Die Casting Process

Die Casting Process

Die Casting Process is a standard manufacturing technology common in every industry. This die casting process may vary in different methods and technology depending on the complex shape and structure.

Today’s article will illustrate a brief knowledge of the die casting processes, their types, application, and pros & cons.

What is die casting?

Die casting is a kind of metal casting that involves pushing molten metal into a mold chamber under high pressure. Operators machined the two hardened tool steel dies into form and operate in the same way as an injection mold throughout the operation to produce the mold cavity. Non-ferrous metals, such as zinc, copper, aluminum, magnesium, lead, pewter, and tin-based alloys, make most die castings. They employ a hot-chamber or cold-chamber machine depending on the kind of metal to cast.

Die Casting Process

You must spray a lubricant into the cavity during the preparation procedure. In addition to assisting in managing the mold’s temperature, lubricants may also assist in removing the casting.

Die Casting Process

First, The machine melts the inserted metals, the type of metals depends on the tool you will create. And then, the machine automatically pours the molten metal into the mold at high pressure. This pressure is generally in the range of roughly 10 to 175 MPa. When the machine pours the molten metal, the pressure is maintained until the casting hardens.

Consequently, the machine opens the dies with the ejector pins and expels the shot (shots are distinct from castings since there may be several holes in a die, producing multiple castings per shot).

After that, High-pressure injection results in a very rapid filling of the mold so that the molten metal may fill the whole mold before any portion hardens. In this manner, you may avoid the surface discontinuities even in thin-walled sections that are difficult to fill.

You may use the most die castings to accomplish construction that casting cannot finish, such as drilling and polishing. After the Injection process, shakeout involves separating the junk, including gates, runners, sprues, and flash. The machine typically does this procedure by extruding the casting via a specific dressing die. Other sand falling techniques include sawing and grinding.

Finally, faults may be verified once the shaking out procedure is finished. The most frequent faults are stagnation and chilly heading.

Types of Die Casting Process          

The kinds of die casting techniques vary depending on the investment and production costs. Every die casting business employs a diverse range of die casting techniques. The most popular die casting types will be discussed in the following sections.

The hot chamber die casting process

In a hot chamber die casting, a puddle of molten metal fills the die under pressure. At the start of the cycle, the machine retracts the piston, enabling the molten metal to fill the gooseneck.

A pneumatic or hydraulic piston squeezes the metal and fills it into the mold. This technique has all advantages of this technique for fast cycle rates (about 15 cycles per minute), easy automation, and the capacity to melt metal.

Application

Die casting companies can develop various interesting die casting applications that result in genuinely unique and highly functioning parts and components. A kind of die casting application may be more advantageous than another depending on your particular characteristics.

Pros
  • Higher Productivity

  • Detailed Integrated casting

  • Reduced porosity

  • Due to lower melting temperatures, die casting dies to have a longer life

  • Die design efficiency reduces waste

Cons
  • Porosity

  • A high initial start-up cost is needed for setting up the die-casting machinery

The cold chamber die casting process

In the cold chamber die casting method, you must melt the metal in a separate crucible. You can then deliver a specific quantity of molten metal to an unheated injection chamber or nozzle. And then, the machine pumps these metals into the mold by hydraulic or mechanical pressure.

Due to the necessity to transport molten metal into the cold chamber, the greatest drawback of this process is the lengthy cycle of time.

Cold chamber dies casting machines are also available in vertical and horizontal versions. Vertical die casting machines are typically tiny, whereas horizontal die casting machines are available in different types.

Application

Cold chamber die casting machines have the casting set situated away from the melt. The machine fills the casting chamber with the alloy and pushes it into the die-cast mold to create a casting. And then, it hardens the casting under high pressure, and the dies are opened.

It is a good technique for metals having a higher melting point, such as aluminum and copper. You may find the cold chamber die castings in portable gadgets, electrical components, and electric housings.

Pros
  • A plunger pushes the metal into a mold with tremendous pressure, ensuring the metal reaches all areas for a perfect fit every time.

  • The dies produced from cold casting are denser than dies generated from the hot casting method because of the high pressure required to make the die.

Cons
  • Lengthy production Process

  • Quality control issue.

The low-pressure die casting process 

As with high-pressure die casting, Operators connect the die sides to a fixed and moving machine plate, but orient the machine vertically. The holding furnace for the molten metal is situated underneath the stationary plate.

Applying pressure of up to max one bar to the furnace drives the molten metal (typically aluminum, but sometimes magnesium) up via an intake port into the die chamber – generally a permanent mold, but sand molds are also feasible.

