shaping


Rekomendasi Kisaran Kecepatan, Pemakanan dan Roda Gerinda

TABLE extra Typical Range of Speeds and Feeds for Abrasive Processes Process variable

Conventional grinding

Creep-feed grinding

Buffing

Polishing

Wheel speed (m/min) 1500–3000 1500–3000 1800–3600 1500–2400 Work speed (m/min) 10–60 0.1–1 — — Feed (mm/pass) 0.01–0.05 1–6 — —

TABLE 9.4 Typical Recommendations for Grinding Wheels for Use with Various Materials Material Type of grinding wheel Aluminum Brass Bronze Cast iron Carbides Ceramics Copper Nickel alloys Nylon Steels Titanium Tool steels ( > 50 HRC)

C46–K6V C46–K6V A54–K6V

C60–L6V, A60–M6V C60–I9V, D150–R75B

D150–N50M C60–J8V

B150H100V A36–L8V A60–M6V A60–K8V B120WB

Note: These recommendations vary significantly, depending on material composition, the particular grinding operation, and grinding fluids used.


Moollight, Beethoven

Hindu temple, Muktinath, 3900 m, Nepal


Geometri Benda Kerja

Figure extra The types of workpieces and operations typical of grinding: (a) cylindrical surfaces, (b) conical surfaces, (c) fillets on a shaft, (d) helical profiles, (e) concave shape, (f) cutting off or slotting with thin wheels, and (g) internal grinding. See also the illustrations in Section 25.6.


Karakteristik Umum Proses Permesinan Abrasif

TABLE extra Process

Characteristics

Maximum dimension (m)*

Surface Flat surfaces on most materials; production rate depends on table size and automation; labor skill depends on part; production rate is high on vertical-spindle rotary-table type.

Reciprocating table L : 6 Rotary table D : 3

Cylindrical Round workpieces with stepped diameters; low production rate unless automated; labor skill depends on part shape.

Workpiece D : 0.8 Roll grinders D : 1.8 Universal grinders D : 2.5

Centerless Round workpieces; high production rate; low to medium labor skill. Workpiece D : 0.8 Internal Bores in workpiece; low production rate; low to medium labor skill. Hole D : 2 Honing Bores and holes in workpiece; low production rate; low labor skill. Spindle D : 1.2 Lapping Flat surfaces; high production rate; low labor skill. Table D : 3.7 Ultrasonic machining

Holes and cavities of various shapes, particularly in hard and brittle nonconducting materials.

—

*Larger capacities are available for special applications. L=length; D=diameter.

VIDEO


Operasi Penggerindaan Permukaan

Figure 9.12 Schematic illustrations of various 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) A vertical-spindle rotary-table grinder (also known as the Blanchard type).

VIDEO


Penggerindaan Permukaan

Figure 9.13 Schematic illustration of a horizontal-spindle surface grinder.

Figure 9.14 (a) Rough grinding of steel balls on a vertical-spindle grinder; the balls are guided by a special rotary fixture. (b) Finish grinding of balls in a multiple-groove fixture. The balls are ground to within 0.013 mm (0.0005 in.) of their final size. Source: American Machinist.


Operasi Penggerindaan Silindris

Figure 9.15 Examples of various cylindrical grinding operations. (a) Traverse grinding, (b) plunge grinding, and (c) profile grinding. Source: Okuma Machinery Works Ltd.

VIDEO


Plunge dan Penggerindaan Non-silindris

Figure 9.16 Plunge grinding of a workpiece on a cylindrical grinder with the wheel dressed to a stepped shape.

Figure extra Schematic illustration of grinding a noncylindrical part on a cylindrical grinder with computer controls to produce the shape. The part rotation and the distance x between centers is varied and synchronized to grind the particular workpiece shape.


Ulir dan Penggerindaan Internal

Figure 9.17 Thread grinding by (a) traverse, and (b) plunge grinding.

Figure 9.18 Schematic illustrations of internal grinding operations.


