Low Pressure Die Casting (LPDC) is a die casting technique that uses low pressure to inject molten metal into a reusable mold, also known as a die. This casting method offers high quality, precision, and efficiency, making it highly favored for components that require complex shapes and high surface finish.
CFS Foundry is a professional low pressure die casting manufacturer in China. With value-added services like heat treatment, CNC machining, surface finishing, and custom packaging, our aluminum foundry positions ourselves as a one-stop-shop for all your casting needs.
Low Pressure Die Casting Process
In low pressure die casting, low pressure, other than gravity, is used to to fill molds with light metal especially aluminum alloys. In this process, a tool or die is designed and manufactured to the required shape of the component to be made. It is then mounted on a holding furnace and is connected to the molten metal by a feed tube or stalk. The furnace is pressurised by the introduction of air above the surface of the molten metal causing it to rise steadily in the stalk and quietly fill the mould. The air in the mould cavity is expelled through suitably positioned vents in the die and when the cavity is filled, solidification commences.
Molten metal is pushed into the die under low pressure. Once solidified, the pressure is released and any residual liquid in the tube or cavity flows back into the holding furnace for recycling. After cooling, the cast part is removed from the die, this process can be repeated many time to obtain the quantity ordered by customers.
Common Aluminum Alloys in Low Pressure Die Casting
| Alloy | Aluminum (%) | Copper (%) | Silicon (%) | Magnesium (%) | Iron (%) | Zinc (%) | Others (%) |
|---|---|---|---|---|---|---|---|
| ADC12 | 80-85 | 1.5-3.5 | 9.6-12 | 0.3 | – | 1 | Trace |
| A380 | 80.0-85.0 | 3.0-4.0 | 7.5-9.5 | 0.1 | 1.3 | – | Trace |
| AlSi10Mg | ~89 | – | 9-11 | 0.2-0.45 | – | – | Trace |
| AlSi9Cu3 | ~87 | 2-3 | 8.5-10.5 | – | – | – | Trace |
| AlSi7Mg | ~92 | – | 6.5-7.5 | 0.25-0.45 | – | – | Trace |
Notes:
- The percentages are approximate and may vary slightly depending on the manufacturer and specific requirements.
- The term “Trace” under “Others” indicates the presence of trace elements that are not in significant quantities but may still affect alloy properties.
- Iron is specifically noted for A380 due to its presence affecting properties, while it is not a significant factor in the other alloys mentioned.
- By understanding the chemical composition of these alloys, one can better choose the appropriate aluminum casting material for a given low-pressure die casting application.
Advantages of Low-Pressure Die Casting
Low pressure casting can use sand mold, metal mold, graphite mold, etc. The filling process is not only different from gravity die casting, sand casting, but also different from high pressure die casting. It has the following advantages:
- The pure metal liquid filling in the mold improves the purity of the casting. Because the slag generally floats on the surface of the liquid metal, and the low pressure die casting is filled by the liquid metal at the bottom of the crucible through the riser pipe, the possibility of the slag entering the mold cavity is completely avoided.
- The liquid metal filling is stable, which reduces or avoids the churning, impact and splashing phenomenon when filling liquid meta, thus reducing the formation of oxidizing slag.
- The filling of liquid metal under pressure can improve the fluidity of the liquid metal, which is conducive to creat casting with clear outline and smooth surface, and is more beneficial to the creat large thin-wall castings.
- The castings crystallize and solidify under pressure, and can be fully fed, and the casting structure is dense.
- In general, no riser is needed, and the uncongealed metal in the riser pipe can be reflux to the crucible for repeated use, so that the recovery rate of the metal liquid is greatly improved, the recovery rate can reach 90%
- Convenient production operation, high production efficiency, and easy to achieve mechanization & automation.
When You Should Consider Low-Pressure Die Casting?
Low-pressure die casting is a versatile and efficient manufacturing process that has been increasingly adopted by various industries. However, this method may not be suitable for all types of components or products. Here are some factors when you should consider using low-pressure die casting:
Complex Geometries
Low-pressure die casting is an excellent choice for parts with intricate geometries, internal cores, or undercuts. The process allows for greater design flexibility, making it easier to manufacture components with complex shapes and features.
High Surface Finish Requirements
This casting method is known for producing parts with smooth, high-quality surface finishes. If your component requires minimal post-processing or surface treatments, low-pressure die casting can offer a more efficient and cost-effective solution.
Medium to High-Volume Production
Low-pressure die casting is best suited for medium to high-volume production runs. The process is relatively fast, and the tooling costs are justified when spread over a large number of parts.
Stringent Dimensional Accuracy
Low-pressure die casting offers high levels of dimensional accuracy, especially when compared to other casting methods like sand casting or gravity die casting. If your part requires tight tolerances, this process is an excellent option.
