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SELF-LUBRICATING BEARINGS - DUROBEARING™

Durobearing™ is the trademark used by Saver to identify its self-lubricating composite bearings and represents a technologically advanced and reliable solution for journal bearings.
Durobearing™ is composed of high-performance fibers and makes use of technology and processes developed directly by Saver to attain a mass-produced product with superior performance.
Self-lubricating composite bearings were developed in the 1950s and 1960s for outer space applications. The functioning of spacecraft and satellites must be reliable and maintenance-free.
In the 1990s major manufacturers begin using self-lubricating composite bearings, as they learnt of their particular properties; Today, composite plain bearings are a standard component for manufacturers of heavy industrial equipment and machines, agricultural equipment, and pneumatic and hydraulic cylinders.
Self-lubricating composite bearings have increasingly taken the place of metal bearings needing lubrication.

Durobearing™ is ideal for high load, low speed applications or where traditional lubrication is difficult, costly or harmful.

Here are just some of the industry applications for Durobearing™ :

  • Aerospace and Defense
    • control systems (aircraft pivot linkages, flight controls, u-joints, door systems, landing gear linkage, helicopter main and tail rotor assemblies, missile launchers, loading ramps
  • Agricultural
    • irrigation equipment, tractors and attachments, combines
  • Automotive
    • car wash machinery, suspension systems, lifting platforms and mechanical parking systems, kingpin assemblies
  • Chemical Processing
    • butterfly valves
  • Communications
    • rotating antennas
  • Energy Installations
    • wind farms, photovoltaics
  • Food Processing
    • canning and bottling
  • General Hydraulics
    • hydraulic cylinders, rotary actuators
  • Hydro
    • floodgates, waste water facilities
  • Marine (surface and submerged vessels)
    • deck machinery, rudders, hoists, water-tight
    • doors, mooring systems, lifeboat launchers
  • Material Handling, Construction, Forestry, Landscaping
    • fork lifts, aerial lifts and booms, scissor lifts, cranes, lift gates,excavating machinery, clamps & grabs, loaders
  • Medical
    • Surgical chairs and tables
  • Mining
    • lift systems
  • Refuse Collection
    • trucks, compactors
  • Robotics
    • points of articulation

Durobearing™ is filament-wound and impregnated with thermoset resins. This lightweight and efficient composite journal bearing features a Teflon™ liner (Teflon™ is a trademark of Du Pont de Nemour) and is characterized by a high load capability well-suited to handling frequent starts and stops. Its self-lubricating properties enable valid engineering.

Durobearing™ accommodates rotary, oscillatory and sliding motions and offers excellent reliability, including the following features and benefits:

  • Self-lubricating with dry lubrication
    • maintenance-free, eliminating the need for greasing systems
    • operational in inaccessible environments
    • appropriate for materials that must avoid contact with lubricant
    • environmentally-friendly
    • reduced operating and warranty cost
    • significant reduction of “systems” cost of assembly
  • Dimensional and thermal stability, corrosion and chemical resistant
    • operates in submerged conditions and hostile environments such as sea water, detergents, alcohol and acids
    • copes with temperature extremes permits a long shelf life
    • can be machined to suit precision engineering requirements (including shaped bore designs) using conventional machining methods
    • operates with a variety of steel shaft materials
  • Advanced composites material

    Teflon™ liner with extremely low coefficient of friction (Teflon™ is a trademark of Du Pont de Nemour)
    • custom size available
    • low initial conversion cost
    • shock resistant
    • static and dynamic coefficients very close, eliminating “stick-slip” behavior
    • low wear of mating parts (shaft and housing)
    • reduced power demand for start-up and running of machinery
    • temperature kept within operation perimeters
  • Non-conductive and non-magnetic
    • can serve as insulating material
    • no galvanic reactions
  • Tight press fit and low running clearances
    • ease of installation—no need for retainers
    • low noise chatter
    • enhanced abrasion resistance

Our basic service starts with initial customer contact that focuses on gaining an understanding of technical and business needs, along with environment and operating conditions where the bearing will be in use. Saver is experienced at coordinating the functional and business requirements to provide our composite bearings in a timely manner. Our technical department is at the disposal of the customer in evaluating how to best optimize all applications also proposing tailor-made solutions.

