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Screw‐assisted material extrusion technique is developed for tissue engineering applications to produce scaffolds with well‐defined multiscale microstructural features and tailorable mechanical properties. In this study, in situ time‐resolved synchrotron diffraction is employed to probe extrusion‐based 3D printing of polycaprolactone (PCL) filaments. Time‐resolved X‐ray diffraction measurements reveals the progress of overall crystalline structural evolution of PCL during 3D printing. Particularly, in situ experimental observations provide strong evidence for the development of strong directionality of PCL crystals during the extrusion driven process. Results also show the evidence for the realization of anisotropic structural features through the melt extrusion‐based 3D printing, which is a key development toward mimicking the anisotropic properties and hierarchical structures of biological materials in nature, such as human tissues.

This paper describes the procedures used in a technologically orientated numerically controlled (NC-) system to determine the optimum culling conditions automatically for turning, drilling, grooving, threading and parting-off operations. In rough turning, the optimum depth and feed combination is determined using a direct search procedure on the allowable depth/feed region for chip control. The system determines the optimum depth of cut, feed and velocity for each pass in multi-pass turning on the basis of a user-selected objective criterion and a number of technological limitations that may apply to the process, such as machine power, dynamic instability, allowable range of depths and feeds for the tool and workholding limitations which include axial slip, circumferential slip and component throw-out. A user-friendly manual option is also provided which allows the user to specify the cutting parameters. Examples are given to illustrate how these procedures determine the optimum cutting conditions. A comparison between the machining costs and times using cutting conditions obtained from handbooks and the aforementioned procedures shows that for all the operations considered, there are cost and time savings when the cutting conditions obtained by the latter are used.