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Periodic Furnaces
The periodic furnaces have a temperature range of up to 3200°F. The furnaces have controlled heating with the top soak temperature confirmed and set using a optical pyrometer.
Tunnel Kilns
The tunnel kiln temperatures range from 2000°F – 3000°F with anything outside this range requiring special adjustments. Push times can range from 3 hours to 16 hours. Depending on the kiln and the push time, total kiln residence time door-to-door can range from 24 hours to 5 or more days.
Three of the four tunnel kilns have one heat zone of control. The fourth tunnel kiln has four zones of control.
Roller hearths
Roller hearths can reach 2400°F, with “door-to-door” time ranging from 90 minutes to 8 hours. Depending on the roller hearth, the “heat zone” is 40% or 60% of the kiln, the remainder being pre-heat and cooling areas.
The main advantages to the roller hearth is the uniformity and consistency of the fired product, responsiveness to processing and temperature changes, short residence time and low product loss.
Depending on the material to be calcined, ceramic saggers composed of alumina, mullite, cordierite or fused silica have been used.
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