Advances in Die-Casting Processes
Die-casting is a popular technique to inexpensively create metallic parts for a range of applications. The process of die casting has been in use for thousands of years, but innovations in techniques and materials have improved the effectiveness of the process and the quality of the final product.
Die-casting by pouring molten metal into a die, commonly known as as the gravity pressure method, is a manufacturing method that has been used for hundreds of years. Innovations in the die-casting process led to an explosion of die-casting for most uses in early 1900’s, especially when zinc and aluminum alloys became far more readily available.
Pressure Injection Die-Casting
By far the most important innovations in the die casting process was the advancement 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 initially used for manufacturing axe heads. Nonetheless, this strategy was limited to parts with rather easy 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 areas of the mold, resulting in the ability to die cast more complex parts with a greater quality surface finish. Because pressure injection die-casting is fast, the mold is completely filled before any of the metal begins to solidify, resulting in more dimensionally stable parts.
Improvements in Materials for Die-Casting
Early die casting processes used lead or perhaps tin alloys as they might be quickly 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 very first half of the twentieth century, giving manufacturers flexibility in the material of theirs and design choices.
Computers and Die-Casting
After the innovation of pressure injection die-casting and the launch 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:
o Mold Design – Digital design systems allow engineers to develop and evaluate mold designs electronically, resulting in fewer design and prototypes iterations.
o Mold Fabrication – Computer-aided manufacturing (CAM) processes and advances in tooling allow for very complex dies to be made with little human labor. complex curvatures and Intricate details can be machined into the mold with a CAM application controller.
o Process Automation – Computer systems are able to control the actual die-casting process and then monitor the health of the part during all portions of the manufacturing process. Systems are able to 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 if the part can be extracted from the mold.
Although the general concept of die casting hasn’t changed significantly over the last few hundred years, advances in process, materials, and technology have allowed manufacturers to create more complicated parts in a cost effective manner.