Flat gasket vs. spring washer
In order to save cost, many people want to save the flat gasket or spring washer. In fact, the flat gasket and spring washer play an indispensable role in the process of bolt use. Today, let’s introduce flat cushion and spring cushion to you.
|flat gasket||spring washer|
What is a flat gasket?
Flat gasket, mainly made of iron plate, is generally a flat gasket with a hole in the middle. The size of the hole is generally determined according to customer requirements.
flat gaskets are usually thin pieces of various shapes and are used to reduce friction, prevent leakage, isolate, and prevent loosening or pressure dispersion. They are found in many materials and structures to perform similar functions. Limited by the material and process of threaded fasteners, the bearing surface of bolts and other fasteners is not large. Therefore, in order to reduce the compressive stress on the bearing surface and protect the surface of the connected parts, the washer is used. In order to prevent the looseness of the connecting pair, spring washer, multi tooth lock washer, round nut lock washer, saddle shaped, wave shaped and conical elastic washer are used.
flat gasket is mainly used to reduce the pressure, when some parts of the tightening axial force is very large, it is easy to press the washer into a disc shape. At this time, materials and hardness can be used to solve the problem.
The locking effect of spring washer is general, the important parts should be used less or not, and the self-locking structure should be adopted. For the spring washer used for high-speed tightening (pneumatic or electric), it is better to use the washer with phosphating treatment on the surface to improve its anti-wear performance, otherwise it is easy to burn or open the mouth due to friction and heat, and even damage the surface of the connected parts. Spring washer structure should not be used for thin plate connection. According to statistics, spring washer is used less and less in automobile.
Because of the large and uniform locking force, the connecting tooth profile in the tooth shaped elastic washer is widely used in the automobile industry, while the spacing tooth type is less.
Flat gasket is used as a part to prevent bolts and nuts from locking. In the use of fasteners will be used in the place of flat gasket, how to choose a suitable flat gasket? Flat gasket is a kind of flat gasket, which is mainly used to increase the contact area between screws and some large-scale equipment and tighten them. When using flat gasket, it is often suitable for nuts and nuts to cooperate with each other. When storing flat gasket, it must be within the most effective sealing time and have essential important characteristics:
- 1. In the harsh environment, the flat gasket should be sealed, when a certain temperature and pressure in the working time is not easy to occur leakage.
- 2. In the flat gasket and contact surface connection, to better ensure the sealing, just like a good effect.
- 3. When the gasket receives the pressure, under the influence of temperature, the anti wrinkle ability should be better, otherwise the screw will be damaged, and there will be hard gas leakage.
- 4. Don’t get infected when using flat gaskets.
- 5. The use of flat gasket can be very good disassembly, this is the biggest role of choosing flat gasket.
- 6. Remember to use the flat gasket at a relative temperature.
In order to better use the flat gasket, when choosing the flat gasket, we should try our best to choose the flat gasket with anti rust and anti-corrosion material, which not only saves time and effort, but also plays a good role in flat gasket.
When used with bolts and nuts, the selection standard of flat gasket is as follows:
- 1. When choosing gasket materials, attention should be paid to the electrochemical corrosion of different metals in contact. The material of flat gasket is generally the same as that of the connected parts, usually steel, alloy steel, stainless steel, aluminum alloy, etc. Copper and copper alloy can be used when there is a requirement for electrical conductivity.
- 2. The inner diameter of the flat gasket shall be selected according to the larger diameter of the thread or screw. The outer diameter of the connected material (such as composite material) or matching with the spring washer should be larger.
- 3. When w-washer is placed on the bolt or screw head, flat gasket with inner hole chamfer can be selected to avoid interference between fillet under head and washer.
- 4. For important bolts with large diameter or in order to increase the anti extrusion ability, steel washer should be used. Steel washer shall be used for tension bolt or tension shear composite bolt connection.
- 5. Special gasket can be used in special requirements, such as copper gasket for conducting electricity and sealing washer for air tightness.
The function of flat gasket:
- 1. Increase the contact area between the screw and the machine.
- 2. Eliminate the damage to the surface of the machine when the spring washer is unscrewed. Use must be: spring washer a flat gasket, flat gasket next to the surface of the machine, spring washer between the flat gasket and nut. The flat gasket is to increase the screw force surface. In order to prevent the screw from loosening, the spring washer plays a certain amount of buffer protection when it is stressed. Although flat gaskets can be used as sacrificial mats.
- 3. But more often it is used as a supplementary gasket or flat pressure gasket.
Advantage of flat gasket:
- ① By increasing the contact area, parts can be protected from damage;
- ② By increasing the contact area, the pressure between the nut and the equipment is reduced, so as to play a protective role.
Disadvantages of flat gasket:
- ① The flat gasket can not play an anti-seismic role;
- ② The flat gasket also has no anti loosing effect.
What is a spring washer?
Spring washer is often called spring washer in screw industry. Its material has stainless steel and carbon steel, carbon steel is also iron. Commonly used spring washer specifications and sizes are m3, M4, M5, M6, M8, M10. M12, M14, M16. These specifications are more commonly used.
