Technology Advantages of Precision Casting
【Rapid】 Its fast speed and low cost allow it to take only 2-3 days to get the lost prototype mold, thus meeting the business needs of many varieties and small batch
【Superior】 The wax mold with complex spatial structure can be printed, and its dimensional accuracy is close to that of the mold-pressing wax mold
【Clean】 Only 0.05% ash residue is produced, with no heavy metal elements and no pollution of casting
【Exquisite】 The surface quality of the mold is excellent, and the details have strong performance. After processing, the surface roughness can reach Ra1.6, and the minimum print size can be only 0.3mm
When is SLA Rapid Precision Casting Needed?
☑ Process design optimization
☑ Tight delivery schedule
☑ A small quantity (within 50 pieces), when the mold production cost is high
☑ Special structure making the opening of the mold possible
☑ Test piece and prototype verification
Details Analysis of the Casting Process
I. Modeling
The shell extraction function of pre-processing software used to process the prototype mold into a hollow structure: to achieve significantly reduced consumption of resin raw materials, and cost savings; eliminate the expansion problem of resin in post-processing basically; greatly reduce the amount of ash left in the process.
Manufacturing of the prototype mold with 3D printing: No matter how complex the prototype mold is, it can quickly manufacture the mold. Free from mold opening procedures, it can achieve huge savings in time and cost.
Software required: UnionTech Polydevs pre-processing software
During data processing, the Polydevs pre-processing software allows users to customize the shell wall thickness, the length and width of the internal supporting arm, and freely choose the location to place the discharge hole. The lightweight process avoids shell expansion during dewaxing.
Equipment: UnionTech Lite600 SLA Printer
Materials: Somos photosensitive resin 111222, Element
It has a very low ash content. And the surface ash is very easy to be cleaned. Moreover, it has such characteristics as low viscosity, stable size, smooth surface of components, easy surface treatment, product stability, etc.
II. Prototype Mold Pre-processing and Assembly
The mold printed through SLA can be directly “welded” to the pouring gate with wax and assembled as normal wax mold.
To allow for the removal of SLA prototype mold, the design of the pouring sprue and passage can be larger than traditional wax mold to facilitate air entry and then the combustion of the prototype mold.
III. Shell Manufacturing
Before hanging the first layer of slurry, it is necessary to attentively observe whether there are bubbles when cleaning the wax tree. If any, it indicates that the sealing of the mold is not good. When the wax tree is immersed in the slurry, it is needed to avoid damage to the wax tree caused by buoyancy. In order to enhance the strength of the shell, an extra shell or reinforcement can be considered.
IV. Dewaxing
The ventilation hole shall be burned through before roasting, which is conducive to gas convection in the process of roasting.
V. Roasting
High-temperature roasting is provided with sufficient air to keep the temperature at 800-1100 degrees for 2 hours (extend the time appropriately according to the size of the parts).
The Somos casting resin (Somos@11122, Somos@Element) specially used for SLA prototype begins to soften at 50-60℃.. Above 300℃, the molecular structure of the resin begins to collapse. At 600℃, the resin material burns and decomposes into carbon dioxide, water and a small amount of residue. At about 800℃, it can reach complete combustion.
VI. Removal of Ash
Ash residue will affect the surface quality of castings and cause internal defects
VII. Preheating and Pouring
The ventilation hole will be blocked with ceramic rod, fire clay and other materials before preheating
Exhibition of Finished Product
The application of 3D printing technology in precision casting is one of the important directions of technology development in the precision casting industry. By combining the advantages of 3D printing and precision casting, it can tackle the original pain points in the industry, such as high cost of small batch molding and great modeling limitations, etc. At present, it has become a trend in the precision casting industry to apply 3D printing technology in production. Applications, whether 3D printed wax mold, 3D printed ceramic core or 3D printed prototype, will greatly strengthen the market competitiveness of precision casting companies.
