Temperature control rings from +660°C to +1750°C

Temperature control rings from +660°C to +1750°C

Temperature control ring (TCR) is a high-accuracy temperature indicator, which looks like a ceramic ring, and which is able to change its geometry depending on absorbed heat amount. TCR takes up both radiation and convection heat effect. Effect is expressed as a single numeric parameter - ring temperature, which is convenient got practical measurements.

CTR can be used in various process furnaces and various media, such as oxygen, nitrogen, air, and vacuum.

6 CTR models designed for operation under different temperature ranges within the interval from 660°C to 1750°C are available.

Technical characteristics
Execution options

Principle of operation

Depending on heat amount, the ring size reduces almost linearly if its is under working temperature range. TCR diameter changes specifically depending on heat amount obtained during heat effect, but not on maximum temperature during the process.
After the use, the ring diameter is measured by micrometer (by digital micrometer for comfort and greater accuracy). According to special tables of exposure time, the result is transformed to conventional "ring temperature", which simplifies results comparing and results correlation with heating process.
After annealing, TCR diameter describes actual thermal effect in the point where the ring has been located. Maximum dispersion of readings for the same TCR type under the same heating process conditions (heating rate, obtained temperature, exposure time under steady conditions) should not exceed 3°C of the "ring temperature" value.
Maximum heating process time is 2 - 10 hours depending on temperature.
For 1-hour heating process, TCR temperature sensitivity is equal to 6 - 10 microns per  1°C of "ring temperature".


CTR diameter can be easily measured by micrometer. Only one measurement is required (as shown at the picture). Special-purpose micrometer has solid ergonomic base with a platform for the ring, which provides correct ring positioning, increases measurement reliability and allows to avoid repeated measurements. Its design not only simplifies measurements, but also increases "ring temperature" measurement repeatability and reproducibility.

CTR modifications

Temperature range

CTR modification




















CTR dimensions: outer diameter 20mm, inner diameter 10mm, height 7mm

Example of ordering:
Temperature indicators CTR-AQS (660-1000°С).

Furnace heating process optimization

Optimal thermal condition establishment process consists in TCRs installation in the whole furnace volume and "ring temperature" values measurement after the end of the thermal process. These measurements allow to find out and determine "cold" and "Hot" areas within the furnace.
"Ring temperature" values allocation map allows to optimize thermal conditions by moving heat sources or control thermocouples according to TCR readings. "Ring temperature" compliance to actual temperature value depends on specific conditions of the furnace thermal process to a large extent.
When furnace temperature field is optimized, it is recommended to use TCR regularly for field monitoring and gradual changes determination as soon as they appear and before they can effect on product quality.

Furnace temperature allocation map

Determination of "nominal ring temperature"

To compare one-type thermal processes by TCR it is necessary to determine "nominal ring temperature". Temperature control rings are inserter in thermal process series, then "ring temperature" values are compared with quality of produced goods and readings of other temperature sensors (thermocouples, pyrometers). "Ring temperature" value, which corresponds to the best quality product and thermal process carried out in compliance with all requirements, without actual temperature deviation from standard, should be used as the nominal ring temperature value.