The optimal operating temperature for a Raymond roller mill can vary depending on the materials being processed and the specific configuration of the mill. Generally, it is advisable to keep the operating temperature below 75°C (167°F) to avoid any potential issues related to overheating, material degradation, or equipment damage. However, the exact temperature may differ based on the manufacturer's guidelines and the nature of your specific application. It's always best to consult the user manual or contact the manufacturer directly for precise recommendations.