Archive for the ‘Thread gauges’ Category

postheadericon The utility of the thread ring gauges and the thread plug gauges

It would seem very easy for any one of us to tighten a screw. One has to have a screwdriver. It is that simple. However, have we ever wondered that the same screw had to go through strict quality checks just to become eligible for use? Of course, the screws have a very important role to play in every kind of machinery. You would not be able to find any machinery without the humble screw. Therefore, when the screw has so much utility, it is natural to have strenuous methods to check their utility and tolerance levels. Many an engineering design has to depend on the screw and the nut to hold the different items of the machinery together. You need to use checking tools such as the thread gauges for checking the tolerance levels and certifying the fitness of the screws.

Have you ever noticed that the screw invariably has the threads on the outside portion whereas the nuts have them internally? They have to, as the use of the nut is to fasten the screw. Similarly, you can find some pipes having external threads whereas some have internal ones. The pipes have different types of threads as well. The industry workers use a lubricant or a pipe tape for ensuring that there are no leakages. They use a special kind of thread known as the NPT thread. The pipes that carry inflammable material like gasses, etc have a higher quality of threading known as the NPTF threads.

Coming back to the thread gauges, you would require different kinds of thread gauges for determining the tolerance levels of different kinds of threaded instruments. The thread ring gauges have utility for checking the tolerance levels of the instruments with external threads such as the screws. They have two kinds of ring gauges, the ‘Go’ type, and the ‘No Go’ type. This might be the only instances in history where the instrument taking the tests has to fail the tests to be successful. When we say ‘fail the test’, it entails that the instrument should not be able to pass through the No Go type of thread ring gauge. On the other hand, it should easily pass through the Go type of gauge.

In the same way, you have the thread plug gauges to determine the tolerance levels of the instruments having internal threads. The plug gauge has to go through the Go side of the implement. The No Go side should not go in for more than two revolutions into the implement. In case it is successful in achieving this unique objective, the implement is fit for use in the industry.

The task appears simple. However, it is not so. It would take a lot of time to set up the machinery required to check the tolerance levels. However, once set, the machine can work tremendously fast thereby obviating the use of human labor. You can call this trait an advantageous one or a disadvantageous one depending on how you look at the issue.