A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is an inclined plane wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread. More screw threads are produced each year than any other machine element.[1]

Threads are generally produced according to one of the many standards of thread systems. Standards Development Organizations such as the American National Standards Institute, American Society of Mechanical Engineers, SAE International, International Organization for Standardization, Deutsches Institut für Normung (German Institute for Standardization), British Association and others produce these standards for manufacturers to follow when producing threaded components.

Currently used thread standards

StandardNameTypeExample
ASME B1.1-2003 (R2018)Unified Inch Screw Threads (UN and UNR Thread Form)V Thread Form14″-20 UNC
#4-40 UNC
ASME B1.5-1997 (R2014)Acme Screw ThreadsTrapezoidal Thread FormTr 60×9
ANSI/ASME B1.9-1973 (R2017)Buttress Inch Screw ThreadsBreech-Lock Thread Form
ASME B1.10M-2004 (R2014)Unified Miniature Screw ThreadsV Thread Form0.60 UNM
ANSI/ASME B1.11-1958 (R2016)Microscope Objective ThreadV Thread Form
ASME B1.13M-2005 (R2015)Metric Screw Threads: M ProfileV Thread Form
ASME B1.15-1995 (R2003)Unified Inch Screw Threads (UNJ Thread Form)V Thread Form
ASME B1.20.1-2013Pipe Threads, General Purpose (Inch)Pipe Thread Form
ANSI B1.20.3-1976 (R2013)Dryseal Pipe Threads (Inch)Pipe Thread Form
ASME B1.20.7-1991 (R2013)Hose Coupling Screw Threads - InchPipe Thread Form
ASME B1.21M-1997 (R2013)Metric Screw Threads - MJ ProfileV Thread Form
BS 84Tables of BS Whitworth, BS Fine and BS Pipe ThreadsV Thread Form (55°)14″-20 BSW
ISO 68-1:1998ISO general purpose screw threads—Basic profile—Part 1: Metric screw threadsV Thread Form
ISO 68-2:1998ISO general-purpose screw threads—Basic profile—Part 2: Inch screw threadsV Thread Form
ISO 261:1998ISO general purpose metric screw threads—General planV Thread FormM6x1
ISO 262:1998ISO general purpose metric screw threads—Selected sizes for screws, bolts and nutsV Thread Form
ISO 724:1993ISO general-purpose metric screw threads—Basic dimensionsV Thread Form
ISO 725:2009ISO inch screw threads—Basic dimensionsV Thread Form 51386
DIN 40400Edison ThreadRound V Thread Form

Obsolete thread standards

StandardNameTypeObsolescence date
BS 93:1951British Association (B.A.) screw threads with tolerances for sizes 0 B.A. to 16 B.A.1966[2]
BS 93:2008British Association (B.A.) screw threads1966[3]

See also

Notes

References

  • Degarmo, E. Paul; Black, J T.; Kohser, Ronald A. (2003), Materials and Processes in Manufacturing (9th ed.), Wiley, ISBN 0-471-65653-4.
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