How to understand the differences between steel and aluminum

The high-strength aluminum alloys available today are feasible alternatives to steel for tooling. Originally used primarily for the production of prototypes because of its lower cost, aluminum offers several other advantages that make it a viable option for production molds.

First and foremost, aluminum molds can cost as little as approximately half of what steel molds cost, and it can be delivered in about half the time, thanks to various key material characteristics. For example, although steel is considerably stronger than aluminum, aluminum weighs only one-third as much, and some aluminum materials can be treated to produce strength comparable to steel. Because aluminum is softer than steel, it is easier to cut. The combination of high strength and low weight makes aluminum attractive for use in a variety of industries, including aerospace, automotive and industrial.

Another advantage of aluminum over steel is its high resistance to corrosion. When aluminum is exposed to air, a thin layer of aluminum oxide forms, providing increased protection against corrosion. Additionally, aluminum does not become brittle with decreasing temperatures as steel does. It actually increases in tensile strength and retains toughness.

Aluminum is known to conduct heat and electricity about six times better than steel, and its higher thermal conductivity plays a critical role in welding and mold repair, resulting in welds that solidify faster. This also contributes to a more “practical” weld, better holding the metal in position and easing onsite repair. High thermal conductivity means that heat energy applied to one section of the metal will transfer quickly to other sections. This allows the material to retain stability while withstanding higher temperatures. To avoid degradation of part quality, however, aluminum requires welding with a more intense heat at a faster rate, because the heat is withdrawn rapidly.