296:
288:
are not uncommon, and systems with tables 9 m (30 ft) in diameter have been constructed. Referring to the second picture again, the lap is the large circular disk on the top of the machine. On top of the lap are two rings. The workpiece would be placed inside one of these rings. A weight would then be placed on top of the workpiece. The weights can also be seen in the picture along with two fiber spacer disks that are used to even the load.
257:
398:
32:
304:
lapping plate and fine adjustment of the load applied to the specimen during the material removal process. Due to the dimensions of such small samples, traditional loads and weights are too heavy as they would destroy delicate materials. The jig sits in a cradle on top of the lapping plate and the dial on the front of the jig indicates the amount of material removed from the specimen.
329:
lack of support, the edges of the opposite piece will tend to dig depressions into it a short distance in from the edge, and the edges of the opposite piece are heavily abraded by the same action - the lapping procedure assumes roughly equal pressure distribution across the whole surface at all times, and will fail in this manner if the workpiece itself deforms under that pressure.
442:. A surface that exhibits an Ra of 8 consists of peaks and valleys that average no more than 8 μm over a given distance. Roughness may be also measured by comparing the surface of the workpiece to a known sample. Calibration samples are available usually sold in a set and usually covering the typical range of machining operations from about 125 μm Ra to 1 μm Ra.
280:
321:
313:
necessarily perfectly flat), separated by a distance determined by the average size of the abrasive particles, with a surface roughness determined by the variation in the abrasive size. This yields closeness-of-fit results comparable to that of two accurately-flat pieces, without quite the same degree of
414:. Each fringe – or band – represents a change of one half wavelength in the width of the gap between the glass and the workpiece. The light bands display a contour map of the surface of the workpiece and can be readily interpreted for flatness. In the past the light source would have been provided by a
216:
for the lap, which is "charged" with the abrasive. The lap is then used to cut a harder material—the workpiece. The abrasive embeds within the softer material, which holds it and permits it to score across and cut the harder material. Taken to a finer limit, this will produce a polished surface such
303:
When there is a requirement to lap very small specimens (from 75 mm (3 in) down to a few millimetres), a lapping jig can be used to hold the material while it is lapped (see Image 3, Lapping machine and retention jig). A jig allows precise control of the orientation of the specimen to the
287:
The second picture is of a commercially available lapping machine. The lap or lapping plate in this machine is 30 cm (12 in) in diameter, about the smallest size available commercially. At the other end of the size spectrum, machines with 2.4-to-3.0-metre-diameter (8 to 10 ft) plates
409:
are all that are needed. The optical flat – which is a piece of transparent glass that has itself been lapped and polished on one or both sides – is placed on the lapped surface. The monochromatic light is then shone down through the glass. The light will pass through the glass and reflect off the
328:
One complication in two-piece lapping is the need to ensure that neither piece flexes or is deformed during the process. As the pieces are moved past each other, part of each (some area near the edge) will be unsupported for some fraction of the rubbing movement. If one piece flexes due to this
312:
Where the mating of the two surfaces is more important than the flatness, the two pieces can be lapped together. The principle is that the protrusions on one surface will both abrade and be abraded by the protrusions on the other, resulting in two surfaces evolving towards some common shape (not
437:
Surface roughness is defined by the minute variations in height of the surface of a given material or workpiece. The individual variances of the peaks and valleys are averaged (Ra value), or quantified by the largest difference from peak-to-valley (Rz). Roughness is usually expressed in
129:
363:
10 in). Again, without resort to special equipment accuracies of 1 to 3 HLB are typical. Though flatness is the most common goal of lapping, the process is also used to obtain other configurations such as a concave or convex surface.
389:
on the opposite side of the part measures parallelism. Flatness is more easily measured with a co-ordinate measuring machine. But neither of these methods can measure flatness more accurately than about 2.5 μm
291:
In operation, the rings stay in one location as the lapping plate rotates beneath them. In this machine, a small slurry pump can be seen at the side, this pump feeds abrasive slurry onto the rotating lapping plate.
136:
134:
131:
130:
422:. Today, laser diodes and LEDs are used, both being inexpensive and narrow-band light sources. With semiconductor light sources, blue is an option, having a smaller wavelength than red.
135:
344:
A typical range of surface roughness that can be obtained without resorting to special equipment would fall in the range of 1 to 30 units Ra (average roughness), usually microinches.
410:
workpiece. As the light reflects in the gap between the workpiece and the polished surface of the glass, the light will interfere with itself creating light and dark fringes called
385:. You must set up the part on three stands and find the minimum variation while adjusting them, just placing the part on the surface plate and using a dial indicator to find
617:
133:
579:
529:
341:; it is also used to obtain very accurate surfaces, usually very flat surfaces. Surface roughness and surface flatness are two quite different concepts.
