preheat

Preheat refers to the act of warming something to a desired or specified temperature before it is used, operated, or processed. The goal is to improve performance, safety, reliability, or quality by reducing temperature shocks, ensuring consistent conditions, or enabling proper functioning of subsequent steps. Preheating can apply to tools, devices, materials, fuels, or environments across various fields.

In cooking, preheating an oven or pan is a common practice to achieve even heat distribution and accurate temperatures, which helps foods rise, brown properly, and cook uniformly. Some recipes require precise preheating times to ensure correct texture and doneness.

In metalworking and welding, preheating the workpiece is used to decrease temperature differentials that can cause distortion, cracking, or residual stresses. It is particularly important for thick sections, high-hydrogen steels, or materials sensitive to thermal shock. Interpass preheating may be used during multiple-pass welds to maintain a controlled thermal cycle.

In engines and machinery, preheating is common in cold environments. Block heaters or glow plugs can raise the engine temperature for easier starting, reduced wear, and better lubrication on startup. Preheating fuels or air in certain systems can improve combustion efficiency and reduce moisture-related problems.

In electronics manufacturing, preheating is part of soldering and reflow processes. Boards and components are gradually raised to the target soldering temperature to prevent thermal shock, improve solder flow, and ensure reliable joints.

Overall, preheating is a preparatory step intended to optimize subsequent performance, efficiency, and durability by mitigating abrupt temperature changes.