Furnace ramp rates
Ramp the empty furnace to 1550 degrees Celsius at the rate of 100 degrees Celsius per hour; then hold at 1550 degrees Celsius for one hour. This procedure conditions the molydisilicide heating elements by allowing formation of a glass protective glaze on the element surface. This is a crucial factor for their optimal performance and ultimate lifespan.
If your furnace has a ceramic hot face lining or uses a ceramic process tube, you should always limit the ramp rate to 100 degrees Celsius per hour. This will protect the ceramics from thermal shock.
For most other models, any ramp rate is acceptable. However, we strongly recommend that you slow the ramp rate for temperatures above 1500 degrees Celsius to 100°C per hour. This precaution is important for prolonging both element and furnace lining life.
Empty Deltech furnaces are capable of coming to temperature very quickly. For example, a one cubic foot bench top model could, if the precaution in the preceding section were ignored(!), be heated to 1700 degrees Celsius within 20 minutes. Once a product load is in place, however, the mass and placement of the product and kiln furniture will determine how quickly the furnace can be brought to the desired uniform temperature. Because of the practically speaking “limitless” variations in product, kiln furniture, and load arrangement characteristics, Deltech cannot predict specific outcomes.
Always refer to your Deltech Furnaces installation and operating manuals. These are supplied in pdf format for easy and convenient storage in your files. If you need additional guidance, please contact us using one of the methods on our homepage. Our Engineering team can assist.