276:. In use, a slurry of emery powder would be spread on the plate and the workpiece simply rubbed against the plate, usually in a "figure-eight" pattern.
405:
Another method that is commonly used with lapped parts is the reflection and interference of monochromatic light. A monochromatic light source and an
418:-neon lamp or tube, using the neon 632.8 nm line, or mercury vapor green line but nowadays a more common source of monochromatic light is the
132:
610:
169:
Lapping can take two forms. The first type of lapping (traditionally often called grinding), involves rubbing a brittle material such as
635:
685:
603:
572:
115:
426:
876:
53:
236:
of light from the commonly used 632.8 nm helium neon laser light source. Surfaces this flat can be molecularly bonded (
1183:
748:
655:
565:
798:
723:
96:
540:
68:
1039:
42:
881:
738:
158:
Lapping often follows other subtractive processes with more aggressive material removal as a first step, such as
871:
509:
419:
378:
75:
49:
20:
1157:
961:
946:
886:
848:
386:
237:
991:
971:
866:
217:
as with a polishing cloth on an automobile, or a polishing cloth or polishing pitch upon glass or steel.
82:
1090:
951:
650:
504:
272:. The small plate shown in the first picture is a hand lapping plate. That particular plate is made of
1075:
981:
680:
64:
1004:
931:
783:
348:
202:
182:
159:
1095:
901:
858:
763:
626:
295:
1132:
1127:
665:
482:
411:
338:
449:, an instrument that measures the minute variations in height of the surface of a workpiece.
1080:
843:
833:
808:
803:
788:
670:
645:
186:
163:
778:
713:
708:
194:
190:
1054:
1014:
936:
813:
476:
221:
178:
425:
For a more thorough description of the physics behind this measurement technique, see
1177:
1070:
1034:
1019:
838:
793:
773:
768:
382:
240:) by bringing them together under the right conditions. (This is not the same as the
225:
209:
205:
as the abrasive rolls about between the two surfaces and removes material from both.
89:
177:
or glass itself (also known as the "lap" or grinding tool) with an abrasive such as
1049:
1029:
916:
588:
464:
446:
406:
256:
245:
241:
397:
999:
926:
818:
728:
470:
458:
268:
may be used as the lap, charged with emery, and used to cut a piece of hardened
31:
1152:
1147:
1024:
941:
733:
233:
1142:
1137:
1105:
1100:
921:
911:
896:
828:
703:
314:
273:
229:
148:
891:
758:
718:
693:
152:
1162:
1122:
1044:
976:
906:
439:
320:
279:
213:
198:
1009:
966:
956:
660:
415:
19:
This article is about the machining operation. For other uses, see
1085:
698:
396:
319:
278:
269:
255:
170:
127:
265:
174:
599:
561:
557:
224:
and specialized polishing machines or skilled hand polishing,
25:
208:
The other form of lapping involves a softer material such as
151:
process in which two surfaces are rubbed together with an
220:
Taken to the ultimate limit, with the aid of accurate
479:– another micro-scale subtractive finishing operation
228:
can produce surfaces that are flat to better than 30
347:
Surface accuracy or flatness is usually measured in
1063:
990:
857:
747:
679:
634:
473:, which often includes lapping action in its action
155:between them, by hand movement or using a machine.
56:. Unsourced material may be challenged and removed.
201:, etc., between them. This produces microscopic
16:Process of removing material from two workpieces
528:Mark Irvin, Engis Corporation (February 2011).
611:
573:
8:
530:"Diamond Lapping and Lapping Plate Control"
503:English, R. E. (1953). "Optical Flats". In
359:), one HLB measuring about 280 nm (1.1
618:
604:
596:
580:
566:
558:
299:Logitech lapping machine and retention jig
485:– measuring the effects of such processes
337:Lapping can be used to obtain a specific
116:Learn how and when to remove this message
513:. Scientific American. pp. 156–162.
294:
495:
381:is with a height gauge positioned on a
539:. Gardner Publications. Archived from
445:Surface roughness is measured with a
260:Small lapping plate made of cast iron
7:
510:Amateur Telescope Making, Book Three
54:adding citations to reliable sources
461:– a variation of very fine grinding
14:
377:The easiest method for measuring
30:
232:. This is one twentieth of the
41:needs additional citations for
877:Electrical discharge machining
666:Numerical control (NC and CNC)
401:Optical flats in a wooden case
333:Accuracy and surface roughness
324:Schematic of two-piece lapping
1:
724:List of drill and tap sizes
248:, although it is similar).
1200:
1040:Magnetic switchable device
173:against a surface such as
18:
1118:
882:Electrochemical machining
595:
317:required for the latter.
