The investment casting process, also known as lost-wax casting, uses wax patterns and ceramic shells to create near-net shape parts. It's a multi-step procedure that starts with an investment casting die and ends with components that have superior finishes and tight tolerances. The investment casting process steps include:
A metal investment casting die is created based on a master pattern that matches the end product, taking shrinking into account.
2. Create Wax Patterns
Wax is injected into the investment casting die to create replicas of the end product. Cores can be incorporated to manufacture highly complex parts.
The wax patterns are attached to a sprue to create a tree. This tree is a gated system that will allow the molten metal to flow freely into every portion of the cast component. If the final product is small, a tree can accommodate numerous wax patterns. For the very largest parts, there may be just one pattern per tree.
The wax trees are dipped repeatedly into a ceramic slurry to build up a shell. Granular refractory stuccos can also be used. Each layer is allowed to harden before a new layer is created. The size and shape of the end product, along with the temperature of the molten metal, determines the thickness of the ceramic shells. In the end, the dried ceramic shells will be sufficiently hard to contain the molten metal.
The ceramic shells are treated to melt and remove the wax. The hollowed-out shells contain a cavity that matches the shape of the desired component.
The ceramic shells are heated to an appropriate temperature, usually around 1,000°F to 2,000°F. At this temperature, the shells are further strengthened, residual wax melts away and any moisture in the shells dissipates. Once the shells reach the target temperature, they're filled with molten metal. The temperature of the metal is usually significantly higher than the mold, ensuring it flows into all areas before solidifying.
Once filled, the ceramic shells are set to cool, allowing the metal to solidify. The cooling rate can be controlled by the thickness of the ceramic shell and the ambient temperature around it. This solidification process can take a few minutes to a few hours.
Once the metal has solidified, the ceramic shells are removed through a knockout operation. The sprues and gates that allowed the metal to flow into the shells are also removed.
The metal castings go through a finishing process. This can include sandblasting to remove any remaining ceramic material, heat treatment to alter the properties of the metal or minor machining to achieve the final dimensions.
The last step is inspecting the final products to ensure they meet all specifications. This may involve visual inspection, dimensional checks or more advanced methods, like non-destructive testing.
Please provide us the detailed information while sending inquiry.
Here is the information we will need to quote:What material do you want part cast out of?
Is the part to be heat treated? If so, is there a hardness requirement? Are there mechanical testing requirements?
What lot quantities of investment castings would you like us to quote? Is this a one time job or a recurring job?
Base on the customer&#;s demand, if there is no idea, we might request the minimum quantity for each furnace capacity.
We need as much information about the part as possible. This is a new part? If it is an existing job, how is it currently being made? If it is currently being investment cast why are you looking for new foundry? Is to get better quality, delivery or price?
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If this is an existing part, does investment casting tooling currently exist for part. If so any tooling rework or modification will be at customer's expense.
We need drawings of 2D and 3D or samples. The more information we receive the fewer questions we will have to ask before we can quote. Ideally we would like to have:
3D CAD files. We would prefer SolidWorks files. If these are not available then this is the desired order.
1. SolidWorks format
2. STEP format
3. X_T format
4. IGES format
5. STL format
2D drawings. We need these for tolerances. We do make many rapid prototype parts without 2D drawings. But if tolerances are important 2D drawings are a necessity. Note if you only send us a 2D drawing and the dimensions and or tolerances are not legible we will not be able to quote.
Samples if available. This is not a necessity, unless that is all you have, but they can be very helpful during our quoting process
Unless critical dimensions are called out on 2D drawings we will need to know what dimensions are critical and what are not critical.