Investment Casting
Production starts with preparation of the moulds to make a wax model using a wax injection press machine. The moulds are made of duraluminium or steel.
The moulds are filled with wax using a manuel or semi-automatic wax injection press machine. The presses have a 300-2000 psi vertical or horizontal injection pressure capacity and presses every 20 C 80 seconds.
The wax models are mounted to rod shaped runners by using a heater like soldering iron. And the head is attached to the models.
The wax assemblies are dipped into the special ceramic beds resulting the assemblies becoming casting molds. The special ceramic plate on the assemblies is coated with sand usung raining process or fluidized beds. This process is repeated allowing drying time after each coat untill the desired resistance and schell thickness is reached. Colloidal silica is used as a binder and alumina and zircon oksides are used as refractories in the ceramic coating. Temperature is regulated at 18 - 20 C and the moisture is %50 - 55
The clusters are placed in an steam autoclave at 7 bar pressure, 200 C for 15 - 20 minutes.
Sintering removes the wax particles and adds resistance to molds. This is done at 1050 C for an hour.
Casting is done at 850 - 900 C to prevent the ceramic coatings cracking or solidifying too quickly.
After casting ceramic cover is breaked using vibrating breaking machine.
The items re cut from the runners and separated from clusters. The runners are with an emery machine. The items are sanded with a sand injection using steel shot or silica sand.
All items are tested for measurement. Dimensional characterictics are measured for 100% compliance to the original print. The chemical composition tests are done by spectrometer. If there is a need for precision controls, special tests can be applied such as metalugical properties, resistance.
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