Direct Manufacturign Systems Need Closed-Loop Controls

Direct digital manufacturing is making fast strides for low-volume applications requiring complex detail, but some significant issues remain.  Design engineers require process verification, particularly for high-end parts. For example, the widespread adaption of closed-loop process controls about a dozen years ago provided verification that required process parameters in the injection molding process were being maintained. Direct digital manufacturing systems were originally developed by companies in the rapid prototyping business, where such requirements were not necessary. Parts were simply required for form and fit, and not so much for functional testing. There is often considerable process variation in the new additive fabrication systems being developed for manufacturing directly from digital files.  Improvements will come, however, and the new systems are certainly worth a look in several situations, particularly those where there are constant design change orders.