What is the accuracy of wire tapping? How to calculate?

In general, our common wire tapping specifications, in addition to the outer diameter and pitch, the other is also very important "accuracy." What exactly is the so-called "precision"? How to calculate it?

"Accuracy" is actually very simple. It refers to the size of the wire tapping diameter. Generally, it can be divided into 4H, 6H, and 7H according to international standards. 4H represents a tight fit between the internal and external threads without gaps; 6H represents a conventional fit; 7H is a fit with a large gap. Basically, 90% of customers use the standard 6H precision, a few are suitable for precision instruments, 4H, and customers who need electroplating after processing need to choose 7H or increase the accuracy level.

In general, manufacturers in the market, such as ET, TPT, YAMAWA, OSG, etc., in order to subdivide the accuracy level of the tapping, according to the above criteria, the so-called: "ET1, ET2, ET3"; "GH1 GH2, GH3"; "P1, P2, P3"; "OH1, OH2, OH3" and other precision grades. This often misleads the user and cannot buy a suitable silk attack. I will briefly describe the way the precision is calculated.