Abstract
Semi-crystalline polymers develop higher amounts of residual stress and part distortion (warpage) compared to amorphous polymers due to their crystalline nature. Additionally, the FDM processing parameters such as ambient temperature play an important role in the resulting residual stresses and part distortion of the printed part. Hence, in this study, the effect of ambient temperature on the in-built residual stresses and warpage of amorphous acrylonitrile-butadiene-styrene (ABS) and semi-crystalline polypropylene (PP) polymers was investigated. From the results, it was observed that increasing the ambient temperature from 50 °C to 75 °C and further to 120 °C resulted in 0.22-KPa and 0.37-KPa decreases in residual stress of ABS, but no significant change in the amount of warpage. For PP, increasing ambient temperature from 50 °C to 75 °C led to a more considerable decrease in residual stress (0.5 MPa) and about 3% increase in warpage. Further increasing to 120 °C resulted in a noticeable 2 MPa decrease in residual stress and a 3.4% increase in warpage. Reduction in residual stress in both ABS and PP as a result of increasing ambient temperature was due to the reduced thermal gradients. The enhanced warpage in PP with increase in ambient temperature, despite the reduction in residual stress, was ascribed to crystallization and shrinkage.
Highlights
Fused deposition modeling (FDM) is one of the additive manufacturing (AM) techniques that has the ability to 3D print complicated shaped geometries by extruding molten material layer by layer on a pre-heated bed [1,2,3]
PP was selected in order to study the effects of ambient temperature on semi-crystalline polymers, while ABS P400 was selected for analyzing the behavior of amorphous polymer under various ambient temperatures during the FDM process
It has been well established in the literature that crystallization kinetics is highly temperature dependent and, with the change in thermal gradient during the printing, crystallization can severely affect the properties of the printed semi-crystalline polymer [40]
Summary
Fused deposition modeling (FDM) is one of the additive manufacturing (AM) techniques that has the ability to 3D print complicated shaped geometries by extruding molten material layer by layer on a pre-heated bed [1,2,3]. On the other hand, semi-crystalline polymers are gaining traction due to their superior impact strength, chemical resistance, excellent mechanical characteristics at high-temperature environments, and wear resistance properties [18,20]. FDM processing parameters such as print bed temperature, layer thickness, nozzle speed, raster pattern including ambient temperature on semicrystalline polymer were investigated [1,25]. In order to gain a better understanding of the effect of ambient temperature on amorphous and semi-crystalline polymer towards the internal developed residual stresses and overall warpage, an in-depth analysis was performed. Along with the crystalline kinetics, the thermo-mechanical properties were taken into consideration
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