Cement-based additive manufacturing: experimental investigation of process quality

Abstract

The interest in additive manufacturing (AM) of cement-based materials is steadily increasing. Moreover, there is a growing need for higher productivity and part quality. In this study, the impact of the different values of the process parameters on part quality was identified. An alternative process-control strategy was investigated, according to which the width of the extruded path is controlled by the ratio of the extrusion speed over the scanner head speed. To conduct linear-and rotational-extrusion experiments, an experimental apparatus was designed. The significance of the effect of the speed ratio on the part quality was found to be the highest, followed by the extrusion radius, whereas the extrusion speed appeared to be of low importance. Therefore, in linear extrusion, high quality and consistency can be achieved by maintaining the ratio value above 0.8. However, in rotational extrusion, the effect of the radius was additionally considered by calculating the ratio on the outer side of the part, rather than on the centerline. Thus, acceptable quality and consistency were ensured for both linear and curved paths by controlling the aforementioned ratio values.

Strand-Morphology-Based Process Optimization for Extrusion-Based Silicone Additive Manufacturing

“…The degree of influence is plasticizing temperature >layer height > filling angle. Foteinopoulos et al [ 34 ] studied the factors (extrusion speed, moving speed) affecting the quality of cement 3D printing process experimentally. Through linear extrusion and rotary extrusion experiments, the main influencing factors and value ranges were determined.…”

Computational and empirical modeling of additive manufacturing processes

“…Manufacturing quality is how well the production process meets design specifications, related to the different features and properties of a product (Geometric characteristics and Physical and/or chemical properties of the materials) [1]. One of the most important issues faced by all AM applications is that of part quality [13]- [17]. This is conclusion has been drawn by the extensive literature review that has been performed (Chapter 2).…”

“…By coordinating the extrusion speed and scanner head speed, an alternative process-control strategy was developed. More specifically, the width of the extruded path is controlled by the ratio of the extrusion speed over the scanner head speed [53]. The advantage of this approach is its higher precision and productivity, since the response time of the scanner head is faster than that of the extrusion head-system for big scale cement-based AM applications [55] (Figure 10).…”

“…The process mechanism is not thermal based, like in the majority of AM applications [14]. The material properties and the difference in scale (nozzle diameter, layer height), which is in the scale of two orders of magnitude, lead to important differences in the phenomena that take place [53]. As a result, studies referring to other AM applications are not suitable.…”

“…Therefore, there is a need for novel modeling solutions, fast and practical, capable of supporting the evaluation of alternatives towards the optimization of the selection of process parameters and scanning strategies, in terms of minimizing thermal stresses and deformations for metal-based AM processes. Scanning speed is important to all AM process groups, especially so to processes that include process mechanism involves material flow from the scanner onto the machine platform [17], [53]. Therefore, there scanner speed and its coordination with extrusion speed directly affects the quality, dimensions and consistency of the deposited path.…”