Plain-bearing material pages often give a maximum permissible static surface pressure at a stated temperature. These values can help screen materials for a stationary load, but they are not interchangeable with dynamic load ratings or complete bearing-life predictions.

This table compares six named igus iglide grades using the manufacturer’s stated permissible static pressure at 68°F. It shows the original psi value and a converted MPa value. The MPa column is a unit conversion, not a second test result. Keep the grade name and reference temperature attached to any value copied from the table.

What static surface pressure means

Average projected surface pressure is commonly estimated by dividing the bearing load by the projected area of the bearing, using its length and shaft diameter. That simple calculation does not reveal local edge pressure, misalignment, housing distortion, shock, or stress concentration. It is a screening calculation and depends on how load and projected area are defined for the specific design.

A manufacturer’s static limit applies to the named material and test conditions. It is not a universal allowable for all polymers, filled plastics or bronze bearings. The temperature matters because polymer stiffness and strength can change with temperature. The actual bearing may also be affected by moisture, chemicals, fit, shaft finish and manufacturing tolerances.

Why static values do not rate motion

A bearing that can support a stationary load may not perform acceptably while sliding or oscillating. Dynamic service adds frictional heat and wear, and performance depends on surface speed as well as load. For moving applications, consult the material-specific pressure-velocity (pv) information, temperature limits and manufacturer lifetime tools. Start-stop duty, short strokes, contamination and poor heat dissipation can make simple average-speed estimates misleading.

Also check the shaft material, hardness and finish, bearing wall thickness, housing support, clearance, lubrication assumptions and load direction. A thin or unsupported bearing can deform even if the nominal pressure is below a catalog value. Loads near an edge or carried through a small portion of the bearing surface require particular attention.

Using the comparison responsibly

Use the table to compare the listed grades under the same stated temperature and static measure. It does not establish a best material for an application. A higher static pressure number alone does not guarantee longer life or lower friction; material choice must account for motion, environment, counterface, geometry and cost.

Before release, confirm that the live product page still lists the same value for the exact grade and market region. Apply the manufacturer’s design method to the actual bearing dimensions and operating conditions. If the load cycles, impacts, rotates or slides, evaluate the dynamic case rather than treating the static figure as a permissible working load.

For a quick screening example, multiply the proposed radial load by the appropriate design factor, then divide by the bearing’s projected area using consistent units. Compare that result only with the manufacturer’s static value if the bearing is effectively stationary and the stated temperature applies. If either condition is false, stop the simple comparison and use the relevant temperature-dependent or pressure-velocity guidance.

The six values are product-specific reference data at 68°F. They are useful for an initial comparison and should remain linked to their source pages and stated conditions whenever they are reused.

igus explains that permissible static surface pressure is a comparative, temperature-specific value and describes projected bearing area and the effect of speed in its surface pressure and load guidance. The individual grade pages provide the material-specific values, including iglide J.

As a unit check, 5,076 psi multiplied by 0.006894757 MPa per psi is approximately 35.0 MPa. The conversion helps compare units but does not change the product-specific scope or operating limits of the source figure.