Impact Of Sintering Time And Temperature On Mechanical Properties In Projection Sintering Of Polyamide-12

In powder bed fusion additive manufacturing (AM), the fusing process is temperature and time dependent. However, little work has been done to understand how different processing temperatures and times might impact the mechanical properties at longer sintering times than are typical in laser sintering (LS) systems. Prior results with projection sintering have shown that heating for longer times (>1 s) improves part toughness compared to laser sintering. In this work, Large Area Projection Sintering (LAPS) is used to sinter entire layers of material simultaneously over the course of a few seconds with spatial control of layer temperature. This work evaluates the effect of time and temperature on the mechanical properties of parts sintered from PA 2202 (Polyamide 12) powder. Toughness is shown to increase significantly with longer sintering times (5-8 s) and higher temperatures (195-205 degrees C) with elongations at break (EaB) over 100% and strengths of up to 51.7 MPa. This represents a small increase in strength and an order of magnitude increase in elongation at break relative to LS datasheet values for the material. Peak mechanical properties are achieved sintering at lower temperature (195 degrees C) and longer times (5-8 s). The density of the samples that maximize toughness and strength is greater than 1.02 g/cm(3) compared to datasheet values of 0.98 g/cm(3). Porosity elimination could be a mechanism for improved performance though it does not fully explain the improvements in strength and ductility.