Installation and Heating
All installation and heating instructions are product specific.
Please select a MORGANITE or NOLTINA crucible.
Excel / Himelt
Indux
ISO Alustar
Salamander Super
Starrbide/Stabil
Syncarb
Ultramelt
EXCEL E
Installation: The stand should be made from the same material as the crucible to ensure uniform heating of the crucible base and provide sufficient mechanical support. The diameter of the stand should be at least the same as the base of the crucible and the height should be such that the base of the crucible is level with the centre line of the burner in fuel-fired furnaces. The stand and crucible should be installed centrally in the furnace.
Preheating / First Use:
Electric Resistance Furnaces: Crucibles should be pre-heated empty on full power until they reach a uniform bright red colour (circa 900°C) and be held at this temperature for 30 minutes in order to pre-condition the glaze. The crucible can then be charged and the controller adjusted to achieve the desired operating temperature.
Gas Fired Furnaces: Crucibles should be pre-heated empty until they reach a uniform bright red colour (circa 900°C) and held at this temperature for 30 minutes in order to pre-condition the glaze. The crucible can then be charged and the controller adjusted to achieve the desired operating temperature. The time taken to reach temperature will depend on the size of the
crucible. In the case of large capacity crucibles and furnaces with high output burners the rate of temperature rise should be controlled in the initial stages to minimise thermal stress before applying the full power of the burner. Avoid direct flame impingement on the crucible surface.
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EXCEL / HIMELT
Installation: The stand should be made from the same material as the crucible to ensure uniform heating of the crucible base and provide sufficient mechanical support. The diameter of the stand should be at least the same as the base of the crucible and the height should be such that the base of the crucible is level with the centre line of the burner in fuel-fired furnaces. The stand and crucible should be installed centrally in the furnace.
Preheating / First Use:
Fuel-Fired Furnaces: Crucibles should be pre-heated empty until they reach a uniform bright red colour (circa 900°C) in order to pre-condition the glaze. The pre-heating time will depend on the size of the crucible. In the case of large capacity crucibles and furnaces with high output burners the rate of temperature rise should be controlled in the initial stages to minimise thermal stress. The typical time taken from ambient to red heat is up to 1 hour. Avoid direct flame impingement on the crucible surface.
Induction Furnaces: The heat-up procedure is dependant on furnace frequency, coil dimensions, and the resistivity of the metal being melted. It is recommended where possible to preheat the crucible empty. The power input rate should initially be limited until the crucible becomes bright red over its entire surface. The time taken to pre-heat will depend on the size of the crucible, but is usually in the range 20 – 40 minutes. Once one third of the crucible is full of molten metal the power can be increased to a higher level. Silicon carbide crucibles absorb proportionally high levels of power from the induction field. Care should be taken not to overheat the crucible. The actual maximum power setting should be assessed from experience and will be dependant on the capacity of the crucible. The appearance of the inside wall of the crucible should be monitored for signs of over-heating and the power reduced once the full charge is molten.
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INDUX
Installation:
Indux Bilge: Bilge crucibles are free- standing. They should be supported fully on the base by a suitable stand. Crucibles must be centralized in the induction coil. If off-center uneven heating will take place.
Indux Cylinder: Cylindrical crucibles are installed with a back-up refractory. The back-up refractory should be magnesia or mullite based and contain no sintering additives. Morganite Starram products are designed for this application. Hard sintered back-up material will restrict expansion of the crucible and cause it to crack. The thickness of the back-up is determined by the crucible size.
Crucibles containing up to 600 lbs copper alloy require 1 3/4” back-up thickness, 600 – 1500 lbs capacity require 2” back-up thickness and over 1500 lbs require 2 1/2” back-up thickness.
A slip plane should be installed against the wall of the furnace to facilitate removal of back-up material and crucible after use. Mica sheet or glass fiber cloth is recommended.