420:low pressure sodium lamp
21:Lapping (disambiguation)
962:Rotary transfer machine
947:Photochemical machining
887:Electron-beam machining
849:Tool and cutter grinder
467:- a lapping consumable
402:
325:
300:
284:
261:
141:
1158:Tools and terminology
400:
323:
298:
283:Small lapping machine
282:
259:
139:
1184:Grinding and lapping
1076:Machining vibrations
982:Ultrasonic machining
537:Production Machining
203:conchoidal fractures
50:improve this article
1096:Tool and die making
784:Cylindrical grinder
238:optically contacted
764:Abrasive machining
505:Ingalls, Albert G.
403:
326:
301:
285:
262:
142:
1171:
1170:
1114:
1113:
483:Surface metrology
353:helium light band
339:surface roughness
308:Two-piece lapping
137:
126:
125:
118:
100:
1191:
1081:Speeds and feeds
834:Sharpening stone
809:Grinding machine
804:Grinding dresser
671:Stewart platform
620:
613:
606:
597:
582:
575:
568:
559:
554:
552:
551:
545:
534:
515:
514:
500:
393:
362:
246:Johansson blocks
187:optician's rouge
183:jeweller's rouge
140:Lapping machine.
138:
121:
114:
110:
107:
101:
99:
58:
34:
26:
1199:
1198:
1194:
1193:
1192:
1190:
1189:
1188:
1174:
1173:
1172:
1167:
1110:
1059:
986:
853:
844:Surface grinder
779:Coated abrasive
750:
743:
714:Drill bit sizes
709:Drill bit shank
684:
675:
637:
630:
624:
591:
586:
549:
547:
543:
532:
527:
524:
519:
518:
502:
501:
497:
492:
455:
435:
391:
375:
370:
360:
335:
310:
254:
195:silicon carbide
128:
122:
111:
105:
102:
59:
57:
47:
35:
24:
17:
12:
11:
5:
1197:
1195:
1187:
1186:
1176:
1175:
1169:
1168:
1166:
1165:
1160:
1155:
1150:
1145:
1140:
1135:
1130:
1125:
1119:
1116:
1115:
1112:
1111:
1109:
1108:
1103:
1098:
1093:
1088:
1083:
1078:
1073:
1067:
1065:
1061:
1060:
1058:
1057:
1052:
1047:
1042:
1037:
1032:
1027:
1022:
1017:
1012:
1007:
1002:
996:
994:
988:
987:
985:
984:
979:
974:
969:
964:
959:
954:
949:
944:
939:
937:Milling cutter
934:
929:
924:
919:
914:
909:
904:
899:
894:
889:
884:
879:
874:
869:
863:
861:
855:
854:
852:
851:
846:
841:
836:
831:
826:
821:
816:
814:Grinding wheel
811:
806:
801:
796:
791:
786:
781:
776:
771:
766:
761:
755:
753:
745:
744:
742:
741:
736:
731:
726:
721:
716:
711:
706:
701:
696:
690:
688:
677:
676:
674:
673:
668:
663:
658:
653:
648:
642:
640:
636:Computer-aided
632:
631:
625:
623:
622:
615:
608:
600:
593:
592:
587:
585:
584:
577:
570:
562:
556:
555:
523:
522:External links
520:
517:
516:
494:
493:
491:
488:
487:
486:
480:
477:Superfinishing
474:
468:
462:
454:
451:
434:
431:
412:Newton's rings
374:
371:
369:
366:
334:
331:
309:
306:
253:
250:
222:interferometry
179:aluminum oxide
124:
123:
38:
36:
29:
15:
13:
10:
9:
6:
4:
3:
2:
1196:
1185:
1182:
1181:
1179:
1164:
1161:
1159:
1156:
1154:
1151:
1149:
1146:
1144:
1141:
1139:
1136:
1134:
1131:
1129:
1126:
1124:
1121:
1120:
1117:
1107:
1104:
1102:
1099:
1097:
1094:
1092:
1089:
1087:
1084:
1082:
1079:
1077:
1074:
1072:
1071:Cutting fluid
1069:
1068:
1066:
1062:
1056:
1053:
1051:
1048:
1046:
1043:
1041:
1038:
1036:
1035:Machine taper
1033:
1031:
1028:
1026:
1023:
1021:
1020:Indexing head
1018:
1016:
1013:
1011:
1008:
1006:
1003:
1001:
998:
997:
995:
993:
992:Machine tools
989:
983:
980:
978:
975:
973:
970:
968:
965:
963:
960:
958:
955:
953:
950:
948:
945:
943:
940:
938:
935:
933:
930:
928:
925:
923:
920:
918:
915:
913:
910:
908:
905:
903:
900:
898:
895:
893:
890:
888:
885:
883:
880:
878:
875:
873:
870:
868:
865:
864:
862:
860:
856:
850:
847:
845:
842:
840:
839:Spark testing
837:
835:
832:
830:
827:
825:
822:
820:
817:
815:
812:
810:
807:
805:
802:
800:
797:
795:
794:Flick grinder
792:
790:
789:Diamond plate
787:
785:
782:
780:
777:
775:
774:Bench grinder
772:
770:
769:Angle grinder
767:
765:
762:
760:
757:
756:
754:
752:
746:
740:
737:
735:
732:
730:
727:
725:
722:
720:
717:
715:
712:
710:
707:
705:
702:
700:
697:
695:
692:
691:
689:
687:
682:
678:
672:
669:
667:
664:
662:
659:
657:
654:
652:
649:
647:
644:
643:
641:
639:
633:
629:and computing
628:
621:
616:
614:
609:
607:
602:
601:
598:
594:
590:
583:
578:
576:
571:
569:
564:
563:
560:
546:on 2012-04-25
542:
538:
531:
526:
525:
521:
512:
511:
506:
499:
496:
489:
484:
481:
478:
475:
472:
469:
466:
463:
460:
457:
456:
452:
450:
448:
443:
441:
432:
430:
428:
423:
421:
417:
413:
408:
399:
395:
394:10 in).
