What is a Lost Wax Investment Casting Process?
The investment casting process is a kind of metal forming technology with a very long history. And when we use a wax pattern for the casting, investment casting is also known as a lost wax casting process.
Generally, the lost wax investment casting process suits products with complex shapes better. The minimum diameter of the hole that we can cast out directly reaches as small as 0.5mm, and the minimum wall thickness can reach 0.3mm. We can usually change one product during the production procedures, which is combined initially from several parts, into a single piece that we can make it out entirely via the investment casting process to save more time and raw materials.
The process is complicated and not easy to control. Also, the auxiliary materials are expensive, so investment casting is more suitable for manufacturing products with complex shapes, high precision requirements, and difficulties of being machined, such as turbine engine blades, etc.
There are several procedures involved in the investment casting process.
1. Molding – Design and make the molds used to produce single wax models;
2. Pattern-making – Trim the wax models and assemble them to form a wax pattern tree;
3. Shell-making – Coat the wax patter tree with the shell materials and repeat several times to a specific thickness, and then dry the shell thoroughly in the air at a particular temperature;
4. Dewax – Melt or vaporize the wax pattern tree in the shells and remove the wax;
5. Shell burnout preheating– Bake the shells to remove the moisture and residual wax;
6. Casting – Melt the applied metals and pour the molten metal into the shells;
7. Castings divesting – Knock off the shells and separate the castings, and then cut off the workpieces and grind them to remove the cutting residues;
8. Heat treatment – Apply the heat treatment to the metal castings as per requirements;
9. Machining – If necessary, machine the dimensions to the required tolerances;