Crucible Care and Use

1. Inspection

Before opening the box for use, please check the outer package and the crucible itself for signs of damage during transportation.

2. Handling

Do not roll the crucible on the ground, so as not to damage the protective glaze layer on the outer surface of the crucible, thus accelerating the oxidation of the crucible, resulting in reduced strength and premature damage; The crucible should be carried on a specific transport vehicle.

3. Storage

The crucible must be kept in a dry, mildly ventilated place and the crucible should be placed on a tray, do not place directly on the ground to avoid the crucible moisture; If the crucible is directly in contact with the melted metal, it may cause the crucible to crack or violent reaction; In addition, it is prohibited to store the crucible with the crucible.

4. Installation

Regularly inspect or replace any damaged or deformed heating elements, and also use a suitable base with a diameter slightly larger than the bottom diameter of the crucible to ensure that the crucible is fully supported when in use.

In the process of using the crucible, the special crucible fixture should be used to slowly lift the crucible into the furnace, ensuring that the crucible is located in the center of the furnace, and the bottom surface of the crucible is not allowed to be lower than the bottom heating element in the furnace.

Put a high temperature resistant fiber blanket on the top of the crucible to ensure that it is not hung on the side wall of the crucible to insulate the top of the crucible.

Make sure there is enough space between the heat resistant fiber blanket and the furnace cover to allow the crucible to heat up and expand.

5, crucible preheat

The correct way of preheating the crucible is very important to extend the service life of the crucible. In many cases, the crucible is damaged during preheating, and the damage is not obvious until the metal begins to melt

The new crucible should be heated to about 200°C before use, and kept for about 30-60 minutes, the purpose of doing so is to remove the moisture that the crucible may absorb, and then the crucible should be heated to more than 800°C as quickly as possible and kept for more than 40 minutes to start adding liquid metal.

6, Slag Removal, Degassing and Refining

Slag remover, grain refiner, etc. should be added to the melted metal, do not add to the empty crucible or as part of the metal material.

Agitate the metal so that the slag remover is evenly distributed to avoid contact with the inner wall of the crucible.

Glass raw materials, such as borax, erode the crucible less than chloride and fluoride, because chloride and fluoride have low melting points, their fluidity is very good, and they can quickly penetrate and erode the crucible.

Additives can be added in powder, flake or spray gun form, but make sure that these additives do not come into direct contact with the inner wall of the crucible. If the spray gun is used, it should be placed in the center of the crucible one third of the bottom surface, and the sheet piece should be penetrated into the molten pool with a bell jar.

Use additives according to manufacturer's instructions. Only the minimum amount required is added to complete the slag removal, in order to extend the service life of the crucible, only before pouring, add the refining agent and ensure that the crucible is not less than one-third of the volume of liquid metal.

After the end of the work every day, the sticky slag in the crucible should be cleaned. In order to prevent the remaining slag removal agent from penetrating into the slag and then diffusing into the crucible, increasing the erosion of the refining agent to the crucible.

The reaction speed of the crucible with the refining agent is proportional to the temperature, and the overheating of the crucible will shorten the service life of the crucible.

The well-flowing refining agent will pass through the crucible wall and attack the crucible from the outside, combining with oxygen in the furnace. The glaze of the bubbles and/or large pits are the main characteristics of this erosion.

Spillage or spatter of the refining agent outside the crucible will produce the same result as above.

7. Clean the Crucible Regularly

It is very important to remove the slag properly, making sure to clean the crucible at the end of each day's work.

The crucible should be cleaned with the correct tool, which should be a circular or curved surface similar to the inner wall of the crucible.

Irregularly cleaning the slag will shorten the service life of the crucible, because during the heating process, the expansion coefficient of the slag is 10 times that of the crucible, which causes the crucible to crack.

The slag also contains refining agent components, which will increase the chance of refining agent erosion on the crucible wall.

The slag attached to the wall of the crucible will prolong the melting time, increase energy consumption, reduce the actual capacity of the crucible, and easily lead to oxidation and cracking of the crucible.

8, the Crucible after Maintenance

Do not let the molten metal solidify in the crucible, and scoop out all the liquid metal as soon as possible after the furnace power is cut off or the gas furnace is cut off.

When the furnace is still hot, the appropriate tools should be used to remove the slag on the wall of the crucible, and the structure of the crucible itself should be avoided, and the slag can be removed by lightly scraping the inner wall of the crucible with a metal stick.

Ensure that the aluminum drain hole is always clean and closed to avoid cold air entering the aluminum drain hole, as this "chimney effect" will cause local cooling of the lower part of the crucible, causing a temperature gradient that will cause the crucible to break.

When removing the crucible from the furnace, appropriate handling tools should be used to avoid damaging the crucible. Do not place a hot crucible in a cold one

This can cause the bottom of the crucible to crack or flake off.

9. About Stopping the Furnace

The aluminum water in the crucible can be scooped out for a short period of time (within 48 hours). When the furnace is turned on, it can be directly raised to the required temperature for heat preservation for more than 30 minutes.

When the furnace is shut down for a long time, because the crucible absorbs moisture in the air, in order to avoid cracking during heating use, it must be preheated according to the preheating method used for the first time to ensure its performance.