In excavator undercarriage wear parts procurement, how to evaluate replacement cycle cost for track chains and rollers?

• Replace track chains when pitch wear exceeds 4mm to avoid sprocket damage.
• Replace rollers if oil leaks or axial clearance exceeds 1.5mm.
• Require HRC hardness report; track pin hardness ≥50HRC.
• Calculate cost per hour: price ÷ expected life, prefer ≥4000 hours.
• Confirm grease channels; maintenance-free type cuts downtime cost.