Saver’s collaboration with customers does not end with the installation of the bearing but continues through a team working together with the customer to explore all possible further optimizations.

Saver has its own technological laboratories for testing, inspecting and improving the product and its performance. Specialized equipment is used to subject the composite bearings to endurance and wear tests. The testing cycles may run in continuous rotation, in oscillation or in translation mode. We go up to dynamic loads of 50,000 kg (110,230 lbs.) and continuously measure the following parameters: Applied Load — Torque — Coefficient of Friction — Wear — Temperature.

The technology and equipment at our disposal enable us to realize our Durobearing® line according to customer requests and designs, not just in terms of non-standard diameters, but also where special shapes and bore configurations are concerned, for example:

  • flanged bearings on one or both sides
  • thrust bearings
  • bearings with self-lubricating external surface
  • bearings with self-lubricating internal and external surface
  • closed-end bearings
  • circular bearings with hexagonal or square cut-outs
  • especially machined bearings (internal or external turning, boring, etc.)
  • bearings stamped by pad-printing
  • large-size bearings up to 1000 mm in diameter (39.37 in.)

To complete the range of bearings for different mechanical solutions, we have developed a series of spherical self-lubricating composite bearings with a steel ball joint inserted in the composite material lining. Using proprietary technology and the best inside liner, Saver has developed an articulated bearing with exceptional properties:

  • low coefficient of friction
  • low clearance between the spherical steel portion and the composite
  • highly wear resistant
  • self-lubricating
  • able to handle high loads
  • no “stick-slip”
  • low chatter
  • vibration absorption
  • may be used for continuous oscillatory and rotary motion

Durobearing™ ENGINEERING DATA

  •  
    metric units
    US units
  • Ultimate Compression Strength
    450 MPa
    60,000 psi
  • Maximum Static Load
    200 MPa
    30,000 psi
  • Maximum Dynamic Load (P)
    140 MPa
    20,000 psi
  • Maximum Velocity
    18 m/min
    60 ft/min
  • Maximum Pressure & Velocity (PV)
    7.5 KN/cm2 m/min
    35,000 psi ft/min
  • Operating Temperature
    -190 °C to +170 °C
    -320 °F to +350 °F
  • Specific Gravity (Density)
    1.9–2
    1.9–2
  • Coefficient of Friction
    0.1–0.4
    0.1–0.4
  • Maximum recommended length
    twice the internal diameter
  • Minimum recommended length
    half the internal diameter

Recommended Shaft Characteristics for Optimal Performance:

  • Material chrome
    alloy steel
  • Hardness
    58 Rockwell C minimum
  • Surface Plating
    chrome, chrome nitrate, electrolytic nickel, mylonite
  • Surface Roughness
    0.2 microns

Acceptable results may also be obtained with shafts having:

  • Material chrome
    alloy steel
  • Hardness
    20 Rockwell C minimum
  • Surface Plating
    chrome, chrome nitrate, electrolytic nickel, mylonite
  • Surface Roughness
    14 microns

Maximum Loads of Various Bearing Materials

Durobearing™ has a special liner, giving it exceptional resistance to wear. Even after hundreds of thousands of cycles (with no lubricant) the condition of the bearing and shaft are still efficient. The chart below shows loss of thickness according to number of cycles.

Durobearing™ contains a Teflon® liner which offers the lowest coefficients of friction of any known fiber. Furthermore, the static coefficient of friction is hardly greater than the dynamic one, thus eliminating the phenomenon of stick-slip (see Engineering Data). With the elimination of stick-slip, Durobearing® allows for a reduction in vibrations and the break- away torque needed to set the shaft in motion, translating into an overall improvement in precision running.

Durobearing™ offers very high performance with specific materials that provide exceptional characteristics —structural robustness of the composite and a minimum coefficient of friction. It is worth noting that the coefficient of friction is lowered to a level of 0.01 with an increase in the applied load and/or temperature, as illustrated in the chart