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How to use electric furnace crucible

How to use electric furnace crucible and intermediate frequency furnace crucible

1. Preparation before installation
(1) Check whether the inner wall and bottom of the crucible furnace are intact.
(2) Check whether there is residual slag in the furnace, and remove it in time if there is.
2. Choose the right crucible base
(1) The base of the crucible should have the same shape and size as the bottom of the crucible (about 2CM)
(2) For different types of crucible furnaces, a crucible base with a suitable height should be selected.
(3) Avoid using waste crucible base, otherwise it will greatly shorten the life of the crucible.
3. Installation and fixing of crucible
(1) Install the crucible for gas or oil-fired furnace: first place the crucible on the base, reserve a certain expansion space between the crucible and the top of the furnace wall, and fix it with wood blocks, cardboard and other materials. Adjust the position of the burner and nozzle so that the flame is aimed at the combustion chamber, not directly at the bottom of the crucible.
(2) Install the crucible for the rotary furnace: support bricks should be used to fix the crucible on both sides of the crucible spout to avoid wedge the crucible. At the same time, between the supporting brick and the crucible, a cardboard and other materials of about 3-4mm are placed as the pre-expansion space of the crucible.
(3) Install crucible for resistance furnace: The crucible should be placed in the center of the resistance furnace, and the bottom of the crucible should be higher than the bottom row of heating elements. At the same time, use insulation cotton to seal between the top of the crucible and the edge of the furnace.
(4) Install crucible for induction furnace: make sure that the crucible is placed in the center of the induction coil to avoid local overheating and cracks in the crucible.
4. Crucible preheating
Preheating the crucible in the correct way can greatly extend the service life of the crucible.
Before use, it needs to be heated in the drying equipment or furnace. The baking temperature is gradually increased from low to high, and the crucible is constantly turned to heat it evenly, and the moisture and moisture in the crucible are removed. The preheating temperature is gradually increased to 500 ~~ Above 600°C, the silicon carbide crucible should reach 900°C for at least 6 hours. It takes 5 hours for 1-380°C. The heating speed should be slow, and then as fast as possible when it reaches 600°C, and it can be faster when it reaches 900°C. The time is not less than 8 hours. (If improper preheating causes the crucible to peel off or burst, it will not be returned if it is not a quality problem). After stopping the furnace, it should be properly baked according to the weather conditions to ensure the service life of the crucible.

5. Adding materials
(1) The metal material must be dried before adding
(2) Put down gently when feeding, and do not throw or pour metal ingots into the crucible to avoid damage to the crucible.
(3) Put the metal ingot into the crucible vertically, and keep enough expansion space between the metal ingot and the crucible wall. Do not place the metal ingot horizontally in the crucible, so as not to damage the crucible due to metal expansion after heating.
(4) You can add some small pieces of metal to the crucible first. As a bedding for large ingots.
(5) During continuous smelting, part of the metal solution can be kept in the crucible to accelerate the melting speed. However, it is necessary to avoid adding large metal materials to a small amount of solution, so as to avoid sudden cooling or solidification of the solution, which may damage the crucible.
(6) When adding liquid metal, avoid overfilling, generally not exceeding 80% of the crucible capacity.
6. Use of additives
When using additives, you must strictly follow the instructions for use of the additives.
(1) Additives can only be added after the metal material is completely dissolved. Do not put additives in empty crucibles or solid metal materials, and do not allow additives to directly contact the walls or outer edges of the crucible, otherwise the crucible will be directly damaged.
(2) When using additives, they must be added in strict accordance with the prescribed dosage. Excessive use of additives will greatly shorten the service life of the crucible.
7. The use of crucible tongs
(1) The size of the crucible tongs must match the size and shape of the crucible, and the upper edge of the crucible must not be squeezed to avoid damage to the crucible or cause safety accidents
(2) The crucible tongs should be clamped in the middle and lower part of the crucible. If it is too high, it will easily fall off or pinch the crucible. If it is too low, it will not be conducive to the pouring operation.
(3) When using crucible tongs to move the crucible, place the crucible on a high-temperature resistant plate or transfer tool. Do not place the hot crucible on the surface of a cold object to avoid damage to the bottom of the crucible.
8. Pouring
When using the crucible for pouring, it should be carried out in strict accordance with the operating specifications to avoid damage to the crucible.
(1) When the metal solution reaches the predetermined casting temperature, it should be poured as soon as possible after removing slag and gas.
(2) When pouring is carried out, heating should not be continued, so as to avoid air inhalation, metal burnout, and uneven corrosion of the crucible wall, thereby shortening the service life of the crucible
(3) When using a rotating crucible furnace, after completing a pouring operation, the crucible should be restored to its original position.
(4) The metal solution should not be kept in the crucible for too long, otherwise it will shorten the service life of the crucible and reduce the quality of the molten metal.
9. Empty the crucible
(1) When it is necessary to temporarily stop using the crucible due to the removal of slag or repair of the crucible, the metal solution in the crucible should be emptied.
(2) When emptying the crucible, the metal solution in the crucible can be poured into the mold to form an ingot for later use.
(3) If the metal solution is kept in the crucible for solidification, it will directly swell the crucible due to expansion during the next heating.
10. Remove molten residue
During the smelting process, additives and impurities in the metal solution will form slag and adhere to the crucible wall. Since the molten slag contains additives that will corrode the crucible wall, the molten slag should be removed once a day.
(1) Special tools should be used to remove molten slag, and the molten slag should be removed in time when it is not solidified. The solidified slag will be difficult to remove.
(2) Avoid scratching the crucible wall when removing molten slag.
(3) When the multi-layer slag solidifies and remains on the crucible wall, it will corrode the crucible and affect the thermal conductivity. It will also cause the crucible to crack when heated and expand, thereby shortening the life of the crucible.

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