Non-lubricated bearings bearing materials are polymers, specialty graphite and carbon ceramic three categories.
    ( 1 ) polymer plastic polymers , also known as the plastic material used is called mechanical engineering plastic . It is a synthetic resin as a main component , also contain various plasticizers , stabilizers , antioxidants, antistatic agents , flame retardants, curing agents, reinforcing filler material and an organic polymer material .
    Many different types of polymers , thermoplastic and thermosetting their features into two categories .
    Thermoplastic polymers commonly used are : polyamide, polyacetal , polyethylene, polytetrafluoroethylene, polypropylene , polyurethane and the like. They are organic polymer compound having a linear or branched chain-like structure , can be repeatedly softened by heat and cools and hardens . Thermoplastics available injection molding, extrusion , blow molding, calendering process methods such as molding .
    Thermosetting polymers commonly used are phenolic resins, epoxy resins and the like. The catalyst or curing agent are added in the process to cure once curing is complete, it will never be melted to become a solid material. The thermosetting polymers may be compression molding, laminating, casting, molding methods .
    Commonly made ??of plastic bearings, guides , piston rings and other friction parts , such as the water pump bearings, rolling mill bearings, stern bearing , in particular, can make non-lubricated bearings with plastic . The PTFE sheet was punched into lip seals , bearings , piston rings and gaskets , etc., successfully applied to the belt conveyor , typewriters , sewing machines, phonograph turntables , pumps, agricultural machinery and textile machinery and other equipment .
    Polymers with light, insulation, anti-friction , wear-resistant , self-lubricating , corrosion resistance, molding process is simple, high production efficiency . And metal materials, the tribological properties of their temperature and humidity sensitive viscoelastic characteristics related to significant mechanical strength at the end, a small elastic modulus, poor adsorption of the lubricant .
2 carbon graphite material is made of carbon graphite elements of a class of non-metallic materials . It is a three isomers of carbon in one , is a hexagonal system , at all levels by the hexagonal rings , level with the level of parallel , overlapping was ordered crystal structure .
    By source of graphite , natural graphite and artificial graphite into two kinds. Artificial graphite is a carbonaceous material by more than 2500 ℃ high temperature treatment from graphite .
    Carbon graphite is generally good conductivity, heat resistance, wear resistance, self lubrication, high temperature stability , chemical resistance ability, higher thermal conductivity than the polymer , linear expansion coefficient. At room temperature and atmospheric and chrome surface friction coefficient and the wear rate is very low. However, when the humidity is low lose lubricity. Abrasion-resistant coating applied to improve the wear resistance of carbon graphite .
    Not only as a solid lubricant graphite , can be added to the resin , metal, ceramics and other materials to increase the friction of these materials can also be used directly as friction materials , such as paper making , wood processing , textile, food and other places avoid oil bearings , high temperature bearings , seals , piston rings , scraping tablets.
    Mechanical engineering " class " represents the symbol for carbon graphite material M, there are four series : carbon graphite materials, electric graphite materials, resin and metal graphite carbon composite material .
    3 . Ceramic materials     Ceramic is a natural inorganic non-metallic mineral or synthetic compounds as raw materials, crushing , shaping and sintering temperature by numerous small crystals of inorganic non-metallic and non-metallic materials consisting of glass phase . Inorganic non-metallic natural minerals , such as clay , feldspar, quartz and other raw materials are made ??of traditional ceramic ; made ??with synthetic compounds are special ceramic materials . General mechanical engineering ceramic is used alumina, magnesia , zirconia, lead oxide , titanium oxide, silicon carbide , boron carbide , silicon nitride , boron nitride, and other man- made ??compounds of special ceramic material .
    Performance ceramics largely determined by their microstructure, including grain size and distribution , composition and content of the glass phase , the nature of impurities , content and distribution . And the microstructure is determined by the material composition and manufacturing processes. Common features ceramic hardness and compressive strength , high temperature , wear , oxidation , corrosion resistance , crisp, the impact of intolerance and non- malleable .
    Ceramics is a relatively new non-lubricated bearings bearing materials, especially SiC and Si3N4, their strength, heat resistance and corrosion resistance are very good, also very good tribological properties .