A combustion cap effusion plate (CCEP) is a term used in the welding industry to describe a type of weld joint that can occur when two pieces of metal are welded together. The weld joint is formed when the gases that are generated during the welding process escape from the molten area and collect on the outside of the Weldment. This can create a thin film of molten metal that forms an impermeable barrier between the two pieces of metal.
The oxidation cap effusion plate allows for a more uniform weld profile and eliminates or reduces the chances of gas flow distortions, cold spots, porosity, and other defects in the final weldment.
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How does a combustion cap work?
A combustion cap is a metal or plastic cover, typically made of thicker materials than the remainder of the engine block, that fits over the exhaust valve and seals it against atmospheric pressure. The purpose of a combustion cap is two-fold: to prevent the emission of harmful gases from the engine, and to provide a heat barrier between the hot exhaust gas and the surrounding engine block.
In order to function properly, a combustion cap must be adequately lubricated. This is accomplished by passing oil through small holes in the top of the cap, which allows it to flow into and around the exhaust valve. The oil serves as an interface between the hot gases passing through the cap and the colder ambient air outside of the engine. In addition, a combustion cap must be sized appropriately so that its weight does not excessively compress or deform the metal surrounding the exhaust valve.