How much do you know about Washers?

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What is a Washer?

A washer is a thin, typically disk-shaped component with a hole in the center, commonly used in conjunction with fasteners like bolts and nuts. It is placed between the fastener and the surface of the object being secured.

• Structural features

It is usually in the form of a thin sheet with a hole in the middle. The size of this hole is determined according to the actual application requirements and is used for passing through bolts or screw rods and other connecting parts.

Most of the shapes are circular, of course, some washers for special purposes may be square or other shapes.

• Main uses

1. Protective function

During assembly, it is placed between the nut or bolt head and the surface of the connected parts. It can prevent the surface of the connected parts from being scratched or crushed when tightening the nut or bolt, because it increases the contact area and makes the pressure distribution more uniform.

Applications of washers

1. Anti – loosening function

For example, a spring washer, with its special shape and elasticity, will produce a certain elastic deformation after being subjected to the pressure of tightening the nut. When the equipment is in operation and vibration occurs, the restoring force generated by this elastic deformation can prevent the nut from loosening, thus ensuring the tightness of the connection.

Main Types of Washers

Washers are very important small parts in mechanical connections. There are a wide variety of them, each with different characteristics and uses. The following are some common types of washers:

1.Flat washers: They are used to expand the area of the bolt seat surface and reduce the surface pressure applied to the fastening object. They are suitable for situations where the material of the fastening object is soft or the contact area is small.

Flat washers

2.Spring washers: They are elastic and are used between bolts and nuts, which can provide anti – loosening effects, especially suitable for bolts in hard – to – see or hard – to – operate parts.

Spring washers

3.Lock washers: Including internal – tooth lock washers, external – tooth lock washers, etc. They prevent bolts or nuts from loosening when there are vibration or load changes through the design of teeth.

4.Stop washers: They are used to limit the movement of bolts or nuts and prevent them from slipping off due to vibration or impact.

5.Sealing washers: They combine the functions of washers and sealing rings and are used to prevent gas or liquid leakage.

6.Special – shaped washers: Such as spherical washers, conical washers, square – bevel washers, etc. These washers are used to absorb uneven surfaces or compensate for gaps of specific shapes.

Special shaped washers

7.Metal – plastic composite washers: They combine the strength of metal and the corrosion resistance of plastic, and are suitable for application scenarios where both advantages are required.

8.Composite material washers: Such as metal – rubber composite washers, which utilize the supporting function of metal and the sealing performance of rubber.

9.Special – material washers: Such as stainless – steel washers, copper washers, aluminum washers, etc. Appropriate materials are selected according to different working environments to provide the best performance.

10.High – performance washers: For example, washers used in high – temperature or high – pressure applications. These washers are usually made of special alloy materials to withstand extreme working conditions.

Materials Used to Make a Washer.

Washers are very important small parts in mechanical connections. They are used for load distribution, leakage prevention, providing locking effects, etc. The material selection of washers directly affects their performance and applicable environments. The following are some materials commonly used to manufacture washers and their characteristics:

• Metallic Materials

1. Stainless Steel: It has good corrosion resistance and is suitable for fields such as marine environments and the chemical industry .
2. Carbon Steel: It has a relatively low cost and good mechanical properties, but its corrosion resistance is not as good as that of stainless steel .
3. Copper: It has good electrical and thermal conductivity and is suitable for electrical connections or occasions where conductivity is required .
4. Aluminum: It is lightweight and has good thermal conductivity, and is usually used in application scenarios where weight reduction is required .

• Plastic Materials

1. Polyamide (Nylon): It has excellent wear resistance and chemical resistance, and is suitable for occasions where wear – resistance and corrosion – resistance are required .
2. Polytetrafluoroethylene (PTFE): It has extremely high high – temperature resistance and a low coefficient of friction, and is suitable for high – temperature, high – pressure or occasions where friction reduction is required .
3. Polyetheretherketone (PEEK): It has excellent high – temperature resistance, chemical resistance and mechanical properties, and is widely used in high – end engineering fields .
4. Polyphenylene Sulfide (PPS): It is a crystalline special – purpose engineering plastic with excellent heat resistance and chemical resistance, and is suitable for high – temperature environments .

• Rubber Materials

1. Nitrile Rubber: It has good oil resistance and solvent resistance, and is suitable for environments in contact with petroleum products .
2. Fluorine Rubber: It has excellent high – temperature resistance and chemical resistance, and is suitable for sealing under extreme working conditions .

• Silicone Rubber: It has good high – temperature stability and anti – aging performance, and is suitable for applications in a wide temperature range .

Rubber washers

Washer Size Standards

Washer size standards are usually formulated by organizations such as the International Organization for Standardization (ISO), the American Society of Mechanical Engineers (ASME), the German Institute for Standardization (DIN), the Japanese Industrial Standards (JIS), and the Chinese national standards (GB). These standards cover dimensional parameters such as the inner diameter, outer diameter, and thickness of the washer, and specify the corresponding tolerances and shape requirements.

