Die casting is a widely used technique to inexpensively […]
Die casting is a widely used technique to inexpensively create metallic parts for a variety of applications. The process of die casting has been in use for hundreds of years, but innovations in techniques and materials have improved the efficiency of the process and the quality of the final product.
One of the most important innovations in the die casting process is the development of the pressure injection process. One of the earliest pressure methods was squeeze casting, which involved putting a metal part that had been heated into a mold and applying pressure via leverage. The squeeze casting method was first used for manufacturing axe heads. However, this method was limited to parts with very simple shapes.
The method of injecting molten metal into a mold was patented in the mid-1800's to create lead printer's type. Using pressure allowed the molten metal to be forced into all portions of the mold, resulting in the ability to die cast more complex parts with a higher quality surface finish. Because pressure injection die casting is quick, the mold is completely filled before any of the metal begins to solidify, resulting in more dimensionally stable parts.
Early die casting processes used lead or tin alloys, because they could be easily melted and handled. The melting points of these alloys were low enough to prevent damage to the die. The development of more durable steel alloys for molds and tooling allowed for alloys with higher melting temperatures to be used. During World War I, new zinc and aluminum alloys were introduced, and the use of tin and lean declined swiftly. Magnesium and copper alloys also came into use in the first half of the 20th century, giving manufacturers flexibility in their material and design choices.
After the innovation of pressure injection die casting and the introduction of new alloys, the die casting process remained fairly constant for many years until the introduction of the computer to the manufacturing industry. Computers are now used throughout the design and fabrication process, including:
1. Mold Design: Digital design systems allow engineers to create and evaluate mold designs electronically, resulting in fewer prototypes and design iterations.
2. Mold Fabrication: Computer-aided manufacturing (CAM) processes and advances in tooling allow for very complex dies to be created with minimal human labor. Complex curvatures and intricate details can be machined into the mold with a CAM application controller.
3. Process Automation: Computer systems can control the actual die casting process and monitor the status of the part during all portions of the manufacturing process. Systems can maintain the correct pressures during casting, monitor the temperature of the molten metal and the mold after casting, control part cooling through water channels, and determine when the part can be extracted from the mold.
Although the overall concept of die casting has not changed significantly over the last few hundred years, advances in process, materials, and technology have allowed manufacturers to create more complex parts in a cost-effective manner.