How soon must preheating begin after the molds have been luted?

The preheating process must begin within 10 minutes after the molds have been luted to ensure optimal conditions for thermite welding. This timeframe is critical because the materials used in thermite welding can cool down rapidly once the luting is completed. If preheating is delayed, it can lead to problems such as inadequate melting of the thermite mixture, insufficient fusion of the metal, or even structural integrity issues in the weld joint. Preheating prepares the mold for the intense heat generated during the thermite reaction by gradually raising the temperature of the surrounding metal, ensuring a smoother and more effective welding process. Following this timeline helps maintain the necessary thermal conditions for a successful weld.