POLYLUBE® Guide Rod Bearings
POLYLUBE® Guide Rod bearings are designed as replacements for traditional metallic guide rod bearings materials. Replacing conventional metallic guide rod bearings with a POLYLUBE® guide rod bearing is a straight-forward change out. Typical replacement programs where metallic guide rod bearings are replaced are driven from one or a combination of several of the following factors:
- Improved stick-slip properties
- Optimal frictional response during cycling
- Significant reduction in shaft scoring
- Extension in the bearing life
- Reduction in bearing profile
- Greatly improved side load/misalignment capacity
- Increase in load capacity of bearing
- Enhanced corrosion resistance
- Tolerance of more cost effective shaft finishes
- Lower in weight
ID seal configurations
Incorporating T-lip wiper seals, radial shaft seals, o-rings or any other similar internal sealing system is not a problem for PolyLube Guide Rod bearings. Polygon's internal fabrication capabilities allow for easy and economical incorporation of ID features required to install common sealing systems.
Two liner thicknesses are available in the standard PolyLube PTFE tape lined bearing configuration: the 0.015" thick liner being standard and a 0.030" thick liner also being available for applications where seal geometry might require the introduction of a thicker liner to accommodate a unique ID feature. The 0.030" thick liner can also be used in applications where boring the ID might be required in order to achieve tighter tolerances in an effort to address sizing and minor misalignment conditions.
Fabrication capabilities
One common fabrication detail seen on guide rod bearing applications deal with corner radiuses on internal and external grooves. Because Polygon uses a diamond wheel or groove tool to form the grooves we need to have at least a .015-.020" corner radius. When threads are used there is usually clearance involved. When assembled with the mating part the bearing could shift to one side or the other impacting the location of the bearing surface in relation to the piston shaft. This could have a negative impact on wear.
The only other fabrication issue commonly seen on incoming prints is a surface finish called out on the internal diameter. This is typically related to an OEM’s historical use of machined bronze bearings in the application. Since the bronze is machined from a solid piece or casting, the surface finish is called out since it is related to the speeds and feeds of their fabrication process. The wear surface on PolyLube bearings is not machined so the surface finish call out can be removed from fabrication requirements.
Polygon is capable of holding a TIR I.D. to O.D. within .002" and straight diameters to +/-.0005".
POLYLUBE® Guide Rod bearings are commonly available in two configurations: a POLYLUBE® bearing utilizing a sintered PTFE liner or a POLYLUBE® bearing utilizing a PTFE fabric liner. The most common POLYLUBE® guide rod bearing in use today is the sintered PTFE liner due to two primary performance enhancements over the PTFE fabric lined bearing: the frictional response under start-up conditions and the transfer of PTFE to the wear surface.
Guide rod bearing properties
Polylube Sintered PTFE Liner
| Ultimate Compression Strength | 40,000 PSI |
|---|---|
| Unit Load Limit | 7,000 PSI |
| Temperature Range (Standard Formulation) | ±325 °F |
| Coefficient of Thermal Expansion | 7 x 106 in/in/°F |
| Thermal Conductivity BTU * in/(hr * ft2 * °F) | 1.8-2.3 |
| Water Absorption as % weight produced (2 hours) | 0.12 |
| Water Absorption as % weight produced (24 hours) | 0.16 |
| Specific Gravity | 1.95 |
Polylube PTFE Fabric Liner
| Ultimate Compression Strength | 60,000 PSI |
|---|---|
| Unit Load Limit | 30,000 PSI |
| Temperature Range (Standard Formulation) | ±325 °F |
| Coefficient of Thermal Expansion | 7 x 106 in/in/°F |
| Thermal Conductivity BTU * in/(hr * ft2 * °F) | 1.8-2.3 |
| Water Absorption as % weight produced (2 hours) | 0.12 |
| Water Absorption as % weight produced (24 hours) | 0.16 |
| Specific Gravity | 1.87 |
Need parts?
Download a Design guide with parts list or Compare parts online.Mechanical and physical properties
PolyLube Guide Rod bearings are manufactured by a filament winding process that results in a continuous fiberglass filament backing ensuring excellent mechanical properties (especially fatigue resistance). The filament wound fiberglass structure uses a high strength, corrosion resistant epoxy resin as the matrix material. The high strength backing permits the use of a thin wall (1/16" to 1/8") bearing which can often reduce the size and weight of the finished bearing assembly. This family of materials exhibits exceptional dimensional stability and performance predictability over wide temperature ranges (±325°F).
Disclaimer
Any ratings are typical for design purposes. Final testing and approval is the customer's responsibility for their application. This information is derived from our testing and published data. There is no assurance of these properties, or warranty provided that these products are suitable for any particular purpose or operational situation.
Polygon certifies that their product will be free from material defect. Polygon will not accept any liability for loss, damages, or costs from use or misuse of our products.
Specifications are subject to change, and may be affected by our continual process of improvement. Changes may be made without prior announcement.
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