Overview of Sand Casting Technology
Sand casting, as one of the oldest metal forming methods, still occupies an important position in modern manufacturing. This process uses sand as a molding material, and obtains the desired casting by pouring molten metal into the sand mold cavity and waiting for it to cool and solidify. Sand casting is particularly suitable for the production of aluminum alloy parts because it has the following significant advantages:
- High cost-effectiveness: Compared with metal mold casting or die casting, the mold cost of sand casting is significantly reduced
- Design flexibility: It can produce castings with complex shapes and different sizes
- Strong material adaptability: Applicable to various aluminum alloy grades
- Flexible production scale: Suitable for both small-scale trial production and large-scale production needs
In the automotive industry, aluminum alloy parts produced by sand casting account for about 35% of all aluminum alloy castings, and are widely used in key components such as engine cylinder blocks, gearbox housings, and wheel hubs. The aerospace field uses this technology to produce structural parts such as aircraft seat brackets and instrument panel frames. In addition, in the fields of power equipment, engineering machinery, etc., sand casting aluminum alloy parts also play an irreplaceable role.
Complete process flow of sand casting
Mold design and manufacturing
The process flow of sand casting begins with mold design. Engineers need to design a reasonable pouring system based on the three-dimensional model of the casting, including components such as the pouring cup, sprue, runner and inner gate. Modern foundries usually use CAD/CAE software for simulation analysis, optimize mold structure, and predict possible casting defects.
The mold manufacturing stage is mainly divided into two links: molding and core making. Molding uses molding sand (usually silica sand) mixed with a binder (clay, resin or water glass), which is compacted around the model by hand or mechanical means to form a casting. For the inner cavity of complex castings, sand cores need to be made separately, which requires higher precision and strength.
Melting and alloy preparation
The melting of aluminum alloys is a key link to ensure the quality of castings. The melting process is usually carried out in the temperature range of 700-750℃, using equipment such as gas-fired reverberatory furnaces or resistance furnaces. Special attention should be paid to the following during the smelting process:
- Raw material selection: Use high-purity aluminum ingots with alloying elements (such as silicon, magnesium, copper, etc.)
- Melt protection: Use covering agents to prevent aluminum liquid from oxidation
- Composition control: Real-time monitoring of alloy composition through spectral analysis
- Melt purification: Add refining agents to remove hydrogen and inclusions
SF-Foundry’s graphite degassing rotor plays an important role in this stage. Its unique rotating design can effectively remove hydrogen from the melt and prevent the occurrence of pore defects.
Pouring and solidification control
When the mold is ready and the aluminum liquid reaches the ideal state, it enters the pouring stage. The following parameters need to be strictly controlled during the pouring process:
- Pouring temperature: usually controlled between 680-720℃, depending on the alloy grade and the wall thickness of the casting
- Pouring speed: too fast will cause turbulence to entrain gas, too slow may cause cold shut
- Mold temperature: affects the solidification sequence and shrinkage compensation effect
In the pouring system, SF-Foundry’s alumina foam ceramic filter is usually installed at the cross runner or pouring cup position. Its unique three-dimensional mesh structure can effectively intercept oxide inclusions and flux residues in the melt to ensure the purity of the aluminum liquid entering the cavity.
Sand removal and post-processing
After the casting solidifies and cools, it needs to be sanded, that is, the sand mold is destroyed to remove the casting. This is followed by a series of post-processing steps:
- Remove the pouring head: remove excess metal by sawing or grinding
- Surface cleaning: use sandblasting or shot blasting to improve surface quality
- Heat treatment: perform T4, T6 and other heat treatments as needed to improve mechanical properties
- Machining: finish machining key parts to meet dimensional accuracy requirements
- Quality inspection: including dimensional inspection, X-ray flaw detection, mechanical property testing, etc.
Typical aluminum alloy products and applications of sand casting
Sand casting can produce various aluminum alloy parts. The following are some typical application cases:
Auto parts
The automotive industry is the largest application area for sand casting aluminum alloy parts. Common products include:
- Engine parts: cylinder block, cylinder head, oil pan, etc., using alloys such as A356
- Transmission system parts: gearbox housing, clutch housing, etc.
- Chassis parts: control arms, steering knuckles and other structural parts
- Body accessories: brackets, brackets and other functional parts
Aerospace parts
The aerospace field has extremely high requirements for the quality of castings, and sand casting can produce:
- Engine accessories: housing, brackets, etc.
- Airborne equipment structural parts: instrument panel frame, seat brackets, etc.
- UAV parts: fuselage structural parts, etc.
These parts usually use high-strength aluminum alloys such as A206, A201, etc., and have strict requirements on the content of inclusions.
Industrial equipment parts
Sand casting is also often used for aluminum alloy parts in various industrial equipment:
- Hydraulic system housing
- Pump valve parts
- Motor housing
- Mechanical transmission parts
SF-Foundry Casting Materials Solutions
As a professional casting material supplier, SF-Foundry provides a complete solution from smelting to pouring:
Alumina ceramic foam filter
Our alumina ceramic foam filter is made of high-purity alumina raw materials and is made through a special sintering process. It has the following characteristics:
- Excellent high temperature resistance, can withstand 1200℃ aluminum liquid temperature for a long time
- Three-dimensional mesh structure ensures a high porosity of more than 85%
- Aperture range of 10-60ppi, meeting different filtration accuracy requirements
- Good chemical stability, no reaction with aluminum liquid
Supporting product series
- Cap-shaped fiberglass mesh filter: used for primary filtration, economical and practical
- Graphite degassing rotor: efficient removal of hydrogen in the melt
- Tap out cone for Aluminum liquid: precise control of pouring flow
Customized service
For special needs, we provide:
- Customization of non-standard size filters
- Design of special shape filter system
- Optimization of the whole process solution
- On-site technical guidance service
SF-Foundry will continue to invest in research and development to provide customers with more advanced and reliable casting solutions.
For more technical details or customized services, please contact SF-Foundry’s professional technical team:
- 📧 info@sf-foundry.com
- 🌐 www.sf-foundry.com
- 📞 +86 13785803358