388:
384:
383:surface plate
380:
372:
367:
365:
358:
354:
350:
345:
342:
340:
332:
330:
322:
318:
316:
307:
305:
297:
293:
289:
281:
277:
275:
271:
267:
258:
251:
249:
247:
243:
239:
235:
231:
227:
223:
218:
215:
211:
206:
204:
200:
196:
192:
188:
184:
180:
176:
172:
167:
165:
161:
156:
154:
150:
146:
120:
117:
109:
98:
95:
91:
88:
84:
81:
77:
74:
70:
67: –
66:
62:
61:Find sources:
55:
51:
45:
44:
39:This article
37:
33:
28:
27:
22:
1050:Rotary table
1030:Lathe center
917:Machine tool
823:
749:Grinding and
589:Metalworking
548:. Retrieved
541:the original
536:
508:
498:
465:Lapping film
447:profilometer
444:
436:
427:interference
424:
407:optical flat
404:
376:
356:
352:
346:
343:
336:
327:
311:
302:
290:
286:
263:
219:
207:
168:
157:
144:
143:
112:
103:
93:
86:
79:
72:
60:
48:Please help
43:verification
40:
1128:Fabrication
1064:Terminology
1000:Angle plate
927:Metal lathe
819:Jig grinder
729:Tap and die
638:engineering
459:Flat honing
368:Measurement
264:A piece of
106:August 2009
1148:Metallurgy
942:Pantograph
734:Tap wrench
550:2011-11-17
490:References
244:effect of
234:wavelength
230:nanometers
226:lensmakers
76:newspapers
1143:Machining
1138:Jewellery
1106:Workpiece
1101:Tramp oil
1091:Tolerance
922:Machining
912:Jig borer
897:Engraving
872:Broaching
859:Machining
739:Threading
704:Drill bit
686:threading
627:Machining
471:Stropping
433:Roughness
274:cast iron
252:Operation
149:machining
65:"Lapping"
1178:Category
1153:Smithing
892:End mill
799:Grinding
759:Abrasive
719:Drilling
694:Die head
681:Drilling
453:See also
379:flatness
373:Flatness
242:wringing
164:grinding
153:abrasive
1163:Welding
1133:Forming
1123:Casting
1055:Wiggler
1045:Mandrel
1015:Fixture
977:Turning
972:Skiving
932:Milling
907:Hobbing
829:Sanding
824:Lapping
751:lapping
507:(ed.).
440:microns
315:testing
214:ceramic
199:diamond
162:and/or
160:milling
145:Lapping
90:scholar
1010:Collet
967:Shaper
957:Reamer
952:Planer
902:Facing
867:Boring
661:G-code
416:helium
92:
85:
78:
71:
63:
1086:Swarf
1005:Chuck
699:Drill
544:(PDF)
533:(PDF)
349:units
270:steel
212:or a
210:pitch
191:emery
171:glass
147:is a
97:JSTOR
83:books
646:2.5D
390:(9.8
266:lead
175:iron
69:news
1025:Jig
683:and
656:CAM
651:CAD
387:TIR
357:HLB
351:of
52:by
1180::
535:.
429:.
197:,
193:,
189:,
185:,
181:,
166:.
619:e
612:t
605:v
581:e
574:t
567:v
553:.
392:×
361:×
355:(
119:)
113:(
108:)
104:(
94:·
87:·
80:·
73:·
46:.
23:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
