ASME B1.10M pdf download UNIFIED MINIATURE SIREW THREADS
This Standard specifies the thread form, series, toler-ance, and designation for the Unified Miniature ScrewThreads. The series covers a diameter range of 0.30 mmto 1.40 mm, extending the metric M-Profile and unifiedthread series that begin at 1.6 mm.
1.2 Unified Miniature Screw Thread Standards
The fourteen sizes published in this Standard wereendorsed by the American-British-Canadian conferenceof April 1955 as the basis of the unified standard amonginch-using countries, and to correspond with the rangeof sizes in the ISO. The sizes are shown in Table 1. ininterest of standardization and where design permits,selection of size should be confined to those indicatedin bold type in Table 1. For more restrictive conditions,those sizes indicated in regular type in Table 1 maybe used.
Unified Miniature Thread sizes of this series shall bedesignated on engineering drawings, in specifications,and on tools and gages (space permitting) by their nomi-nal diameter in hundredths of a millimeter followed bythe symbol“UNM”(e.g.,0.80 UNM).
On internal threads, the full limits of minor diameter,as given in Table 2,shall normally be considered applica-ble.Where this is not permissible, the designation shallbe supplemented by the minor diameter limits.
1. Reference Documents1
The following is a list of publications referenced inthis Standard.
ASME B1.7,Nomenclature,Definitions, and Letter Sym-bols for Screw Threads
ASME B1.30M,Screw Threads —-Standard Practice forCalculating and Rounding Dimensions
Publisher: The American Society of Mechanical Engi-neers (ASME International),Three Park Avenue, NewYork, NY 10016-5990; Order Department: 22 LawDrive, Box 2300,Fairfield, NJ 07007-2300
ISO/R15012, ISO Miniature Screw Threads
Publisher: International Organization for Standardiza-tion, 3 rue de Varembe,1211 Geneve 20,Switzerland/Suisse
Additional recommended methods for determiningthe acceptability of miniature screw threads will beincluded as further experience with this thread standardis reported. Until such time,agreements must be reachedbetween purchaser and vendor regarding the basis fordetermining acceptance, since practices are likely to dif-fer considerably, particularly for external threads. Wherea free choice is possible, the procedures given below,which are being used with considerable success by someproducers, are isuggested.
1.5.1 External Threads.The major diameter of theexternal thread is measured by either contact gagingoptical projection,or laser inspection equipment. Allother dimensions, such as pitch diameter,lead, threadform, and minor diameter may be inspected by opticalprojection methods, with a magnification of 10ox recom-mended. A suggested chart for this method is shownin Appendix A. The thread plug gages and the tap areinspected in a similar manner to externally threadedparts. Contact gaging. such as the use of“Go” andNOT Go” ring gages, measuring wires, and set pluggages may be used for sizes 0.70 UNM and above.
1.5.2 lnternal Threads.The minor diameter of theinternal thread is gaged with”GO”and “NOT Go”plain cylindrical plug gages. All other elements arechecked only for assemble-ability limits by means of a“GO” thread plug gage, taking extreme care not to dam-age the thread. For the minimum material limits of theinternal threads, the accuracy and performance of thetap is relied upon.This implies that the major and pitchdiameters of the tap do not exceed the maximum inter-nal thread limits for these elements, and disregards overcutting, which is rarely incurred because of the flexibilityof these small taps and the manner in which they aregenerally fluted.
lt is recommended that the minor diameter of theinternal thread be gaged with one insertion of the”NOTGo” plain cylindrical plug gage first. The”NOT Go”plain cylindrical plug gage shall be inserted only until it meets some resistance. The minor diameter is then gaged with only one insertion of the plain cylindrical plug gage per thread, as the act of gaging can wear the thread oversize. At this point, the minor diameter is considered to be acceptable. The thread is gaged with only one insertion of the ” G O thread plug gage. The thread is accepted or rejected on the basis of this one insertion. Repeat insertions can wear out/damage the thread.
1.5.3 Reference Temperature. The reference tempera- ture is 20°C for the dimensions defined by this system.
1.5.4 Units of Measure. All dimensions in this Standard, including all tables, are in millimeters unless other- wise specified. Inch conversions may be found in Nonmandatory Appendices B, C, and D.
1.5.5 Federal Government Use. When this Standard is approved by the Department of Defense (DOD) and federal agencies, and is incorporated into FED-STD- H28 /5, Screw-Thread Standards for Federal Services, Section 5, the use of this Standard by federal government will be subject to ali requirements and Limitations of FED-STD-H28 /5.