Basics of qualitative research: Grounded theory procedures and techniques

Materials for additive manufacturing

We employ the high-speed synchrotron hard X-ray imaging and diffraction techniques to monitor the laser powder bed fusion (LPBF) process of Ti-6Al-4V in situ and in real time. We demonstrate that many scientifically and technologically significant phenomena in LPBF, including melt pool dynamics, powder ejection, rapid solidification, and phase transformation, can be probed with unprecedented spatial and temporal resolutions. In particular, the keyhole pore formation is experimentally revealed with high spatial and temporal resolutions. The solidification rate is quantitatively measured, and the slowly decrease in solidification rate during the relatively steady state could be a manifestation of the recalescence phenomenon. The high-speed diffraction enables a reasonable estimation of the cooling rate and phase transformation rate, and the diffusionless transformation from β to α
 ’
 phase is evident. The data present here will facilitate the understanding of dynamics and kinetics in metal LPBF process, and the experiment platform established will undoubtedly become a new paradigm for future research and development of metal additive manufacturing.

Real-time monitoring of laser powder bed fusion process using high-speed X-ray imaging and diffraction

As the number of prosumer printers has expanded rapidly, they now make up the majority of the 3-D printer market and of these printers those in the open-source lineage of the RepRap also have expanded to dominate. Although still primarily used for prototyping or hobbyist production of low-value products, the RepRap has the capacity to be used for high-value distributed manufacturing. A recent study found that RepRap printed parts printed in realistic environmental conditions can match and even out perform commercial 3-D printers using proprietary FDM in terms of tensile strength with the same polymers. However, tensile strengths of the large sample set of RepRap prints fluctuated. In order to explain that fluctuation and better inform designers on RepRap print properties this study determines the effect of color and processing temperature on material properties of Lulzbot TAZ deposited PLA in various colors. Five colors (white, black, blue, gray, and natural) of commercially available filament processed from 4043D PLA is tested for crystallinity with XRD, tensile strength following ASTM D638 and the microstructure is evaluated with environmental scanning electron microscope. Results are presented showing a strong relationship between tensile strength and percent crystallinity of a 3-D printed sample and a strong relationship between percent crystallinity and the extruder temperature. Conclusions are drawn about the effects of color and processing temperature on the material properties of 3-D printed PLA to promote the open-source development of RepRap 3-D printing.

The effects of PLA color on material properties of 3-D printed components

By synergistically combining additive and subtractive processes within a single workstation, the relative merits of each process may be harnessed. This facilitates the manufacture of internal, overhanging and high aspect ratio features with desirable geometric accuracy and surface characteristics. The ability to work, measure and then rework material enables the reincarnation and repair of damaged, high-value components. These techniques present significant opportunities to improve material utilisation, part complexity and quality management in functional parts. The number of single platform workstations for hybrid additive and subtractive processes (WHASPs) is increasing. Many of these integrate additive directed energy deposition (DED) with subtractive CNC machining within a highly mobile multi-axis machine tool. Advanced numerical control (NC), and computer aided design (CAD), manufacture (CAM) and inspection (CAI) help to govern the process. This research reviews and critically discusses salient published literature relating to the development of WHASPs, and identifies future avenues for research and development. It reports on state-of-the-art WHASP systems, identifying key traits and research gaps. Finally, a future vision for WHASPs and other hybrid machine tools is presented based upon emerging trends and future opportunities within this research area.

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Hybrid additive and subtractive machine tools – Research and industrial developments

Wohlers Report 2018: 3D printing and additive manufacturing state of the industry: Annual Worldwide Progress Report

This book provides a wealth of practical guidance on how to design parts to gain the maximum benefit from what additive manufacturing (AM) can offer. It begins by describing the main AM technologies and their respective advantages and disadvantages. It then examines strategic considerations in the context of designing for additive manufacturing (DfAM), such as designing to avoid anisotropy, designing to minimize print time, and post-processing, before discussing the economics of AM.The following chapters dive deeper into computational tools for design analysis and the optimization of AM parts, part consolidation, and tooling applications. They are followed by an in-depth chapter on designing for polymer AM and applicable design guidelines, and a chapter on designing for metal AM and its corresponding design guidelines. These chapters also address health and safety, certification and quality aspects. A dedicated chapter covers the multiple post-processing methods for AM, offering the reader practical guidance on how to get their parts from the AM machine into a shape that is ready to use. The book’s final chapter outlines future applications of AM.The main benefit of the book is its highly practical approach: it provides directly applicable, “hands-on” information and insights to help readers adopt AM in their industry (Less)

A Practical Guide to Design for Additive Manufacturing

Wohlers Report 2017 3D Printing and Additive Manufacturing State of the Industry : Annual Worldwide Progress Report

Cell immobilization on 3D-printed matrices: A model study on propionic acid fermentation

This article examines the process of redesigning a conventionally manufactured hydraulic manifold to one designed for additive manufacturing (DfAM). In this case, the factors to be optimized included minimizing the support material, and post-processing required to make the part, as well as minimizing the products’ weight and print time. Improvement in product functionality would also be a desirable outcome of the project. The paper also compares the new and old manifold in terms of material usage, weight, costs, Manhattan distances, and residual stress. The DfAM process used in this article includes the steps of removing all material that doesn’t serve a specific engineering function, exploring the effects of different print orientations, techniques for eliminating support material and post-processing. These techniques are demonstrated in the redesign of the hydraulic manifold and present the resulting printed product. The design steps used in the case study are also described in a generic manner to make them applicable to other AM parts printed in either metal or polymer.

Olaf Diegel

Papers

Wohlers Report 2018: 3D printing and additive manufacturing state of the industry: Annual Worldwide Progress Report

A Practical Guide to Design for Additive Manufacturing

Wohlers Report 2017 3D Printing and Additive Manufacturing State of the Industry : Annual Worldwide Progress Report

Cell immobilization on 3D-printed matrices: A model study on propionic acid fermentation

Design for additive manufacturing process for a lightweight hydraulic manifold