PowderMet          AMPM          Special Interest

167 - Atomization Design Fundamentals: It’s All Connected—How Gas Die Geometric Designs Influence Atomization Efficiency and Reliability
Dave Byrd, Ames National Laboratory

Close-coupled gas atomization (CC-GA) is an excellent method for producing metal powders for both production and research applications.  As the need to produce high quality powders for additive manufacturing (AM) has become extremely important, precise tuning of the atomization process is important to increase efficiency and yield.  The gas die is the central component in the CC-GA process, and plays a crucial role in melt flow rate, melt stream breakup, and particle size distribution. Through careful study and understanding of gas die behavior the resulting effects can be understood and predicted.  Several gas die designs were studied and evaluated for gas flow patterns, gas consumption, aspiration characteristics, and resulting powder size distributions.  Support from USDOE-EERE-AMO through Ames National Laboratory under contract no. DE-AC02-07CH11358.

203 - Close-Coupled Transferred Arc Plasma-Wire Atomization
Joseph Strauss, FAPMI, HJE Company, Inc.

162 - Atomization Design Fundamentals: Isentropic Jets–A Benefit to Atomization Efficiency or Simply an Added Manufacturing Cost? 
Jordon Tiarks, Ames National Laboratory

For decades, powder producers have been searching for the “perfect” close-coupled gas atomization technology to tune powder size distributions for maximum yields of salable powders while maintaining high production rates and low gas inputs. Countless iterations of gas die geometries coupled with widely varying process conditions (pressure, mass flow rates, temperature, and gas composition) have created a nuanced design space from which powder producers carve out best practices, but many do not know the exact reason their design works or how to take it to the next level. Converging-Diverging (C-D), or “isentropic” jet geometries have been speculated to increase breakup efficiency, but these designs are often more difficult and expensive to manufacture and researchers have reported varying effectiveness. In this presentation, we will present an overview of C-D jet design principles and examine their effectiveness through both computational and surrogate experimental testing.  Supported by US-DOE-EERE-AMO through Ames Lab contract DE-AC02-07CH11358.

164 - Metal Binder Jetting and Metal Material Jetting as Complementary Technologies: A User Perspective
Mattia Forgiarini, Azoth

Metal Binder Jetting and Metal Material Jetting are two Additive Manufacturing techniques included under the Sinter Based Additive Manufacturing umbrella category.
In this work, Azoth, an independent part fabricator utilizing both technologies, presents how the two technologies complement each other from a capabilities, throughput, and operational point of view.
Azoth discusses unique insight into why customers and parts makers might choose one technology over the other. While many outsiders view the technologies as competing technologies, Azoth will explain their viewpoint of how the technologies co-exist and complement each other by addressing different markets and consumer demands.
A technical analysis of process differences, and resulting benefits of each technology will be presented.

153 - Green Body Photopolymerization and Sintering: Shining a Light on Multi-Step Additive Manufacturing of MIM-Quality Metal Parts
Brian Adzima, Holo Inc.

Multi-step additive manufacturing (AM) processes have been explored as a means to quickly create sinterable polymer and powder metal green bodies. These methods reduce the fixed tooling costs of traditional manufacturing processes, but none have yet gained widespread commercial traction. One of the least explored multi-step AM methods for metals is photopolymerization. This is unfortunate, as it has both high print speeds and excellent feature resolution. The primary challenge is that metal-filled photopolymers have a high viscosity and low light transmissivity, which makes printing green bodies near-impossible with existing printers. In addition, existing photopolymers introduce high levels of residual carbon to sintered parts. This manuscript will demonstrate that specialized photopolymer 3D printers can produce intricate green bodies using standard metal injection molding (MIM) powder cuts and custom binders. These feedstocks produce high density metal parts, and surface roughness values superior to other AM processes. We will highlight this process’s capability for producing thin walls, internal channels, and other complex geometric features. We will show that specialized binders have eliminated residual carbon incorporation during sintering, and that the resulting chemical, tensile, and corrosion properties of 17-4PH, 316L, and high purity copper are in-line with standard MIM specifications. Ultimately, not only can MIM-like parts be rapidly produced with unmoldable micro-scale individual features, but this can be done without tooling, in a highly flexible range of volume quantities.

128 - Cold Metal Fusion—Reliable Serial Production in Metal AM
Christian Fischer, Headmade Materials GmbH

Headmade Materials pushes the Powder Metallurgy further into the Metal AM market with its sinter-based 3D-printing technology ColdMetalFusion and partners with industry leaders in the ColdMetalFusion Alliance to leverage the potential of reliable serial production in Metal AM. Headmade Materials combines standard PM metal powders with its proprietary binder system to form a powdery feedstock that can be processed into green parts on standard plastic laser sintering systems. The subsequent debinding and sintering step is again PM industry standard and the part characteristics are fully comparable to MIM in terms of density and strength. The ColdMetalFusion process offers several advantages over beam-based processes and stands out from other  sinter-based 3D printing processes due to its high green part strength and an already existing, partially automated process chain.

