The resulting surfaces may look flat to the human eye, and some even sport a mirror finish, but on a microscopic scale, there will be peaks and troughs in the surfaces that prevent perfect contact across the entire area. Firstly, while the surfaces of metal components are often machined to make them flat, you’d need an almost impossibly-flat surface to achieve the best thermal transfer – if it’s not completely flat, you quickly start compromising the two surfaces’ ability to conduct heat between themselves. In reality, though, there are several factors preventing an efficient transfer of heat. You might think that placing one metal component against another one would result in good enough contact for heat to conduct effectively from one component to the other.
