Rapid Investment Casting
What is Rapid Investment Casting
Investment casting is also known as the “lost wax” processor “precision” casting. In this process, a wax pattern must be made for every casting and gating system; i.e., the design is expendable. This process offers the end-user good value for money. A good surface finish, complex geometry, and cast features are desirable without the necessity of extensive machining or other fabrication/ finishing work required to provide a usable end item.
Historically, the reluctance of the Designer or Buyer of a new part design that is considered low volume, short lead, or prototype to consider the investment casting process has been due to the long lead times and high cost required to build the initial tooling. Depending on part complexity, the tool building process alone can take 8 to 20 weeks and cost $50,000 to $100,000 or more. As a result, many potential investments casting users have historically been driven away to other traditional metalworking processes. The advent of SLA 3D Printing has filled in this niche for reducing the total turnaround time in investment casting.
By using Stereolithography 3D Printed parts as expendable patterns for investment casting without the need for tooling. The actual turnaround time can be reduced to 2 to 3 weeks, and potentially, the entire production run of designs can be built for less than a wax tool would have cost. The SLA 3D Printed part is used as a substitute for the wax pattern part in the investment casting process, eliminating the need for low-production-run wax pattern tooling.
Traditionally low volume and prototype orders tend to make the investment casting process less effective because of the high tooling costs and long lead times for wax pattern tooling. SLA 3D Printed investment casting patterns flip this age-old problem on its head and opens the door for much smaller quantity orders of investment cast parts to begin to make economic sense for manufacturers.
When to use Rapid Investment Casting
Low Volume and Prototype Orders
The mold cost can be avoided when there is a small batch demand for casting products, such as automobile manifolds, impellers, pump casings, brackets, casings, etc.
Spare parts out of Stock
For parts that are out of stock and lose their supply channels, you can use rapid casting to obtain spare parts at a lower cost.
Instead of Metal 3D Printing Part
Rapid precision casting has a high degree of freedom of modeling, meets the production requirements of a considerable number of metal printing parts, and can be used as a high-quality, low-cost alternative to metal printing.
Urgent Order
When the demand for metal casting products is urgent, the metal casting products can be obtained within 2-3 weeks
Prototype verification at the trial production stage
Use a more economical method to quickly obtain prototypes in the trial production stage to verify the product and facilitate multiple iterations.
Benefits of Rapid Investment casting
Less Time
Compared with traditional casting, it takes less time. For small batches of metal parts, the production time can even be comparable to metal printing.
High Quality
The quality of castings made by mold wax molds can reach or be close to and can be directly used for product-level parts
Good Economic
Eliminate the cost of small batches of molds, and reduce the cost of small-batch production quickly
Material Diversity
Various grades of stainless steel and aluminum alloy materials can be cast as required to meet material requirements
The high degree of freedom of geometric structure
Close to the dimensional freedom of metal printing, it can produce highly complex product parts, replacing part of the metal printing needs.
Rapid Investment Casting Process
1、First, the investment casting pattern is designed on a 3D CAD system and saved to an STL which is then uploaded to the SLA machine, where it is produced in a matter of hours out of Photosensitive resin.
2、Each investment casting pattern component is sealed and leak-checked once it comes off the SLA machine and has its build support removed. It is recommended that leak-checking also be completed at the foundry after gating and sprue assembly, before the first dip
3、Once the assembly gets to the foundry, the investment casting patterns are secured to a central wax bar with gates, called a sprue
4、A shell mold is created by dipping (investing) the cluster into a very fine ceramic slurry. The first layer, the face coat, allows for the reproduction of finely detailed features.
5、After the first layer, the shell is layered with a fine ceramic refractory grain like sand. Upon drying, the process of dipping the shell mold into the slurry and layering the sand is repeated (with coarser grains) to obtain the desired shell thickness.
6、After the shell mold dries, it is typically flash-fired in a furnace to sinter the mold and remove the investment casting pattern from the shell
7、The mold is preheated before pouring in the molten metal
8、The ceramic shell is removed from the solid metal through mechanical vibration, chemical cleaning, or water blasting depending on the particular metal used
9、The original parts are now cut from the sprue and gates and ground smooth so that they are ready for additional processes.
Things to Remember When Using Rapid Investment Casting
Why Make your Casting at Unionfab？
- Endless Options Choose from millions of possible combinations of materials, finishes, tolerances, markings, and certifications for your order.
- Easy to Use Get your parts delivered right to your door without the hassle of sourcing, project management, logistics, or shipping.
- Vetted Network We are ISO 9001:2015 certified and AS9100D compliant. Only the top shops that apply to become Suppliers make it through our qualification process.
Compare our 3D Printing Services
| Service | Lead Times | Materials | Tolerances | Max Part Size |
| SLA | 1 – 3 days | Resin / Somos | +/- 0.003 in. | 800 x 800 x 550 mm |
| SLS | 2 – 5 days | PA12/ PA12GB | +/- 0.002 in. | 350 x 350 x 400 mm |
| MJF | 2 – 5 days | PA12/ PA12GB | +/- 0.002 in. | 380 x 280 x 380 mm |
| FDM | 2 – 5 days | PLA / ABS | +/- 0.003 in. | 500 x 500 x 400 mm |
| Poly Jet | 2 – 5 days | Resin | +/- 0.003 in. | 490 x 390 x 200 mm |