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TECHNOLOGY OF MICROLINE
All equipment for microfusion consists of flask, centrifuges and burners.
Flask is a piece of pipe with a wall thickness of 2-3 mm . It is necessary to prepare several flasks of different diameters for models of different sizes. The essence of the condition is that the largest flask can freely fit on a centrifuge stand.
Manufacturing centrifuges. In a wooden handle skip a metal rod with a diameter of 5-6 mm . An earring is fixed to the rod. The rod should rotate freely in the handle. The stand for the flask is made of metal (in my case it is also soldered from galvanized). Its diameter is 7-8 cm , the height of the side is 2.5-3 cm . Rivet a bracket with a height of 11-12 cm from the base of the stand to the side. At the top of the bracket make a twisted ring. The bracket connects to the earring with a wire arm with rings bent at the ends. The length of the rocker is 25-30 cm , diameter - 4 mm .
The casting alloy is 64% copper, 32% zinc, 3% tin, 1% lead. It is not necessary to adhere to exact proportions. In the extreme case, you can use molten "copper" coins (old fines). The material for the model is wax, for the form - gypsum, alabaster, cement mixes (finely sieved), talc or pumice powder.
Burners can be used any, as long as the temperature of the flame could reach about 1100 degrees.
When making a model of wax, carefully trim the surface, otherwise the metal will repeat all the flaws of the model. Attach wax gates to the model. A benign pin is obtained from a sewing needle with a broken tip. Pins attached to the model closer to the edges also set them so that they converge at one point. Considering the size of the model, select the flask so that the distance between the bottom is also a model, only it seems that between the model also the top of the molding material is no less than 1 cm .
Prepare the molding mass from 2 gypsum elements, one talc or pumice stone (I advise you to experiment with different mixtures to get the best results). Mix well the composition and pour it into the water. The mass should own the consistency of thin sour cream. Put the flask on a sheet of asbestos and fill the mixture. So far, the mass has not hardened. Take the model by the pins and immerse it in it, vibrating slightly to remove atmospheric bubbles. In half an hour, cut the sprue bowl, carefully remove the pins. The runner channels must be located in the center of the bowl, have each independent outlet (see the figure above). Place the flask in the oven with gating channels down and also for a couple of hours gradually raise the temperature up to 350 degrees . After this, place the side plate on the gas stove to burn the remaining wax. Firing to produce redness of the flask. At the same time, transfer the flask to a centrifuge, put the necessary amount of metal in the sprue bowl, a little bit of borax. Melt the metal with the torch, start to hastily rotate the centrifuge (due to the centrifugal force, the necessary pressure is created to penetrate the metal into the mold). Twenty turns is enough for a filled form filling, metal crystallization. To remove casting, hot casting must be placed under a stream of water. Bleach casting in 15% sulfuric acid solution.