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The Main Difference between Round Nuts and Hex Nuts

Mar. 02, 2020 | 11:00:24
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People often compare round nuts with Hex Nuts and don't understand what their main difference is? In my opinion, the main difference between a round nut and a hex nut is that the hex nut is used to fix a stationary workpiece, and the round nut is mainly used to lock a moving workpiece on a shaft. In general, round nuts are not much different from hex nuts, except that round nuts are cheaper and can save raw materials. Large equipment has more round nuts.

Hex Nuts

Hex Nuts


Why the round nut is so easy to use, because the invention of the round nut not only solves the problem of loosening the connection between the round nut and the bolt, but also improves the connection strength of the thread. Simple operation, good applicability, etc. Round nuts are mainly used for shaft end locking. They are usually used with non-return rings and are generally fine-threaded. The concept of nuts is relatively broad. Generally, there are ordinary hexagon head nuts, Butterfly Nuts, self-locking nuts, etc., which are usually used for bolts The small round nut is used to fix the axial displacement of the transmission and rotating parts. It is also often used with a back washer to lock the inner ring of the rolling bearing. Hook wrenches are required for nut assembly and disassembly.


In the case where the total strength of the connection is determined, selecting a product with a higher strength is more reliable than selecting a product with a lower emphasis. This is because the selection of high-strength products can reduce the number of fasteners required. According to the aforementioned reliability formula, the reliability score of the system connection is high.


So, how is a round nut used? When using a round nut, it must be used in conjunction with a stop washer for a round nut, which has teeth both inside and outside. Holes or grooves shall be made in the external threads to be fitted with the round nut to incorporate the internal teeth of the washer. After the round nut is tightened in place, the outer teeth of the washer corresponding to the nut wrench groove should be bent into the groove. This secures the nut.


Then why does the round nut become loose after being fixed? When we tightened the nut, it was squeezed flatter and pressed thinner depending on the microscopic chips, particles, or sparsely or densely interposed between the inner and outer interdental spaces on the surface of the screw teeth. And it is combined with other dirt, like a "thin sand layer" in the gap. When subjected to external vibrations, the above-mentioned "fine sand layer" first loosens, causing the radial and lateral clearances of the internal and external threads to become larger, and thus causing a relatively small amount of axial relative movement and a relatively small amount of relative rotation in the circumferential direction, which in turn causes the nut to loosen. Vibration is only the external cause or inducement of loosening of the nut, and the "fine sand layer" sandwiched between the teeth is the internal or root cause of the loosening of the thread.


The above is the main difference between round nut and hex nut introduced by Fastener Bolt Exporter.