How to choose the suitable kiln furniture for ceramic products?


Choosing the right kiln furniture involves considering several factors such as the type of kiln, firing temperature, the size and shape of your objects, and the desired outcome. Here are some steps to help you choose the right kiln furniture:

1. Understand your kiln:

 Different types of kilns have specific requirements for kiln furniture.

1) Electric kilns

Electric kilns typically use shelves, posts, and stilts etc.

2) Shuttle kilns

Shuttle kiln includes kiln cars, it requires more refractory materials, setter plates, posts or spacers, beams, etc.

3) Tunnel kilns

In a tunnel kiln, various types of kiln furniture are typically used to support and transport the products being fired. It includes kiln cars, kiln walls and kiln roofs system, burners, etc.

4) Roller kilns

Ceramic rollers are the main supporting bases in the kiln. Others may also use SiSiC rollers, cover plates, saggers, etc.

2. Determine firing temperature:

Kiln furniture materials have temperature limitations. Consider the firing temperature range you will be working with. Low-fire kilns typically use materials like cordierite-mullite shelves and posts, while high-fire kilns may require more durable and refractory materials like silicon carbide shelves and beam.

3. Assess size and shape requirements:

 Evaluate the size and shape of the objects you plan to fire. Kiln furniture should provide adequate support and airflow for your ceramics. Consider the dimensions and weight of your pieces to ensure that the kiln furniture can safely accommodate them. Shelves should be large enough to hold your objects without overcrowding.

4. Consider material compatibility:

 Different kiln furniture materials have varying characteristics.

1) Cordierite-Mullite

Feature: Commonly used for general firing. They can withstand fast heating or cooling and is used when thermal shock is a concern traditionally used in top loading electric kilns.

Cordierite-mullite kiln shelves are more susceptible to warping at higher temperatures with maximum firing temperature is 1280℃.

2) Alumina

Feature: High alumina oxide products have high thermal conductivity and resistance to chemical and corrosion. They have a high dielectric strength with excellent resistance attributes.

Compared to Cordierite-mullite, they are more dense and therefore more resistant to glaze drips, but they are still porous and required kiln wash(coating).

3) Silicon Carbide

Silicon carbide is a high-performance ceramic material made of high-quality, non-oxide powders and can be manufactured to different requirements of a wide range of applications.

There are 4 main types of silicon carbide kiln furniture.

  • Oxided-Bonded Silicon Carbide (SiC/OBSiC)

Feature: Silicon carbide can withstand higher temperatures and higher mechanical strength.

Max. Working temperature: 1450℃.

  • Reaction Sintered Silicon Carbide (SiSiC)

Feature: With higher density, high mechanical strength, exceptional thermal shock resistance, good corrosion resistance.

Max. using temperature can be up to 1350℃.

  • Nitride-Bonded Silicon Carbide (NBSiC)

Feature: With high mechanical strength, good thermal shock resistance, excellent to chemical attack.

Max. Working temperature is up to 1450℃.

  • Recrystallized Silicon Carbide (RSiC)

Feature: High-temperature stability, very good thermal shock resistance, high corrosion resistance.

Max. Using temperature is 1650℃.

4) Other materials

Zirconia, Aluminum Titanate, Silica, etc.

Research the properties and benefits of each material to determine which one suits your needs best.

5. Thermal stability:

Look for kiln furniture that has excellent thermal stability to withstand repeated heating and cooling cycles without warping or cracking. This is especially important if you frequently fire at high temperatures.

6. Load-bearing capacity:

Consider the weight and size of your ceramic products to determine the load-bearing capacity required from the kiln furniture. It should be strong enough to support the weight of your pieces without sagging or deforming during firing.

Heavy load weight will expedite kiln shelves drooping if too thin or wrong shelf type selected.

7. Airflow and heat distribution:

Kiln furniture should allow for proper airflow and even heat distribution within the kiln. This helps ensure uniform firing and minimizes hotspots or cool areas. Look for furniture designs that promote good circulation and allow heat to radiate efficiently.

8. Kiln Atmosphere (reduction or oxidation):

It’s important to consider the specific firing requirements and the compatibility of kiln furniture materials with the kiln atmosphere to ensure optimal performance and longevity of the kiln furniture. Different kiln atmospheres may require the use of specific kiln furniture materials or protective coatings to mitigate the potential effects.

9. Frequency of firing:

Firing frequency is a big contributor to the shortened lifespan of kiln furniture.  If you are operating a kiln that is constantly being used, then a material that has a very high thermal shock rating is recommended.

10. Evaluate cost and durability:

Kiln furniture can be a significant investment, so consider your budget and the expected lifespan of the materials. While some options may be more expensive upfront, they might offer better durability and longevity, resulting in cost savings over time. Like: SiSiC, NBSiC, RSiC kiln furniture.

11. Test and experiment:

If possible, conduct small-scale tests with different kiln furniture materials to observe how they perform with your specific clay bodies and glazes. This experimentation can help you determine the most suitable option for your needs.

12. Seek recommendations and expert advice:

Consult with experienced expert or kiln manufacturers for recommendations. They can provide insights based on their experience and help you make an informed decision.

Remember that kiln furniture selection is a personal choice based on your specific requirements and preferences. By considering factors such as kiln type, firing temperature, cycle time, object size, loading weight, energy saving, material compatibility, cost and seeking advice from experts, you can choose the right kiln furniture for your firing needs.

Share this post with your friends