Skutt KilnMaster Kilns Manufactured between 2000 and 2006 - Manual (Page 40)

38
Orton Pyrometric Cones
Self -Supporting Regular
Cone
Number
10
9
8
7
6
5
4
3
2
1
01
02
03
04
05
05 1 / 2
06
07
08
09
010
011
012
013
014
015
016
017
018
019
020
021
022
Final
Temperature
at 108˚ F/hr
2345˚ F
2300
2280
2262
2232
2167
2124
2106
2088
2079
2046
2016
1987
1945
1888
1859
1828
1789
1728
1688
1657
1607
1582
1539
1485
1456
1422
1360
1319
1252
1159
1112
1087
Final temperature for cone maturity depends
on rate of temperature increase during final
300 to 400˚ of firing. Courtesy Edward Orton
Jr. Ceramic Foundation.
1940
1950
1960
1930
1920
1910
1900
1890
1880
50˚F/hr 100˚F/hr 150˚F/hr 200˚F/hr
Shut-off Temperature (˚F)
Heating Rate Increase
Cone 04, 90˚ drop, Relationship of heating rate and shut-off temperature.
1890˚F
1938˚F
1946˚F
1957˚F
How the KilnMaster
can emulate cones.
As you have just seen, a cone drops
according to a complex set of factors.
The KilnMaster has been designed to
take these factors into account when it
shuts off the kiln. Most important to
the KilnMaster is the heating rate if a
cone correlation is to be accurate.
Here’s how the KilnMaster does it.
Cone Fire mode
• By selecting Slow, Medium or Fast,
the controller goes into a set routine
for finishing the firing to insure a
good cone correlation.
• The controller has a preset final
heating rate that allows the
KilnMaster to adjust the final tem-
perature value up or down from the
108˚/hour standard heating rate that
is used on Orton’s Cone chart.
• If the kiln cannot produce the rate,
the KilnMaster still measures the
actual rate and adjusts the final tem-
perature accordingly.
Ramp/Hold mode
In Cone Fire mode, the KilnMaster
does all the calculating and thinking
that goes into emulating a cone. In
Ramp/Hold, you the operator must
participate to get accurate cone firing
results.
• If you are trying to fire to a cone
temperature in this mode, you must
use a rate/temperature combination
in the last hour of firing that the kiln
can reasonably accomplish and that
is predictable. Yes, you can program
200˚ or 300˚/hr, but a heating rate of
108˚/hour is about the maximum
final heating rate you can achieve
with an electric kiln when high fir-
ing.
• If you program a target heating rate
that the kiln can’t achieve, overfiring
will probably result. That final
Ramp/Hold segment will run until
the desired temperature is reached.
However, the slower actual rate will
cause more heat work to be done
than you desired.
• We recommend using Cone Fire
mode to emulate a cone because the
controller will automatically com-
pensate for the firing rate of your
kiln. When you need to achieve a
temperature between cones, we rec-
ommend making the last hour of the
firing your final segment and using
a rate less than 108˚/hour. Use the
108˚F data from the Orton Cone
Chart shown here instead of any
other charts you may be using.