Full definition
The belt body (compound) refers to the bulk elastomeric material that forms the main structure of a power transmission belt. This material encases the tension cords, which are essential for maintaining the belt's integrity under load. The compound's properties are crucial for providing the necessary flexibility, environmental resistance, and overall durability required in various industrial applications. The choice of elastomer significantly influences the performance characteristics of the belt, such as its resistance to heat, chemicals, and environmental factors, which are critical for ensuring long service life and reliability in power transmission systems.
Two primary compounds dominate the market for belt bodies: Neoprene (CR) and EPDM. Neoprene was the industry standard from the 1950s through the 1990s, offering resistance to mineral oils and moderate heat up to 90°C for continuous applications. It is also noted for its flame retardancy, making it suitable for environments where fire hazards are a concern. On the other hand, EPDM excels in providing superior resistance to ozone, UV radiation, and weathering, with a wider operational temperature range of -40 to +130°C. This makes EPDM an ideal choice for outdoor and varying climatic conditions, along with a longer lifespan of 20-40% in clean environments compared to other compounds.
The hardness of the belt body typically ranges from 55 to 75 Shore A, affecting its flexibility and ability to handle bending stresses. The compound selected also determines the minimum flex radius and the heat generated under cyclic bending conditions, which are vital for applications that require frequent motion and flexibility. Specialty compounds, such as HNBR, offer enhanced performance in oil and heat resistance, while polyurethane is often used for timing belts due to its tensile strength and durability. Understanding the properties of the belt body compound allows engineers to select the appropriate material for specific applications, ensuring optimal performance and longevity in power transmission systems.