Die casting for auto parts is one of the most cost-effective and
time-efficient forming methods. The benefits of this manufacturing method
include the ability to manufacture hundreds of thousands of castings in a short
amount of time with just one mold. All of the components manufactured are of
consistent quality and have minimal unit prices. But, exactly, what does the
manufacturing process entail? What materials are acceptable, and where are
castings used?
“Die Casting” is a term used to describe the process of casting metal.
Die castings for auto parts is an automated
casting method in which a liquid melt is forced into a mold at a fast filling
speed (up to 540 km/h) and under high pressure (150 to 1200 bar).
Typically, low-melting-point alloys are
employed. Unlike sand casting, for example, this casting technique uses
permanent metal molds that do not have to be destroyed after casting, making it
ideal for the series and mass manufacturing of components. Low wall thicknesses
allow for the production of big, complex components.
Molds
Die casting molds are made of two halves
that form a cavity into which the liquid melt is pressed during the casting
process. They are made of high-quality, heat-resistant steel grades. On a fixed
and moveable machine plate, the halves are located.
The mold halves are subjected to
significant pressure during the casting process, so locks are included.
Furthermore, specific mold portions are cooled and heated to ensure that the
casting solidifies properly.
The molds are expensive and
time-consuming to make, yet they can generate anywhere from tens of thousands
to over a million castings with only one.
Procedures and functionality.
There are two types of die casting components:
hot-chamber dies casting and cold chamber die casting. Before the casting
process in both manufacturing techniques, the mold is sprayed with a release
agent to guarantee that the subsequently cast item may be easily removed from
the mold.
On the other hand, the melt is put into
the castings for auto parts machine’s
casting chamber before being poured into the mold cavity. A piston (the
so-called casting set) then presses the alloy into the mold through several
channels. The structure of the casting chamber, as explained below, is the
difference between the two procedures.
Die Casting in a Hot Chamber.
The casting chamber is continually in
contact with the liquid alloy is a distinguishing feature of hot chamber die
casting machines. The melt enters the casting chamber through a valve, where
the piston forces it into the closed die casting mold at high speed. This
method is utilized for alloys with a low melting point, such as zinc, lead, or
tin.
Die Casting in a Cold Chamber.
The casting set is situated outside the
melt in cold chamber die casting machines. The alloy is poured into the casting
chamber and forced into the die casting mold through channels to create a
component. This method works well with materials that have a higher melting
point. Aluminum and copper, for example, are examples of these materials.
In both techniques, when the alloy has
been forced into the mold, the component solidifies under high pressure,
allowing the mold latches to be opened.
Automatically operated ejection pins remove
the gated portion from the mold, allowing it to be further treated if
necessary. In simple terms, the casting process can be broken down into the
following processes, which occur in fractions of a second – or even thousandths
of a second – in practice.
- Filling the casting mold quickly with the alloy.
- High-pressure curing of the component.
- The component is removed from the mold after it
has been opened.
In the mass production of light metal
castings, cold chamber dies casting is the most common method.
Materials
Aluminum, followed by zinc and
magnesium, is one of the most significant materials, accounting for more than
80%. Copper, lead, and tin, on the other hand, can be used. The characteristics
of the alloys vary. Aluminum and magnesium, for example, have high melting
points of 600°C and 520°C, respectively, while zinc (380°C) and lead (320°C)
have low melting points.
Low-Pressure vs. High-Pressure
In foundry practice, a variety of
processes are used. Castings for
auto parts can also be made without using a lot of pressure. For
example, the alloy is poured into a sand mold in the sand-casting technique,
which must be destroyed to reveal the created component (lost foam).
The molds and models (typically
made of wax or plastic) are also destroyed following the casting process in
investment casting, which is used to make very small cast parts. Gravity Die
Casting, for example, uses a permanent metal mold but does not employ
significant pressure to force the melt into the mold. Rather, the mold is
filled by gravity, or the casting is made.
The casting for auto parts technique has its own set of
differences. Some techniques use either high or low pressure to manufacture
components, for example. Low-pressure die casting accounts for little under 20%
of total light metal casting output, whereas high-pressure die casting accounts
for roughly 50% of production.
Low-melting-point alloys are commonly
used in low-pressure die casting. Components from 2 to 150 kg can be cast. The
benefits include achieving extremely high strength values and complex
geometries and enhanced material use and dimensional precision.
Only a minimum wall thickness of 3 mm
may be achieved, and the method is less suitable for very thin-walled objects.
It’s also worth noting that low-pressure die casting cycles are slower than
high-pressure die casting cycles.
The melt is forced into the mold at high
pressure, and high speed in high pressure die casting, which speeds up the
casting cycle. Castings with thinner walls (minimum wall thickness of 1 mm) and
smoother surfaces can also be made.
The downside of this manufacturing
process is that it has high operating and investment costs, lower strength
values, and a limited die casting weight because it is dependent on the machine’s
closure force.
Conclusion
Die casting for auto parts technology has advanced at a breakneck
pace. Initially, die casting was mostly done with lead and tin, two metals with
low melting temperatures and strong ductility. Around 1914, research on higher-strength
zinc and aluminum alloys began. In the 1930s, copper and magnesium alloys were
added.
Magnesium, which has a specific
density of 1.74 g/cm3 and is employed mostly in the automotive industry, had
its first boom as a die casting material between 1946 and 1978: the VW Beetle’s
engine and gearbox were constructed of this material.
Thank you for your blog Zinc High Pressure Die Casting Manufacturers
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