Polypropylene

PP (Polypropylene) plain bearings are lightweight, self-lubricating plastic bearings known for their excellent chemical resistance to acids and alkalis, and suitability for applications involving moisture, food contact, or frequent washdowns.
Key Features and Benefits
Excellent Chemical Resistance: Polypropylene is highly resistant to a wide range of organic solvents, acids, and alkalis, making it a reliable choice in chemical processing and pharmaceutical industries.
Low Moisture Absorption: PP has a very low moisture absorption rate, which ensures good dimensional stability in humid or wet environments, a significant advantage over other plastics like nylon.
Lightweight: Among plastics, PP has one of the lowest specific densities, making it a very lightweight material beneficial for applications where weight reduction is desired.
Cost-Effective: Polypropylene offers a good balance of performance and price, serving as a lower-cost alternative to Acetal for applications with lighter loads and lower speeds.
Food and Hygiene Compliance: Specific grades of polypropylene are FDA-approved for direct food contact and resistant to sterilization processes and cleaning chemicals, ideal for sterile environments.
Good Electrical Insulation: PP exhibits excellent electrical insulation properties, making it suitable for various electrical and electronic applications.
Considerations
Limited Heat Resistance: PP has a moderate heat resistance compared to other engineering plastics. The maximum continuous use temperature is typically around 82°C (180°F), and it softens at approximately 110°C (230°F).
Lower Stiffness/Load Capacity: It generally offers lower stiffness and load-carrying capacity compared to materials like Acetal, making it suitable for lower-speed, lighter-load applications.
UV Sensitivity: Standard polypropylene can be susceptible to UV degradation during long-term outdoor exposure if not treated with appropriate additives.
Applications
PP plain bearings are widely used where their chemical and moisture resistance are critical:
Food and Beverage Processing: Ideal for use in machinery and conveyor systems that require frequent washdowns and meet strict hygiene standards.
Chemical Processing: Employed in equipment used for processing and storing chemical products, where exposure to acids and alkalis is a factor.
Medical Equipment: Used in various medical devices and lab equipment requiring sterility and chemical resistance.
Textiles and Fabrics: PP fibers and components are used in textile machinery and products due to their strength and resistance to moisture.