Detecting abnormal operation of moving parts in additive manufacturing systems

A method for use in an additive manufacturing system, the method comprising:

• first measuring temperatures of a printbed area of the system at a first time during additive manufacture of an object in the printbed area;
• second measuring temperatures of the printbed area of the system at a second, subsequent time during additive manufacture of the object in the printbed area;
• first analysing data associated with the first measured temperatures at the first time for the presence of a predetermined emissivity difference to determine a position of the moving part at the first time;
• second analysing data associated with the second measured temperatures at the second time for the presence of the predetermined emissivity difference to determine a position of the moving part at the second time;
• and
• in response to the first analysis and the second analysis indicating a difference in position below an expected difference in position, determining that the moving part is operating abnormally.

A non-transitory computer-readable storage medium storing instructions that, if executed by a processor of a three-dimensional printing system, cause:

• a thermal camera to measure temperatures of a printbed area of the system at a first time and a second, subsequent time during additive manufacture of an object in the printbed area;
• and
• a controller to:
• receive, from the thermal camera, information associated with the measured temperatures at the first time and the second time;
• process the received information to determine a first position of a moving part of the system at the first time and a second position of the moving part at the second time, the moving part having a different emissivity than that of the printbed of the system, the processing comprising processing the received temperature information for an indication of the different emissivity;
• and
• in response to the processing indicating that the moving part has not moved by a sufficient amount between the first time and the second time, determine that the moving part is operating abnormally and halt additive manufacturing of the object by the system.