Additive manufacturing: rapid prototyping comes of age

Purpose – The purpose of this paper is to provide a personalised view by the Editors of the Rapid Prototyping Journal. Design/methodology/approach – It collects their years of experience in a series of observations and experiences that can be considered as a snapshot of where this technology is today. Findings – Development of these technologies has progressed according to application, materials and how the designers have applied their creativity to such a unique manufacturing tool. Originality/value – The paper predicts how the future of additive manufacturing will look from the perspective of three key elements: applications, materials and design

Development of virtual surgical planning models and a patient specific surgical resection guide for treatment of a distal radius osteosarcoma using medical 3D modelling and additive manufacturing processes

In this study we will assess the design and fabrication of a patient-specific resection guide to augment surgical procedures, such as bone grafts and implant placement. Medical imaging data was used to form a 3-dimensional, digital template model of the target anatomy to incorporate surface topography information into the guide. The surgical guide was then designed to incorporate slots for bone cutting, holes for drilling of fixation points, and an optimised geometry which ensure ease of placement and use. The final device was then manufactured using additive manufacturing, to accurately replicate the complex surface topography and design features. To validate the design, the target patient anatomy was replicated using additive manufacturing and a 'mock' surgery was performed to assess the device performance. We found our design allowed for efficient placement and use during the mock surgery, confirming the potential of the devised process as a robust methodology for clinical implementation

Design optimisation of a thermoplastic splint

Following partial hand amputation, a post-surgery orthosis is required to hold the remaining ligaments and appendages of the patient in a fixed position to aid recovery. This type of orthosis is traditionally handmade and fabricated using laborious and qualitative techniques, which would benefit from the enhancements offered by modern 3D technologies. This study investigated the use of optical laser scanning, Computer Aided Design (CAD) and Material Extrusion (ME) additive manufacturing to manufacture a polymeric splint for use in post-surgical hand amputation. To examine the efficacy of our techniques, we take an existing splint from a patient and use this as the template data for production. We found this approach to be a highly effective means of rapidly reproducing the major surface contours of the orthosis while allowing for the introduction of advanced design features for improved aesthetics, alongside reduced material consumption. Our demonstrated techniques resulted in a more lightweight and lower cost device, while the design and manufacturing elements afford greater flexibility for orthosis customisation. Ultimately, this approach provides an optimized and complete methodology for orthosis production

Ecoprinting: investigating the use of 100% recycled acrylonitrile butadiene styrene (ABS) for additive manufacturing

Many commonly found polymers have the potential to be recycled, such as Acrylonitrile Butadiene Styrene (ABS), a prevalent 3D printing material. In this study we examine the potential of using 100% recycled ABS to form filaments for use in Fused Deposition Modelling (FDM) 3D printing. We then characterise the resulting changes in the printing quality and mechanical properties, over a single recycling cycle. We found that ABS can undergo recycling and reforming into consistent printer filaments without the addition of virgin material. However, notable changes in polymer characteristics were observed, reflected by degradation in mechanical properties during tensile tests and a decrease in the polymer melt flow, which required reduced raster speed to achieve repeatable prints. Despite these limitations, we demonstrate that recycling and reprinting is possible with acceptable loss of material integrity, and could provide unique opportunities for sustainable use of waste ABS using 3D printing technology

Design for additive manufacturing: trends, opportunities, considerations, and constraints

© 2016 CIRP. The past few decades have seen substantial growth in Additive Manufacturing (AM) technologies. However, this growth has mainly been process-driven. The evolution of engineering design to take advantage of the possibilities afforded by AM and to manage the constraints associated with the technology has lagged behind. This paper presents the major opportunities, constraints, and economic considerations for Design for Additive Manufacturing. It explores issues related to design and redesign for direct and indirect AM production. It also highlights key industrial applications, outlines future challenges, and identifies promising directions for research and the exploitation of AM's full potential in industry

Augmented patient-specific facial prosthesis production using medical imaging modelling and 3D printing technologies for improved patient outcomes

Facial prosthetic offer patients a low risk and high impact treatment option to address underlying facial defects. Such devices are generally handmade, requiring several labour-intensive manufacturing phases and numerous patient consultations to develop the final device. Therefore, production is a time-consuming and costly process with significant inconvenience to the patient and highly dependent on the skills of the prosthetists, making the whole process highly subjective. We investigate the potential of medical imaging, 3D design modelling and high-resolution 3D printing to augment the production of an auricular prosthesis for a patient who was previously using a handmade prosthesis. We reproduce the patient’s uncompromised anatomy from CT scan data, before printing a mirrored template to use in the casting process for a silicone prosthesis. This technique realises a superior end prosthesis with a realistic look on the patient while streamlining the current production methodology

Investigation on the effect of heat treatment and process parameters on the tensile behaviour of SLM Ti-6Al-4V parts

Additive manufacturing (AM) has various independent parameters that affect the mechanical properties and quality of the produced parts that are not linearly the function of each other. Process parameters in metal AM are very hard to control, analyse and optimise because they affect each other even though they can be independently changed. Changing process parameters in a wide range is not possible due to the formation of problems such as cracks, balling, unmelted powders, porosity and distortion. In this paper, a numerical model to predict the value of tensile strength of selective laser melting (SLM) Ti-6Al-4V parts and analyse the effect of process parameters on the results has been proposed. Taguchi L25 Design of Experiment (DOE) across 125 samples to create a comprehensive and general overview of influential parameters on the build process was investigated. Specifically, parameters included laser power, scan speed, hatch spacing, laser pattern angle and heat treatment (HT). To evaluate and analyse the build process according to established statistical variances, a minimum of five samples based on ASTM standard (for tensile test) were prepared. Heat treatment was added to the DOE to analyse the combined process and post-process effects. Results were compared (cross-validated) against existing values found in the literature and were found to effectively predict and explain the behaviour of tensile strength when changing process parameters

Oscillation characteristics of low Weber number impinging micro-droplets

Oscillation characteristics of micro-droplets, when in partial contact with a dry and homogeneous substrate, are investigated using a volume of fluid (VOF) numerical method. Water is used as a fluid in both numerical and experimental studies. The velocity vectors are plotted along the phase boundary line, i.e. along the droplet interface, to show how the contact angle impacts the droplet shape during the entire oscillation process. It has been predicted that when the surface/liquid combination is of larger contact angle, the water droplet tends to spread partially as the contact velocity dynamics dominate over inertia, thereby restricting the change in shape, i.e. resulting in lesser mode of oscillations. However, all droplets that are considered here show a damped harmonic motion with the amplitude gradually decreasing to zero. Particularly, at a lower Weber number impact, it is predicted that both the height and spreading dynamics exhibit a unique decaying function for each droplet size considered