Plain bearings and sleeve bearings (also referred to as bushings or journal bearings) are used to constrain, guide or reduce friction in rotary or linear applications. They function via a sliding action instead of the rolling action used by ball, roller and needle bearings.
Bushings and journal bearings are made from a variety of materials and are often self-lubricating to provide smooth operation and greater durability. Plastic is among the chief bushing materials in the market today.
Why Plastic?
Plastic is among the most obtainable and cost-effective materials used in many applications, including bearings and bushings. It’s ease in fabrication, its qualities that make it a durable and efficient enough material, and its relative cheapness make it an ideal substance for all bushing and bearing applications.
Plastics and plastic materials are organic, synthetic or processed polymers that are supplied as raw materials or stock shapes. They typically consist of thermoplastic or thermosetting resins, and can be made into many forms. Stock shape forms includesheets, plates, rods, tubes,films, or extruded profiles.Often, thermoplastic resins are supplied as pellets for feeding into molding machines or extrusion presses.
Because of plastic’s sheer usefulness and malleability, some plastic bushing products can be designed for extreme environments and can withstand high or low temperatures. Others are even suitable for hazardous environments with high levels of shock and vibration.
Examples of a Plastic Bushing
Plastic bushings are available in a wide variety of shapes and configurations. Each bearing series is available as cylindrical bushings or bearings, flanged bushings, thrust washers and wear plates. Custom size requirements are also available.
In particular, some plastic bushings include housing and a plurality of disclosed plastic bushings. The plastic bushing includes a pair of ends, both with an aperture, a bore running between the apertures, and a flange with a poly-sided perimeter.
These plastic bushings have a plurality of glass fibers aligned with a longitudinal axis of the bore. The bushing may also be electrolytic dissolution resistant and corrosion resistant. The plastic bushing also has a thermal coefficient matching that of the plastic housing.
Also, each plastic bushing member can be provided with diametrically spaced locking fingers with locking windows defined in the body of the bushing members for snap-locking to the locking fingers when aligned within the wheel assembly opening.
Simply put, with plastics’ versatility, innovation, and accessibility, there’s little wonder that it’s such a popular material for bushing and bearing use.
Plastic Bushing Applications
The applications for plastic bushings are wide-ranging, and can include food processing machinery, home appliances, packaging equipment, office machines and automotive equipment, pumps and motors, water, health, electronics, and more.
Just to give you a better idea, here’s an example. A lot of woodworking tools operate in harsh environments characterized by high shock loads and heat generation. Flying chips and sawdust can clog passages and prevent smooth operation. These were problems engineers and architects had to overcome when designing a new 2-hp plunge router. The problems were solved with plastic bushings and their ability to take said harsh environments, as well as their strong resistance to heat.
The plastic bushing can also be used with wheel assemblies for low speed, off-highway vehicles of the type of hand trucks, wheelbarrows and the like. The type of plastic bushing that can be used for this application is constructed of two substantially identical bushing members molded of a self-lubricating, pre-selected plastic, and each having a flanged end for abutting the central opening of a wheel assembly.