051 - Design of a Tool for Evaluating the Suitability of Powder Feedstocks and Process Parameters for Powder Bed Fusion Recoating Operations
Amalia Thomas, Freeman Technology

The quality of printed parts in Additive Manufacturing (AM) Powder Bed Fusion (PBF) depends on a precise balance and optimisation of a number of unit operations. The recoating step is an essential operation that typically requires the formed powder layer to have uniform, consistent and controllable thickness and density. Lack of repeatability and control of the recoated layer attributes can lead to inadequate finished parts with defects or poor material properties, yet an accurate prediction of powder behaviour is very difficult to achieve. This is because the arrangement of particles as they are recoated will be influenced by the balance numerous factors, including physical properties of the particles and bulk behavioural properties such as flowability, density and permeability, as well as environmental conditions and the powder transport and treatment history.
In this presentation we propose a tool to replicate realistic recoating processes and assess the quality of the formed layer. The tool offers flexibility in the powdered materials it can test, as well as in the process parameters such as layer thickness and recoater type and speed, within real typical ranges. Furthermore, the tool incorporates a method for quantifying spreading performance, and we present data for several typical feedstock powders.

200- Powder bed fusion of strut-based conformal metal metamaterials: Design considerations to ensure a uniform cross-sectional profile for inclined struts
Ma Qian, Royal Melbourne Institute of Technology

Additive manufacturing (AM) has enabled the emergence of strut-based lattice materials with controlled structural or functional properties unfeasible for conventional materials. A striking feature of these novel materials is the substantial number of constituent strut elements contained in them, e.g., more than 5´10⁵ (diameter: 0.5 mm; length: 5.0 mm) in a common tetrahedron lattice with dimensions of 200´200´200 mm³.  A prerequisite for realizing the full design potential of these structures is to ensure the robust additive continuity of each constituent strut layer by layer. Additive continuity refers to the geometric continuity between two successive layers of a strut in lattice materials fabricated by powder bed fusion (PBF) based AM and robust continuity ensures high structure integrity of lattice materials. This critical issue has, however, remained unanswered. Herein we formulate a design-and-manufacture interlocked strut additive continuity model for PBF and apply it to the entire design gamut of Ti-6Al-4V struts. On this basis, a strut additive continuity threshold value (j = 0.9) is proposed and validated with 23,100 inclined struts in Ti-6Al-4V lattices manufactured by electron beam PBF (EB-PBF). Design maps are then constructed for EB-PBF of lattice materials. Furthermore, a minimum powder-bed density for powder selection and a powder-specific baseline initial layer thickness are recommended. This work establishes a necessary basis for the design and manufacture of robust lattice materials by EB-PBF including graded lattices.

146 - Comparing the Spreadability of Powders on a Powder Bed and a Solid Surface to Study the Physics of Powder Layer Formation Over Parts Being Printed and Unbound Powder Areas in AM Printers
Greg Martiska, Mercury Scientific Inc.

In an AM printer, powders are spread over a powder bed and over the part being printed. The part is a hard surface as opposed to the area around the part which is a soft and elastic powder bed. This creates different powder spreading physics in the printer. Over a hard surface, the gap between the recoater blade is fixed and powder particles with a size near or larger than the gap will not pass through the recoater. This changes over a powder bed where particles can be embedded in the bed and the gap between the recoater and bed can be increased by the action of the recoater. The density, thickness, and quality of layer formation are presented for several powders spread on both a powder bed and a hard surface. This illustrates the difference between powder spreadability physics over parts being printed and powder bed areas.

120 - Improving the Properties of Titanium Alloy Parts via HIP (Hot Isostatic Pressing)
Jane LaGoy, Bodycote

Most parts built by additive manufacturing (AM) processes require secondary treatments to render them suitable for intended use.  Even with the most robust techniques, the powder bed fusion (PBF) process still creates small internal voids during the build.  We evaluated the effect of post-build hot isostatic pressing (HIP) parameters on Ti 6/4 (titanium-6% aluminum-4% vanadium).  Advanced characterization techniques such as computed tomography (CT) scanning x-ray, scanning electron microscope (SEM) fractography, and fatigue analysis were used to evaluate the effects on properties.  Results demonstrate the removal of the defects and corresponding improvement in material properties.  This is especially important for critical components in industries such as nuclear, aerospace, medical, and subsea applications where fatigue is a major cause of premature failure.  Additional work  concentrates on optimizing HIP parameters to minimize grain growth.

