First Time Usage; The Ptcr Micrometer; The Temperature Conversion Table; Interpretation Of The Ring Temperature - schupp PTCR Handbuch

PTCR
Technique & Application
once, the special PTCR
independent, reliable and accurate reading of the ring diameter. In
order to assure the reliability the diameters have always to be
measured between the two T's. Rings from new batches already have
a new stamp impressed with predefined measuring points (see
following 2 pictures).
Step 4) Conversion of the diameters into RT
The outer ring diameter can be converted into a Ring Temperature
(RT) using the conversion table delivered with every new batch of
PTCR. The RT value thus obtained is an accurate representation of the
total (cumulative) amount of heat transferred to the products during
the temperature cycle.

5.2 First time usage

The first time the PTCR is applied, different (trial) runs with different
parameter settings have to be made and the resulting products have
to be compared to the quality standard. In this way the optimal
process settings and RT values are coupled. In a new run, if the RT
values are the same, the firing conditions have been the same and the
quality of the product is assured.
It has to be emphasized, that RT values do not necessarily compare
to absolute temperatures. Because it measures the heat transferred
to the ring, a longer soak time at the same top temperature will cause
the ring to shrink further, resulting in a higher RT value. However the
PTCR allow you to accurately determine differences in the heat
treatment both within and between certain kiln loads.
The same measured RT values guarantee the same amount of heat
transferred. This means that so exactly the same firing conditions
have been applied.
5.3 PTCR Micrometer
The PTCR Micrometer is specially developed for the measurement of
the outer diameter of each ring. Because of the unique metal
construction on which the Micrometer is attached, each ring has
each time exactly the same position. These results in one-time-only
measurements while the reliability and accuracy is assured. Other
normal Micrometers can be used for the measurement of the
diameter, but these results in less accurate and reliable results.
Therefore we strongly advise to invest once in the official PTCR
Micrometer.
Rev. 4_26.01.2018
Micrometer ensures an operator
Page 3 of 6

5.4 The temperature conversion table

The shrinkage of the diameter of the ring has to be converted in to
the Ring Temperature (RT). This table is updated for every batch of
rings to be delivered which means that both the product and the
conversion table have a unique relation.
By this re-calibration, all possible effects caused by differences in raw
material(s) and deviations of green (zero hour) diameter value are
compensated for. This ensures the reading of the shrinkage always to
result in the same RT value and thus eliminating batch to batch
differences for PTCR. This is one of the reasons why the repeatability
and reproducibility of the RT readings is very high. It is important to
keep in mind that mixing up of tables and PTCR batches leads to false
readings of the RT value
Example of a temperature conversion table

5.5 Interpretation of the ring temperature

The main purpose of PTCR is to ensure the repeatability of the firing
process and to ensure in this way the constant quality level of the
different kiln loads. The Ring Temperature (RT) represents the total
amount of heat transferred to the products and thus a constant RT
value ensures firing conditions to be identical. The importance of the
PTCR is to provide an accurate determination of DIFFERENCES in
total heat transferred and to monitor any deviation in the processing
conditions. The RT reading has not necessarily a direct relation to the
M.E. SCHUPP Industriekeramik GmbH & Co. KG
Neuhausstraße 4-10, 52078 Aachen/Germany
Tel.: +49 (0) 241 -93677-0
www.schupp-ceramics.com info@schupp-ceramics.com
Fax: +49 (0) 241 -93677-15