How are the joints of the belt part of the treadmill heat-sealed

The thermal bonding process for treadmill belt splices (the jointed section of the treadmill belt) typically employs high-frequency (RF) welding or thermal compression molding. Treadmill belts are usually made of elastic thermoplastic materials such as PVC, PU (polyurethane), or other polyurethane-based compounds. These materials become pliable when heated to specific temperatures, allowing deformation. Proper splice treatment ensures a strong, smooth seam to maintain safety and functionality during treadmill operation.

I. Splice Design

Treadmill belt splices are typically designed as butt joints, where the two ends of the belt are aligned and bonded thermally. The splice design must ensure precise alignment to prevent misalignment or slippage during operation. Common designs include:

1. Overlap Joint: The two belt ends are overlapped and thermally bonded.
2. Tongue-and-Groove Joint: One end is inserted into a slot on the opposing end, followed by thermal fixation.

II. Application of High-Frequency (RF) Welding Technology

High-frequency welding uses electromagnetic waves to heat and weld thermoplastic materials (e.g., PVC, PU), making it ideal for treadmill belt splices. The process involves:

1. Heating and Softening:

   • The splice section is placed between RF welding electrodes.
   • High-frequency electromagnetic waves excite material molecules, generating localized heat to soften the belt.
   • Heating time and temperature are precisely controlled based on material thickness, type, and required joint strength.

2. Pressure and Bonding:

   • Once softened, the joint surfaces are pressed together under mechanical force.
   • The combination of heat and pressure fuses the materials into a seamless bond without adhesives or stitching.

3. Cooling and Solidification:

   • The bonded joint rapidly cools and solidifies, ensuring durability to withstand operational tension.

III. Thermal Compression Molding

Thermal compression is often used for splices requiring specific thickness or shape, especially with thermoplastic elastomers (TPE) or polyurethane (PU).

1. Heating and Compression:

   • The splice section is placed in a preheated mold.
   • Heat and pressure fuse the belt ends into a uniform joint.

2. Cooling and Curing:

   • After a controlled heating duration, the material cools to form a high-strength, fatigue-resistant seam.