THREAD GAGING SYSTEMS - Nomak

1 Glastonbury Southern Gage Erin, TN THREAD GAGING SYSTEMS (Back to Screw Threads/ THREAD GAGING Contents)(Back to Variable THREAD GAGING Contents) A THREAD GAGING system comprises a list of THREAD characteristics that must be inspected and the GAGING necessary to inspect these characteristics to assure product acceptability. Many organizations through their quality system provide methods / SYSTEMS for the inspection and acceptability of their product. ASME has set an industry standard of GAGING SYSTEMS for screw threads known as ASME These SYSTEMS provide different levels of inspection to insure dimensional conformance has been achieved. system 21 system 21 provides for interchangeable assemble with respect to functional size only. Functional size must be measured at the maximum material limit within the length of standard GAGING elements. The characteristic known as NO GO functional diameter must also be verified.

2 This can be accomplished by using fixed limit GAGING or variable GAGING with functional elements. system 21A (FOR METRIC THREADS IN ACCORDANCE WITH ANSI ) system 21A provides for interchangeable assemble with functional size verified at the maximum material limit using standard length GAGING elements. This can be accomplished using fixed limit GAGING or variable GAGING with functional elements. system 21A also states that the minimum material limit (minimum pitch diameter) must be verified by inspecting two THREAD flank locations over the length of the THREAD . This Glastonbury Southern Gage Erin, TN can be accomplished by using variable GAGING or THREAD roll snap gages with pitch diameter elements. system 22 system 22 provides for the interchangeable assemble with functional size verified at the maximum material limit using standard length GAGING elements.

3 This can be accomplished using fixed limit GAGING or variable GAGING with functional diameter elements. system 22 also states that the minimum material limit (minimum pitch diameter) must be verified over the full length of the THREAD . This can be accomplished using variable GAGING with pitch diameter elements. system 23 system 23 provides for interchangeable assemble with functional size verified at the maximum material limit using standard length GAGING elements and minimum material limit (minimum pitch diameter) must be verified over the full length of the THREAD . The GAGING requirements for system 22 would also apply here but in system 23 other THREAD characteristics such as lead, flank angles, taper and roundness my have to be independently verified. Only THREAD characteristics, which are specified, will have to be inspected for system 23 compliance.

4 See ASME for a complete explanation of GAGING SYSTEMS and gage compliance before selecting GAGING for your application.