Pola Siklus pada Penggerindaan Silindris

Figure 25.20


Penggerindaan Tanpa Senter

(c)Figure 9.19 Schematic illustrations of centerless grinding operations: (a) through feed grinding. (b) Plunge grinding. (c) A computer numerical control cylindrical grinding machine. Source: Courtesy of Cincinnati Milacron, Inc.

VIDEO


Penggerindaan Pemakanan Merangkak (Creep-Feed Grinding)

(a) (b) (c)

Figure 9.21 (a) Schematic illustration of the creep-feed grinding process. Note the large wheel depth of cut, d. (b) A shaped groove produced on a flat surface by creep-feed grinding in one pass. Groove depth is typically on the order of a few mm. (c) An example of creep-feed grinding with a shaped wheel. This operation can also be performed by some of the processes. Source: Courtesy of Blohm, Inc., and Manufacturing Engineering Magazine, Society of Manufacturing Engineers.

VIDEO (cut grinding)


Rekomendasi Umum untuk Cairan Gerinda

TABLE 9.5 Material Grinding fluid Aluminum Copper Magnesium Nickel Refractory metals Steels Titanium

E, EP CSN, E, MO FO D, MO CSN, EP EP CSN, E CSN, E

D: dry; E: emulsion; EP: Extreme pressure; CSN: chemicals and synthetics; MO: mineral oil; FO: fatty oil.


Operasi Pengakhiran

•Coated abrasives•Wire brushing•Honing•Superfinishing •Lapping•Polishing•Buffing•Electropolishing•Magnetic-field-assisted polishing


Coated Abrasives (Abrasif Terlapisi)

Figure 9.23 Schematic illustration of the structure of a coated abrasive. Sandpaper, developed in the 16th century, and emery cloth are common examples of coated abrasives.

•Abrasives are coated on the backing


Gerinda Sabuk (Belt Grinding)

Figure extra Example: Belt Grinding of Turbine Nozzle Vanes.

•Coated abrasives


Honing dan Superfinishing

Figure 9.24 Schematic illustration of a honing tool used to improve the surface finish of bored or ground holes.

Figure 9.25 Schematic illustrations of the superfinishing process for a cylindrical part. (a) Cylindrical mircohoning, (b) Centerless microhoning.

•Stone: Al2O3 or SiC bonded abrasives

: very light


Lapping

Figure 9.26 (a) Schematic illustration of the lapping process. (b) Production lapping on flat surfaces. (c) Production lapping on cylindrical surfaces.

•Lap: cast iron, copper, leather, or cloth

(embedded in the lap)


Pemolesan dengan Medan Magnet

Figure 9.27 Schematic illustration of polishing of balls and rollers using magnetic fields. (a) Magnetic float polishing of ceramic balls. (b) Magnetic-field-assisted polishing of rollers. Source: R. Komanduri, M. Doc, and M. Fox.

•Bearing steels of 63 HRC have been mirror finished in 30 seconds

•Magnetic force: press the abrasive grains on the workpiece


Permesinan Aliran Abrasif (Abrasive-Flow Machining)

Figure 9.28 Schematic illustration of abrasive flow machining to deburr a turbine impeller. The arrows indicate movement of the abrasive media. Note the special fixture, which is usually different for each part design. Source: Extrude Hone Corp.


Robotic Deburring

Figure extra A deburring operation on a robot-held die-cast part for an outboard motor housing, using a grinding wheel. Abrasive belts or flexible abrasive radial-wheel brushes can also be used for such operations. Source: Courtesy of Acme Manufacturing Company and Manufacturing Engineering Magazine, Society of Manufacturing Engineers.

•Vibratory and barrel finishing•Shot blasting•Abrasive-flow machining•Thermal energy method: melting of burrs• • •Manually with files•


Symphony No. 5, Beethoven

Bridge over Kali Gandaki (River), Nepal

Be awake !

Bangun!깨어나 !

Ch09-2008.Abrasive n Finishing -Kalpakjian-. Ina

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