198 - Wear Resistant AM Components Enabled With In-HIP Heat Treatment
Chad Beamer, Quintus Technologies

Additive Manufacturing (AM) technology is being used increasingly to produce parts quickly, as an alternative option to forging or casting processes. Components can be printed in a matter of days, leading to less need for spare parts near the point of use making it an attractive technology for many industries. VBN Components has patented very high wear resistant materials that are produced using powder technology which is then printed to a near-net-shape using AM. The finished properties of these materials are then enhanced using a combined hot isostatic pressing and heat treatment strategy in modern equipment outfitted with uniform rapid quenching capabilities. This paper will offer a brief background on these technologies with examples of intended end use. Then the resulting material performance and productivity enhancement will be captured for these high performing VBN Component material systems.  

 188 - How the production of high quality pre-alloyed powder changed over the years from HIP to Additive Manufacturing
James Sears, Amaero Additive Manufacturing

Stemming from the Manhattan Project, in the early 50’s, the Atomic Energy Commission (AEC) had a need for a process to bond components of small Zircalloy-clad pin-type nuclear fuel elements while maintaining dimensional control. This led to the invention of “gas-pressure bonding” by the engineers at Battelle Laboratories in Columbus, OH. Today that process is known as Hot Isostatic Pressing “HIP” and is used for casting densification, metal, and ceramic powder consolidation, cladding, heat treatment and more recently a treatment step in metal additive manufacturing.

Commensurate with the development of HIP technology was the invention of various inert gas atomization techniques for high quality pre-alloyed powders (including super alloys and other reactive alloys based on Zr, and Ti) to be used as source materials. However, since that time the primary consolidation techniques of the use of high quality pre-alloyed powder for component manufacturing has shifted from HIP and extrusion to Additive Manufacturing. This has resulted in the change powder size requirements to finer powders. This presentation will elaborate on these developments.

057 - Examining Alternative Metal Powder Feedstock for Metal Binder Jetting Process
Mats Perssons, Digital Metal AB

Metal Binder Jetting (MBJ) is one of the most promising additive manufacturing technologies for commercial mass production of parts. It has many similarities with Metal Injection Molding (MIM), e.g. shaping a green body with metal powder loading in the 40-70% range and subsequently densifying the same by sintering. 
Metal powder feedstock is hereto more versatile in MIM where powder flow characteristics is less of a consideration. Mixes of elemental and master alloyed powders, pre-alloyed water and gas atomised  powders are applied in the MIM process. In MBJ mostly spherical atomised powders are applied as they are associated with better flow properties and a higher packing density than alternatives.
In this study water atomised (stainless steel 316L) powder is explored as feedstock for the printing process with a typical gas atomised powder as reference point. Powder bed properties, printing process and green components are characterised. Dimensional and mechanical properties after de-binding and sintering are compared and advantages and disadvantages discussed.

174 - Effect of Particle Size Distribution on the Physical Properties of Binder Jetted 17-4 as a Function of Print Axis
Nanna Bush, Penn State University

    Binder jetting is quickly becoming recognized as one of the most desirable methods to produce high-volume printed components and future printed material development.  Although this technique of printing has been available for a while, the understanding of the impact of particle size distributions on the physical properties of the components and directions in which they are printed remains an area of investigation.  

In this work, 17-4 material of varying particle size distributions will be printed in the X, Y, and Z axes.  Particle size distributions, physical testing, densities, and electron microscopy will be completed to better understand the printing process.
 

079 - Exploring the Potential of a Novel Multi-Modal 17-4 PH Stainless Steel Powder for Binder Jetting
Arulselvan Arumugham Akilan, Uniformity Labs

Metal binder jetting has been the subject of much interest due to modularity of its process flow enables the efficient management of mass production & cost optimization. 17-4 PH stainless steel is conventionally one of the most widely-used of the precipitation hardening steels. 
Brown part uniformity and absolute shrinkage drive geometric variation in sintered parts. The key to improve yield and efficiency of the prints is a tighter tolerance and repeatability of physical and mechanical properties of jetted parts. The present research explores the effects of powder properties (cohesion, particle size, tap density, binder absorption, binder saturation) and print parameters (compaction ratio, humidity, and layer thickness) on the brown and sintered porosity, sintering shrinkage and mechanical properties of binder jet printed 17-4 PH samples. 
Results indicate that Uniformity Labs binder jetting 17-4 PH powder (wider distribution-multimodal) shows lesser average shrinkage than less than 22 µm powder (standard MIM cut) of 14%, 9%, 9% in X, Y, Z directions respectively upon sintering. The brown density of UL parts is 4.99g/cc +/- 0.10 (2 st. dv.) compared to 4.50 g/cc +/- 0.20 (2 st. dv.) for those from MIM powder. Both powders densify to 99% relative density after sintering. The as-sintered parts from Uniformity Labs 17-4 binder jetting powder also showed tighter tolerances in mechanical strength and elongation values than the parts from the MIM powder.

