Cracking and Chipping of Polyurethane Pads in Vertical Jacks
Polyurethane pads in vertical jacks are critical for load distribution and stability. Cracking or chipping of these pads can compromise safety and reduce service life. Understanding causes, effects, and preventive measures is essential.
1. Causes of Cracking and Chipping
Overloading: Exceeding the rated capacity of the jack causes excessive stress, leading to cracks or chipping.
Impact or Shock Loads: Sudden drops or jerks on the jack can fracture polyurethane pads.
Material Defects: Poor-quality polyurethane, air bubbles, or improper curing during manufacturing reduce durability.
Environmental Factors: Exposure to extreme temperatures, UV radiation, or chemicals can degrade the polyurethane.
Aging and Fatigue: Repeated loading cycles cause material fatigue, leading to micro-cracks that propagate over time.
2. Effects of Pad Damage
Reduced Load-Bearing Capacity: Cracks or chipped areas concentrate stress, increasing the risk of pad failure.
Instability During Lifting: Uneven or damaged pads compromise contact with the vehicle chassis, increasing tipping or slipping risk.
Accelerated Wear: Damaged pads wear more quickly and may damage the jack or the lifted object.
Safety Hazards: Failure under load can lead to equipment damage or operator injury.
3. Preventive Measures
Load Compliance: Always operate within the manufacturer’s rated capacity and avoid shock loading.
Material Quality: Use high-quality, properly cured polyurethane pads free from air pockets or defects.
Environmental Protection: Avoid prolonged exposure to UV, extreme temperatures, or aggressive chemicals.
Regular Inspection: Periodically check for cracks, chipping, or signs of fatigue; replace pads showing damage.
Proper Storage: Store jacks and pads in dry, shaded areas away from heat sources and chemical exposure.
4. Conclusion
Cracking and chipping of polyurethane pads in vertical jacks are primarily caused by overloading, shock impact, material defects, and environmental stress. Preventive strategies, including proper load management, material selection, inspection, and storage, are key to ensuring safety and prolonging pad service life.
References
Gent, A. N. Engineering with Rubber: How to Design Rubber Components. Hanser Publishers, 2012.
ASTM D412 – Standard Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension.
ISO 7619-1 – Rubber, Vulcanized or Thermoplastic — Determination of Indentation Hardness.
Lake, G. J. “Fatigue and Fracture of Elastomers.” Rubber Chemistry and Technology, 2000.
ASTM D2240 – Standard Test Method for Rubber Property—Durometer Hardness.
