In machining operations, what is the process of lengthening a piece of stock while reducing its cross-sectional area called?

The process described, where a piece of stock is lengthened while simultaneously reducing its cross-sectional area, is known as "upsetting." Upsetting, sometimes referred to as forging, involves compressive forces that not only increase the length of the material but also cause its diameter to decrease, leading to a change in its shape. This is commonly seen in processes such as forging, where metal is heated and then shaped through a series of compressions to optimize its mechanical properties and create desired geometric forms.

In contrast to the other terms presented, upsetting specifically relates to this phenomenon in metalworking. Bloating, spreading, and draining out do not accurately describe the process of lengthening metal stock in the same way. Bloating is not a recognized term in this context, and while spreading may imply some alteration in dimensions, it does not denote the specific process that affects cross-sectional area in a manner defined by upsetting. Draining out is unrelated to material shaping and implies the removal of fluid rather than a change in the form of solid materials. Thus, upsetting is the correct term for the process in question.