Common Problems & Solutions for Dental Zirconia Sintering Furnaces

1. Broken Heating Rods (The Most Common Hardware Problem)
Two types of heating rods are widely used in the market: Molybdenum Disilicide (MoSi₂) and Silicon Carbide (SiC). They need different replacement ways once broken.
Signs of problem
The furnace heats up very slowly, cannot reach the required high temperature (1530℃~1550℃). The temperature inside the furnace is not even. Some zirconia crowns are not fully baked, and the touch screen shows temperature error warnings.
Causes
Fast heating or cooling for a long time brings strong heat impact; heating rods grow old and oxidize at high temperature; power voltage changes greatly; zirconia beads or baking trays hit the heating rods by accident.
Simple fixing methods
1.Use a multimeter to check if each heating rod can conduct electricity, and find out the broken ones.
2.MoSi₂ heating rods: You only need to change the single broken rod. No need to replace the whole set.
3.SiC heating rods: If one rod breaks, all SiC rods must be replaced together. Old and new SiC rods have different aging levels, which will cause uneven heat and shorten the life of new rods.
Tip to make heating rods last longer
Do not use programs with extremely fast heating or cooling. Keep the inside of the furnace clean to reduce dirt that damages heating rods at high temperature.

2. Dirt Inside the Furnace (Makes Zirconia Crowns Turn White or Yellow)
Signs of problem
After baking, zirconia crowns look foggy white, pale yellow or have dark spots. These marks cannot be removed by polishing.
Sources of dirt
1.Dirty or old zirconia beads: Powder left from previous baking sticks to beads and turns into gas at high temperature.
2.Outside dirt: Remaining coloring liquid, cutting dust, oil from the furnace door rubber ring.
3.Low-quality heating rods: Cheap heating rods release metal gas under high temperature. This is the main reason for stained crowns in most labs.
4.Bad zirconia blocks: Raw materials of poor-quality blocks release impurities during baking.
Fixing and prevention methods
1.Clear dirt sources one by one: Clean or change old zirconia beads regularly; fully dry colored crowns before putting them into the furnace; wipe the furnace door rubber ring to clear oil.
2.Choose original heating rods from our factory. Our original heating rods are made of high-purity materials, stable under high temperature, and will not release dirt to pollute zirconia crowns.
3.Run a high-temperature empty furnace cleaning program every month, to burn off dust and organic dirt inside the furnace.

3. Uneven Temperature Inside the Furnace
Signs of problem
Zirconia crowns placed in different positions on the baking tray have different transparency and colors. Some crowns are not fully baked while others are over-baked.
Causes
1.Some heating rods are broken or old, so certain areas do not get enough heat.
2.Broken heat-insulating cotton inside the furnace: Peeling or cracked cotton makes heat escape fast around the furnace edge.
3.Too many crowns placed too close together: Crowded crowns block hot air flow inside the furnace.
Solutions
1.Check and replace broken heating rods as mentioned above.
2.Check the heat-insulating cotton inside the furnace often; replace it once peeling is found.
3.Leave enough space between each zirconia crown when placing them on baking trays, so hot air can flow smoothly.

4. Slow Heating Speed, Cannot Reach Required Baking Temperature
Signs of problem
The furnace spends much more time than normal to heat up, and cannot reach the high temperature needed for baking zirconia.
Causes
1.Heating rods grow old or partly broken, so the total heating power drops.
2.Broken heat-insulating lining makes a large amount of heat escape.
3.Low or unstable power supply voltage limits the maximum heating power of the rods.
Solutions
1.Check and replace broken heating rods.
2.Repair or change broken heat-insulating lining inside the furnace.
3.Install a voltage stabilizer for the furnace if the factory power supply changes frequently.

5. Touch Screen and Program Errors
Signs of problem
The touch screen does not respond to taps; the baking program stops halfway automatically; the machine keeps sending alarm sounds.
Causes
Loose wires connected to heating rods, or broken temperature sensors, leading to wrong temperature reading.
Sudden power voltage surge damages the main control board of the furnace.
Solutions
1.Check wires of temperature sensors and heating rods for looseness or breakage; replace broken temperature sensors.
2.Cut off power and restart the furnace to reset the control program. Contact our technical team to repair the main board if the problem still exists.

Daily Maintenance Advice
Do simple maintenance every week, and deep clean the furnace every month. Using original factory spare parts including heating rods and zirconia beads can greatly cut down machine faults and reduce waste of bad zirconia crowns.

Weizhen is a scientific and technological innovation company specializing in the research and development of dental equipment and materials.
Since the beginning of the company in 2008, it has established the development direction, adhering to the continuous spirit of innovation, and is committed to building a good dental field products.
Established more than ten years has served thousands of high-end dental studios and dental clinics at home and abroad, and has been recognized by the majority of users.
Weizhen is committed to creating a good user experience, improving user production efficiency and reducing user costs.
We look forward to working with you, welcome to contact us.

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www.weizhendental.com
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