What Is a Thread Gauge?
A Thread Gauge is an inspection tool used to check if the male or female thread of a screw is manufactured in the correct shape.
A ring gauge is used to measure male threads. The shape of a screw is standardized, but there are various specifications. For example, thread outer diameter, effective diameter, thread pitch, and thread valley diameter.
Measuring these parameters one by one is time-consuming. However, using screw thread gauges, it is possible to quickly determine whether the manufactured screw shape is acceptable or not. Thread gauges are widely used in screw manufacturing.
Uses of Thread Gauges
Thread gauges are mainly used in the manufacturing of screws. Thread shapes are standardized, but there are various specifications.
For example, thread outer diameter, effective diameter, thread pitch, and thread trough diameter. Measuring these parameters one by one is time-consuming.
Screw thread gauges allow us to quickly determine whether the manufactured screw shape is good or bad. They are widely used in screw manufacturing because of their ability to improve operational efficiency.
Principle of Thread Gauge
The principle of thread gauge depends on the type used. Thread gauges commonly used in manufacturing are as follows:
1. Limit Screw Thread Gauge
The limit thread gauge is an inspection jig used to easily determine if a manufactured screw shape is acceptable or not. Using gauges made to the upper and lower limit specifications of the screw to be inspected, the shape is judged as good or bad by passing through one gauge and not the other.
For a male thread such as a bolt, the ring gauge on the upper end of the gauge will pass the ring gauge on the lower end of the gauge, but not the ring gauge on the lower end of the gauge.
If the product is a nut or other female thread, it will pass the plug gauge at the lower end of the gauge, but will not pass the plug gauge at the upper end. Also, the standard here refers specifically to the effective diameter of the screw.
2. Thread Gauge for Wear Inspection
The wear inspection thread gauge is a gauge used to guarantee the accuracy of the limit thread gauge. The limit screw thread gauge wears out as it is passed through the object to be inspected. As the amount of wear increases, it becomes impossible to make correct judgments.
Therefore, a thread gauge for wear inspection is used to check whether the limit screw thread gauge has not exceeded the wear limit for correct inspection. A ring gauge for wear inspection is used to inspect the wear of the limit screw plug gauge, and a plug gauge for wear inspection is used to inspect the wear of the limit screw ring gauge.
3. Standard Thread Gauge
Thread gauges are made according to the standard thread profile and standard dimensions of the screw standard, and are a set of a plug gauge and a ring gauge. Thread gauges are the standard for measurement.
Compared to the limit screw thread gauge, the quality assurance accuracy is inferior. However, it is not necessary to prepare a set of both the thread side and the stop side like the limit screw thread gauge. This allows the cost to be kept low.
4. Pipe Screw Thread Gauges
There are two main types of pipe screw thread gauges. There are two main types of pipe thread gauges: parallel thread gauges and tapered thread gauges.
The parallel thread gauges are used to measure the threads at the threaded end and the tapered end. Thread gauges for tapered threads are notched on the end face and are accepted as long as the tip of the thread is within the notch.
Types of Thread Gauges
Thread gauges are broadly classified into ring gauges and plug gauges. From there, they can be classified in detail as described above.
Ring gauges are used to inspect screws. They are called ring gauges because they are ring-shaped with a female thread in the center of the disk so that the screw to be inspected can be screwed in.
On the other hand, a brag gauge inspects a female thread. They are called plug gauges because they are used by screwing them into the female threads to be inspected.