High Pressure vs. Low Pressure Die Casting For Aluminum Parts

Die casting is an efficient way of manufacturing light metal parts for a wide of industries.

High pressure die casting and low pressure die casting are the two common die casting methods for creating complex aluminum parts. So, if you are new to die casting industry, when deciding a proper die casting method, it is necessary to understand the main differences between this two processes.

High Pressure Die Casting

High-pressure die casting is the process of pouring the metal liquid into the pressure chamber, filling the mold cavity shortly, then crystallizing and solidifying under high pressure, and finally solid cast aluminum parts are formed. High pressure Die Casting is an ideal process for manufacturing high volume aluminum parts that require high dimensional accuracy and good surface finish with a minimum of machining. This is a good solution for creating aluminum castings which allows for high strength. And thinner wall sections could be made by high pressure die casting, which is not available by gravity casting or low pressure die casting process.

Attention needs to be paid that high pressure die castings cannot be heat treated, while T6 heat treatment is mainly suited for aluminum gravity casting. With high pressure die casting, it is not easy to produce casting effects such as porosity. Although the innitial mold cost is high, it delivers low unit cost with high volume production.

Low Pressure Die Casting

In low pressure die casting, molten metal is subjected to low pressure up to 10 MPa.

It is a vertical process that shoots the molten metal upward against gravity. The metal travels from the furnace below by a piston using low pressure through a shot chamber into the two molds. The two molds are made of aluminum alloys; one is fixed while the other is able to be pulled away to let the casting free itself from the mold once cooled. The pressure is maintained in the mold while the metal cools to ensure an even and accurate fill. As the metal cools, further molten metal can be added to fill any missed or shrinking cavities. The only downside to low-pressure is the slower casting cycle, however, this die casting process is a cheaper, less-complicated technology as compared to high-pressure die casting, and lends itself to automation.

High Pressure Or Low Pressure Die Casting For Aluminum Parts?

	Low Pressure Die Casting	High Pressure Die Casting
Advantages	Good strength values No complicated machinery and die technology High material utilization, No feeders needed Well-suited for automation High dimensional accuracy	Short casting cycles Good for thin-walled components Smooth surfaces Good for automation
Disadvantages	Slow casting cycles Has a minimum wall thickness of 3mm (in die)	Complicated and expensive dies Lower strength values Die-cast weight limited by the locking force of the machine

Any inquiry on aluminum die casting project, pls feel free to contact our aluminum foundry!