When we receive a worn gear with no material certificate, we take a small cross-section sample (from a broken tooth or a non-functional area, with customer approval) and perform optical emission spectroscopy (OES) to determine the exact chemical composition and choose the equivalent gear material to be used. We identify key alloying elements such as chromium, nickel, molybdenum, vanadium, and manganese. Based on the composition, we cross-reference with international standard grades (e.g., ISO, SAE, DIN, JIS) to find the closest equivalent. Typical recommendations include 18CrNiMo7-6, 20MnCr5, SAE 8620, or 17CrNiMo6. If the exact grade is not available in our inventory, we propose the nearest substitute and provide comparative data on hardenability, tensile strength, and fatigue limits. We always obtain customer approval before proceeding with the chosen alternative material.