Carbolite CAF DIGITAL IMAGING - Manual (Page 25)

CAF Digital Imaging
MF36-3.21
page 25
5.4.4.4.Deviations from limits.
If some or all of the recorded individual melt temperatures fall outside the maximum or
minimum permissible temperatures for the relevant material, but the spread is within the
maximum permissible spread, then it is possible to correct the temperature displayed by the
control instrument using the instrument set-up; see section 5.4.5.
If the spread lies outside the permissible limit, then the furnace will require rectification of its
temperature uniformity; contact Carbolite for further advice.
Any servicing or modifications to the furnace or controls may affect the calibration of the
furnace and will require a re-test.
5.4.5. Control Instrument Calibration Adjustment.
A two point calibration function within the furnace controller allows adjustment of the displayed
value at both the Gold and Palladium melt temperatures. Proceed as follows:
5.4.5.1.Calculate the lower calibration temperature (displayed Gold melt temperature) correction factor:
Calculate the Gold mid melt temperature from the results obtained, as given in section 5.5.4.
Calculate the lower calibration temperature correction factor as the difference between the Gold
actual melt temperature and the Gold mid melt temperature:
Gold:
actual melt temperature - mid melt temperature = lower calibration temperature correction factor
For example: actual melt temperature = 1063°C (from table)
mid melt temperature = 1060

C (calculated from test)
lower calibration temperature correction factor (1063°C – 1060°C) = 3.
5.4.5.2.Calculate the upper calibration temperature (displayed Palladium melt temperature) correction
factor:
Calculate the Palladium mid melt temperature from the results obtained, as given in section
5.5.4.
Calculate the upper calibration temperature correction factor as the difference between the
Palladium actual melt temperature and the Palladium mid melt temperature:
Palladium:
actual melt temperature - mid melt temperature = upper calibration temperature correction factor
For example: actual melt temperature = 1554°C (from table)
mid melt temperature = 1559

C (calculated from test)
upper calibration temperature correction factor (1554°C

1559°C) =

5.
5.4.5.3.Adjust the lower an upper calibration temperatures.
Lower calibration temperature adjustment:
Use the Up and Down buttons () to adjust the instrument set point to the value of the Gold
mid melt temperature, and allow the furnace to heat to that temperature.
When the furnace has stabilised select ‘iP-LiSt’ using the Page button ().
Press the Scroll button () until the ‘CALS nonE’ is displayed; select ‘CAL.S iP1.L’ using the
Up and Down buttons ().
Press Scroll () to display the ‘Adj’ value; this is the lower calibration value.
Add the lower calibration temperature correction factor to the ‘Adj’ value, and enter the new
value using the Up and Down buttons ().
For example, if the lower calibration temperature correction factor is calculated as ‘3’ and the
‘Adj’ value is ‘1065’, adjust the displayed value to read 1068 (1065+3=1068).