ASME B [Revision of ASME B (R)] Unified Inch Screw Threads (UN and UNR Thread Form) A N A M E R I C A N N AT I O N A L STA N DA. Nominal Diameter, Major Diameter Inch, Major Diameter mm, Tapping Drill Size mm, TPI, Pitch mm. 5/16″ – 20 UNR, , , , 20, 5/16″ – IFI NOTES: 1. ASME B is a standard developed through the procedures of The This abstract presents the requirements of ASME B as they ap- ply to the.
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The authors of the standard are doing their part to eliminate the Xsme screw threads. So what changed in the B1.
This is something that all engineers need to address. The customer is always right. It does not eliminate the UNS designation, but will eventually restrict their use to those willing to do the math to engineer the thread because as of the next revision of the standard the chart will disappear.
Several axme in thread form have been developed for unified threads; however, this Standard covers only [Unified] UN and UNR [external threads only] thread forms. The seemingly random number changes hit many of the listed standard screw thread sizes.
I personally will do everything I can to eliminate the confusion which can lead to controversy. Second, the thread nomenclature was changed from N to UN.
ANSI/ASME B Change Summary
Your Alert Profile lists the documents that will be monitored. Proceed to Checkout Continue Shopping. This did not affect only the pitch diameters, but also several other unified inch screw thread dimensions throughout Table 2. This is a seemingly innocuous statement, but this is where the pitch diameters change by 0. If the document is revised or amended, you will be notified by email. This Standard specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.
When the drawing indicates the N-series screw thread, it is known that the thread is specified in B1. The intention is to provide accurate information; regardless; errors may exist in the supplied information. How do we get the message across that when a standard changes, go with the flow and change your drawings and internal procedures to accommodate the revised version of reality?
Several times in the standard they remind the reader that the N-series is mechanically interchangeable with the UN-series. Because of this, most gage makers are not moving to change to the new pitch diameters. The first sentence in the Foreward is their strongest move to eliminate the N-series screw threads once and for all. Well here we are in and I daily get screw thread gage requests for the N-series thread.
If the pitch diameter stated on the drawing is 0. We have no amendments or corrections for this standard. Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards. By replacing all previous versions of the standard the N-series screw thread, defined in B1. What is the big controversy? It removes certain screw thread combinations from the select status of Standard Special. Need more than one copy? This standard is also available to be included in Standards Subscriptions.
The N-series thread is obsolete. First the pitch diameters of the threads were adjusted by 0. To get the complete details, buy a copy and read the Foreward. It informs all who make 60 degree inch screw threads that all previous versions of the standard have been replaced.
Please first verify your email before subscribing to alerts. In order to emphasize that unified screw threads are based on inch modules, they may be denoted unified inch screw threads. It is suggested that you obtain a copy of the revised standard and begin implementation of the new standard immediately.
UNR Thread ASME B1.1-2003
You may delete a document from your Alert Profile at any time. If the drawing change process is too daunting, issue a blanket engineering change order dictating that 60 degree inch series screw threads will be made to the most current version of B1. Already Subscribed to this document.
There are several other changes in the standard, as would be expected. After all that explaining the requestor replies that: The N-series screw thread was replaced in with the UN-series.
For easy reference, a metric translation of this Standard has been incorporated as Asms Appendix C. The N-series is fully mechanically interchangeable with the UN-series. The drawings are not under his control and it takes an act of congress to get a drawing change.
As the voice of the U. This is a smart move to encourage standardization. The last time the screw thread standard was revised this drastically was B1.
It has been over half a century and high quality ISO registered companies are still making screw threads to the long obsolete B1.