This study investigates a two-colour laser-induced fluorescence (LIF) technique for
thermometry in cooling lubricants (CL) for machining. The diagnostic technique should enable
a simultaneous determination of cooling film thickness and film temperature, which is relevant
for typical machining processes like turning and milling processes. The temperature
determination is based on a temperature-sensitive fluorescence intensity ratio of a special dye
determined in suitable spectral regions representing common band pass filters. For this purpose,
two CL emulsions CL6 (6 vol.% CL, 94 vol.% water; normal machining) and CL10 (10 vol.%
CL, 90 vol.% water; heavy machining) and its individual components were doped with the
fluorescence dye Eosin-Y. Temperature dependent spectral LIF intensities were recorded in the
range of 273–313 K, which are relevant for milling and cutting operations. Furthermore,
absorption spectra were analysed as well. The temperature-dependent fluorescence
measurements revealed a temperature limit for the emulsion stability. The emission peaks of
Eosin-Y are shifted with increasing temperature towards longer wavelengths. The sensitivities
of CL10 (1.88%/K) and CL6 (1.58%/K) are comparable to or even higher than the sensitivities
of other LIF dyes provided in the literature. The literature-based dyes were however not
determined in those CL. The measurements showed, that the investigated tracer-CL/water
emulsions mixed with the dye enable a reliable temperature determination.
«This study investigates a two-colour laser-induced fluorescence (LIF) technique for
thermometry in cooling lubricants (CL) for machining. The diagnostic technique should enable
a simultaneous determination of cooling film thickness and film temperature, which is relevant
for typical machining processes like turning and milling processes. The temperature
determination is based on a temperature-sensitive fluorescence intensity ratio of a special dye
determined in suitable spectral region...
»