Durobearing
®
Il cuscinetto composito autolubrificante
The self-lubricanting composite bushing
SAVER and Durobearing®
Durobearing® is the trademark used by Saver srl to identify its self-lubricating composite bearings and represents a technologically advanced and reliable solution for journal bearings. Durobearing® is composed of highperformance fibers and makes use of technology and processes developed directly by Saver to attain a massproduced product with superior performance.
Saver is a privately-held European company for composite materials production and sales with plants in
Northern Italy, near Milan. The company has resources for developing, producing and selling standard and tailor-made components in composite material. Our technicians and sales force have many years
of experience in the composites field, which allows
for efficient collaboration with customers as we find
the most advantageous solutions, in keeping with specific customer requests.
SAVER is certified to ISO 9001 and TS 16949
BACKGROUND INFORMATION
•
•
•
•
Filament-winding technology for producing composite bearings is first developed in the 1950’s in the U.S. aeronautics
sector.
Self-lubricating composite bearings are developed in the
1950’s and 1960’s for outer space applications. The functioning of spacecraft and satellites must be reliable and maintenance-free.
In the 1990’s major manufacturers begin using self-lubricating
composite bearings, as they learn of their special properties;
prices start becoming competitive.
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 come to
take the place of metal bearings needing lubrication
COMPOSITE MATERIALS AND SAVER
Composite materials are known to the general public through their use in the sports
and aerospace industries (e.g. Formula 1 racing, structural parts for aircraft, spacecraft and launchers), and were originally developed for the space program, with scientific and technological fallout that has allowed the resulting products to be applied
to more “earthly” areas of daily use. The remarkable performance of these materials
has enabled them to supplant many metals; without our even realizing it, they have
impacted our daily lives. With over 25 years of experience, Saver is leveraging its
expertise, working hard as a developer of solutions and new, more advanced composite material products for mass-produced applications. We are making effective
use of our know-how in new materials (polymers, fibers, additives), and are working
hard as a developer of solutions that make use of new and more advanced composite material products. Saver researches the most efficient methods and technology to
apply industrial processes to new solutions for both established and innovative products. Our experience shows that the best results are achieved by working in teams
with our customer’s engineers and technicians, pooling a network of knowledge.
Through in-depth knowledge of the application, the product and the process, a new
and successful product may be realized. Saver has had a number of cases of this
kind, which in turn has enabled us to grow and be a leader in several areas.
Durobearing®
OUR CONCEPTS:
ZMC® Zero Maintenance Concept®
We help our customers find a solution that guarantees Durobearing® for the life of the machine
or apparatus, with no need for maintenance. This considerably reduces costs while increasing
reliability and adding value for you, our OEM customer, as well as for end customers.
ZLC® Zero Leakage Concept®
Durobearing® does not require lubricants, thus releasing no contaminants into the environment,
guaranteeing an eco-compatible solution.
FBC® FlexiBuild Concept®
The technology used for producing Durobearing® allows us great flexibility of construction and size;
For our customers that means a simple and easy substitution/adaptation of older and more
costly solutions.
Durobearing®
OUR SERVICES
•
Our basic service starts with initial customer contact that focuses on gaining an understanding of
your 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.
•
Saver’s collaboration with customers does not end with the installation of the bearing in the customer’s product. Saver continues working as a team together with the customer’s engineers and
buyers to explore new ideas and techniques to optimize the product from the standpoint of performance and costs.
•
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.
•
Saver also takes advantage of the expertise of prestigious research centers in the area of tribology
and composite materials structure.
Durobearing®
ENGINEERING DATA:
metric units
Ultimate Compression Strength
Maximum Static Load
Maximum Dynamic Load (P)
Maximum Velocity
Maximum Pressure & Velocity (PV)
Operating Temperature
Specific Gravity (Density)
Coefficient of Friction
Maximum recommended length
Minimum recommended length
US units
450 MPa
60,000 psi
200 MPa
30,000 psi
140 MPa
20,000 psi
18 m/min
60 ft/min
7,5 KN/cmq2 mt/1’
35,000 psi fitt/1’
-190 °C to +170 °C
-320 °F to +350 °F
1.9–2
1.9–2
0.1–0.4
0.1–0.4
twice the internal diameter
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
Comparison of Maximum Loads of Various Bearing Materials
Comparative Dynamic Load M Pa KPSi
Bearing Materials
C ast B ro nze+grease
A llo yed B ro nze+grease
Z inc A luminium+grease
P o ro us B ro nze+o il
P o ro us Iro n+o il
Steel-backed B ro nze
F abric-R einfo rced P heno lic
C arbo n-Graphite
R einfo rced T EF LON ®
D UR Obearing®
Green M aterial plus lubrificant
Orange M aterial witho ut lubrificant
MPa
KPsi
0
0
35
70
5
10
105
15
140
20
Durobearing®
WEAR RESISTENCE
Durobearing®’has a special liner, giving it exceptional resistence 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.
