Pyrometry has advanced to the extent that it can now be used in conjunction with flame heating.  Infra-red Pyrometry requires the selection of an instrument with the
correct wavelength for the application. This depends on the temperature
to be measured as well as the nature of the material. All manufacturers
offer a range of models because of the need to transmit the measured
energy through the atmosphere - specific models are more immune to
possible problems such as combustion fumes, smoke etc. It is also
necessary to use the shortest possible wavelength but the wavelength
that gives peak energy depends on the source temperature. This means
that low temperature measurements (say 200∞C to 700∞C) require longer
wavelength units with shorter wavelength units used for very high
temperatures (700∞C to 1000∞C).
An ideal selection for long wavelengths is 3.9 microns with short
wavelength units 1.6 microns being suitable for elevated temperatures.
The accuracy of Infra-red temperature measurement typically +/- 2 to
4∞C, allows precise control to be effected with associated
instrumentation to read, record and react to workpiece temperatures
rather than flame temperatures.
Recent research aided by a DTI Regional Enterprise Grant, has resulted
in the production of a Semi-automatic Aluminium Brazing System using
flame heating (compressed air and a gas) which can be used in
conjunction with brazing alloy wire feed units or preplaced rings. The
system incorporates infra-red pyrometry and a special air/gas mixing
system that allows flame intensity, as well as the overall time cycle,
to be varied.
The use of a PLC control system means that the temperature profile can
be pre-programmed to dwell at various stages to cope with differing
metal thickness and configurations within the joint.
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Marking - All solbraze equipment is manufactured and tested
to stringent specifications to meet current Health and Safety Standards.