- 1 Recompenses of Each Metal Alloy
- 2 Types of Die Casting Mold Processes
- 3 Die Casting Mold Process Cycle
- 4 Advantages of Die Casting Mold
- 5 Disadvantages of Die Casting Mold
Die casting mold is a process in which a molten metal is used to manufacture new metalloid products. In this process, a molten metal is forced into a molded cavity under high pressure.
The three main components of the die casting process are the die casting machine, metal, furnace, and above all a die.
Die castings are produced in a variety of sizes and shapes, starting from a few ounces and reaching up to 100 pounds. These castings are most commonly used to manufacture pumps, gears, thin-walled enclosures, propellers, and many more.
However, the metals which are used in this process are non-ferrous metals such as copper, pewter, aluminum, lead, zinc, tin, and magnesium-based alloys.
Recompenses of Each Metal Alloy
There are specific benefits of each metal alloy which is being used in the die casting process. A synopsis of the recompenses shown by each metal alloy is mentioned below.
Copper is known to have the highest number of advantages when it comes to die casting process. Copper has a very high weathering resilient capabilities and it can be drawn into various shapes quite easily as it is referred to as a stable metal.
Moreover, the strength of the copper can be unarguably compared with that of steel. Copper is also a very hard metal with great mechanical characteristics.
This metal is the most light-weight metal. Aluminum has a number of physical and chemical properties because of which it is used in the die casting process primarily having good weathering resilient capabilities.
Moreover, aluminum is a good conductor of heat and electricity. Aluminum can also be drawn into a variety of complex shapes due to its configurational stability.
Lead and tin
Both of these metals have a significant amount of corrosion resilient properties. They have very high densities; therefore, they are being used in the die casting process. However, these two metals are used in a short amount and contain small amounts of copper as well.
Out of all the metals, zinc is the most convenient to use in the die casting process as it can be cast more easily as compared to other metals. Zinc has a very lengthy die life and it is affordable to be cast on smaller parts. Moreover, zinc has high flexibility and it can be effortlessly plated onto different surfaces.
Most of the metals have some difficulty while passing through any machine except magnesium. Magnesium is the most convenient metal to pass through any machine. Moreover, it has outstanding strength/weight fraction. Thus, it is a major metal to be used in the die casting process which can’t be neglected.
Types of Die Casting Mold Processes
Die casting mold has a wide range of applications. Currently, many industries are taking advantage of this process. However, there are two main types of die casting mold processes.
Hot-chamber Die Casting Mold Process
This process is so named as it primarily uses a hot-chamber die casting mold machine. For this casting process, the metals with low melting temperatures are usually used because a high temperature may destroy the machine altogether.
Therefore, metals like aluminum which requires high temperature can’t be used in this process whereas the metals like zinc, lead, and tin-based alloys are the best-fit for this process.
In this process, the metal is first melted under a specific temperature in a furnace. The melted metal is then plunged into another chamber where a die is present under hydraulic pressure.
The molten metal flows into this chamber through a gooseneck channel. Thus, this process is also termed as gooseneck casting process.
The plunger remains in the die cavity until the molten metal hardens to maintain the hydraulic pressure. Once the metal is hardened, the plunger is then emitted out of the die cavity. This process is usually more convenient because it enables 15 cycles per minute.
Cold-chamber Die Casting Mold Process
Typically, in this process, the machine used is named as cold-chamber die casting mold machine. The metals which are unable to use in the hot-chamber die casting mold process are used in this process.
The metals such as aluminum and zinc alloys which have a high concentration of aluminum and magnesium are normally used. Thus, this is the process which takes place at high temperatures.
In this process, the metal is first melted at an elevated temperature in a furnace.
However, rather plunging the molten metal into the die cavity, it is ladled to the cold-chamber under hydraulic pressure. The die cavity is separated from the furnace and the molten metal is transferred to the die cavity using a plunger.
As in the hot-chamber die casting mold process, the plunger remains in the die cavity until the molten metal solidifies into the desired shapes.
Once it is the hardened, the plunger retreats from the die cavity. This process takes a lot of time as it is done at a slower pace because it includes the transfer of the molten metal.
There are two die halves which are commonly used in the die casting process. These two die halves are named as a ‘cover die’ and the ‘ejector die’.
The cover die half consists of a sprue in case of a hot-chamber machine or a shot hole in case of the cold-chamber machine.
On the other hand, the ejector dies half consists of the runner and the ejection pins from which the molten metal is drawn from the cover die half. The cover die half is fixed to a platen whereas the ejector die half is clamped to a movable platen.
