The Die Casting Process
Die casting is a casting procedure for metal, which is characterized by the use of molten metal forced under high pressure into a mold cavity. This cavity is created by use by two hardened steel dies, machined into exact shapes, and are used similar to injection molding. Most die casting uses non-ferrous metals, particularly zinc, copper, aluminum, lead, magnesium, pewter, and tin-based alloys. Depending on the metal-type being cast, a cold- or hot- chamber machine is used.
Die casting is particularly suited for a large quantity of small to medium sized castings, which is why this process produces more castings than any other casting process. Manufacture of parts using die casting is relatively simple, involving only four main steps, which keeps the incremental cost per item low. Die castings are characterized by a very good surface finish (by casting standards) and dimensional consistency. The casting equipment and the metal dies represent large capital costs and this tends to limit the process to high volume production.
Automation in Mass Production
Die-cast products comprise the bulk of mass-produced items manufactured by the metalworking industry, from alloy-based children’s toys to automotive engine parts, and the integrated design of a die-casting work cell is critical to make these products at competitive rates.
As with other manufacturing processes, robots have become a vital component in automated die-casting cells, and there are many factors that must be considered when designing an automated cell.
The size and shape of the product drives the design of the dies used in die casting, and the shape and size of the die help to define the size and capabilities of robots that are used to service diecasting machines. The use of robots also relies on the reach they will have to have and the accessability of the cast product.
Besides die-cast product shape and size, factors such as temperature, payload and force requirements have to be considered when designing an end-effector for a robot.
While environmental conditions are important in choosing a robot, payload, reach and part access within the die also are key factors. The mass, center of gravity and moments of inertia about the mounting face of the robot all combine to determine the robot model that must be used to handle the payload capacity – the part size – for which the cell is designed.
(sources: Wikipedia, Charles Bates)