Five Things you should know about Furnace Startup

Five Things you should know about Furnace Startup

  1. Control Parameters. Deltech is responsible for the initial configuration of your temperature and limit controllers prior to the shipment of your furnace system. This includes setting the thermocouple type, temperature scale, upper and lower temperature limits, PID values, and events. Should you wish to verify or change any of these parameters, refer to the controller setup guides in your Deltech furnace manual.
  2. Element Conditioning. If your furnace features molydisilicide heating elements, it is very important to element life and performance that you run a conditioning cycle. The furnace should be ramped at 100 degrees Celsius or less to 1550 degrees, then held at this temperature for one hour. (Then you can simply turn the furnace off unless your furnace is a tube model; the process tubes are subject to breakage from thermal shock.) This puts a protective coating of silica on the molydisilicide core. This operation should be done with an empty furnace; i.e. no product should be in place.
  3. What’s that smell? As you are ramping the temperature to condition the elements, you may notice that at a few hundred degrees you begin to notice acrid fumes – and sometimes smoke – coming from the furnace. This is the binder burning out of the low temperature insulation layers. This process cannot be avoided; pre-firing of the board causes it to be fragile and therefore likely to be destroyed during shipment. Once a temperature of about 800 degrees Celsius is reached, the odors will subside.
  4. What’s wrong with my controller? If type B thermocouples were included with your furnace system, when you first start the temperature ramp you may note that the temperature controller is behaving erratically. This is normal. Type B thermocouples don’t send a sufficient signal until the furnace reaches at least 500 degrees Celsius. The controller will stabilize. 
  5. Cracks!?! Insulation is like concrete – it’s either brand new or it’s cracked. So after firing your furnace, you may see some hairline cracks, especially on the furnace roof hot face. No worries; these are a normal feature of alumina silicate insulating materials. If you see fissures, then you should contact us.
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