The two die halves are manufactured in such a way that the molten metal flows from the cover die half to the ejector die half and smoothly out of the ejector die half by the help of the ejection pins.
Ejection pin plate is used to steer these ejection pins which are assembled together for the smooth casting. These ejection pins are accelerated at the same pace so that it won’t damage the die casting mold.
Additional die machinery includes cores and slides. Cores are the machinery which is used to make a cavity or an orifice. Cores are of three distinct types.
- Fixed Cores are those cores which are disposed of in the direction of the die opening. Hence, they remain fixed to the die.
- Moveable Cores are those cores which are disposed of in some other means or paths than in the direction of the die opening. However, it must be noted that these cores should be detached once the injection hardens but prior to the opening of the die cavity.
- Loose Cores are the cores which are only used to imprint sophisticated structures, for example, threaded hovels.
Like movable cores, the sides work on the same principle but they are primarily used to construct undercut planes.
Die Casting Mold Process Cycle
Every process cycle has some significant stages each of which holds an immense importance. Die casting mold process cycle has five distinct stages through which the desired metal is manufactured.
This is the first step of the die casting mold process in which the two die halves are attached for the preparation of a new material.
Before fastening the two die halves, the two sections are cleaned and lubricated from the former inoculation. Water-based lubricants are usually used for this process because of the several environmental, safety and health reasons. Lubrication is not a continuous process but it is done after two or three injections.
Once the two die halves are properly cleaned, they are safely clamped together. Considerable strength is provided to keep the two halves caulked during the injection of a molten metal.
The next step in this process is the injection of the molten metal into the die cavity using any of the above-mentioned methods depending upon the kind of metal being used.
The metal which is being transferred to the die cavity is termed as a shot. The melted metal is supplied to the hot or cold chamber under specific pressure.
The injection time is defined as that time in which the molten metal completely fills up all the canals and grooves in the die cavity.
After the injection of the molten metal, it is subjected to the process of cooling. This metal remains in the die cavity until it is hardened and drawn into a specific shape. It is forbidden to withdraw the molten metal or open the die halves before the end of the cooling time.
The cooling time primarily depends upon the thickness of the die casting wall, the die, and the type of metal being used.
After the molten metal is properly cooled, the die halves are opened and the injected metal can be taken out.
However, a considerable amount of force is required to eject the cooled injection because during the cooling process, the molten metal contracts and clings to the walls of the die casting chambers.
After ejection, the two halves are then shut down and get ready for the subsequent shot.
This process is essential for cutting off the extra edges that are formed during the cooling process. These supplementary edges can be formed because of the incorporation of the die into the molten metal.
Trimming can be done by hand or by the use of the trimming press. The trimmed off material can be reused in the next cycle by adding adequate amounts of chemicals comparable to the next shot.
Advantages of Die Casting Mold
There are several distinct benefits of the die casting mold process because of which this die casting process in such a high demand.
Every metallic part which is processed through this process has a top-notch quality. The metals used in this process are durable and long-lasting. Thus, whatever metal is being manufactured by this process is certainly long-lasting and highly corrosion resilient.
The products formed by the die casting mold process require minimal time and guarantees a long-lasting service. These parts entail trifling upkeep.
The products formed by this process demands a minimal assembly of certain features or structures. Assembly of drill holes, bosses and studs are usually done to enhance the visual appeal of the products being formed. However, this assemblage doesn’t take up any extra time.
The molten metal can be drawn into various shapes and sizes comprising of any specific geometry. Moreover, a certain amount of texture or luster can be added in the manufactured parts which add in the versatility of the products.
Die casting mold process takes place in such a way as to instill high conformity between the manufactured products. Every metallic alloy used in this process consists of high ductility and great configurational stability which inculcate exceptional qualities of consistency which are unarguably long-lasting.
Disadvantages of Die Casting Mold
Every beneficial thing has certain limitations as well. Likewise, die casting mold has some highlighting factors which can’t be ignored.
Only used for soft parts
One of the drawbacks of the die casting mold process is that it can only be used to manufacture those products which have a certain amount of softness. Those parts which require tempering or hardening should resort to other casting processes.
Air must be evacuated from that place where the die casting mold process is being carried out. This is because air can penetrate into the surface of the products. Thus, if this product is subjected to welding or heating, mini-cracks will be formed on the product. This is because gas expands when it comes in contact with heat.
Great Preliminary Cost
This is the main disadvantage of the die casting process. Every machinery of the die casting process including the hot and cold chambers along with the die halves can prove to be extremely exorbitant. Hence, a large sum is required in order to start a die casting mold process.