FEROFORM PR Bearings
WHY USE FEROFORM PR GRADE SEFE LUBRICATING BEARINGS?
- No need to use grease or other lubricants
- Where lubricant films are unable to be maintained
- To reduce maintenance costs
- Where using a lubricant is not suitable because of bearing inaccessibility
- The cost of a central lubricating system can be eliminated
- To eliminate contamination of the bearing caused by surplus grease which
is expensive to dispose of
- Where high static impact loads are encountered
- To Avoid corrosion that occurs with conventional bearings.
- To avoid stick slip and achieves smooth running of the bearing
- For aggressive environments where corrosive substances or abrasive
particles are present, that will damage and contaminate greased metal bearings
- Where unusual temperature conditions prevail
BEARING PROPERTIES & BENEFFITS
- Can operate with or without lubrication
- High load carrying capacity up to : 60Mpa at safety factor of 4;80Mpa at
safety factor of 3
- High strength to weight ratio (20% the weight of bronze)
- Low Coefficient of friction (down to 0.04)
- Freedom from stick slip
- Resistant to corrosive stick
- High wear resistance
- Good dimensional stability
- Very low swell in water (0.2%)
- Very low thermal expansion (100 x 10-6/c)
- Easy to install and machine
- High resistance to fatigue under shock loads
- Capcity to be formed and maintain close tolerance.
- Excellent abrasion resistance
- Wide range of mating materials exceptable
- Inherent dampening qualties
- Electrically non conducting.
FEROFORM PR Adavantages
Many factors affect the wear rates of individual bearings and it is difficult to predict lifetimes
accurately. In applications where the above types of motion occur then wear rates will by very low providing
"years" of operational use.
For all of the FEROFORM PR grade range an initial wear-in period occurs during the initial operating cycles. During
this the synthetic fibers will be re-orientated where the high spots of the fabric seave are flattened out. This results in
adjacent fires fires closing together and the bearing becoming smooth and shiny.
In intensive tests at 20N/mm2 load and with over 2km of shaft movement the wear rate was measured at less than 0.2mm. This was
with an amplitude of +/-300, a cycle time of 19 secs and a stainless steel 316 shaft.
Coefficient of Friction
COF depends on type of movement, finish of mating surface, ambient temperature applied load and velocity. Typical figures for the FEROFORM PR
grades range from 0.06-0.12 inducating that all of the products demonstrate extremely low friction properties.
Bacause all of the range have very low COF values stick slip will not occur,even where the shaft has not rotated for long periods of time.With FEROFORM PR 814 PTFE is transferred from the bearing onto the
shaft providing aPTFE-PTFE contact which reduces COF further.
Increasing the bearing allowing the minimum size to be used to achieve the lowest COF,permitting efficient design of the bearing allowing the minimum size to be used to achieve the lowest COF.
All composite material show degree of swelling when completely submerged in water .
Typically for FEROFORM PR grades this 0.1% across the bearing wall.
However where bearings are installed above the water line and in "humid" conditions than the swell
across the wall thickness is typically 1/2 of the figure. If oil or grease are used to lubricate the bearing then swell across the wall thickness is typically 1/4 of this figure.
Coefficient of Thermal Expansion
FEROFORM PR grades have low CTE'S, Typically 100X10-6/oC and can be considered negligible at most
operating temperatures. This results in a bearing that does not expand or contract significantly
when in its housing.
Normally operating temperatures should be kept below 80oC for FEROFORM PR grade bearings. Above this
maximum temperature the bearing will need to be cooled, typically using water.
Increased wear may be incurred on the bearing surface as the temperature nears the maximum, reducing the performance of the bearing.
Also (environmental+generated friction heat), the Pv Value is reduced to prevent the maximum oprating temperature of 80oC beong exceeded.
FEROFORM PR grade bearings perform extremely well in dirty,and can tolerate ingress of solid material. It has to be accepted thet bearing life
will be reduced in such conditions, but FEROFORM PR grade bearings perform signficantly better than other materials in such conditions. Scouring
of the shaft sufface may occur where there is excessive contamination.
In salt and sea water environments FEROFORM PR grades retain there performance characteristics
without losing structural integrity. They are also stable to most chemicals and contaminants. TENMAT Ltd. should be
contacted for specific details.
Housing and Shaft Fits
FEROFORM PR grade bearings are generally installed using using a press,shrink or adhesive fit with the housing bore. The following
tolerances can be used :
Housing Bore H7
Shaft Tolerance e7 low load,turning motion, axial motion
F7 medium load,oscillating motion,interrrupted turning
h7 high load, impact loads, close running fit
Bearing Machining Min 0.08mm