The upward flow of the molten metal is against gravity. After filling the die, the pressure is maintained. At the same time, the metal cools to allow the injection of additional molten metal to offset any volume shortfalls (shrinkage holes) as the metal transitions from its molten to solid-state.

Application

The automobile industry has depended upon low-pressure die casting for decades to produce robust, high-quality aluminum castings. However, owing to its rather lengthy casting process, its usage was mainly confined to the luxury segment of the automobile industry, where smaller volumes and greater prices are anticipated.

Pros
  • High Strength Values

  • Possible complex geometries                   

  • Higher material utilization

  • No need for feeders                                        

  • High dimensional accuracy

  • Well-suited to automation

  • Less complication

Cons
  • Lower productivity

  • 3 mm minimum thickness

The vacuum die casting process

You may think of Vacuum Die Casting as an improved version of the conventional pressure die casting. It is a high-pressure die casting aided by a vacuum pump to remove the air contained inside the die cavity. That’s why you can also call the technique as Vacuum-assisted High-pressure Die Casting. Vacuum Die Casting is primarily used to minimize certain casting flaws in components that arise from air entrapment.

So, die casting producers who wish to guarantee higher quality for the manufactured components would choose vacuum-assisted die casting equipment.

Application

Vacuum die Casting is becoming increasingly popular in various sectors owing to its capacity to manufacture better quality components. Die Casting Manufacturers are also focusing their emphasis on Vacuum Die Casting.

Vacuum die casting is widely popular in the following industries, automotive, aircraft, military, marine, construction, etc.

These sectors require high-quality and durable components for their products. Traditional die casting may not be able to satisfy the strength and quality standards. So, more and more manufacturers are beginning to offer vacuum die casting solutions to consumers.

Pros
  • Require Lower cost

  • Limited Orders

  • Fast overturns

  • Capable of manufacture large pars

  • Repeatability

Cons
  • A problem with complex detailing

  • Molds and tooling pieces need to be routinely repaired

  • Hollowness is a possible problem

Squeeze die casting process

Squeeze casting is a mix of casting and forging techniques. The technique may result in the most significant mechanical characteristics possible in a cast product. The invention of the squeeze casting method may usher in the enormous potential for producing components of aluminum alloys, which the manufacturers didn’t fully market yet. It may also be helpful for the import replacement of critical parts.

Application

The squeeze casting has been commercially successful in producing components, including an Aluminium dome, ductile Iron mortar shell, and Steel bevel gear. Aluminum automotive wheels and pistons, and gear blanks made of brass and bronze.

Compared with the HPDC, the squeeze casting method with high applied pressure is a potential option for thick magnesium castings. Other components that have been Squeeze cast include stainless steel blades, super alloy discs.

Pros
  • It offers a wider variety of forms and components than conventional production techniques

  • Little or no machining is needed after the casting process

  • Low levels of porosity

  • Good surface texture

  • Fine micro-structures with greater strength components

  • No waste material, 100 percent usage

Cons
  • Costs are prohibitive owing to complicated tooling

  • No flexibility since tooling is devoted to particular components

  • The process has to be regulated, which slows the cycle time down and raises process expenses.

  • Significant expenses imply high production quantities are required to justify equipment investment

The semi-solid die casting process

Semi-solid metal casting (SSM) is a near-net form variation of die casting. Industries are utilizing the technique today with non-ferrous metals, such as aluminum, copper, and magnesium, but also may operate with higher temperature alloys for which no presently appropriate die materials are available.

The technique combines the benefits of casting and forging. You can call this process after the fluid characteristic thixotropy, which is the phenomenon that enables this process to operate. Thixotropic fluids flow when sheared but thicken while standing.

Application

Usually, industries utilize semi-solid casting for high-end applications. For aluminum alloys, typical components include structural medical and aerospace parts, pressure containment parts, defense parts, engine mounts, air manifold sensor harnesses, engine blocks, and oil pump filter housings.

Pros
  • Net shaped complex parts

  • Porosity free

  • Standard mechanical performance

  • Pressure tightness

  • Tight tolerances

  • slim walls

  • Temperature treatable

  • Perfect finishing

Cons
  • sensitive at ambient temperature

Gravity die casting vs. pressure die casting

Both types of die casting using a metal mold into which non-ferrous molten metal, typically injects an alloy of Aluminium, Zinc, Magnesium, Lead, Tin, or Copper. The significant difference between Gravity Die Casting and Pressure Die Casting is how molten metal gets in the mold.

In Gravity Die Casting, the machine pours the molten metal into the mold from above, which fills from the bottom up solely under gravity power. In Pressure Die Casting, the machine pours the molten metal into the mold at high pressure (between 1500 and 25,400 psi) (between 1500 and 25,400 psi). It maintains this pressure until the casting solidifies.

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