| Load and contact area | Maximum static and dynamic load, load distribution, and the pad’s rated capacity. | Estimate average pressure as load divided by the effective contact area. Uneven or concentrated loads can create higher local pressure than the average. | Compare the calculated loading with the manufacturer’s stated limits and test conditions. Allow for movement, impact, and safety requirements where applicable. |
| Rubber compound | Compatibility with water, oils, fuels, cleaning agents, weather, ozone, and other exposures. | EPDM is commonly selected for outdoor weather and water exposure; NBR is commonly considered for oil exposure; natural rubber is often used where resilience and abrasion resistance are important. Suitability depends on the specific formulation. | Request a chemical-compatibility assessment for the actual fluid, concentration, temperature, and exposure duration. Do not select by polymer name alone. |
| Operating temperature | Continuous and peak service temperatures, including cold starts and temperature cycling. | Temperature limits vary substantially by compound and formulation. Heat and cold can change stiffness, flexibility, and service life. | Check the product data sheet for both continuous and intermittent limits, and confirm that the stated limits apply to the intended environment. |
| Hardness and flexibility | Shore A hardness, thickness, and required compression or vibration isolation. | Hardness is commonly reported on the Shore A scale. A softer pad may deform more; a harder pad may provide less deflection. Hardness alone does not establish load capacity or isolation performance. | Verify the test method and tolerance, such as ASTM D2240 or ISO 48-4, and request performance data at the expected load where needed. |
| Dimensions and tolerances | Length, width, thickness, hole pattern, flatness, and dimensional tolerances. | Dimensions affect fit, contact area, and load distribution. Molded, cut, or fabricated parts may have different tolerances. | Check a dimensioned drawing against the equipment and mounting surface. Confirm whether dimensions are nominal or finished-part tolerances. |
| Compression and recovery | Compression set, deflection under load, and ability to recover after compression. | Compression set is a laboratory measure of deformation remaining after a specified compression, time, and temperature; it is not a direct guarantee of service life. | Compare results only when the test method and conditions match. Ask for the applicable test report, such as ASTM D395 or ISO 815-1. |
| Surface and mounting | Surface finish, friction needs, fasteners, adhesive requirements, and possible movement. | A clean, even support surface helps the pad sit uniformly. Adhesives and mechanical fasteners should be compatible with the rubber compound and the surrounding materials. | Follow the supplier’s preparation and bonding instructions. Do not assume an unbonded pad will remain in place under shear or vibration. |
| Installation conditions | Alignment, cleanliness, seating, compression, and access for inspection. | Remove dirt, oil, burrs, and sharp edges that could damage the pad. Avoid twisting, stretching, or trapping debris during installation. | Install to the equipment or product instructions. Record the pad location and any specified torque, preload, or adhesive cure time. |
| Inspection and maintenance | Cracks, cuts, swelling, hardening, permanent flattening, slippage, and loose fasteners. | Inspection frequency should reflect load, exposure, operating hours, and the consequence of failure. There is no single interval appropriate for every application. | Set an initial inspection schedule, document findings, and shorten intervals if deterioration or movement is observed. Replace damaged pads and investigate the cause. |
| Documentation and quality | Product data sheet, drawing revision, material identification, test reports, and batch traceability. | Values are meaningful only when their test methods, conditions, and tolerances are stated. | Confirm the delivered part matches the approved specification and retain relevant documentation for future replacement. |