About Investment Casting
Investment casting is one of the world’s oldest manufacturing procedures, capable of producing excellent quality castings.
Investment casting also goes by the name ‘lost wax casting’. This name derives from the methods implemented in the process in order to produce a casting. Tooling is used to produce a wax replica of the desired casting. This replica, often on a wax ‘tree’, is coated in layers of ceramic material. Each layer increases in coarse particles. Once the ceramic is dry, the wax inside the ceramic shell is melted leaving behind a negative impression of the desired casting within the shell.
The shell is filled with molten metal and as this cools it becomes a solid casting. Once solid and cooled, the shell is broken off usually by vibration. The parts are then cut away from the tree.
This process is capable of producing excellent surface finishes and complex, intricate shapes requiring little, if any, subsequent machining or secondary processes. It is normally used for the manufacture of smaller castings, although it is possible to produce steel castings up to 200 kg and aluminium castings up to 25 kg using the investment casting process.
In addition, metals that are hard to machine or fabricate are excellent candidates for this process, particularly products that cannot be produced by normal manufacturing techniques, such as turbine blades with complex shapes or aero parts that have to withstand high temperatures.
This process produces excellent quality castings, however due to the steps involved, it is a slower process with typical total production cycle times varying from 2/3 days to 6/7 days.