Reliable Sand Heating and Delivery

Jan. 21, 2011
Accurate, high-efficiency fluidization, and low maintenance

Preparing molding sand can be managed reliably with Palmer Manufacturing’s H-Series of electric sand heating systems.

The Model H design features a standard heating package and uses an SCR drive controller to monitor sand temperature. It applies power effectively to all heating elements to achieve the desired sand temperature, without temperature swings. The SCR controller eliminates all electrical contactors and allows the H-Series to operate with no moving parts. Sand temperatures generally can be controlled within 2° of set point.

The H-Series uses a high-tolerance processor and a type-J thermocouple for accurate sand temperature control. A second thermocouple monitors over-temperature. Palmer notes that each thermocouple tip is directly exposed to sand in the heater, so they deliver actual measured and controlled temperatures.

The systems deliver compressed air into the bottom of the heater to fluidize the sand, and the air is distributed effectively so that fluidizing air enters the body but prevents sand from falling into the air manifold.

The air manifold has a high-efficiency bowl filter, dual-stage cartridge filtering device, heavy-duty fluidization solenoid, air pressure regulator, and air pressure switch, in a set-up that eliminates the saturation problems typical of fluidized bed membranes.

The Model H maintains a constant fluid bed depth, which aids heating and fluidizing thanks to an inlet control valve to shut off the supply of sand to the heater when it’s not needed by the mixer. The valve prevents packing in the heater and eliminates inconsistent sand temperature, inconsistent fluidization, inconsistent sand flow, and similar common problems. In addition, the valve allows fluidization to continue after a heating cycle.

The H-Series has all electrical controls housed in dust-tight enclosures, with primary electrical controls mounted at floor level and the heater body suspended above the mixer. The heater body has three primary electrical connection areas: the air valve enclosure, the power distribution enclosure, and the body top enclosure.

The mechanical configuration features a heating bundle that is integrated and fully wired. Operators can access the heating elements either from the bottom or the side, making it simple to replace elements and inspect the heater. It’s heavy-gauge steel fabrication resists damage from exposure to abrasives.