- Genral Engineering Plastics
- Advance Engineering Plastics
- Fluro Polymers
Low co-efficient of friction
With built-in lubricants, there is no need for elaborate lubrication systems.
Water can also be used to lubricate METALON bearings.
High impact and abrasion resistance
METALON bearings can absorb punishing, random high shock loads. With its memory, the bearing returns to its original
shape and size, without cracking, deforming, or deteriorating.
Long life, low wear
METALON materials are tough and have excellent wear resistance characteristics in any environment: salt,
fresh or dirty water.
Bearings made of METALONs , a homogenous, non-metallic material, resist most types of corrosion at
the bearing surface and between the bearing and the housing.
METALONs are very versatile materials. You can turn, drill, tap, shape, jig saw, mill all grades.
Outperforms traditional bearing materials
METALONs are tough, non-metallic, synthetic, polymer alloy, which provides exceptional abrasion resistance. Combining
this with qualities of flexibility and high load-carrying ability, they can withstand a great amount of abuse in adverse
operating environments often found in sleeve bearing applications. In fact, under many severe conditions.
METALON Industrial bush bearings out-perform bronze, Babbitt, Teflon, phenolic and a host of other non-metallic
materials in providing longer trouble-free operation.
Because of its exceptionally high impact strength. METALONs possesses unusual ability to absorb shock loads. They performs extremely well under vibration and misalignment conditions.
SHAFT OR MATING SURFACE WEAR
Since METALON tends not to carry abrasives, shaft wear may be reduced when compared to other bearing materials. In making an evaluation, however, shaft wear should be related to length of service. If, for example, an METALON - Oillon bearing outwears extruded nylon by 2:1, a fair comparison of shaft wear would be with the total wear down produced by two nylon bearings. In comparative test, METALON-OILLON has caused less shaft wear than the other METALON grades.
RESISTANCE TO OIL, WATER, SOLVENTS, AND CHEMICALS
METALONs possesses excellent corrosion resistance and resistance to oil, water and chemicals. It is not affected by lubricants normally used with sleeve bearings. METALON absorbs approximately 0.6% water by volume under atmospheric conditions and at a temperature of 23 o C. This expansion is gradual and may take up to 4,000 hours to complete, under static conditions. Under dynamic conditions, absorption can occur much faster. The majority of the expansion occurs, however, within the first 1,000 hours. If the pressure or temperature is increased, not only does the volumetric swell percentage increase, but also the rate of absorption. In tests using water at 60 o C, the volumetric swell increased to between 1.9% and 2.1% within 100 hours. In practical tests, when hot water is not present, the average bore closure effect of water absorption was 0.022 times the wall thickness. A conservative indication of METLON's behavior in a wide range of chemical environments is vailable in a " Chemical Compatibility Chart . In critical situations, testing of METALON before putting bearings in actual operating equipment is recommended, by immersion for 30-60 days, measuring sample
dimensions before and after immersion, and also checking hardness. Any significant variance from the METALON standard would indicate possible compatibility problems.
When METALON is subjected to immersion in hot water, i.e. above 60 o C the material, begins to deteriorate chemically. This deterioration or breakdown is called hydrolysis. The surface of the material softens initially, and eventually cracks and breaks appear throughout the material. METALON is not recommended for use in hot water above 60 o C
METALON has a higher coefficient of thermal expansion/contraction than metallic bearing materials, although not as high as many " plastics . This factor offers a significant advantage when fittingbearings, as freezing causes contraction and therefore makes fitting with interference fit very easy. When bearings are subjected to higher temperatures, allowance must be made for the reduced running clearance caused by thermal expansion. When METALON bearings will operate in a cold environment, an appropriate amount of extra interference must be provided to offset thermal contraction.
Unlike plastics and metals. METALON is not a malleable material. It resists the " pounding out of shape which frequently occurs when metal or plastic bearings are subjected to impact. As wear clearance develops in conventional bearings, the increased potential for " hammering can cause rapid failure. It should be note that greater clearances in METALON bearings as a design consideration, will not result in this type of failure.
WATER FLOW :
On full rotational bush bearings where high PV's dictate that a forced water-cooling system is required, the recommended minimum flow of @ 0.15 liters per millimeter of shaft diameter.
