Normally, when you hear that the machines have to pass quality checks, we get the impression that they have to pass through tough tests. It is right in many ways. The main objective of the machinery is to function properly and aid in the production. However, do you have an idea that the parts that go into the machine have to undergo quality checks at the initial stage in its production? We are talking about the humble screw and the nut. They may seem very trivial pieces of machinery, but they require passing the stringent tests. There are implements known as the thread gauges that determine whether the screw or the nut is fit for use at all.
The natural question that could arise is that what should be the necessity of the screws to pass these tests. The reason is that the screws have a variety of uses inside a machine. An ill-fitting screw can come loose and lodge at any crucial place thereby causing great harm to the machine. The machines may contain moving parts. A loose screw can cause great damages to such moving parts. Imagine what could happen if the screws that hold the wheels of your car come out just as you are cruising at high speeds. This would be a sure recipe for disaster. Thence, there is great significance for checking the tolerance levels of the screws at the initial stage.
An astute observer, you would have seen that certain implements possess threads on the external sides whereas certain instruments have threads on the interiors. It depends on instrument to instrument. The screws are implements having external threads at all times. The pipes can have external threads or internal ones depending on their usage. When the end of the pipe has to go inside a joint, the pipe should have external threads. At the same time, when you affix the taps onto the pipes, you expect them to have internal threads. Therefore, you would require different kinds of checking tools for determining the tolerance levels of different implements.
The thread ring gauges are the best bet for certifying the fitness of the instruments having external threads. Of course, you need different sizes of ring gauges. At the same time, you need the thread plug gauges to determine the tolerance levels of the instruments having internal threads. You have the Go and the No Go kinds of the ring gauges and the plug gauges. These are unique tools. They function in a peculiar manner. The ring gauges seem like ordinary rings. However, they are far from ordinary. The screws and the pipes having external threads should pass freely through the ring gauges without much effort on your part. At the same time, they should not go for more than two to three turns in a No Go ring. This determines the tolerance level of the screw. Similarly, the plug gauge should slide smoothly through the Go section whereas the No Go end should not go for more than a couple of turns.