The Importance And Working Principle Of Fasteners

Fasteners are widely used and play an important role in the automobile industry. In a car, the average fastener per vehicle is about 500 kinds /50Kg/4000. All kinds of fasteners are used in heavy vehicles 88Kg/7100, of which high-strength fasteners account for about 1/3. The cost of fasteners on an automobile accounts for about 2.5% of the cost of the vehicle, accounting for 40% of the total number of basic parts of the vehicle, and the workload of fastening connections on the assembly line accounts for about 70%!

The importance of fasteners

If the force is too small, the gasket may not be in place; Too much force, however, will wear the thread. According to recently published data, in the automotive industry, 23% of maintenance problems are caused by loose fasteners, and 12% of new cars have incorrect fastener tightness. Bolt is one of the most important factors to determine the quality of assembly. Threaded fasteners can not reach the corresponding capacity, which is an important cause of assembly accidents!

Tightening principle of fastener bolts

The bolted connection must be able to resist the action of external forces so that the assembled parts will not move in the direction of separation. Otherwise, the bolt connection may loosen, damage or fall off.

So the minimum clamping force of the bolt must be able to prevent the clamping part due to external force apart and to maintain friction clamping or ensure sealing and so on.

The bolt is inserted into the connecting part and tightened with the nut or internal thread to make the bolt stretch and deform. This elastic deformation produces axial tension, which will be squeezed together by the clamping part, known as the pre-tightening force.

In theory, as long as sufficient clamping force is generated, the clamping parts can be guaranteed to work safely in vibration, high and low temperatures, and other harsh environments, without the use of adhesive and other auxiliary methods.

Clamping force of fasteners

The sole purpose of the tightening procedure is to keep the clamping force within the appropriate tolerance!

The clamping force in the assembly must be large enough to ensure that the assembled parts absolutely do not move relative to each other. But at the same time, it must be ensured that the clamping force applied during fastening will not cause bolt damage or plastic deformation.

Clamping force control is the core purpose of the bolt assembly, improper clamping force control will cause serious consequences.

Screw torque distribution of fasteners

By oiling the fastener surface, friction can be reduced and preload increased with the same torque. In other words, to achieve the same tightening effect, the oiled bolt requires a smaller torque.

Test method of torque:

(1) Loosening method: fastening is needed after loosening, which is difficult to operate and rarely used;

② Fastening method: the most commonly used, the detection torque is larger than the actual tightening torque range;

③, marking method: the most accurate, complex operation, rarely used.

A common tightening method for fasteners

Torque control method: is the most widely used tightening method, suitable for most non-critical parts of the bolt connection.

Advantages: Simple operation, low cost, relatively cheap tightening tools, torque can be easily detected and controlled.

Disadvantages: large friction coefficient, discrete clamping force, and the low utilization rate of bolt materials.

Other tightening methods include the torque-angle control method and yield point control method.

Anji Xinchi Fasteners Co., Ltd. is a one-stop fastener and fastener solution company. As a reliable fastener supplier, we can offer a wide range of T-nuts, screws, washers, sleeves, bolts, rivets, and more. If you would like to know more about fasteners or have any fastener purchasing requirements, please do not hesitate to contact us and our experienced sales staff will get back to you as soon as possible.