Roof tile production

Roof tiles undergo a complex firing process during their production to harden the material and attain their final properties. Various challenges can arise during the firing process that may affect the quality of the manufactured roof tiles. Process Temperature Control Rings (PTCR) assist you cost-effectively in minimizing these issues and accurately monitoring and documenting all kiln cycles.

What are Process-Temperature-Control-Rings?

PTCRs are ceramic rings that shrink proportionally to the heat input. The extent of shrinkage depends on factors such as the furnace temperature profile, heat conduction conditions, and the dwell time in the furnace. These PTCRs, small with an outer diameter of 20mm, can be placed directly on the product almost anywhere on the furnace car.

PTCRs can assist you in addressing the following challenges in roof tile production and help minimize any potential issues that may arise.

Challenges in the production of roof tiles

Cracks and Breaks:
Cracks or breaks in the roof tiles can occur when the temperature in the furnace is not homogeneous or if the tiles are cooled too rapidly. This can compromise the structural integrity of the tiles, making them less durable.

Deformations:
Deformations can occur when the tiles are not stacked correctly during the firing process or when there are temperature fluctuations in the kiln. This can lead to uneven or irregularly shaped tiles.

Color Deviations:
Color discrepancies may arise when the composition of the clay mixture isn’t precisely controlled or if the furnace temperature isn’t consistent. This can result in some tiles having a different color, impacting their aesthetic quality.

Overfiring or Underfiring:
Inadequate control of temperature and firing duration in the furnace can cause the tiles to either overfire, becoming too hard, or underfire, remaining too soft. Both scenarios can influence the tiles' performance.

Energy Efficiency:
An inefficient firing process can lead to increased energy consumption, escalating production costs. Therefore, optimal kiln design and control are crucial to optimize energy usage.

Utilization of Process Temperature Control Rings

After the firing, the rings are removed, their diameter measured, and using the provided temperature tables, the so-called reference temperature is determined. This temperature represents the heat input at the location in the kiln where the ring was placed. With the help of PTCRs, determining heat input and continuously monitoring kiln operation becomes straightforward.

To minimize potential deviations and optimize the process's energy efficiency, precise control and monitoring of the firing process are crucial. In the temperature range of roof tile production, two primary ring variants are available: PTCR ETH (850 - 1.100 °C) and PTCR LTH (970 - 1.250 °C). When selecting the most suitable ring type, consider placing your firing/sintering process temperature roughly in the middle of the temperature range covered by the ring type. If the maximum process temperature falls at the border between two ring types, choose considering process conditions such as holding time and atmosphere, as both factors significantly influence ring shrinkage. In total, eight different PTCR ring types are available for the temperature range of 560 °C to 1.750 °C.