Glass Melting Furnace
The Orton Model GMF-1700 glass melting furnace is a large sample batch melter designed for formula development and product improvement. The maximum continuous service temperature of the hot zone is 1700C and the maximum crucible size can accommodate approximately 2000 grams of molten glass. The bottom loading furnace is equipped with a variable speed electrically driven screw jack for rapid sample removal at operating temperature; the screw jack is remotely operated for user safety. Furthermore the unit is equipped with an automatic glass stirring mechanism (IKA® Eurostar 100 control) complete with torque reading, automatic speed control up to 1300 rpm, integrated timer and USB/RS-232 communication compatibility. A standard Orton instrument control module (based on Honeywell UDC 3200 PID controller) is also included, providing all standard safety features (over temp, over current, thermocouple break) and USB communication capability for data logging and remote setup operations.
The high temperature furnace consists of 6 molybdenum disilicide hairpin heating elements (I2R Moly-D ®) vertically suspended inside an insulation package made from vacuum formed 1800oC high density fiber. A hearth pedestal made from 1760oC insulating firebrick (BNZ 3200 IFB ®) is provided to hold the crucible accurately in the center of the hot zone; the crucible may be as large as 15 cm diameter by 17.5 cm high. Power to the elements is provided by a 7.5 kVA transformer mounted in the base of the furnace support frame, regulated via a solid state relay. Control feedback is provided by a type B platinum/rhodium thermocouple for long life at high service temperature.
The footprint of the GMF-1700 is 69 cm x 69 cm; the height is 210 cm with the overhead stirring motor attached and 160 cm without. The total mass of the furnace and controller is 200 kg. The support frame is constructed of 6061-T6 aluminum coated with an attractive combination of durable clear anodized and black powder coat finishes. All fasteners are stainless steel, providing additional contrast that is both aesthetic and functional. Also the support frame assembly is equipped with adjustable feet for leveling the furnace on any floor.
Electrical service requirements are quite modest at 7.5 kVA 230 volt 50/60 Hz single phase, though a 50 A breaker is recommended. One separate outlet is required for operation of the stirring motor, though this may optionally be included in the back panel of the control module upon request.