What is 2A thread?
Class 1A is a loose commercial fit for easy assembly and disassembly. Class 2A is a medium fit. Class 3A is a tight fit used where a closed fit between mating parts is required.
What is un 2B thread?
A 3/8″-16UNC 2B is defined as a 3/8″ diameter Unified coarse pitch 2B class of fit inch screw thread. If the thread is a 3/8″-16NC2 and the letters U, A and B do not appear in the thread designation, the thread conforms to the outdated American National thread.
What is the difference between 2B and 3B threads?
The 2B Thread has wide application, accommodates plating, finishes, and coating to a limited extent and, therefore, has fair tolerance allowances. Class 3B Thread means a 3A screw in a 3B nut or threaded hole for applications that are close to tolerance limits.
What is a 3A thread?
Class 3 threads are tight tolerance threads that have no allowance and have very tight tolerances. Class 3 threads are often specified for tight tolerance fastener applications in critical use situations where safety and strength are a primary concern, such as the aerospace industry.
What is the difference between UNF and UNJF?
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. The Special UNJ threads are designated by the nomenclature UNJS.
What does UNJF 3B mean?
The 1/4-28 UNJF is a Unified fine pitch UNJ inch thread for aerospace. There are other Unified UNJ threads such as UNJC coarse pitch threads and UNJEF ultra fine pitch threads. The thread accuracy is referred to as a 3B class of fit or a 2B class of fit.
What is a 1B thread?
Class 1B Thread Is wherea 1A screw can run in readily for quick and easy assembly. The hole is classified as 1B. The fit is a 1B thread, (very seldom used in modern metal working)
What is UNJF 3B thread?
There are other Unified UNJ threads such as UNJC coarse pitch threads and UNJEF ultra fine pitch threads. The thread accuracy is referred to as a 3B class of fit or a 2B class of fit. A 3B class of fit is considered a precision internal thread with a tighter accuracy.
What is the difference between 2A and 2B threads?
Classes 2A and 2B are by far the most popular thread classes specified for inch series mechanical fasteners. Close to 90 percent of all commercial and industrial fasteners produced in North America have this class of thread fit. Class 2A external threads have an allowance, Class 2B internal threads do not.
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. UNS = Special Unified National thread series.
What are J form threads?
Threads specified with a “J” designation are intended for applications in which high-temperature and high stress levels are experienced and a high fatigue life is required commensurate with the size and weight of the component.
What is the difference between UNF and UNJF threads?
What is NC and NF thread?
NC and UNC mean coarse thread. NF and UNF mean fine thread. NS means special thread. Pitch Diameter is the basic dimension of a screw, threaded hole, or a tap the diameter of an imaginary cylinder, the surface of which passes through the thread where width of thread and space between threads are identical.
What is the difference between UNF and unjf?
UNJC = Unified National Coarse thread series with external thread controlled root radius UNF = Unified National Fine thread series UNJF = Unified National Fine thread series with external thread controlled root radius UNEF = Unified National Extra Fine thread series
What is UNJ threading?
UNJ Threads. The UNJ thread standard (ASME B1.15) defines a system of threads for highly stressed applications requiring high fatigue strength.
What is the difference between UN and UNJ tooling?
Use of Unified Tooling. Many of the UNJ thread form characteristics are the same as for a UN threads. Therefore, some of the tooling used to produce one form can be used to produce the other. External UNJ threads must be produced with a prescribed root radius; therefor, standard Unified Screw Thread (UN) may not be used.
What is the difference between UNC and UNJC?
UNC = Unified National Coarse thread series UNJC = Unified National Coarse thread series with external thread controlled root radius UNF = Unified National Fine thread series