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removing the brinell marks by hand with fine sandpaper and these reworked bearings were installed in automobiles that were loaded onto a train and shipped from
Detroit to California as an experiment. A tool maker traveled on the same train and then inspected the bearings when they arrived in California. He found the bearings to be damage-free, making this the first method to have any effect on the problem.
75:, but with a bonded abrasive stone rather than loose or embedded abrasive. The geometry of the abrasive depends on the geometry of the workpiece surface; a stone (rectangular shape) is for cylindrical surfaces and cups and wheels are used for flat and spherical surfaces. A lubricant is used to minimize heat production, which can alter the metallurgical properties, and to carry away the
91:(3 to 10 psi), but can be as high as 2.06 MPa (299 psi). Honing is usually 3.4 to 6.9 MPa (490 to 1,000 psi) and grinding is between 13.7 to 137.3 MPa (1,990 to 19,910 psi). When a stone is used it is oscillated at 200 to 1000 cycles with an amplitude of 1 to 5 mm (0.039 to 0.197 in).
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The abrasive cuts the surface of the workpiece in three phases. The first phase is when the abrasive first contacts the workpiece surface: dull grains of the abrasive fracture and fall away leaving a new sharp cutting surface. In the second phase the abrasive "self dresses" while most of the stock is
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in 1934 in response to widespread damage sustained by wheel bearings installed in automobiles shipped by rail from
Detroit to California. The problem manifested as a buzzing or clicking sound that annoyed buyers of new cars and trucks, but the cause was unclear and so car dealerships in the Western
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The average rotational speed of abrasive wheel and/or workpiece is 1 to 15 surface m/min, with 6 to 14 m/min preferred; this is much slower compared to grinding speeds around 1800 to 3500 m/min. The pressure applied to the abrasive is very light, usually between 0.02 to 0.07 MPa
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of the bearing races was eventually identified as the cause of the noise, but a way to prevent this damage proved elusive. Thousands of design and process variations were tried in attempting to prevent brinelling, but none had any effect. A batch of bearings that had been brinelled was reworked by
142:
Abrasive cups or wheels are used to superfinish flat and spherical surfaces. The wheel and workpiece are rotated in opposite directions, which creates the cross-hatching. If the two are parallel then the result if a flat finish, but if the wheel is tilted slightly a convex or concave surface will
109:
This type of superfinishing is used for cylindrical workpieces. The workpiece is rotated between two drive rollers, which also move the machine as well. Four to eight progressively finer abrasive stones are used to superfinish the workpiece. The stones contact the workpiece at a 90° angle and are
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stone. The stone is oscillated or rotated while the workpiece is moved in such a way that each bonded grain of abrasive follows a random path with variations in speed, direction and pressure. This multi-motion is a key feature of superfinishing because it prevents the sort of smeared finish that
171:
Aluminum oxide is used for "roughing" operations. Silicon carbide, which is harder than aluminum oxide, is used for "finishing" operations. CBN and diamond are not as commonly used, but find use with specialized materials such as
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It has been proven that superfinishing certain parts makes them more durable. For example, if the teeth in a gear are superfinished they will last up to four times as long.
383:
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This type is used to finish irregularly shaped surfaces. The workpiece is rotated while the abrasive plunges onto the desired surface.
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operation beforehand, which increases cost. Superfinishing has a lower cutting efficiency because of smaller chips and lower
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United States eventually resorted to replacing all factory-installed wheel bearings with virgin bearings prior to sale.
199:, closer tolerances, higher load bearing surfaces, better sealing capabilities, and elimination of a break in period.
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being removed. Finally, the abrasive grains become dull as they work which improves the surface geometry.
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may be mixed with other abrasives to add lubricity and to enhance the appearance of the finish.
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oscillated axially. Examples of parts that would be produced by process include tapered rolls,
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210:. Superfinishing stones are softer and wear more quickly, however they do not need to be
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Abrasive grains must be very fine to be used with superfinishing; usually 5–8 μm.
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surface layer of fragmented or smeared metal left by the last process with an
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There are three types superfinishing: Through-feed, plunge, and wheels.
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Advantages of superfinishing include: increasing part life, decreasing
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The main disadvantage is that superfinishing requires grinding or a
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stone or tape; this layer is usually about 1 μm in magnitude.
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and workpiece geometry. This is achieved by removing just the thin
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447:"For Superfinishing Excellence, Start With The Right Finish"
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to an initial finish, it is superfinished with a finer grit
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Superfinishing can give a surface finish of 0.01 μm.
445:
Schwarz, Jeff; Darmann
Abrasive Products (1998-12-15),
485:
Gear
Durability Shown To Be Improved by Superfinishing
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Todd, Robert H.; Allen, Dell K.; Alting, Leo (1994),
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152:Common abrasives used for superfinishing include
550:
527:
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346:. Ann Arbor, Michigan: The Ann Arbor Press.
71:. In this way, superfinishing is similar to
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531:Manufacturing Processes Reference Guide
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261:Superfinishing was conceived of by the
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510:Precision Engineering in Manufacturing
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250:, and sharpening stones and wheels.
482:Krantz, Timothy L. (1 March 2000).
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414:Todd, Allen & Alting 1994
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222:Common applications include:
191:Advantages and disadvantages
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7:
384:"The Art of Superfinishing"
382:Darmann Abrasive Products.
344:The Story of Superfinishing
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16:Workpiece finishing process
10:
575:
465:"Microfinishing Solutions"
256:
49:
534:, Industrial Press Inc.,
513:, New Age International,
318:"What is Microfinishing?"
342:Swigert, Arthur (1940).
303:
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83:is a common lubricant.
34:process that improves
208:material removal rate
559:Grinding and lapping
488:(Technical report).
263:Chrysler Corporation
507:Murty, R L (1996),
451:Modern Machine Shop
416:, pp. 135–136.
162:cubic boron nitride
28:short-stroke honing
283:Abrasive machining
520:978-81-224-0750-1
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22:, also known as
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242:cylinder rods,
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158:silicon carbide
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154:aluminum oxide
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116:shock absorber
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36:surface finish
24:microfinishing
20:Superfinishing
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541:0-8311-3049-0
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232:fuel injector
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224:steering rack
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69:built up edge
67:results from
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501:Bibliography
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398:. Retrieved
391:the original
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268:
260:
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234:components,
230:components,
228:transmission
226:components,
221:
218:Applications
204:hard turning
201:
194:
186:
180:. Note that
170:
151:
106:Through-feed
101:
93:
89:
85:
53:
32:metalworking
27:
23:
19:
18:
112:piston pins
433:Murty 1996
400:2017-02-01
299:References
270:Brinelling
178:tool steel
164:(CBN) and
240:hydraulic
148:Abrasives
58:piece is
40:amorphous
553:Category
277:See also
236:camshaft
182:graphite
176:and M50
174:ceramics
81:kerosene
64:abrasive
54:After a
44:abrasive
293:Lapping
257:History
238:lobes,
212:dressed
166:diamond
124:needles
73:lapping
50:Process
30:, is a
538:
517:
469:Neuteq
352:568009
350:
322:Neuteq
288:Honing
139:Wheels
131:Plunge
122:, and
120:shafts
118:rods,
60:ground
394:(PDF)
387:(PDF)
304:Notes
143:form.
98:Types
77:swarf
56:metal
536:ISBN
515:ISBN
490:NASA
348:OCLC
197:wear
26:and
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467:.
449:,
421:^
360:^
330:^
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168:.
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