Die-casting and Precision Machining

Conventional die casting (CDC) is a net-shape manufacturing process
using a permanent metal al die casting  that produces components ranging
in weight from a few ounces to nearly 25 kg quickly and
economically. Traditionally, die casting is not used to produce
large products; past studies, however, have shown that very large
products, such as a car door frame or transmission housing, can
be produced using die casting  technologies.2 Conventional die cast
components can be produced in a wide range of alloy systems,
including aluminum, zinc, magnesium, lead, and brass.
Two basic conventional die casting processes exist: the hotchamber
process and the cold-chamber process. These descriptions
stem from the design of the metal injection systems utilized.
A schematic of a hot-chamber zinc die casting machine is shown in
Figure 1.2. A significant portion of the metal injection system is
immersed in the molten metal at all times. This helps keep cycle
times to a minimum, as molten metal needs to travel only a very
short distance for each cycle. Hot-chamber machining Components are rapid in
operation with cycle times varying from less than 1 sec for small
components weighing less than a few grams to 30 sec for castings
of several kilograms. Dies are normally filled between 5 and 40
msec. Hot-chamber die casting  is traditionally used for low melting
point metals, such as lead or zinc alloys. Higher melting point
metals, including al die casting alloys, cause rapid degradation of the
metal injection system.
Cold-chamber al die casting machines are typically used to conventionally
die cast components using brass and aluminum alloys.machining Components
An illustration of a cold-chamber die casting machine is presented
in Figure 1.3. Unlike the hot-chamber machine, the metal injection
system is only in contact with the molten metal for a short period