Sand casting allows you to make individualized molds out of sand.
Casting, or the process of pouring a liquid into a mold and allowing it to dry, can create complex shapes difficult to produce by other means. Sand casting uses sand as a cheaper alternative to metal for the molding process. Sand casting yourself may seem intimidating, but with a some time, a few pieces of specialized equipment and a little know-how, you can learn to create quality molds for practical or decorative purposes.
Instructions
1. Place your pattern material, or wax, wood, plaster, metal or plastic material in the desired shape, into a frame used to contain molds for casting, called a flask. Leave at least an inch between all sides of the pattern in the flask for gating, or expansion.
2. Apply a heavy layer of parting dust over the pattern material to repel moisture. Spread a layer of sand over the pattern with a riddle, or large sieve. Fill sand up to the top of the flask with the riddle.
3. Hold your flask in one hand and the wood rammer in the other. Pound in the edges of sand in the flask with the rammer, holding the paddle side out. Hold the butt of the rammer out and pound the sand, separating each rammer stroke by one inch. Pound lightly in an east-to-west direction over the sand, then, pound down forcefully in a north-to-south direction to pack in the sand.
4. Fill more sand into the flask by hand or using a small bucket until it extends 2 inches above the flask's top. Hold the flask in one hand and the rammer in the other and pound the rammer down in hard strokes over the flask in a north-to-south and then east-to-west direction. Push off excess sand with the rammer until the sand is level with the flask's top corners.
5. Position the bottom board over the top of the flask so that it seals the flask. Flip the flask over, holding the bottom board in place. Take off the cope and pattern board of the flask, and smooth out any rough spots or edges with the back of a spoon. Put the cope back on and apply a layer of parting dust. Check the flask to ensure all hinges and latches are positioned on the same side. Repeat steps 2 through 4.
6. Smooth out the sand in the flask with the back of your trowel. Remove the cope and hold the flask on its side. Cut a sprue hole into one corner of the flask with a copper pipe hole cutter. Still holding the flask, insert the dowel, or fastener pin that prevents motion, into the middle of the flask. Smooth away any hole edges with your finger.
7. Carve out an area around the sprue hole in the shape of a pouring cup with the trowel. Smooth down the edges of the area with your dowel. Remove the runner pattern and gate wood pattern from the flask. Press a screw partially into the mold pattern and lift it using the screw. Touch any rough spots on the pattern to smooth them out. Place the cope back onto the flask and clamp it.
8. Feed aluminum into a crucible and heat the crucible in a furnace to between 1,325 and 1,400 degrees C. Remove the crucible and pour the aluminum through the sprue hole in the flask. Let the mold cool for five minutes. Shake out the mold pattern into a sand container.