METALON stays flexible at temperatures down to 60 o C. METALON is not recommended for hot water or steam applications due to potential Hydrolysis problems. Water over 60 o C should be avoided unless exposure times are short. An upper limit on environmental operating temperature of 120 o C is suggested and although test conducted in laboratory where METALON bearings have successfully performed at higher temperatures, physical properties of the material are reduced, where operating temperatures in excess of 120 o C are expected, do not hesitate to consult us.
SELECTION PROCESS :
In any bearing application, the primary consideration is to ensure that the frictional heat developed in the sliding action is either absorbed and dissipated by the surrounding mechanism or that it is conducted away by a lubricant or coolant. There must be a balance in the system where temperature equilibrium is reached, and this must be below the temperature limit of the material. If not, bearing failure will result. The secondary consideration is the type of environment that the bearing is running in, e.g. very abrasive or clean, as this will affect material selection. For high pressure applications where the frictional heat generated is not a factor due to either oscillating motion or very slow speeds, the bearing needs to be designed with a very high shape factor
NOTE: Frictional heat generated in high-pressure applications must be dissipated at the same rate to avoid seizure.
METALON-6 is recommended for use where there is external lubrication available. It is not recommended for dry running because of its high dry coefficient of friction. This would apply to sliding applications where frictional heat is retained. METALON - OILON is the most popular grade and has a good balance of abrasive resistance and co-efficient of friction. It is used for a variety of industrial and Pharmaceutical applications and is stocked or
available in Rods, Sheets & Tubes METALON-OILON has the best dry running capability, abrasion resistance too It is the most unique grade of METALON-OILON , and is becoming increasingly popular. It is used in high-pressure thin walled bearings, and for highly loaded rudder bearing applications where there is a risk of adhesive wear. POLY ACETAL & is used in the food industry in non-food contact areas where no grease is permitted. For food contact applications, a special FDA grade is available. ERTALYTE is to be used. In the manufacture of METALON Compact bearings supported by a metallic sleeve to give rigidity to the softer liner. These Composite bearings are available as per customer's requirement.
DESIGN GUIDE SHAPE FACTOR
This term is used in connection with elastomer engineering. It is influenced by wall thickness and he bearing L/D ratio. Since an average METALON-OILON bearing has an L/D ratio of 1.25:1, and a wall thickness proportional to shaft diameter, a typical shape factor of 8 can be used. Increasing the shape factor can increase the load bearing capability of the bearing. The METALON-OILON bush bearings are based on use of a high shape factor.
When a load is applied to METALON , it acts like a spring and moves in accordance with the force exerted on it. This is generally referred to as " compression , but in the case of an elastomer such as METALON the
material does not undergo a change in volume, but rather a change in shape. The extent to which such a change in shape can be acceptable in a bearing application depends on the type of movement involved. We define the maximum acceptable amount of deformation for full rotation as 1.25% of the wall thickness. For oscillating movement this limit can be extended to 4.0%.
In order to determine the feasibility of using an METALON bearing in a specific application, the factors of pressure, velocity and time should be considered. The basic concern with most non-metallic including METALON is the risk of heat build-up, and the ability of the assembly to dissipate of this heat. The pressure on a bearing is the load applied divided by the loaded area. By convention, the loaded area is calculated as the bearing length multiplied by the shaft diameter. This is not entirely accurate, but it is convenient. Velocity when applied to a
bearing configuration refers to peripheral velocity (and not rpm) in either feet per minute or meters per second. It is impossible to separate pressure and velocity when dealing with a bearing application because both are potential sources of frictional heat. They must be considered together. Our studies have indicated that it is not possible
to publish absolute dry PV (pressure-velocity) figures for the METALON grades. We must consider the specific combination of pressure and velocity and relate this to the time factor (duty cycle) as this too influences the probability of heat accumulation. If the assembly operates over a short duty cycle, it has time to cool down between operations and therefore may be able to accept higher pressure and velocity figures than a similar assembly running continuously. Obviously lubrication has a major influence on PV-T limits, and therefore grooves are provided for dry, grease lubricated, oil bath and water bath conditions. He PV-T graphs were developed using a bath of oil or water. If the system can be designed to incorporate a forced flow of lubricant instead of a bath, much of the frictional heat will be dissipated by the flow of lubricant. Once the bearing is operating under hydrodynamic conditions, no additional frictional heat is develop as the speed is increased, other than a slight increase in frictional drag of the lubricant. This increase is so low that it does not affect the bearing operation. Velocity can be increased significantly (compared to a bath-type system) as long as there is sufficient flow of cool lubricant to dissipate the frictional heat generated.