Factors for Washer Size Selection

When selecting washers, the following factors need to be considered:

• Thread Diameter: The inner diameter of the washer should match the thread diameter of the bolt or screw.
• Application Occasions: Different application occasions may require washers made of different materials, such as metal (steel, stainless steel), rubber, plastic, etc.
• Environmental Conditions: Factors such as the temperature, humidity, and corrosiveness of the working environment will affect the choice of washer material.
• Load Requirements: According to the magnitude of the load borne at the joint, select a washer of an appropriate thickness to ensure sufficient support and sealing.
• Installation Space: The outer diameter of the washer should be adapted to the size of the installation space to avoid being too tight or too loose.

Examples of Common Washer Standards

• SO Standards: The ISO 7089, ISO 7090, ISO 7091 series, etc., specify the size requirements for different types and specifications of flat washers.
• ASME Standards: The ASME B18.21.1 series specifies the size and shape requirements for flat washers.
• DIN Standards: The DIN 125 standard, etc., specifies the basic size and material requirements for flat washers.
• JIS Standards: The JIS B1256, JIS B1259 standards, etc., are applicable to the size and material requirements of washers in the Japanese market.
• GB Standards: Chinese national standards such as GB/T 97.1 and GB/T 97.2 specify the size and technical requirements of flat washers .

Details to Pay Attention to When Choosing Washers

When choosing washers, it’s important to pay attention to several key details to ensure optimal performance and compatibility with your application:

• Material Compatibility: Select a washer material that is compatible with the operating environment and the media it will come into contact with. For example, use non-metallic materials like rubber or PTFE in environments where chemical resistance is required.
• Operating Temperature and Pressure: Make sure the chosen washer can withstand the operating temperatures and pressures without degrading its properties. High-temperature applications might necessitate using materials like silicone or fluorocarbons.
• Size Matching: The inner diameter of the washer must match the shank of the fastener, while the outer diameter should fit within the bore of the component being fastened to provide adequate bearing surface area.
• Thickness: Choose a washer with an appropriate thickness to accommodate the necessary preload without causing excessive stress on the bolting system. Thicker washers offer greater load distribution but may require higher torque during assembly.
• Surface Finish: Ensure the washer has a suitable surface finish to prevent galling or damage to mating surfaces. Surface treatments such as zinc plating or black oxide can improve corrosion resistance and reduce friction.
• Hardware Grade: Match the grade of the washer to the hardware you are using. Higher-grade fasteners often require washers of matching quality to maintain their strength and longevity.
• Special Features: Consider any special features required for your application, such as locking capabilities to prevent loosening due to vibration, or elastomeric coatings for enhanced sealing performance.
• Standard Compliance: Where possible, choose washers that comply with international or industry standards, such as ISO, DIN, or ANSI, to ensure interchangeability and quality.

Types of washers

Judging the Corrosion Resistance of Washers

When choosing washers, it is very important to judge their corrosion resistance because washers will come into contact with corrosive media in many applications. Here are some methods for judging the corrosion resistance of washers:

• Consult Material Data Sheets: Washer manufacturers usually provide material data sheets, which contain information about the material’s corrosion resistance, such as acid – alkali resistance and solvent resistance.
• Refer to Certifications and Test Reports: If the washer has passed relevant international standards such as ISO tests or has a corrosion – resistance test report issued by a third – party organization, these are important bases for judging the corrosion resistance of the washer.
• Understand Washer Materials: Different materials have different resistance to corrosion. For example, metal washers such as stainless steel, Hastelloy, Monel, and titanium alloys, as well as non – metal washers such as polytetrafluoroethylene (PTFE) and fluororubber, usually have good corrosion resistance.
• Analysis of Application Environments: Select an appropriate material according to the specific environment in which the washer will be used (such as temperature, pressure, types and concentrations of chemicals in contact). For example, the polytetrafluoroethylene washer developed by Yonggong Sealing Parts Co., Ltd. in Yangzhong City, which is resistant to acid – alkali corrosion, is suitable for occasions requiring a higher sealing effect .
• Consideration of Patent Technologies: Consider whether the washer adopts special patented technologies to improve its corrosion resistance. For example, the patent technology of Yonggong Sealing Parts Co., Ltd. in Yangzhong City may make the washer easier to achieve a better sealing effect during use, reducing the limitations of use .
• Seek Professional Advice: If professional advice is required, you can consult materials scientists or engineers in relevant fields. They can provide professional material selection advice according to the specific application of the washer.

Conclusion

Washers play an important role in mechanical connections and other aspects. In terms of types, there are flat washers, spring washers, etc., with different functions.

The materials used for manufacturing include metals (such as carbon steel and stainless steel) and non – metals (such as rubber and plastic). The size of the washer should meet relevant standards, and there are specific requirements for the inner diameter, outer diameter and thickness.

When choosing a washer, it is necessary to consider the suitability of the material, the accuracy of the size, environmental tolerance, etc. Among them, the judgment of corrosion resistance is crucial for the use of washers in special environments.