Background: Molten pool temperature in Laser Additive Manufacturing (LAM) will affect
powder efficiency, structural compositions of reactants and products in the molten pool, thus determining
the microstructure evolutions and mechanical properties of the final part. An interest in molten pool
temperature measurement has been around for a long time since the appearance of LAM. However, a
comprehensive summary of the existing methods and their applications does not exist in the literature.
Objective: The state-of-the-art of the existed devices and methods for molten pool temperature measurement
in various of LAM processes is reviewed in this paper.
Methods: The existing temperature measurement methods for molten pool monitoring in LAM processes
are discussed. For each method, the existed patents, detailed procedures, advantages and disadvantages,
specific applications are specified. In the end, comparisons among the current temperature
measurement techniques are made according to data accuracy, operation complexity and cost of implementation.
Results: Four methods are currently being used for the molten pool temperature measurement in LAM
processes, including (i) Thermocouples, (ii) Infrared pyrometers, (iii) Infrared cameras, and (iv)
Conclusion: Different measurement methods represent different characteristics of the signal, and each
has merits and defects. Selecting suitable measurement method according to different process characteristics
will be helpful to achieve a preferable and more convincing results.