Lightweight Components
This process is often used in industries like automotive and aerospace, where the weight of the components is a critical factor. Low-pressure die casting allows for the production of lightweight yet durable parts.
Cost-Effectiveness
If you are looking for a cost-effective solution that does not compromise on quality, low-pressure die casting offers a balanced combination of cost and performance.
In summary, low-pressure die casting is an ideal choice when your project requires high-quality surface finishes, complex geometries, dimensional accuracy, and medium to high-volume production runs. By understanding the specific needs of your application, you can make an informed decision on whether low-pressure die casting is the right option for you.
Low Pressure Die Casting vs. Other Casting Processes
| Feature | Low-Pressure Die Casting | High-Pressure Die Casting | Gravity Die Casting |
|---|---|---|---|
| Pressure Applied | 20 to 100 psi | Over 10,000 psi | Atmospheric Pressure |
| Complexity of Shapes | Moderate to High | High | Low to Moderate |
| Dimensional Accuracy | High | Very High | Moderate |
| Surface Finish | Excellent | Excellent | Good |
| Material Options | Aluminum, Magnesium | Aluminum, Zinc, Magnesium | Aluminum, Brass, Iron |
| Production Speed | Moderate | Fast | Slow to Moderate |
| Tooling Cost | Moderate | High | Low to Moderate |
| Volume Suitability | Medium to High | High | Low to Medium |
| Wall Thickness | Can be thin | Very thin | Generally thicker |
| Post-Processing Required | Minimal | Minimal | Moderate |
| Mechanical Properties | Good | Excellent | Good |
| Cost Effectiveness | Moderate | Moderate to High (depends on volume) | Moderate to Low |
| Tolerance Level | ± 0.005 in | ± 0.002 in | ± 0.010 in |
Low Pressure Die Casting Applications
Low pressure die casting is the earliest anti-gravity casting technology, which began to be used in industrial production in the 1940s. Today, Low Pressure Die Casting (LPDC) is a versatile metal casting method that offers several advantages such as high-quality surface finish, reduced porosity, and the ability to produce complex geometries. Because of these attributes, LPDC finds applications across various industries.
Automotive Industry
- Engine Blocks: LPDC is commonly used to produce aluminum engine blocks, which are lighter and exhibit improved thermal properties compared to iron counterparts.
- Gear Casings: The high dimensional accuracy achieved through LPDC makes it ideal for casting gear casings that require precise alignment.
- Wheel Rims: Aluminum wheel rims manufactured using LPDC offer a balance of strength and light weight, making them highly desirable for performance vehicles.
- Suspension Components: LPDC allows the production of complex geometries, which is essential for suspension components like control arms and struts.
Aerospace Industry
- Housing Components: Aluminum and magnesium alloys used in LPDC are perfect for creating lightweight yet sturdy housing components in aircraft.
- Structural Parts: LPDC is used for manufacturing parts like wing components and engine mounts, where high strength-to-weight ratio is essential.
Electrical and Electronics
- Heat Sinks: LPDC is popular for manufacturing heat sinks, as the process lends itself well to aluminum alloys with high thermal conductivity.
- Electrical Enclosures: LPDC offers excellent surface finish and dimensional stability, which are crucial in electrical enclosures to ensure safety and durability.
Marine Applications
- Propellers: LPDC’s capability to produce complex shapes with high dimensional accuracy makes it suitable for marine propellers.
- Structural Parts: Components like hull fittings and frames benefit from the corrosion-resistant properties of aluminum alloys used in LPDC.
Medical Devices
- Surgical Equipment: LPDC is used in the production of medical equipment such as surgical instruments, where weight and material properties are crucial factors.
- Mobility Aids: Wheelchair frames and other mobility aids benefit from the lightweight and strong properties of LPDC-produced parts.
Consumer Goods
- Kitchenware: LPDC is used for making high-quality kitchenware like pots and pans, thanks to its excellent surface finish capabilities.
- Decorative Elements: LPDC allows for the production of complex and intricate designs, making it suitable for decorative pieces like statues and ornaments.
Industrial Machinery
- Pump Casings: LPDC provides the strength and surface finish required for pump casings used in industrial settings.
- Conveyor Parts: The durability and low wear of LPDC components make them ideal for industrial conveyor systems.
CFS Foundry: Your Reliable Low Pressure Die Casting Partner
As a top leading casting manufacturer in China, CFS Foundry provides comprehensive casting solution to deliver finished components. If you are looking for a reliable low pressure die casting partner, CFS Foundry is the right company to work with. Any inquiry on low pressure die casting process, pls send your CAD drawings to cathy.sales01@cnool.net, we will offer a free quote within 24 hours!