In the realm of mechanical engineering, the secure connection of bolts and nuts is crucial for the proper operation of various equipment. However, during actual use, due to factors such as vibration, impact, and temperature changes, fasteners are prone to loosening, which can lead to serious safety accidents. To effectively prevent the loosening of fasteners, locking washers were created, and they have become an indispensable “guardian” in fastener connections.

I. Definition of Locking Washers

A locking washer is a mechanical component specifically designed to prevent nuts or bolts from loosening due to external forces during use. They are typically made from metal materials such as carbon steel, stainless steel, and alloy steel. These materials possess good strength and toughness, enabling them to withstand certain pressures and impact forces. Locking washers come in various shapes, including spring washers, wave washers, toothed washers, and nylon insert lock washers. Different shapes and structures endow them with different locking principles and application scenarios.

II. Types and Principles of Locking Washers

(i) Spring Washers

The spring washer is the most common type of locking washer. It has a disc shape and is elastic. When the nut is tightened, the spring washer is compressed and undergoes elastic deformation, which generates a reactive force. This force acts between the nut and the connected part, increasing the friction between the nut and the bolt, effectively preventing the nut from loosening due to vibration and other external forces. The locking principle of the spring washer mainly relies on its own elastic deformation to produce a preload force, which to some extent counteracts the loosening effect of external forces on the nut.

(ii) Wave Washers

The wave washer has a wavy shape, with alternating peaks and valleys. During the tightening of the nut, the wave washer is compressed, and the contact points between the peaks and valleys generate significant pressure. These pressure points are distributed across the entire contact surface of the washer, thereby increasing the friction between the nut and the connected part. At the same time, the wavy structure of the wave washer allows it to undergo elastic deformation when subjected to external forces, which further enhances the locking effect of the washer. The locking principle of the wave washer mainly involves increasing the pressure at the contact points and utilizing its own elastic deformation to increase friction and prevent nut loosening.

(iii) Toothed Washers

Toothed washers are divided into internal tooth lock washers and external tooth lock washers. The internal tooth lock washer has sharp teeth on the inner circle and a smooth arc shape on the outer circle; the external tooth lock washer has sharp teeth on the outer circle and a smooth arc shape on the inner circle. When the nut is tightened, the sharp teeth of the toothed washer embed into the surface of the nut and the connected part, generating significant friction. This friction effectively prevents the nut from loosening when subjected to external forces. The locking principle of the toothed washer mainly relies on the friction generated by the embedded teeth to prevent nut loosening. It has a relatively good locking effect and is particularly suitable for applications with high locking requirements.

(iv) Nylon Insert Lock Washers

The nylon insert lock washer is a new type of locking washer, consisting of a metal washer and a nylon insert. The metal washer serves to support and transmit force, while the nylon insert has good self-locking properties. When the nut is tightened, the nylon insert is compressed and undergoes elastic deformation, which tightly grips the bolt or nut, increasing the friction between the nut and the bolt, and effectively preventing the nut from loosening. The locking principle of the nylon insert lock washer mainly relies on the elastic deformation and self-locking properties of the nylon insert to increase friction. It has a good locking effect and also features corrosion resistance and wear resistance, making it suitable for a variety of harsh working environments.

III. Functions of Locking Washers

(i) Preventing Nut Loosening

This is the most basic and important function of locking washers. During mechanical operation, due to external forces such as vibration and impact, nuts are prone to loosening. Once a nut loosens, it may lead to gaps in the equipment’s connection parts, which in turn can affect the normal operation of the equipment and even cause safety accidents. Locking washers increase the friction between the nut and the bolt or utilize their own elastic deformation to generate a preload force, effectively counteracting the loosening effect of external forces on the nut. This ensures the tightness of the nut, guarantees the close connection of the equipment’s parts, and maintains the normal operation of the equipment.

(ii) Enhancing Connection Reliability

In some important mechanical structures, such as automotive engines and aerospace equipment, the reliability of the connection parts is extremely high. The use of locking washers can significantly improve the reliability of these connection parts. For example, in automotive engines, the connection of cylinder head bolts needs to withstand high temperatures, high pressures, and strong vibrations. If the bolts loosen, it may lead to engine air leakage, oil leakage, and even engine failure. After using locking washers, the loosening of cylinder head bolts can be effectively prevented, ensuring the normal operation of the engine and improving the engine’s reliability and service life. In the aerospace field, the connection of aircraft structural parts must be flawless. Locking washers can ensure that these connection parts remain stable during flight, providing strong safety assurance for flight safety.

(iii) Reducing Maintenance Costs

If fasteners frequently loosen, it is necessary to conduct regular inspections and tightening, which not only increases the maintenance workload of the equipment but also extends the equipment downtime, thereby increasing maintenance costs. The use of locking washers can effectively reduce the frequency of nut loosening, decrease the equipment maintenance workload, shorten the equipment downtime, and improve the equipment operating efficiency, thus saving a significant amount of maintenance costs for enterprises. For example, in some large industrial equipment, the maintenance cycle can be extended several times after using locking washers, greatly reducing the enterprise’s maintenance costs.

