Dental technician, have you experienced the below situation? You take the final products out of the furnaces and find out dental crowns or bridges are polluted? You set up the correct sintering curve, you did everything according to the user’s manual. Why are some batches polluted? While maybe it is time for you to clean your sintering furnace now.
Sintering furnaces that contain MoSi2 heating elements require maintenance or cleaning cycles. Absent regular cleaning or maintenance, it is likely that the final products will change colors. It might be darker than the normal color or a bit greenish.
MoSi2 heating elements develop a quartz ceramic coating on the elements. Over time the quartz will develop a lower melting point. This melting temperature is lower than the upper-end temperature of the sintering cycle. Once this occurs, running a normal cycle will result in quartz pollutants throughout the muffle in each cycle. These pollutants contaminate the zirconia and result in poor shade matches. In addition to polluting your work, the quartz also becomes attached to the thermocouple. The thermocouple is the device inside the chamber that sends actual muffle temperatures to the control board. Once the thermocouple becomes contaminated the temperature reading becomes lower. This happens naturally over time (6-12 months) and results in an increase in temperature above what was programmed. This overheating can be as much as 100 degrees.
Now you know what is happening in the furnace without regular cleaning or maintenance. Next time if you have a shift in the color of the dental crowns or bridges, then it's time to change or clean the MoSi2 heating. Check out Vsmile heating elements for sintering furnace here: https://www.vsmilecadcamzirconia.com/dental-equipment/heating-elements-for-dental-element.html