Which production method involves pouring molten metal into a mold and allowing it to cool?

The production method that involves pouring molten metal into a mold and allowing it to cool is known as casting. This process is fundamental in manufacturing and allows for the creation of complex shapes and forms that would be difficult to achieve through other methods.

In casting, after the molten metal is poured into the mold, it takes the shape of the cavity and, once it solidifies upon cooling, the mold is removed to reveal the finished item. This process is particularly advantageous for producing large quantities of items with intricate designs, as well as for creating parts with excellent surface finishes.

The other methods listed—welding, forging, and machining—operate on different principles. Welding involves joining metal pieces together through the application of heat, forging shapes metal through compressive forces, and machining removes material from a solid block to create a desired shape. While all these methods are important in manufacturing, casting specifically pertains to the use of molten metal and molds, making it distinctly suited for certain applications.