The use of composite bearings in the many
fields of engineering can offer designers and engineers significant advantages over
conventional bearing materials. The ability to offer maintenance free bearing
solutions or reduced maintenance intervals can give both savings in costs and expensive
down time of equipment. The ability to be installed and work directly
in conditions that would normally require sealing system and lubrication for conventional
metal bearings makes them a very desirable bearing solution. In sensitive areas of marine,
hydro power, water supply or food processing, this environmentally friendly solution has
many benefits and the potential of significant cost saving opportunities.
One of the significant growth areas for the use of composites is in the offshore industries,
a move towards light weighting of topside equipment has seen composites become common
place. Bearing applications in this market sector
have also significantly taken the place of conventional metal bearings.
The big advantage is the maintenance free, fit and forget capability of these composite
bearing solutions. Maintenance doesn’t happen most of the time; the environment can be very
aggressive so the ability to perform straight out of the box is very beneficial.
Many benefits can be gained in rotating mass equipment. The low density of the material
at 1.35 grams/cc, and a high strength to weight ration can offer considerable weight saving
opportunities. Applications below the waterline need no sealing
or lubrication provision. The selection of the correct material for the bearing counter-face
will give long term bearing performance. It’s an excellent insulator and prevents the potential
of bi-metallic corrosion. We can paint a glowing picture for the use
of composite bearings but we must be realistic. Although they can offer many advantages it
can’t do everything. There is a limitation to its capability, and
it’s important to recognise what those limitations are. We need to ensure that all the details
and dynamics of the application are carefully considered. It’s important to understand
by comparison to metal bearings, our materials have much higher levels of thermal expansion
and much lower thermal conductivity and a considerable difference in modulus values.
Unlike metal bearings with a single Young’s modulus our composite materials are anisotropic
and require different design criteria. It’s most important to understand that metal
bearing tolerances and fits do not work for our composite bearings due to that significant
difference in modulus values. With the correct design criteria applied a
certain amount of compensation for these characteristics can be accommodated and a changeover to composite
bearings can in most cases be achieved. The real Achilles’ heel is elevated temperatures
and most bearing failures can be attributed to not recognising the compensation for loss
of performance attributed to this fact, or its inability to tolerate the thermal excursions
that many metal bearings can work under. However in the final reckoning our Tufcot
materials have found hundreds if not thousands of very successful applications around the
world, but as a company we are investing in R & D projects to develop the next family
of high performance Tufcot composite bearing materials for the next 37 years.