(iv) Enhancing Equipment Safety

In some special situations, such as mining equipment and construction machinery, if the connection parts of the equipment loosen, it may lead to serious safety accidents. The use of locking washers can effectively prevent these dangerous situations from occurring. For example, in mining equipment, if the support bolts loosen, it may cause the supports to collapse and trigger mining accidents. After using locking washers, the tightness of the support bolts can be ensured, enhancing the safety of the equipment and protecting the lives of miners. In construction machinery, such as tower cranes and cranes, the stability of the connection parts directly relates to the safety of construction personnel and the quality of the project. Locking washers can ensure that these connection parts remain stable during construction, preventing accidents caused by bolt loosening and enhancing the safety of the equipment.

IV. Application Fields of Locking Washers

Locking washers are widely used in various industrial fields, covering almost all equipment and structures that require bolt connections.

(i) Automotive Manufacturing

In automotive manufacturing, the engine, chassis, body, and other parts require a large number of bolt connections. Locking washers are widely used in key parts of the automotive engine, such as cylinder head bolts, crankshaft bolts, connecting rod bolts, etc. These parts need to withstand high temperatures, high pressures, high-speed rotation, and strong vibrations. The use of locking washers can effectively prevent bolt loosening, ensure the normal operation of the engine, and improve the safety and reliability of the car. At the same time, in the suspension system and braking system of the car chassis, locking washers also play an important role, ensuring the stability and safety of the car during driving.

(ii) Aerospace

The aerospace field has extremely high requirements for the reliability and safety of equipment. In key parts of aircraft, such as the fuselage structure, engine, landing gear, etc., the use of locking washers is crucial. For example, in the installation bolts of fan blades and compressor blades in aircraft engines, locking washers can ensure that these bolts remain tight in the harsh environment of high-speed rotation and high-temperature and high-pressure conditions, preventing blade loosening and脱落, and ensuring flight safety. In the connection bolts of aircraft landing gear, locking washers can withstand the huge impact force during aircraft takeoff and landing, ensuring the stability of the landing gear and providing safety assurance for the safe takeoff and landing of the aircraft.

(iii) Mechanical Manufacturing

In various mechanical manufacturing enterprises, such as machine tool manufacturing, mining machinery manufacturing, construction machinery manufacturing, etc., locking washers are widely used in the main shaft bolts of machine tools, the support bolts of mining machinery, the boom bolts of construction machinery, and other parts. These equipment will be subjected to different degrees of vibration, impact, and wear during operation. The use of locking washers can effectively prevent bolt loosening, improve the operating stability and service life of the equipment, reduce the equipment failure rate, and improve production efficiency.

(iv) Electronic and Electrical Equipment

In electronic and electrical equipment, such as large transformers and high-voltage switch cabinets, bolt connections are also common. Locking washers in these devices can prevent bolts from loosening due to electromagnetic vibration, ensuring reliable electrical connections and preventing electrical short circuits, ground faults, and other issues caused by bolt loosening, thus ensuring the normal operation of electronic and electrical equipment.

V. Selection of Locking Washers

When selecting locking washers, it is necessary to choose the appropriate type and specification based on the specific application and requirements.

(i) Selection Based on Working Environment

If the working environment is harsh, such as high-temperature, high-pressure, or corrosive conditions, locking washers with corresponding high-temperature, high-pressure, and corrosion-resistant properties should be chosen. For example, in chemical equipment, where there are corrosive media such as acids and alkalis, stainless steel locking washers should be used; in high-temperature environments, such as boilers and steam pipes, alloy steel locking washers with high-temperature resistance should be selected.

(ii) Selection Based on Load Type

If the equipment mainly bears static loads, spring washers or wave washers can be chosen; if the equipment is subjected to dynamic loads, such as vibration and impact, toothed washers or nylon insert lock washers, which have better locking effects, should be prioritized. For example, in the connection of crankshaft bolts in automotive engines, where significant vibration and impact loads are generated during engine operation, toothed washers or nylon insert lock washers should be used to ensure the tightness of the bolts.

(iii) Selection Based on Bolt Specifications

The specification of the locking washer should match the specification of the bolt. Different bolt specifications require different sizes of locking washers to be used in combination to ensure that the washer can effectively exert its locking function. When selecting a locking washer, the bolt’s nominal diameter, pitch, and other parameters should be considered to choose the appropriate washer specification.

Although a locking washer is just a small mechanical component, it plays a vital role in the field of mechanical engineering. It can effectively prevent nuts from loosening, enhance the reliability of equipment connections, reduce maintenance costs, and improve equipment safety. With the continuous advancement of technology, the types and performance of locking washers are constantly developing and improving, providing more reliable assurance for the stable operation of various equipment. In future mechanical manufacturing and equipment maintenance, locking washers will continue to play an indispensable role in safeguarding the smooth progress of industrial production.

Handan Guocheng Trading Co., Ltd

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