Multi-axis Additive Manufacturing Research Articles

Variable-depth curved layer fused deposition modeling of thin-shells

Abstract This paper presents a framework containing thin-shell modeling, curved layer slicing, and process planning algorithms for a variable-depth curved layer multi-axis additive manufacturing process for printing thin-shells. Currently, to print a thin-shell part such as a blade, under the popular paradigm of fused deposition modeling (FDM), the traditional type of flat layer three-axis printing suffers from the severe stair-step effect on the printed surface. Even with a more advanced multi-axis 3D printer that enables curved layer FDM (CLFDM), at present, only uniform-thickness layers are supported, which again is unable to resolve the pronounced stair-step problem. However, by allowing the sliced layers to have variable thicknesses and adjusting the build direction adaptively with respect to the surface normal, the stair-step effect can be either completely eradicated or reduced to the minimum. While the presented framework is targeted specifically at the algorithmic aspect of this ideal five-axis CLFDM printing, we have also performed physical experiments on a prototype five-axis FDM printer. The experimental results have validated the feasibility of our proposed methodology and demonstrated its potential in many applications.

Reinforcement of fabricated objects by surface deposition in multi-axis additive manufacturing

Reinforcement of fabricated objects by surface deposition in multi-axis additive manufacturing

Multi-axis additive manufacturing process for continuous fibre reinforced composite parts

There has been considerable research in recent years on the additive manufacturing (AM) of continuous-fibre-reinforced thermoplastic composite parts (CFRTPs) based on fused-deposition modelling (FDM). Most current AM processes are achieved by sandwiching long fibres between the matrix material, which confines the specimens to a single fixed building direction and leads to inferior interfacial performance. Herein, we present a new strategy for printing CFRTPs in three-dimensional space using a novel self-designed multi-axis AM machine. Two head systems are introduced to deposit the thermoplastic and long fibres. Moreover, the multi-axis movement approach advantageously enables the fibre to be deposited on any programmed surface, or wound around the parts. Three types of wound material specimens are manufactured, tested, and compared with specimens produced by a traditional flat layer stacking process. The results show that the tensile and flexural strengths of the composites are significantly enhanced by the continuous fibre, and the interlaminar shear performance of the wound fibre parts were also improved. Additionally, the proposed process makes the manufacturing of complicated composites more convenient, and exhibits significant potential for practical applications.

Reduction of Support Structures and Building Time by Optimized Path Planning Algorithms in Multi-axis Additive Manufacturing

Additive manufacturing is an emerging technology that enables new product design. However, major inhibitors are long building times and a fixed build direction of the workpieces. In this article, new optimization and path planning methods for multi-axis additive manufacturing are presented going beyond conventional three-axis systems. This includes an adaptation of the building direction and an algorithm for the special case of cylindrical axes. These methods can reduce the production time drastically by avoiding support structures and by using the integration of predefined building blocks to substitute the infill. We present both, the new manufacturing process and the necessary computation methods for optimal process and path planning. Decreasing the building time and the amount of support structures paves the way for new application domains of additive manufacturing in the future.

A framework for future CAM software dedicated to additive manufacturing by multi-axis deposition

Deposition processes, such as Wire & Arc Additive Manufacturing (WAAM), have important perspectives in industry, due to their capacity to produce large near-shape parts with high productivity. Beyond process-material issues, deposition path planning is one of the major challenges to allow a wide use of these processes using multi-axis machines or robots. Early CAM software solutions dedicated to multi-axis additive manufacturing have been already commercialised. However, few elementary deposition strategies are currently available. In this article, the possibilities of multi-axis deposition and the developments needed to improve deposition path generation are highlighted through the analysis of a hollow half-sphere as a case study. Deposition strategies are experimentally tested on two different robotised polymer deposition systems. Based on the comparison of the trials, the issues related to the portability of technology from a specific machine setup to a different one are discussed. Finally, a framework for future Computer-Aided Multi-Axis Additive Manufacturing (CAMAAM) software is proposed.

Geometry-Based Process Planning for Multi-Axis Support-Free Additive Manufacturing

In contrast to standard layer based additive manufacturing methodologies, multi-axis material deposition can print structures without the need for support material. However, this method is jeopardized by potential collisions between a depositing unit (nozzle, wire, power and powder sources, etc.) and the already deposited material. The goal of this research is to initiate development of a methodology to check manufacturing feasibility of geometries and generate subsequent process planning strategies. The paper describes a geometry-based concept to decompose the product geometry into discrete volumes by using space partitioning with infinite planes and considering advantages and constraints of multi-axis additive manufacturing. The discrete volumes are used to generate process planning variants and to compute and generate boundary conditions for such process planning strategies. The algorithm generates multi-axis slices that require no support structures because of relative nozzle/workpiece orientation. In addition, the planning tackles more complex scenarios, in which overhangs, nozzle orientation, and gravity can be considered.

Workpiece and Machine Design in Additive Manufacturing for Multi-Axis Fused Deposition Modeling

Additive Manufacturing (AM) technologies require innovative design paradigms and guidelines that exhaust the offered freedoms in geometry and material. The aim of the Design for Additive Manufacturing is to provide design opportunities and to enhance workpiece properties taking into account constraints of the process, e.g. kinematics and limitations of print technology. Most AM applications are constrained to three-axis movements limiting the fabrication of workpieces layer by layer to one fixed building direction only. This causes limitations of strength properties, surface quality and the need of supporting structures. Multi-axis AM enables completely new design possibilities going beyond current optimization and design strategies of conventional AM workpieces. This innovation requires multiple design and manufacturing changes in the internal and external geometry of the workpiece as well as in machine and printing head technology. This paper identifies the requirements and capabilities of multi-axis AM and presents possible solutions to overcome the identified challenges. Preliminary results for multi-axis AM are described on an exemplary workpiece.