Is The Higher The Nut Grade The Better?

Higher nuts usually have better mechanical properties, which often leads people to believe that the higher the nut grade, the better. In fact, the higher the nut level is not the better, and the appropriate level should be selected according to the actual application scenario. As a professional fastener manufacturer, Xinchi is happy to share with you the key considerations in choosing the right nut grade.

The selection principle of nut grade

Load matching: High grade nuts (such as class 10.9) are suitable for high load scenarios (such as Bridges, heavy machinery), but the cost is higher; Low-grade nuts (such as 4.8) can meet the needs of light loads (such as furniture, home appliances), and the cost is better.

Material compatibility: High-grade nuts must be used with bolts of the same grade (for example, Class 8.8 nuts with Class 8.8 bolts) to avoid thread damage due to strength mismatch.

Environmental adaptability: In high temperature/corrosive environments, stainless steel or specially coated nuts (such as A2-70, A4-80) are preferred, rather than simply pursuing high-grade carbon steel nuts.

The risk of blind use of high-grade nuts

Cost waste: The price of high-grade nuts may be 2-3 times the price of low-grade nuts, and unnecessary scenarios cause resource waste.

Brittleness increase: the hardness of the nut above 10.9 is high, but the toughness is decreased, and brittle fracture is easy to occur in vibration scenes.

Assembly difficulty: Higher grade nuts require greater preload; if the tool does not match, it may lead to slide wire or bolt tensile failure. If the nut grade is too high and the bolt is not strong enough, then the bolt may break first when bearing the load, failing the connection. Too high a nut grade will make the bolt a weak link in the connection.

Recommended selection reference for choosing the right nut grade

Application Scenario Recommended Level Remarks about typical materials

If it is a common structure connection, the recommended nut grade is 4.8 to 6.8, and the typical material is Q235, low carbon steel, such as the nuts used in household appliances and light frames.

If it is the bearing part of mechanical equipment, the recommended nut grade is 8.8~10.9, and the typical material is 45 steel and 40Cr, such as the nuts used in automobile chassis and construction machinery.

If it is a high temperature/corrosive environment, the recommended nut grade is A2-70, and the typical material is stainless steel 304/316, such as chemical equipment and marine engineering applications.

The nut grade requires a combination of load requirements, cost control, and environmental conditions, and blindly pursuing a high grade may be counterproductive. The design should follow the “enough is enough” principle and consult professional engineers if necessary.

XINCHI is a trustworthy fastener company, especially in furniture nuts. We have a factory,  founded in 2007. We are the designated fastener supplier to“STAPLE”. As a trusted fastener supplier,  XINCHI can offer a wide range of high-quality fasteners, including nuts, screws, bolts, rivets, washers, etc. If you want to know more about fasteners or want to wholesale fasteners, please feel free to contact us. Our experienced and expert service team will reply to you as soon as possible.