What are UN and UNR threads?
What are UN and UNR threads?
Screw Thread Work Plug Gages
| Designations | Thread Series |
|---|---|
| UN | Basic Unified National Thread Series |
| UNR | Basic Unified National Thread Series with external thread controlled root radius |
| UNS | Special Unified National Thread Series |
| UNRS | Special Unified National Thread Series with external thread controlled root radius |
What is the difference between UN and UNF threads?
UN (Unified) is a specification of the shape and dimensions of the thread for a given size (diameter) of fastener and number of threads per inch of fastener length. UNF (Unified Fine) is the same as UNC except that for each size of bolt, the number of threads per inch is higher, so the thread is finer.
What does UNR thread mean?
Basic Unified National thread series
Thread Designations: UN = Basic Unified National thread series. UNR = Basic Unified National thread series with external thread controlled root radius.
What is the difference between UN and UNC threads?
UNF and UNC are two symbols of Unified Screw Thread Series, which defined based on the amount of threads per inch and standardized with gauge. UNF threads are Unified fine pitch threads, while UNC threads are Unified coarse pitch threads.
What is the difference between UNC and UNJC?
UNJ, UNJC, UNJF and UNJEF threads are almost identical to UN, UNC, UNF, and UNEF threads except that the external J thread has a much larger root radius than the standard UN threads and inspection must be performed on this element.
Are UNJ threads rolled?
Today, all fasteners that are roll threaded should have a UNR thread because thread rolling dies with rounded crests are now the standard method for manufacturing most threads. UNJ Threads UNJ thread is a thread form having root radius limits of 0.150 to 0.180 times the thread pitch.
What is the J in UNJF?
J screw threads feature a root radius which improves the tensile stress area of the fastener and helps to reduce the stress concentration factor in the thread thus making the thread stronger. Additionally, the requirement for high strength is achieved with 3A and 3B classes of fit.
What is un 2A thread?
2-56 UNF 2A means it is a #2 thread (sometimes called also 0.086, as this is 0.086 inch) with 56 threads per inch, manufactured, dimensioned and checked according to Unified National Fine Standard and this is a normal external thread.
What is UNC 2A?
2A (external) & 2B (internal): most commonly used class for general applications. 3A (external) & 3B (internal): for applications where closeness of fit and/or accuracy of thread elements are important.
What are the dimensions of a UNF screw thread?
Internal Thread Dimensions for Unified UNF Screw Threads Diameter Threads Per Inch (TPI) Thread Fit Class Major Diameter Pitch Diameter Minor Diameter Stress Area Min Max Min Max Min in² No 0 80 2B 0.0600 0.0542 0.0519 0.0514 0.0465 0.00180 No 1 72 2B 0.0730 0.0665 0.0640 0.0635 0.0580 0.00278
What is the difference between UNS and 2A in threading?
Can be a decimal number such as 4.5 threads per inch. UNS: Thread series designation. 2A: Class tolerance. determines if it is an external or internal thread. 2 starts: Number of starts. It does not need to be specified for 1 start threads.
What is the size of a 2B internal thread?
External Thread /Internal Thread Nominal Size, TPI, Series Class Allowance Maxa Major Max Minor Ext. 1 / 4 -48 UNS 2A 0.0008 0.2492 Int. 2B 0.2320 Ext. 1 / 4 -56 UNS 2A 0.0008 0.2492 Int. 2B 0.2350