0,012
0,305
0,009
0,228
0,006
0,152
0,003
0,076
0
0
5
Te s t Param e te rs :
50
Wear in millimeter
Wear in Inches
Wear Curve DURObearing ®
100 150 200 250 300 350 400 450 500
Thousands of Cycles
Shaf t: case-hardened;chrome-planed; 58 rockw ell C; 8 rms f inish.
Lo ad: 25500 lbs o n bearing pro ducing 17000 psi
M o vem ent Oscillatio n +/- 45 degrees at 18 C P M
The photographs below show the test machine and the state of the shaft and that of Durobearing ® following the wear test
Durobearing® FRICTION, LOAD AND TEMPERATURE
Slip-Stick Phenomenon
joules
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.).
Stick-slip occurs as the difference of “start-up” force between the material when it is set in motion and the reduction in force
when the system becomes dynamic. With the elimination of stick-slip, Durobearing ® allows for a reduction in vibrations and the
breakaway torque needed to set the shaft in motion, translating into an overall improvement in precision running.
Frictional Pe rformance of Automotiv e Suspe nsion Joints
Compre ssion Load,1000 lbs (454 Kg)
14
12
10
8
6
4
2
0
Lubricated standard joint
Non-lubricated joint DURO b earing
1
3
5
7
9
11
15
17
19
21
23
25
27
Time (seconds)
speed = 0,1inch/s ( 2,5 mm/s)
Durobearing®
13
®
Friction factor as a function of load and temperature.
Effe ct of Load and Te mpe rature on Coe fficie nt of Friction of
DURObearing ®
Thrust Wassher Test, 0,1 inch/s - (2,5 mm/s -)
Coefficient of Friction
0,0 6
0 ,05
0,0 4
0,0 3
70°F (21°C)
0,0 2
300°F (145°C)
150°F (66°C)
0,0 1
0
8 00
160 0
24 00
3 20 0
400
4 80 0
56 00
640 0
72 00
8 00 0
(0,55)
(1,1)
(1,65)
(2 ,2)
(2,75)
(3 ,3)
(3,8 5)
(4,4)
(4,9 5)
(5,5)
4
Load psi (Pascals x 10 )
Durobearing® offers very high performance with specific materials that provide exceptional charac-
teristics—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.
Durobearing® SPECIAL DESIGNS
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
Bearings with a closed end
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.)
Our technical department is at your disposal to assist you in evaluating how to best optimize all your applications.
Durobearing®
COMPOSITE SPHERICAL BEARING
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
used for continuous oscillatory and
rotary motion
Our technical department is ready to assist you in the best choice and appropriate size of bearing.
Durobearing®
ADVANTAGES
Durobearing is filament-wound and impregnated with thermoset resins. This lightweight and effi®
cient composite journal bearing features a Teflon® liner and is characterized by a high load capability well-suited to handling frequent starts and stops. Its self-lubricating properties enable value 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 (ways and zerts)
• operational in inaccessible environments
• appropriate for materials that must avoid contact
with lubricant
• environmentally-friendly
• reduced operating and warranty cost
“systems” cost of assembly is significantly reduced
•
Dimensional and thermal stability
Corrosion and chemical resistant
Advanced composites material
Teflon® liner with extremely low coefficient
of friction
operates in submerged conditions and hostile
liquids such as sea water, detergents, alcohol and
acidic environments
• copes with temperature extremes
• affords 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
•
•
•
•
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
•
Tight press fit and low running clearances
•
•
®
Teflon is a trademark of Du Pont de Nemour
can serve as insulating material
no galvanic reactions
ease of installation—no need for retainers
low noise chatter
enhanced abrasion resistance
Durobearing®
APPLICATIONS
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, belt
tensioner
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,
and Landscaping — fork lifts, aerial lifts and
booms, scissor lifts, cranes, lift gates, excavating machinery, orange peel grabs, loaders
Medical—surgical chairs and tables
Mining—lift systems
Refuse Collection— trucks, compactors
Robotics— points of articulation