Aluminium Gravity Die Casting Manufacturers Process review

Gravity die casting parts

What is aluminium gravity Die casting ?

Aluminium Gravity Die casting is a gravity permanent mold casting process, which means gravity Die Casting, commonly known as die casting, which is made of metal materials and is made of gravity. A process for casting a molten metal into a mold to obtain a casting products. Since a metal type mold can be poured hundreds to thousands of times,Therefore, metal casting is also called permanent casting.

Metal casting is suitable for large batches production of non-ferrous alloy castings; such as aluminum alloys and magnesium alloys with complex shapes, and also suitable for the production of castings, ingots, etc. for steel and with metal insert.

Gravity Casting with Metal insert
Permanent mold parts

The molten Aluminium alloy material is usually poured into the gate by hand, relying on the weight of the molten metal. Filled with cavity, Venting, Cooling, Mold opening to get products

Aluminium Gravity Die Casting Process Flow Chart

Process: Melting⇒Filling⇒Venting⇒Cooling⇒ Mold opening⇒Eject Parts⇒heat treatment⇒CNC and post processing

Aluminium Gravity Die Casting Youtube Video

Aluminium Gravity Die Casting Materials

As a Top lead Aluminium Gravity die casting foundry, The aluminium gravity die casting materials we familiar with as below.







Alloy Aluminium bars

Difference between Aluminium gravity die casting and Aluminium High pressure die casting

Permanent mold Manufacturer

The characteristics of Aluminium gravity die casting are:

1. There are few sand holes in the casting, heat treatment can be carried out, and the strength of the product can be greatly improved after heat treatment, like make T4 and T6(A356) even exceeding the die casting product.

2. The product has low density and is formed by liquid self-weight. The compactness of the product is lower than that of die casting, and its strength is also slightly worse, but its elongation is higher.

3. The surface finish of the product is not high, and the surface of the cast product is easy to form pits after cooling and shrinking.

4. Slow filling, low production efficiency, and its production efficiency is only 1/4 of high pressure casting, resulting in higher product cost.

5. The life of the mold is longer than that of die casting, and the cost of the mold is lower.

6. The process is simple

7. Not suitable for the production of thin-walled parts

High pressure aluminium die casting characteristics

1. Fast filling, high production efficiency

2. Forming under high pressure, product compactness, product strength and surface hardness are high, but the product elongation is low.

3. The surface finish of the product is good, generally reaching Ra6.3.

4. can produce thin parts with thin wall thickness, aluminum die-casting wall thickness can be as thin as 0.5mm

5. Fast filling, internal gas entrapment, poor product porosity

6. can not be heat treated, the internal gas will expand when heat treatment, resulting in defects such as bulging or cracking of the product.

7. The processing allowance is small (as small as possible is less than 0.25mm), the processing volume is too large, the surface dense layer is destroyed, and the internal pores are exposed, resulting in a decrease in product strength.

8. Mold costs are high. Small mold life

Gravity Die Casting vs High Pressure Die casting and Low Pressure Die casting 

ComparisonProcessMold PriceMold LifeSand HoleHeat treatmentMachining allowanceSmooth surfaceSuitable productProduction Efficiency
High pressure die castingComplexHighShortExistNoneSmallHighThin wall partsHigh
Low pressure die castingSimpleLowLongLessCanBigHighGeneral PartsMiddle
Gravity die castingSimpleLowLongLessCanBigLowThick-walled partsLow
Tilt gravity Casting machine

In terms of strength, the strength difference is also large due to the different aluminum alloy materials involved. Due to the high-pressure molding of die-casting products, the product has high density and high strength. For example, the die-casting products of A380 can reach 360Mpa, and its elongation can only reach about 3.7%.

Gravity Die Casting products are generally lower in strength than die casting. The ZA101A with better material can only reach 310Mpa after heat treatment, its elongation rate is high, it can reach 5-6%, and there are materials with strength up to 380Mpa, such as ZL201A, ZL204A.

Conclusion, when we choose which process to use for the production of the product, it is mainly based on the wall thickness of the product. Due to the high production efficiency of high-pressure casting, high-pressure casting should be preferred under the premise that the production process and product performance can meet the requirements.

When the product wall thickness is more than 8mm, the product cast by high pressure may not be able to meet the expected strength due to too many internal Sand holes. Consider gravity casting or low pressure casting. Maybe you also have interesting in Aluminium Extrusion and Lost Wax Casting

Foundry Sand Core

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Using these basic steps, other variations on permanent mold casting have been developed to accommodate specific applications. Examples of these variations include the following:

  • Slush Casting – As in permanent mold casting, the molten metal is poured into the mold and begins to solidify at the cavity surface. When the amount of solidified material is equal to the desired wall thickness, the remaining slush (material that has yet to completely solidify) is poured out of the mold. As a result, slush casting is used to produce hollow parts without the use of cores.
  • Low Pressure Permanent Mold Casting – Instead of being poured, the molten metal is forced into the mold by low pressure air (< 1 bar). The application of pressure allows the mold to remain filled and reduces shrinkage during cooling. Also, finer details and thinner walls can be molded.
  • Vacuum Permanent Mold Casting – Similar to low pressure casting, but vacuum pressure is used to fill the mold. As a result, finer details and thin walls can be molded and the mechanical properties of the castings are improved.