2134/17440
Mike Vasquez
Mike
Vasquez
Barry Haworth
Barry
Haworth
Neil Hopkinson
Neil
Hopkinson
Optimum sintering region for laser sintered nylon-12
Loughborough University
2015
Additive manufacturing
Thermal degradation
Thermogravimetric analysis
Stable sintering region
Laser sintering window
Materials Engineering not elsewhere classified
Mechanical Engineering
2015-05-07 10:43:46
Journal contribution
https://repository.lboro.ac.uk/articles/journal_contribution/Optimum_sintering_region_for_laser_sintered_nylon-12/9234155
It is well known that the mechanical properties of laser sintered Nylon-12 improve
with increased applied energy. However properties can reach a maximum after which, the application
of additional energy can a lead to a decline in part properties. It is thought that the reason
for this decline is that the additional energy causes polymer chain degradation or other changes
in molecular structure. This paper aims to use thermogravimetric analysis (TGA) to investigate
the thermal degradation of nylon-12 and explain the deterioration of mechanical properties when
high energy density conditions are applied during processing. The key findings are the application
of modelling methods to predict the temperatures achieved during laser sintering of nylon-
12. It is shown that temperatures in the laser sintering machine can achieve levels above 3008C. At
these temperatures, TGA data show that mass loss occurs and could cause mechanical property
breakdown. This practical work coupled differential scanning calorimetry and TGA as a means of
identifying thermal transitions in the material. The term ‘stable sintering region’ is proposed as a
novel concept for the laser sintering community, and can have implications for better understanding
of how process parameters can affect parts built in the machine. In addition, the concept
could be used in the material selection process when screening potential new polymers for the
process. One limitation of laser sintering, compared to other polymer processes such as injection
moulding, is the limited understanding of the connection between machine parameters and part
properties. This work aims to improve that understanding by discussing the pattern of thermal
behaviour, including degradation, seen in polyamide exposed to high laser parameters.