Industrial Process
In lost wax investment casting, a sacrificial detailed wax pattern of the desired finished part is created and mounted onto a wax “tree” which includes the metal delivery system (gates and risers). The tree is alternately dipped into a ceramic slurry and sprinkled with stucco material, and is allowed to dry.
This process is repeated until a thick shell is created over the wax pattern. The wax pattern is melted out leaving a cavity in the shape of the pattern. The cavity is filled with molten metal. After solidification, the shell is broken away, the gating material is removed and the finished part remains. The range of alloys which can be investment cast is wider than that for any other single manufacturing process. Some of the alloy types that are used in wide production are: Aluminium, Magnesium, Titanium alloys and Stainless steels. |
1st Stage: The Wax
The first step in investment casting is to manufacture the wax pattern for the process. Since the pattern is destroyed in the process, one will be needed for each casting to be made. Similar to the mold that may be employed in the expanded polystyrene casting process to produce foam polystyrene patterns, the mold to create wax patterns may be cast or machined. The metal casting pattern is then dipped in a refractory slurry whose composition includes extremely fine grained silica, water and binders. A ceramic layer is obtained over the surface of the pattern. Once the refractory coat over the pattern is thick enough, it is allowed to dry in air in order to harden. |
2nd Stage: Cheramic mold
Next step in this manufacturing process is the key to investment casting. The hardened ceramic mold is turned upside down and heated to high a temperature. This causes the wax to flow out of the mold, leaving the cavity for the metal casting. The ceramic mold is then heated to around 1000F-2000F (550C-1100C). This will further strengthen the mold, eliminate any leftover wax or contaminants and drive out water from the mold material. The metal casting is then poured while the mold is still hot. |
3rd Stage: Casted part
The final step in this manufacturing process involves breaking the ceramic mold from the investment casting and cutting the parts from the tree. Parts can be anodised or colored in different colors, isostaticly pressed and hardened. |
Quality of the Castings
Since almost all types of alloys can be casted there is a significat difference in quality compared to other products produced with different process. For an exemple - die cast of aluminium - castings have much better mechanical characterists, we can even used high strength aluminium alloys like 7075, which is not the case with traditional casting methods.. Additionaly, heat treatment and hot isostatic pressing (HIP) help to achieve characteristics similar to solid raw stock.
Hot isostatic pressing (HIP)HIP is a form of heat treatment that uses high pressure to improve material properties. That pressure is applied by an inert gas, usually argon. Time at elevated temperature and pressure allows plastic deformation, creep and diffusion to occur. Castings for critical applications are HIPed to eliminate internal microporosity thereby improving mechanical properties by removing defects. Using HIP process, the metal part is very homogeneous, getting close to forging.
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Heat treatmentSome times the end usage of Investment castings don't require any heat treatment, however, many times parts may require: stress relieving, normalizing, annealing, water/oil quench hardening, vacuum heat treatment, vacuum hardening
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Colors
Comprehensive range of colors, covering virtualy all needs.
Anodising and Hard Anodising
Anodising is a process for producing decorative and protective films on articles made from alumnium and its alloys. It is essentially a process where a thick film of oxide is built up on the surface of the part through the use of a direct current electrical supply.
Anodising is a process for producing decorative and protective films on articles made from alumnium and its alloys. It is essentially a process where a thick film of oxide is built up on the surface of the part through the use of a direct current electrical supply.