Crucible - #4 Silicon Carbide
A crucible is a ceramic pot use to hold metal for melting in a furnace. This is a very high quality, industrial grade crucible used by the commercial foundry industry.
What It Does:
A crucible is needed to withstand the extreme temperatures encountered in melting metals. The crucible material must have a much higher melting point than that of the metal being melted and it must have good strength even when white hot.
It is possible to use a home made steel crucible to melt metals such as zinc and aluminum, because these metals melt at a temperature well below that of steel. However scaling (flaking) of a steel crucible interior surface is a problem. This scale can contaminate the melt and thin the crucible walls rather quickly. Steel crucibles will work if you are just getting started and don't mind dealing with the scaling.
These are a carbon bonded silicon-carbide. This material can withstand the highest temperatures in typical foundry work. It is also the strongest crucible material at high temperatures. Silicon carbide has the added advantage of being a very durable material. It is less effected by the action of fluxes.
Our Silicon Carbide Bilge Shape crucibles are rated for 2750 °F (1510 °C). They will handle zinc, aluminum, brass / bronze, silver and gold alloys. They are not recommended for iron. Made in Mexico.
A bilge shaped ("B" Shape) crucible is shaped like a wine barrel. The "bilge" dimension is the diameter of the crucible at its widest point. If there is no bilge diameter shown then the top diameter is the maximum width.
A rule of thumb states that the # of a "bilge" crucible gives its approximate working capacity in pounds of aluminum. For brass or bronze use 3 times the crucible #. For example a #4 crucible would hold approximately 4 pounds of aluminum or 12 pounds of brass. These amounts are for a really full crucible. It's best not to fill them to this amount, for safety when handling.
Our "B" shape Sic crucibles are typically used by schools, artists and industrial casters. These are a high quality, long lasting commercial grade crucible.
How To Use It:
All crucibles should be handled with properly fitting tongs (lifting tool). Improper tongs can cause damage or complete failure of a crucible at the worst possible time.
A disk of cardboard can be placed between the crucible and the furnace base prior to heating. This will burn off, leaving a layer of carbon in between and prevent the crucible from sticking to the furnace bottom. A coating of Plumbago (Carbon Black) does the same thing.
It is best to use a different crucible for each type of metal to avoid contamination. Also be sure to completely empty the crucible after use. Metal left to solidify in a crucible can expand on re-heating and destroy it.
Silicon carbide crucibles are the least likely type to absorb water in storage and typically don't need to be tempered before use. It is a good idea to fire a new crucible to a red heat prior to its first use to drive off and harden factory coatings and binders.
The material should be placed into the crucible VERY loosely. NEVER "pack" a crucible, as the material will expand on heating and can crack the ceramic. Once this material has melted into a "heel", carefully load more material into the puddle for melting. (WARNING: If ANY moisture is present on the new material a steam EXPLOSION will occur). Once again, don't tightly pack in the metal. Keep feeding the material into the melt until the required quantity has been melted.
WARNING!!!: Crucibles are dangerous. Melting metal in a crucible is dangerous. Pouring metal into molds is dangerous. A crucible may fail without warning. Crucibles can contain hidden defects in materials and manufacturing which can lead to failure, property damage, personal injury, injury to bystanders and loss of life. By purchasing a crucible from Budget Casting Supply LLC the purchaser agrees to assume all risks and agrees to indemnify Budget Casting Supply LLC from all losses arising from their use.
PLEASE NOTE THAT THE DIMENSIONS SHOWN ARE APPROXIMATE.
B4 Carbon Bonded Silicon Carbide: Height: 5-3/4", Top Diameter: 4-3/4", Bilge Diameter: 4-3/4", Bottom Diameter: 3-1/8"
ALL CRUCIBLES VARY IN SIZE FROM LOT TO LOT.
PLEASE CALL IF YOU NEED EXACT DIMENSIONS OF A CRUCIBLE.