Effect of Curing Parameters on Warp in the SLA Printing Process

Abstract Heat during the ultraviolet (UV) curing step of stereolithographic (SLA) printing can affect dimensional accuracy. The goal of this study was to quantify how curing affects warp. Six warp curtain specimens were printed out of a Draft material using a Form 2 SLA printer. After printing, the specimens were washed in isopropyl alcohol to remove any uncured resin. Two of the specimens were left uncured after the washing step. Two of the specimens were cured with no heat and two specimens cured with heat. Next, a high-resolution camera was used to take a picture of each specimen and digitize five layers. A line was fit to each horizontal set of points and used to calculate a warp index. Curing significantly decreased warp between the non-cured specimen and specimen cured with no heat by 0.16 (p = 0.023). The specimen cured with heat was also lower than the uncured specimen by 0.18 (p = 0.017). No difference was observed in warp between the specimens cured with or without heat (p = 0.758). However, these changes in warp did not prove practically significant as the differences were less than the minimal detectable change (MDC) of the system. The warp indices were found to be less than 1 in all specimens, smaller than the literature on warp in polyamide (PA) of up to 4. Warp in these SLA parts is likely small since there is no uneven heating between layers during the printing process.