Spring washer is widely used in the bearing and non bearing structures of general mechanical products. It is characterized by low cost, convenient installation and suitable for parts with frequent assembly and disassembly.
Function of spring washer:
- 1. The function of spring washer is that after tightening the nut, the spring washer gives the nut an elastic force to tighten the nut so that it is not easy to fall off. The basic function of the spring is to give a force to the nut after tightening the nut to increase the friction between the nut and the bolt.
- 2. Generally, spring washer is not used for spring washer (except for protecting the surface of fastener and mounting surface, spring washer and spring washer are considered).
- 3. spring washer is generally used in the connector, one is soft, the other is hard and brittle, its main role is to increase the contact area, disperse pressure, to prevent the soft texture from being crushed.
Spring washer is used to prevent looseness. For example, the bolt connecting the motor and the base should be added with spring washer. If the motor vibrates, if there is no spring washer, the nut will be loose. Generally, spring washer is installed on the fastener of equipment with vibration, and no gasket is needed on flange! Whether the flange is added with or without spring washer is related to the medium flowing through the pipeline. If it is easy to generate pulse, it is better to add spring washer, as well as high-speed fluid, and the caliber changes frequently. Don’t generalize. Some valves need spring washer for packing gland flange. The automatic selection of spring washer is included.
Generally, the bolt connecting the motor and the base should be provided with spring washer, because if the motor vibrates, if there is no spring washer, the nut will be loose. Generally, spring washer is installed on the fastener of the equipment with vibration, and no gasket is needed on the flange! Whether the flange is added with or without spring washer is related to the medium flowing through the pipeline. If it is easy to generate pulse, it is better to add spring washer, as well as high-speed fluid, and the caliber changes frequently. Don’t generalize. Some valves need spring washer for packing gland flange. The automatic selection of spring washer is included.
Advantage of spring washer:
- ① The spring washer has good anti loosing effect;
- ② The spring washer has good anti-seismic effect;
- ③ Low manufacturing cost;
- ④ The installation is very square.
Disadvantages of spring washer:
Spring washer is greatly affected by material and process. If the material is not good, heat treatment is not good, or other processes are not in place, it is easy to crack. Therefore, reliable manufacturers must be selected.
When to use flat gasket and when to use spring washer?
- 1. In general, flat gasket can be used only when the load is small and does not bear vibration load.
- 2. Under the condition of large load and bearing vibration load, flat cushion and spring cushion must be used.
- 3. Basically, spring washer is not used alone, but combined.
In the actual use process, due to the different emphasis of flat gasket and spring washer, the two are used together in many occasions, which can protect parts, prevent nut loosening and reduce vibration at the same time, which is a great choice.
Application and failure mode analysis of flat gasket combined bolt:
According to statistics, there are hundreds and thousands of various types of fasteners used in an automobile, among which various types of flat cushion combination screws are widely used in automobile fasteners.
The main functions of flat gasket in assembly are as follows:
- (1) Provide bearing surface: when the bearing surface of bolt or nut is not enough to cover the connected parts, the gasket can provide larger bearing surface;
- (2) In order to reduce the pressure on the bearing surface or make it uniform. When the bearing surface area is too small or the bearing surface pressure is too high, the gasket can reduce the bearing surface pressure or make it more uniform.
- (3) Friction coefficient of stable bearing surface: when the flatness of the bearing surface of the connected parts is poor (such as stamping parts), it becomes sensitive to the biting caused by local contact, which leads to the increase of the friction coefficient of the supporting surface, and the gasket can stabilize the friction coefficient of the bearing surface.
- (4) Protection of bearing surface: when tightening the bolt or nut, there is a risk of scratching the surface of the connected part, and the gasket can protect the bearing surface.
The failure mode of flat gasket combination bolt: the gasket interferes with the fillet under the bolt head.
(1) Failure phenomenon
- One of the most important failure forms of the flat gasket composite bolt is the interference between the gasket and the fillet of the bolt head, which causes the abnormal torque and poor follow-up of the gasket during assembly;
- The most intuitive manifestation of the interference between the gasket and the lower fillet of the bolt head is that there will be an obvious gap between the gasket and the lower bearing surface of the bolt head, which will lead to the failure of the bolt and the gasket to fit properly when the bolt is tightened.
(2) Failure reason
The main reason for the interference between the gasket and the fillet under the bolt head is that the fillet under the bolt head is too large, or the design of the inner diameter of the gasket is too small, which leads to the interference after the combination of the gasket and the bolt.
(3) Improvement measures
In order to reduce the risk of interference after the combination of bolt and gasket, the design under the bolt head can refer to type u in ISO 10644 standard to do the concave design under the head; in this way, the interference problem caused by the excessive fillet under the bolt head or the small aperture of the gasket can be avoided.
Source: China Gaskets Manufacturer – Yaang Pipe Industry (www.steeljrv.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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