Gears durability

AGMA 211.02, Surface Durability (Pitting) of Helical and Herringbone Gear Teeth, Washington, D.C., 1969. 

Applications Ion implantation is widely employed to improve the life of tools. Thus press tools, dies and gear cutters can be treated to increase their durability by three times or more. Nitrogen-implanted tungsten carbide drawing dies for copper and iron wire can be improved up to fivefold. By implanting chromium, aluminium or silicon a considerable increase in the corrosion resistance of steel can be obtained. Implantation of chromium into aircraft bearing alloys has improved their durability in marine environments . 

Friction modifiers (1 or 2) 0.0-0.5% Controls gear shift feel and synchronizer friction durability... 

A variety of polymers are used in engineering and medical applications which have relatively little impact on the environment. These are mainly high performance and relatively expensive polymers such as the silicones in rubbers, the specialised polyamides referred to above in gear wheels, polycarbonates (in office equipment), chlorinated and sulfonated rubbers, fluorinated polymers such as poly tetrafluoroethylene) Teflon ) in metal coating and the polyimides which, owing to their ladder structure, are extremely stable in high temperature apphcations. Since these polymers are high-cost durable materials, they rarely appear in the waste stream. 

Super-tough poly(sulfone)s can be produced by blending PES with acrylate rubber and a polycarbonate as an impact modifier. From this high impact strength composition, films and molded articles are useful in automotive applications, durable goods and appliances, medical and plumbing applications where resistance to hot, humid environments may be particularly important, and safety equipment and protective gear. 

Usually the standard firefighters turnout gear or coat comprises a multilayer construction with a durable fire retardant outer shell fabric, of which the outer shell may... 

While the polyketone terpolymer derived from carbon monoxide, ethylene, and propylene is economical with some attractive properties, such as heat, chemical, permeation, and abrasion resistance, it suffers from low-impact strength. One cost-effective approach to overcoming this shortcoming and upgrading its performance profile for automotive applications such as wheel covers, wheel caps, fuel filter necks, fuel tanks, fuel tubes, center fascias, door handles, roof rack covers, gears, junction boxes, connectors, and seat backs, as well as electric/electronic components and durable household items involves blending with polyamides including a rubber modification (Lee et al. 2013). 

Wear, scoring, material flow, pitting, fracture, creep, and fatigue cause plastic and metal gears to fail. Continuous lubrication can increase the allowable bending stress by a factor of at least 1.5. However there are plastics (acetals, nylons, fluoropolymers, and others) that operate efficiently with no lubrication. There are plastics with wear resistance and durability of plastic gears makes them exceptionally useful. 

---