Screw Thread Go and No Go Gauge Standard

[saisai]

hi, All,

I am now using the go and no go gauge for the screw thread of hex nut.

Does anybody know if there is standard showing how to apply go and no go gauge on screw thread of hex nut? e.g. how much torque applied? etc.

different people use the same gauge may have different result in inspecting screw thread by using go and no go gauge. If there is a common method everyone can follow the same procedure, this could be better.

thanks
Saisai

 

[Hodgepodge]

"Basic use of Go/NoGo Thread Plugs & Rings

Using thread gages is really pretty simple if the Go thread plug goes in to the threaded hole and the NoGo does not then the product is usually considered within the tolerance limits and acceptable. The inverse is true of rings. Questions arise in some areas of how to judge if the product is not good using the NoGo gage. The specifications state that the product can be acceptable if the No Go thread ring engages the end threads of the product being tested but should not thread over more than 3 (three) complete turns on the product. Do not force the gage on to the product and on thin walled parts, be especially aware that the gage may be more easily forced into or over the product distorting the product."

There isn't a torque specification related.

 

[saisai]

this is not as easy as generally think about. AS different operator will drive the go gauge with different force - torque, into the thread hole. Some operator feel blocked, then they will stop and judge it is failed; but the other operator apply more force, will have different result.

This is why I am asking if there is some method to follow so that everyone use the same method, no any argument.

 

[Hodgepodge]

If you have to apply some force to get the gage to go, then the part is out of tolerance.

 

[Hodgepodge]

MIL-STD-120 Page 53

"6.3.4.2 ?Go? thread plug gages. ?Go? thread plug gages should check simultaneously as many elements as possible, therefore, the gage is designed to have a full form thread and to check pitch diameter, major diameter, thread

angle, and lead. ?Go? thread plug gages control the extent of the product tolerance in the direction of the limit of maximum-metal, and represent the minimum limit of internal threads. The gages should not be allowed to be used when worn beyond the product limit. The gage should enter the full threaded length of the product freely, with no more force than can be applied by the fingers..."​

 

[saisai]

where have this MIL-STD-120 Page 53 in the forum?

 

[Hodgepodge]

See the attached extact.

 

[RSEGRIGGY]

One of our vendors pointed us to IFI-166 which is the "Industrial Fastener Institute Inspection Procedure for Thread Nicks - Inch Series".

Among other things, this provides a maximum torque value to drive a male thread into a ring gage. I know it is the opposite of what you are doing, but there may be some other standard published by IFI that will better fit your needs. If not, at least it is a start....

(Since it is not a free standard, I'm not sure I can quote the exact torque value or formula from it. Or you could look at this: http://www.greensladeandcompany.com/pdf/Threads-Nick Acceptability Procedure.pdf )

 

[DRAMMAN]

I worked at a company that used thread ring/plug gauges EXTENSIVELY. We always followed the rule that the go gauge must go on freely with no drag. A No-Go could not go on at all. We would at times accept rejected product. An example would be a long threaded part where the first few threads are not used in the application. Plus, a waiver decsion would also be made taking into account other measurement methods such as pitch mics, optical comparator inspection, etc. You also have to remeber that thread ring/plug gauges are not the be-all to end-all. As you learn more about thread inspection you learn there is no one best method.