Purpose With the development of 3D printing or additive manufacturing (AM), curved layer fused deposition modeling (CLFDM) has been researched to cope with the flat layer AM inherited problems, such as stair-step error, anisotropy and the time-cost and material-cost problems from the supporting structures. As one type of CLFDM, cylindrical slicing has obtained some research attention. However, it can only deal with rotationally symmetrical parts with a circular slicing layer, limiting its application. This paper aims to propose a ray-based slicing method to increase the inter-layer strength of flat layer-based AM parts to deal with more general revolving parts. Design/methodology/approach Specifically, the detailed algorithm and implementation steps are given with several examples to enable readers to understand it better. The combination of ray-based slicing and helical path planning has been proposed to consider the nonuniform path spacing between the adjacent paths in the same curved layer. A brief introduction of the printing system is given, mainly including a 3D printer and the graphical user interface. Findings The preliminary experiments are successfully conducted to verify the feasibility and versatility of the proposed and improved slicing method for the revolving thin-wall parts based on a rotary 3D printer. Originality/value This research is early-stage work, and the authors are intended to explore the process and show the initial feasibility of ray-based slicing for revolving thin-wall parts using a rotary 3D printer. In general, this research provides a novel and feasible slicing method for multiaxis rotary 3D printers, making manufacturing revolving thin-wall and complex parts possible.

Purpose The rapid development of three-dimensional (3D) printing makes it familiar in daily life, especially the fused deposition modeling 3D printers. The process planning of traditional flat layer printing includes slicing and path planning to obtain the boundaries and the filling paths for each layer along the vertical direction. There is a clear division line through the whole fabricated part, inherited in the flat-layer-based printed parts. This problem is brought about by the seam of the boundary in each layer. Hence, the purpose of this paper is to propose a novel helical filling path generation with the ideal surface-plane intersection for a rotary 3D printer. Design/methodology/approach The detailed algorithm and implementation steps are given with several worked examples to enable readers to understand it better. The adjacent points obtained from the planar slicing are combined to generate each layer's helical points. The contours of all layers are traversed to obtain the helical surface layer and helical path. Meanwhile, the novel rotary four-degree of freedom 3D printer is briefly introduced. Findings As a proof of concept, this paper presents several examples based on the rotary 3D printer designed in the authors’ previous research and the algorithms illustrated in this paper. The preliminary experiments successfully verify the feasibility and versatility of the proposed slicing method based on a rotary 3D printer. Originality/value This paper provides a novel and feasible slicing method for multi-axis rotary 3D printers, making manufacturing thin-wall and complex parts possible. To further broaden the proposed slicing method’s application in further research, adaptive tool path generation for flat and curved layer printing could be applied with a combination of flat and curved layers in the same layer, different layers or even different parts of structures.

Due to solid freeform fabrication (SFF)’s manufacturing capability, additive manufacturing (AM) or 3D printing, is developing rapidly and has received much attention, leading to various aerospace, military and robotics applications. Slicing and path planning are two critical steps of AM, determining the manufactured part’s geometric accuracy and mechanical performance to a large extent. Many research works focus on the detailed strategies and algorithms of slicing and path planning. However, instead of 3D printing, most available studies concentrate only on 2.5D printing, where slicing and printing along the Z direction and filling 2D contours in the XY plane are applied. Although multi-direction and curved layer slicing have been proposed, little attention has been paid to path planning on the curved layers, especially tool path generation for the revolving parts requiring supports, such as screw conveyors and the propeller or fan. Hence, the primary purpose of this paper is to propose a novel cylindrical slicing strategy (a type of curved layer slicing) based on the triangle mesh model for curved layer Material Extrusion (CLMEX). It could be learned that the support structure is necessary for cases with traditional bottom-up printing, while supportless printing may be feasible with cylindrical slicing. Besides, a preliminary experiment is conducted to illustrate the proposed method and validate its feasibility based on a novel 2T2R-type rotary Material Extrusion (MEX) 3D printer designed in the authors’ previous research. This early-stage work generally intends to investigate the process planning and show the initial feasibility of cylindrical printing using a novel 2T2R-type rotary 3D printer. This research provides process designers with a novel and feasible slicing method for multi-axis 3D printers having a rotary build platform.

To explore hostile extraterrestrial landforms and construct an engineering prototype, this paper presents the task-oriented topology system synthesis of reconfigurable legged mobile lander (ReLML) with three operation modes from adjusting, landing, to roving. Compared with our preceding works, the adjusting mode with three rotations (3R) provides a totally novel exploration approach to geometrically matching and securely arriving at complex terrains dangerous to visit currently; the landing mode is redefined by two rotations one translation (2R1T), identical with the tried-and-tested Apollo and Chang’E landers to enhance survivability via reasonable touchdown buffering motion; roving mode also utilizes 2R1T motion for good motion and force properties. The reconfigurable mechanism theory is first brought into synthesizing legged mobile lander integrating active and passive metamorphoses, composed of two types of metamorphic joints and metamorphic execution and transmission mechanisms. To reveal metamorphic principles with multiple finite motions, the finite screw theory is developed to present the procedure from unified mathematical representation, modes and source phase derivations, metamorphic joint and limb design, to final structure assembly. To identify the prototype topology, the 3D optimal selection matrix method is proposed considering three operation modes, five evaluation criteria, and two topological subsystems. Finally, simulation verifies the whole task implementation process to ensure the reasonability of design.

3D printing or Additive Manufacturing (AM) is significant in various applications. The authors’ previous research indicates that higher-degree-of-freedom (DOF) 3D printers have the potential for curved layer printing and multi-direction AM. Hence, this paper focuses on designing a novel 2T2R FDM 3D printer. Performance-chart-based design methodology (PCbDM) has been used for multiple parameters optimization problems due to its reliability, globality, and intuition. While its limitation is the number of optimization parameters less than four. The printer’s print head is attached to a planar parallel 1T1R mechanism (4R1P, 3R1P, and passive P). Objectives and requirements require the print head to move over a more considerable distance with a constant swing range and proper pressure angle. So, the 4R1P five-bar (virtual double-rocker, crank-rocker, and rocker-crank) has been investigated to facilitate PCbDM. Meanwhile, one DOF remote center of motion (RCM) mechanism has been integrated for decoupling motion control. Finally, the selected parameters are verified by comparing the numerical and simulation results and experiments. Besides, this novel 3D printer’s initial feasibility of flat and curved layer printing is studied with several printed parts to give qualitative analyses. This early-stage work generally intends to investigate the dimension synthesis and show the resulting 2T2R-type rotary 3D printer’s initial feasibility for curved printing. The research can help people understand how to carry out the dimension synthesis of 4R1P and a novel mechanism with multi-chain with the help of Grashof criteria to reduce the design space dimensionality.