GRAPHALLOY was originally developed over 100 years ago for electrical brushes and contacts and was found to also possess outstanding mechanical properties. Today, this self-lubricating bearing material is widely used for bushings, wear rings, and thrust washers. It’s particularly useful where petroleum lubricants cannot be used.
GRAPHALLOY brush and bushing materials are graphite-metal alloys. The self-lubricating properties depend on the combined properties of graphite and the metal used. The metal increases graphite’s strength, rapidly removes the heat generated at the contact surface, and reduces wear. GRAPHALLOY Bushings deposit a thin graphite-metal film on the shaft which provides lubrication. Babbitt GRAPHALLOY, Nickel GRAPHALLOY, Copper GRAPHALLOY and Bronze GRAPHALLOY are the most common grades. Silver and other alloys are employed for special applications.
Submerged (Pumps, Guide Bearings, Mixers, Dye Rolls, Bleaching and Washing Tanks) GRAPHALLOY is not soluble in most industrial liquids. The bushings are used in water, hydrocarbon, chemical and fuel oil pumps, meters, mixers, and rotary filters. They’re also used extensively for submerged bushings in cleaning fluids, weak acids and alkalies. The textile dyeing and paper/pulp industries employ many GRAPHALLOY Bushings.
Pump applications include guide, foot, line shaft and bowl bushings for vertical pumps. Users and OEMs specify GRAPHALLOY for case rings in horizontal pumps where peak performance is required. CO₂ pipeline pumps use GRAPHALLOY Case Rings to reduce clearance and to boost efficiency. Refineries have replaced bronze and chrome rings for light hydrocarbon and condensate service to extend the service life from weeks to years.
Grooves are often specified on the ID of submerged bushings so that the gritty material may be washed away from the bearing surface. In especially severe applications, clean water or pumpage can be injected into the bushing.
In the paper/pulp industries, GRAPHALLOY has been saving maintenance dollars in bull screens, lime conveyors, washers, mixers, scrap burners, bleach tanks, Fourdriniers and pumps. In short, anywhere that bearings are subjected to difficult operating conditions!
High Temperatures (Ovens, Dryers, Conveyors, Steam Turbines, Kiln Cars, Pumps)
GRAPHALLOY is especially useful in applications where the temperatures are too high to permit the use of oil or other lubricants. It does not soften at high temperature or extrude under load. The standard grades are suitable for temperatures to 750°F in air (1800°F in non-oxidizing atmospheres). If your applications require service above 750°F in air, the GRAPHALLOY engineers can recommend high-temperature grades.
It can operate dry, or water/steam can be used to maintain it in its working temperature range. The combination of GRAPHALLOY and water/steam as lubricant is far more economical than trying to lubricate bronze or other material with grease.
Room Temperatures (Textile, Paper, Food, Instruments)
GRAPHALLOY Bushings eliminate the need for oil or grease lubrication in many ambient temperature applications. This is particularly important in the textile, paper and food industries, because the material contains no oil to contaminate the product.
In the Textile Industry, oil lubrication collects abrasive lint and fibers. These particles work into the oil-lubricated bushings to wear away the bushing and shaft. GRAPHALLOY reduces maintenance costs by eliminating wear and by eliminating the oiling schedule. These textiIe Bushings can run years without attention.
Low Temperatures (Cryogenic Applications, Pumps for Liquid Gases)
GRAPHALLOY Bushings are suitable for low temperature applications because there is no lubrication to congeal or solidify. It can be used in pumps pumping liquid gases such as oxygen where oil contamination is a problem and will not mix with the liquid gases. It maintains its lubricating qualities over a wide temperature range.
GRAPHALLOY Bushings have been used for loads as high as 2,000 psi. In applications where there is vibration or high load, grease is forced out of grease-lubricated bushings, resulting in metal-to-metal contact. Solid GRAPHALLOY soIves this problem. Dimensionally stable, it wiII not creep under load. GRAPHALLOY has been used as turbine guide bearings and as turbine safety bushings. Safety bushings prevent damage to the turbine vanes when the oil supply is lost. These bearings are designed to carry the load when the oil film is lost.
GRAPHALLOY Bushings are used to conduct current in packaging machines, radar rotary joints, and welding equipment. These Bushings have been employed in radar relays where ball bearings or needle bearings had become pitted and inoperative due to the passage of high frequency currents. GRAPHALLOY Bushings provide current paths for signal and power applications. The positive grounding provided by these Bushings are essential in munitions plants. A food wrapping machine uses them to conduct power to roll heaters.
Whatever your bushing problem, a GRAPHALLOY engineer can help you with a long-lasting solution!