A quantity of back-up is placed in the base of the furnace to support the crucible and establish it at the correct height in relation to the induction coil. This should be built up in layers of approximately 2”, de-aired and compacted using a forked tool. The “star wires” should be arranged such that an earth leakage detection is provided. The outer surface of the back-up should be scored to provide a key for the material to be added for the sidewall.
Lower the crucible into the furnace ensuring that the earth leakage probe is sited such that it is in contact with the base of the crucible. Centralize the crucible within the coil to avoid uneven heating.
Add back-up material evenly around the crucible, de-airing with a forked tool to achieve compaction evenly around the crucible. The back-up material should be added in layers approximately 2” to 3” in thickness. Score the surface of each layer to provide a key with the next layer. Repeat this process until the top of the coil is reached.
Any excess slip plane material can be cut off. There are a number of options for forming a pouring lip. Morganite manufactures a variety of cylindrical crucibles with an integral lip that can be seated into plastic refractory. Alternatively, a pouring lip can be hand- formed using plastic refractory. The top of the crucible and back-up lining should be sealed in position with plastic refractory, such as Morganite Starrpatch 350.
Preheating / First Use:
Indux Bilge: The procedure recommended for preheating INDUX bilge crucibles depends on the frequency of the furnace.In 3 kHz furnaces, crucibles should be preheated with the crucibles empty. Run the furnace for
1/2 hour at 20% of maximum power and then increase to 50% until the crucible shows signs of red heat. Loosely charge the crucible with metal. Keep the power at 50% of maximum until approximately half the crucible contains molten metal. Then increase to maximum power.
In 1 kHz furnaces the crucible does not absorb power; therefore the crucible should be preheated with a charge loosely in place. Run the furnace at 20% of maximum power until the crucible shows signs of red heat. If after 1/2 hour the crucible shows no evidence of red heat, increase the power input to 50% of maximum. Hold at 50% until half the crucible contains molten metal, then increase to maximum power.
Indux Cylinders: INDUX crucibles are prone to thermal shock if the rate of temperature charge is too rapid. To preheat the crucible use which ever power level is smaller, 100KW or 50% maximum power input. Heat until the crucible is bright red, this should take 20–40 minutes. The crucible can be pre-heated with or without charge material, depending on the specific furnace conditions.
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ISO ALUSTAR
Installation: The stand should be made from the same material as the crucible to ensure uniform heating of the crucible base and provide sufficient mechanical support. The diameter of the stand should be at least the same as the base of the crucible and the height should be such that the base of the crucible is level with the centre line of the burner in fuel-fired furnaces. The stand and crucible should be installed centrally in the furnace.
Preheating / First Use:
Electric Resistance and Gas Fired Furnaces: Crucibles should be pre-heated empty. A new crucible should initially be heated slowly to 200°C over a period of two hours to eliminate any moisture that may be present. Subsequently the crucible should be heated to 600°C on low power before the full heating rate is used to reach 950°C, or the desired working temperature if higher. Iso-Alustar crucibles used for holding applications should be held at 950°C for one hour in order to
fully develop the anti-oxidant glaze system. The time taken to reach temperature will depend on the size of the crucible but will typically be in the range two and a half to three hours. Avoid direct flame impingement on the crucible surface.
The same heat up procedure should be repeated prior to re-use after a cool-down period. The two hour drying period can be omitted except where the crucible has not been used for a long period in which case moisture that has been absorbed by slag will need to be slowly removed.
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SALAMANDER SUPER
Installation: Salamander Super crucibles are used free standing in lift out furnaces. In fuel fired furnaces the stand should be made from similar material to the crucible to ensure uniform heating of the crucible base and provide sufficient mechanical support. The diameter of the stand should be at least the same as the base of the crucible and the height should be such that the base of the crucible is level with the centre line of the burner. The stand and crucible should be installed centrally in the
furnace. In induction furnaces the crucible stands on a refractory pedestal and must be installed centrally within the coil. A thin layer of coke dust or other carbonaceous material should be sprinkled on to the stand or pedestal to prevent the crucible sticking to it.
