The weeks are passing much too quickly. I’m still receiving the final orders, and expect that there will be some learning curves with the 3D printer and the finesse required for the post operations. Four major steps are required for production. After converting the designed 3D models into wire-frame format, the 3D printer will then develop the solid model. This is usually hand carved in wax, but the 3D printer will bypass that procedure and produce the model with a castable resin similar to plastic.
The next step is mixing the investment, a plaster-like liquid, and purging it of air using a vacuum machine. This investment is then poured into a steel flask that has the “wax” model attached in the bottom of it, on a rubber base. The model is attached to the base using a “sprue”, a thick wax stem, and the flask is purged of air again.
After the investment sets and hardens, the rubber base is removed and the flask is transferred to a kiln to “burn out” the “wax”. This leaves a cavity, a negative image, of the model which is the mold into which the molten metal will be injected. The flask is heated to a temperature close to that of the molten metal. This will take several hours of ramping up the temperature from the wax burnout stage to the casting temperature.
The flask is then transferred to the centrifugal casting arm, in which the arm is wound against an internal restraining spring and held in check. It will rest in a cradle behind the melting crucible. This crucible is heated to casting temperature and the solid metal is placed into it, either silver, gold or brass. A welder’s torch is used to melt the metal to liquid state, the spring is released and the liquid metal is flung into the mold by the centrifugal force of the spinning arm.
After the arm stops its spin, the flask is removed with a pair of tongs and quickly immersed into a bucket of water. The investment dissolves leaving the cast piece to be refined with post finishing, deburring, buffing and shining. And there we have our finished piece.
Quote of the week:
“People think focus means saying yes to the thing you’ve got to focus on. But that’s not what it means at all. It means saying no to the hundred other good ideas that there are.”