Long ago in a galaxy not far from here, fuel was cheap. Vehicles were large and not particularly efficient. Devices were heavy and tended to stay in one place, and iron was king. That was then; today, all that has changed. Energy is costly, vehicles are smaller and lighter, our devices travel with us in pockets or purses, and iron is something you pump for exercise. To meet our ever-growing demands for economy and portability, we have been steadily replacing iron with aluminum and plastic, and increasingly with magnesium.
Magnesium is finding its way into a growing variety of applications, particularly those in which it helps reduce energy consumption. In aerospace applications, it’s used in engines, airframes, and internal parts. In automotive applications, it turns up in steering components, seat and sunroof tracks, and interior frames, not to mention “mag” wheels. More recently, it’s being used in roof, hood, and rear-deck lids, manifolds, cylinder head covers, and oil pans. It is even being tested for use in engine blocks. And for similar reasons, magnesium is showing up in motorcycle and bicycle parts, such as lightweight frames. In consumer applications, magnesium is often used in laptops, cell phones, digital cameras, power tools, and sporting goods. Military applications include hand-held communication devices, night-vision gear, and robotics.
This is for good reason. Magnesium is the lightest usable structural metal — widely available and easy to produce. By weight, it’s the seventh most common material in the Earth’s crust and the third most common in seawater. It is found in every cell of the human body and is an essential element in the chlorophyll in green plants. Because of its reactivity, it is one of nature’s more sociable elements and does not naturally occur in elemental form. It is, however, relatively simple to separate from its salts, and once in solid form, its surface oxidizes, producing a tenacious protective layer that resists further oxidation. Additionally, it can be coated by various means for further protection.
While it can be used in essentially pure form, magnesium typically is found in lightweight alloys, most commonly with aluminum, zinc, or manganese. It’s nearly as strong as aluminum and about one-third lighter, giving it a significant strength-to-weight advantage. It has excellent electrical characteristics, excellent thermal conductivity, is reasonable in cost, and is easily recyclable. For these reasons, it’s a very desirable material, and we can expect to see magnesium in a growing range of applications as technology for its use and fabrication continues to develop.
Besides machining, which is typically used when small numbers of parts are needed, the primary fabrication methods for magnesium are:
- Extrusion: typically used for simple forms;
- Lost wax casting: a complex process of about a dozen steps that produces near-net parts and can be used for prototyping of complex designs; and
- Die casting and thixomolding: net-shape processes typically used for larger runs of complex magnesium parts.
Read the full article on die casting, thixomolding and other magnesium prototyping and production applications at Designfax.