Preheating/First Use:
Fuel-Fired Furnaces: A new crucible should be pre-heated empty in order to minimise the temperature gradient across the crucible wall. If the furnace refractories have been repaired or if there is a risk of the crucible having absorbed some moisture, then the furnace should initially be heated slowly up to circa 200ºC and held at this temperature until all moisture has been driven off.
A new crucible should initially be heated slowly and evenly to 600ºC on low power, avoiding local impingement of flame. Subsequently the full heat input rate should be utilised to achieve a uniform bright red condition over the whole crucible (circa 900ºC / 1650ºF) at which point the crucible should be charged immediately taking care to avoid packing metal tightly or bridging ingots across the crucible. The furnace controls can then be set to achieve the desired metal operating temperature and heating should continue at the full rate until the metal has reached the desired temperature.
In the case of crucibles to be fed with molten metal, it is important that the crucible body temperature is equivalent to or slightly above that of the molten metal in order to minimise thermal stress.
Induction Furnaces: Small Salamander Super crucibles are sometimes used in medium to high frequency induction furnaces. The heat-up procedure is dependent on furnace frequency, coil dimensions, and the resistivity of the metal being melted. It is recommended where possible to preheat the crucible empty.
The furnace should initially be run at 20% of maximum power until the crucible shows signs of red heat. After 30 minutes the power can be increased to 50% of the maximum. Loosely charge the crucible with metal and maintain the power level at 50% until approximately half the crucible contains molten metal.
The power should then be increased to maximum.
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STARRBIDE / STABIL
Installation: The use of a base block made of the same material will ensure uniform heating of the crucible base and help reduce thermal strains. The base block should have the same or slightly larger diameter as the base of the crucible to provide adequate support. For optimum heat transfer and melting efficiency, the height of the base block should be such that the base of the crucibles is level with the center line of the burner. The base block and crucible should be installed centrally in the furnace.
Preheating / First Use: Crucibles should be preheated empty until they reach a bright-red color 1472ºF (800ºC). This procedure drives off any moisture absorbed in shipping and sets the glaze to achieve maximum oxidation resistance. The time needed to preheat depends on the size of the crucible. Typical times from cold to red heat are 30 minutes for crucibles with 700 lbs aluminum capacity, up to 70 minutes for crucibles with between 700–2000 lbs aluminum capacity.
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SYNCARB
Installation: The use of a base block made of the same material will ensure uniform heating of the crucible base and help reduce thermal strains.
The base block should have the same or slightly larger diameter as the base of the crucible to provide adequate support.
For optimum heat transfer and melting efficiency, the height of the base block should be such that the base of the crucibles is level with the center line of the burner. The base block and crucible should be installed centrally in the furnace.
Preheating / First Use: Crucibles should be preheated empty until they reach a bright-red color. Heat to 400ºF (200ºC) over two hours, then heat to 1100ºF (600ºC) in the next hour. Heat at full power to 1740ºF (950ºC) or to the working temperature of the metal. Hold at this temperature for one hour. The cover should be in place throughout the process. This procedure drives off any moisture absorbed in shipping and sets the glaze to achieve maximum oxidation resistance. After first use, the crucible should be heated from cold to 1100°F (600°C) in 90 minutes.
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ULTRAMELT
Installation: The use of a base block made of the same material will ensure uniform heating of the crucible base and help reduce thermal strains. The base block should have the same or slightly larger diameter as the base of the crucible to provide adequate support. For optimum heat transfer and melting efficiency, the height of the base block should be such that the base of the crucibles is level with the center line of the burner. The base block and crucible should be installed centrally in the furnace.
Preheating / First Use: Crucibles should be preheated empty until they reach a bright-red color 1472ºF (800ºC). This procedure drives off any moisture absorbed in shipping and sets the glaze to achieve maximum oxidation resistance. The time needed to preheat depends on the size of the crucible. Typical times from cold to red heat are 30 minutes for crucibles with 700 lbs aluminum capacity, up to 70 minutes for crucibles with between 700–2000 lbs aluminum capacity.
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