What Is a Thrust Washer?
A thrust washer is a part that receives the sliding surface of a part in rotational motion.
Like a washer (washer), it receives the load generated in the thrust direction (axial direction) and also receives the rotational motion generated at the seating surface.
Like bearings, thrust washers are used to facilitate rotation, reduce abnormal noise generated from rubbing of sliding surfaces, and protect moving parts.
The difference between a thrust washer and a bearing is in its structure.
While bearings contain balls or rollers inside, thrust washers are simple doughnut-shaped as shown in the photo.
The mating parts of a thrust washer rotate while sliding on the surface of the thrust washer.
Thrust washers are lightweight, compact, and inexpensive.
In terms of maintenance, they do not require periodic oil replenishment, and they function simply by being inserted between the sliding shaft, bearing, and bearing stopper.
Uses of Thrust Washers
The purpose of using thrust washers is to reduce wear, noise, and other problems caused by sliding, and to ensure that rotating parts move smoothly.
For this reason, thrust washers are used on the end faces of rotating parts and the sliding parts that occur on the receiving side.
For example, various actuators built into automobiles, small motors, CD players, cameras and other precision machinery, cell phones and smart phones, notebook PCs, copiers, printers, sewing machines, washing machines, fans, fax machines, bicycles, reels, air conditioning hot water equipment, food machinery, and automatic assembly machines in factories, general industrial machinery, and much more.
By properly selecting the thrust washer material, it can be used with light to heavy thrust loads and high speed rotation.
They are thin, ranging from 0.5 mm to 5 mm in thickness, and most of them are maintenance-free.
In addition, some of them have a specific direction of installation when used, and care may be required.
Principle of Thrust Washers
Thrust washers are used on parts that rotate under load in the thrust direction (axial direction), so thrust washers are required to have wear resistance and low friction.
To satisfy these requirements, stainless steel (carbon steel) and brass alloys are commonly used as metallic materials.
Resin-based thrust washers are also available, such as fluorine compounds, nylon resins, and polyamides.
Metal thrust washers not only have a smooth surface, but are also coated with Teflon or other materials and have holes or grooves that contain lubricant or grease.
Resin-based thrust washers are available with numerous pores to impregnate oil, or with low-friction characteristics of the material itself.
All of them are basically maintenance-free. There is no need to lubricate during use.
Selection of the type of material to be used depends on the temperature and loading conditions at the location of use, the space available for mounting, and other factors.
Selection can also be made in consideration of chemical resistance, heat resistance, conductivity, or insulation.
How to Select a Thrust Washer
There are two types of thrust washers: metallic and plastic.
Resin thrust washers are selected unless there is a high load.
Metal thrust washers are superior to plastic thrust washers in thrust direction (axial) load carrying capacity.
On the other hand, plastic thrust washers are suitable for average loads and are less expensive than metal thrust washers. They can also provide electrical insulation, chemical resistance, and resistance to ultraviolet rays.
For the same size, they are lighter than metal.
When load carrying capacity is important, metallic thrust washers are the choice; otherwise, plastic thrust washers are used.
Other Information on Thrust Washers
Manufacturing of Thrust Washers
Metallic thrust washers are manufactured by punching thin sheets or sintering alloys.
In the case of punched, the surface is coated with Teflon or similar material to provide low friction.
In the case of sintering, they are made porous. They are filled with polyacetal resin (POM), lipophilic fibers, and oil for fusing.
Resin thrust washers are produced by punching or sintering thermoplastic resin plates with low friction and high durability. Thrust washers produced by sintering resin are also porous and easily retain oil.