I. Visual Inspection: Basic but Crucial
A high-quality PU conveyor belt should possess the following characteristics:
1. Smooth and flat surface: Free from bubbles, cracks, impurities, or uneven coloring.
2. Regular edges: Free from burrs, serrations, or delamination to prevent tearing during operation.
3. Uniform core: Observe the cross-section; the skeleton layer (such as polyester fabric) should be evenly distributed and of consistent thickness to ensure stable tensile strength.
✅ Tip: Under light, tilt the belt and check if the surface reflection is continuous. Intermittent reflection may indicate uneven calendering or internal defects.
II. Simple Material Characteristic Identification Methods
The following on-site tests can be used to quickly determine the authenticity and quality of the material:
1. Resilience Test: Fold the conveyor belt and then unfold it. A PU conveyor belt will rebound quickly without creases; PVC will rebound slowly and easily leave white marks.
2. Surface Hardness and Scratch Resistance
Lightly scratch the surface with a fingernail or a hard object. PU conveyor belts are less prone to dents and recover quickly; PVC is easily scratched and recovers slowly.
Press firmly; PU material feels harder, while PVC is softer and stickier.
3. Combustion Test (Proceed with Caution)
Ignite a small sample:
PU burns with a yellow flame and a slightly blue base, producing little milky white smoke with a slightly sweet or spicy odor. The residue is black and viscous, with noticeable stringiness.
PVC burns with black smoke and a pungent odor; the residue is carbonized and brittle.
⚠️ Note: Combustion tests should be conducted in a well-ventilated environment and are only for supplementary judgment, not the sole basis for assessment.
III. Key Physical Performance Indicators (Third-Party Testing Recommended)
To ensure long-term operational reliability, the following items should be tested:
1. Tensile Strength: ≥20MPa is ideal, reflecting resistance to fracture.
2. Elongation at break: ≥300%, ensuring flexibility and adaptability.
3. Abrasion resistance: Low volumetric abrasion (e.g., ≤90mm³/N·m), determining service life.
4. Interlayer bond strength: ≥3.0 N/mm, preventing peeling of the cover layer from the skeleton.
5. Hardness (Shore A): Typically between 85–95°; too high a hardness leads to brittleness, too low a hardness leads to deformation.
IV. Compliance and Safety Verification
1. Food-grade applications must comply with FDA standards: Verify that the supplier provides FDA certification documents or test reports.
2. Environmental and safety requirements: Check for the presence of prohibited plasticizers, heavy metals, or halogens, especially when used in pharmaceutical or children's food production lines.
