The application of 3D printing technology in the investment casting process is one of the important directions of the technical development of the investment casting industry. By combining the respective advantages of 3D printing and precision casting, it can break through the pain points of the industry’s original small batch mold making, such as high cost and large modeling limitations. At present, the application of the 3D printing process to production has become a trend in the investment casting industry. Whether it is 3D printing wax mold, 3D printing ceramic core 3D printing master mold, and other applications will strengthen the market competitiveness of investment casting companies. In this issue, we share a digital precision casting process based on light curing (SLA) 3D printing technology and casting special resin, which can reflect the advantages of 3D printing and precision casting, and when the process is suitable.
3D printing digital casting process detail analysis
1. Mold making
3D printing production mold: Regardless of the level of complexity, the mold can be quickly produced. No mold opening procedure saves a lot of time and cost.
The extraction function of 3D printing pre-processing software processes the mold into a hollow structure: greatly reducing the consumption of resin raw materials and saving a lot of costs; Basically eliminating the swelling of resin in the post-treatment process; Greatly reducing the amount of ash remaining in the exit mold step.
2. Mold preprocessing and assembly group tree
The 3D printed molds of SLA equipment can be “welded” directly on the runner with wax, and assembled as normal wax molds. The gate and runner can be designed to be larger than the traditional wax mold, taking into account the way the SLA mold is removed, which facilitates air entry into the combustion mold.
3. Make the shell
Before hanging the first layer of paste, watch for bubbles when cleaning the wax tree. If yes, it means that the mold seal is not good. The wax tree is immersed in the slurry to avoid damage to the wax tree by buoyancy. To enhance the strength of the shell, it can be considered to make more than one layer of shell or use reinforcement.
The ventilation hole is ironed through before roasting, which is conducive to gas convection during roasting.
Step 5 Bake
Enter sufficient air for high-temperature roasting and keep the temperature at 800-1100 degrees for two hours (according to the size of the part, extend the time appropriately).
Somos casting special resin (Somos@11122, Somos@Element) used in the SLA prototype starts to soften at 50-60 ℃, and the molecular structure of the resin begins to collapse when it exceeds 300℃. At 600℃, the resin material is burned and decomposed into carbon dioxide, water, and a small amount of residue. The temperature of complete firing instability is about 800℃.
6. Remove the ashes
Ash residue will affect the surface quality of castings and cause internal defects.
7. Preheat and pour
Plug the vent hole with a ceramic rod, refractory mud, and other materials before preheating.
Precision casting products:
3D printing digital precision casting process is excellent
Fast speed, low cost, 2-3 days to obtain disappearing mold, to meet the needs of multi-variety, small batch business
The wax mold with complex spatial structure can be 3D printed, and the dimensional accuracy is close to the mold pressure wax mold
Only 0.05% ash remains, does not contain heavy metal elements, does not pollute castings
Mold surface quality is good, detail expression is strong. After treatment, the surface roughness can reach Ra1.6, and the minimum print size is only 0.3mm.
The above is a summary of the advantages of 3D printing digital precision casting process based on SLA technology. So, under what circumstances do precision casting enterprises apply this process to make the best use of it? Here are five classic application scenarios.
Process design optimization
Urgent delivery date
For a small amount (less than 50 pieces), the cost of making molds is higher
Special structure, can not open mold
Test pieces, prototype verification