Die Cast Magnesium
Die Cast Magnesium
During the casting process, metal parts manufacturers pour molten metals (and typically) metal alloys into molds. As this liquid cools, it will assume the solidified shape of the mold cavity. For centuries, casting has provided an excellent way to create new products in a variety of different shapes and sizes. Casting today utilizes temporary, semi-permanent or even permanent (i.e. long lasting and reusable) molds formed from a variety of materials.
Die casting has gained popularity as a way to manufacture a high volume of metal parts comparatively rapidly. During this largely automated process, a manufacturer creates one or more dies and forces or presses hot metal into the die cavity. When the die mechanically ejects the part, the metal work piece will have assumed modified dimensions due to the shape of the dies and the pressure applied by the manufacturer during injection.
Die casting operations typically occur in a well-planned assembly line array. Today, computerized automation frequently plays a key role in the die casting process. Work pieces may proceed through a series of die casting stations during the production of metal components. Die casting permits manufacturers to generate large runs of small, detailed parts very cost-effectively.
Alloys Used in The Die Casting Process
Metal workers for centuries have created alloys by adding one metal to another, or to another element, such as carbon. Typically, a manufacturer melts the constituents together in the presence of heat. Different alloys display distinct physical, mechanical, chemical and conductive (or nonconductive) properties based upon their unique combinations of constituents. As a result, they permit the production of metal parts which demonstrate markedly different degrees of weight bearing and tensile strength, density, corrosion resistance and wear resistance.
Currently, although manufacturers around the world still rely extensively upon ferrous and steel alloys during the production of metal parts through casting, during die casting four other types of metal alloys have assumed great importance:
Aluminum Alloys: During the Twentieth Century, lightweight aluminum alloys gained widespread use due to the comparatively low cost of aluminum. Today these alloys predominate within the die casting industry. Metallurgists developed a wide array of aluminum alloys by combining aluminum with different percentages of other elements, including copper, manganese and silicon.
Magnesium Alloys: Magnesium alloys achieved increasing importance as a die casting raw material during recent years. When alloyed with other elements, including aluminum, magnesium offers low density and reasonable strength.
Zinc Alloys: Zinc alloys weigh considerably more than aluminum or magnesium alloys, but reportedly they have gained popularity in die casting due to low cost and corrosion resistance. Manufacturers frequently combine zinc alloys with aluminum and copper.
Zinc-Aluminum Alloys: This group of alloys combine properties of zinc and aluminum. The low cost and improved wear-resistance offered by some zinc-aluminum alloys contributes to the popularity of these alloys in mass production environments.
Magnesium Die Casting
Magnesium alloys hold numerous advantages for commercial die casting purposes. While the metal magnesium poses significant handling challenges as a raw material for metal working due to its combustibility, during recent years metallurgists have developed a number of magnesium alloys suitable for injection die casting. Some popular magnesium alloys for this purpose include: AM20, AM50A, AZ91D and AM60B. In general, manufacturers don't attempt to die cast magnesium alloy parts weighing more than 40 pounds, and most production facilities use die casting to generate far smaller parts:
- AZ91D: This magnesium alloy has gained widespread popularity for use in die casting facilities. It permits the production of detailed, strong parts. It also furnishes better corrosion and wear resistance than some other magnesium alloys. Probably for these reasons, it has become the most widely utilized magnesium alloy.
- AM20: Also employed frequently in commercial die casting, this magnesium alloy supplies excellent ductility.
- AM60: A magnesium alloy which casts readily, AM60 contributes to strong components displaying a high degree of ductility.
- AM50: This magnesium alloy possesses less strength than AM60. It won't cast as readily, either. However, manufacturers prefer this alloy for some applications because it displays higher ductility than AM60.
Die Cast Magnesium: Properties And Applications
Many properties of magnesium contribute to popular magnesium alloys. Die cast parts formed from magnesium alloys tolerate machining well, although (depending upon the purpose) they may require extensive finishing. They also display light weight and excellent strength-to-weight ratios. They possess a high modulus of elasticity.
Some popular applications for parts made from die cast magnesium alloys occur within the aviation, aerospace and automotive industries. The light weight and comparatively high strength-to-weight ratios of magnesium alloy components enable them to replace some aluminum alloy parts in vehicles, helping to create lighter weight products which consume less fuel. Die cast magnesium alloys today contribute to automotive instrument display panels, seating frames, and even some powertrain and engine components.
Advantages of Magnesium Die Casting
Die cast magnesium parts offer several advantages.
- Die casting permits manufacturers to generate large runs of comparatively lightweight components. Classified as a structural metal, magnesium possesses a lower density than aluminum.
- In some cases, manufacturers can reduce their investment in finishing by employing die casting. Parts may display excellent dimensional accuracy and surface detail. Magnesium alloys permit die casters to create thin walled parts, for example.
- Manufacturers machine some die cast magnesium alloy parts readily. The use of alloys can facilitate much easier handling than relying upon pure magnesium alone.
- Although magnesium today still remains more costly than aluminum, during recent years manufacturers have learned to extract this metal from many sources and global production has increased.