1. Preparation work 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 if so, remove it in time.
2. Select the correct crucible base
1) The crucible base should be the same shape as the bottom of the crucible and slightly larger (about 2 CM).
2) For different types of crucible furnaces, use the right crucible base with the right height.
3) Avoid using a used crucible base, as this will significantly shorten the crucible life.
3. Installation and fixing of the crucible
1) Installation of crucible for gas or oil furnace
First place the crucible on the base, leave a certain space for crucible expansion between the crucible and the top of the furnace wall, and fix it using wood blocks, cardboard and other materials. Adjust the position of the burner and nozzle so that the flame is aligned with the combustion chamber and not directly with the bottom of the crucible.
2) Installation of crucible for rotary furnace
The crucible should be fixed using support bricks on both sides of the crucible pouring nozzle to avoid wedging the crucible tightly. At the same time, a material such as cardboard of about 3-4 mm is padded between the support brick and the crucible as a pre-expansion space for the crucible.
3) Installation of the crucible for resistance furnace
The crucible should be placed in the central part of the resistance furnace, with the bottom of the crucible above the bottom row of heating elements. The crucible should also be sealed with insulation wool between the top of the crucible and the furnace rim.
4) Installation of the crucible for the induction furnace
Make sure that the crucible is placed in the central part of the induction coil to avoid local overheating and cracks in the crucible.
Graphite crucible charging
1）The metal material must be dried before adding.
2）The metal ingot should be gently put down when adding material, and should not be thrown or poured into the crucible to avoid damaging the crucible.
3) Place the metal ingot vertically in the crucible with sufficient expansion space between the metal ingot and the crucible wall. Do not place the metal ingot horizontally in the crucible, so that the expansion of the ingot after heating will not swell the crucible.
4) Some small pieces of metal material can be added in the crucible first as a bedding for the large ingot material.
5) When continuous melting, you can keep part of the metal solution inside the crucible to speed up the melting speed. However, avoid adding large pieces of metal material to a small amount of solution to avoid sudden cooling or solidification of the solution, which may damage the crucible.
6) When adding liquid metal, avoid overfilling, generally not more than 80% of the crucible capacity.
How to Achieve Optimal Performance
The crucible's optimal performance can be maintained and the crucible's service life can be effectively extended if the following points are followed during the use of the crucible.
1）The crucible should be selected for each molten metal for which it is designed.
2） When heating the crucible, pay attention to the following.
- Preheat the new crucible as specified to remove moisture from the crucible.
- Heat the crucible so that the outer surface of the crucible is evenly heated.
- Use the crucible lid to seal the crucible above to reduce heat loss and oxidation of the crucible. However, allow sufficient expansion space to avoid tight pressure on the upper edge of the crucible.
- When using gas or oil-fired crucible furnaces, use a lightly oxidized flame and avoid direct flame injection at the bottom of the crucible.
- When adding additives, immediately stir the metal solution and promptly remove the slag from the crucible. When adding flakes or lumps of additives a bellows should be used to immerse them.
3）During the pouring process, avoid bumping or knocking the crucible with tools such as crucible tongs and pouring ladle.
4）When cleaning the crucible, use the special tool that comes with the crucible while it is still hot.
5）When the crucible is temporarily out of use, the following matters should be noted：
- If a gas or oil furnace is used, turn off all fans so that cold air does not attack the crucible exterior and cause oxidation or even rupture.
- Allow the cyanoskeleton to cool itself to room temperature. Accelerating or retarding the self-cooling may increase oxidation or cause rupture of the crucible.
- For crucibles that are used infrequently, they should be stored in a fixed area and kept dry in the storage environment.
6）The crucible furnace should be checked frequently to ensure that the crucible furnace is in proper working condition. The slag on the lining of the crucible furnace should be cleaned in time.