A heatsink is a passive heat exchanger that transfers heat. The heatsink is typically a metallic part which can be attached to a device releasing energy in the form of heat, with the aim of dissipating that heat to a surrounding fluid in order to prevent the device overheating.
Heatsinks can be manufactured in a variety of ways depending on the required performance, cost and volume. These include:
Machining - where a CNC machine is used to cut the metal
Extrusion - where metal is heated and pushed through a mold
Forging - where metal is heated and shaped by pressurization
Stamping - where the metal fin is cut, and then soldered onto the base
Skiving - where a blade is used to slice, and push up the single block of metal