Rubber pads are widely used under hydraulic jacks, lifting equipment, and heavy machinery to enhance stability and prevent surface damage. However, when used on oily or contaminated surfaces, rubber pads can lose friction and slip, posing serious safety risks. Understanding the causes of slippage and implementing design or material improvements is essential for ensuring operational safety.
1. Reduction of Friction Coefficient on Contaminated Surfaces
Rubber’s anti-slip performance depends on the coefficient of friction between the pad and the surface. Oil or grease contamination significantly lowers this friction:
Creates a lubricating layer that reduces grip
Causes hydrodynamic slip, especially under heavy loads
Rubber materials with smooth surfaces are particularly vulnerable to sliding
2. Surface Hardness and Deformation Effects
The hardness of the rubber pad affects its ability to conform to surface irregularities:
Soft rubber deforms more, increasing real contact area and friction, but may compress excessively under heavy loads
Hard rubber resists deformation but contacts fewer asperities, reducing grip on slippery surfaces
Optimized hardness (typically Shore A 65–75) is often recommended for balancing load support and slip resistance
3. Surface Texture and Pattern Influence
Surface design significantly affects anti-slip performance on oily ground:
Smooth pads slide easily under lubrication
Textured surfaces (diamond knurling, ribbing, cross grooves) enhance mechanical interlocking
Micro- or macro-patterned surfaces help channel oil away, increasing friction and grip
4. Load and Weight Distribution
Slippage is more likely when:
The load exceeds the pad’s design capacity, causing lateral deformation
The load is unevenly distributed, producing tilt or lateral forces
The contact area is small relative to the applied weight
Pads must be designed with sufficient area and thickness to maintain stability under expected loads.
5. Environmental and Maintenance Considerations
Oily or greasy floors require regular cleaning or protective mats beneath pads
Rubber aging, surface contamination, or embedded debris can further reduce grip
Environmental temperature affects rubber elasticity, impacting friction: low temperatures can harden rubber, while high temperatures may soften it
6. Design and Material Optimization
To mitigate slippage on oily surfaces:
Use soft to medium-hard rubber compounds with high friction additives
Apply surface texturing or over-mold patterns to improve mechanical grip
Consider dual-layer or reinforced pads, with a softer contact layer over a rigid base
Introduce anti-slip coatings such as polyurethane or silicone-based compounds for oily conditions
Conclusion
Rubber pads can slip on oily surfaces due to reduced friction, improper hardness, insufficient surface texture, uneven load, and environmental factors. Optimizing material selection, pad geometry, surface patterning, and user practices (cleaning and load management) is essential to prevent slippage and maintain operational safety.
References
Gent, A. N. Engineering with Rubber: How to Design Rubber Components. Hanser Publishers.
ISO 20344 – Footwear Testing: Slip Resistance and Friction Tests.
Brown, R. (2020). “Effect of Surface Contamination on Rubber Friction Performance.” Journal of Tribology and Materials Science.
Smith, J. & Lee, K. (2019). “Design Considerations for Anti-Slip Elastomer Pads under Contaminated Surfaces.” Journal of Elastomer Technology.