501 - Sinter-Based Additive Manufacturing of Cemented Tungsten Carbides
Animesh Bose, FAPMI, Optimus Alloys

Hardmetal, also known as cemented tungsten carbide, is a class of two-phase composite where the hard tungsten carbide grains are embedded in a relatively softer matrix of a binder phase (generally consisting of cobalt and/or nickel with some tungsten and carbon in solution).  This composite exhibits a unique combination of high compressive strength and hardness, good corrosion resistance, and excellent resistance to wear and abrasion.  Hardmetals have been used for almost a century in numerous wear and cutting applications and have been mainly processed by press and sinter technology and more recently by powder injection molding, both of which require the use of tooling.  Additive manufacturing (AM) on the other hand is a process capable of fabricating complex shapes without any tooling.  This presentation will discuss a couple of sinter-based AM processes for fabricating complex shaped hardmetal parts.  

502 - Processing of WC-Co Parts by Solvent-on-Granules 3D-Printing
E. Carreno-Morelli, University of Applied Sciences and Arts Western Switzerland

Solvent-on-Granules 3D-Printing (SG‐3DP) consists in the selective jetting of a solvent on powder-binder granule beds to grow a green part layer by layer. The solvent softens the polymer binder to paste the granules to each other. The printed part is subsequently consolidated by debinding and sintering. The main advantages of the process are: (1) a higher flexibility for alloy formulation (metal, ceramics and its composites), because several combinations of fine elementary powders can be included in the granules, (2) no clogging of printheads, which are “self‐cleaned”, and (3) improved recyclability of granules.
WC-17Co and WC-12Co parts have been processed from commercial presintered powders. Full densification is achieved by hot isostatic pressing when necessary. Microstructures meeting the standards of classical press and sintered parts are obtained. Shape preservation and tight tolerances are achieved in both simple test and complex geometry functional parts. Improving surface condition and lowering the cobalt content remain the challenges.

503 - Binder Jetting 3D Printed Cemented Carbide: Mechanical and Wear Properties of Medium and Coarse Grades
Juan Trasorras, Global Tungsten & Powders Corporation

Selective laser melting (SLM) is the most widely used additive manufacturing (AM) technology to 3D print metals. Several researchers have tried, unsuccessfully, to produce cemented carbide by SLM. Binder jetting 3D printing (BJ3DP) and micro-extrusion-based methods are two AM technologies that have been successfully applied to the printing and sintering of cemented carbide. We report the development of medium and coarse WC-Co powders for BJ3DP with Co contents of 10%, 12%, and 17%. The free flowable (Carney flow < 20 s/200g) spherical powders exhibit very good printability and can be sintered to full density under standard sinter-HIP conditions (temperature 1435-1485oC, pressure 18-50 bar). The sintered mechanical properties, hardness, and fracture toughness, compare well against cemented carbides produced by powder metallurgy. Vickers hardness and fracture toughness (determined by the Palmquist method) are in the range HV30 990-1300 and 17-23 MN·m-3/2, respectively.  We evaluated the wear properties under abrasion and erosion using the ASTM B611 and ASTM G65 standard testing procedures. The wear resistance of the BJ3DP cemented carbide matches, and, in some cases, can exceed the resistance of conventionally produced cemented carbide. We have manufactured components of varying geometric complexity with weights ranging from 0.53 g to 21 kg. BJ3DP enables the manufacture of components that are not feasible by pressing and sintering, even with extensive use of green machining.

To Be the Best by Any Measure

192 - How to Create and Sustain a High-Performance Organization
Pat Magee (aka Gary Ramsey)

A presentation and discussion about the Three-Legged Magee Stool which provides a roadmap for success and offers a proven formula: A Healthy Organizational Culture + Ongoing Leadership Development + Comprehensive Strategic Planning = A High-Performance Organization. 
Organizational Culture:
Research and practice demonstrate that an organization’s culture can have a significant impact on its long-term performance and success. 
We will discuss:
•    Characteristics of healthy and unhealthy cultures
•    Examples of very positive core values and norms of behavior
•    Assessing and changing your culture
•    Barriers to change which you may encounter
Leadership Development:
It is absolutely necessary to have many leaders, at all levels of the organization, in order to communicate the vision and the desired values and norms of behavior, implement the strategic plan and ultimately sustain the High-Performance Organization.
We will discuss:
•    Roles and responsibilities of leaders
•    How to identify potential leaders – the necessary Characteristics
•    How effective leaders are different from managers, supervisors and even presidents.
Strategic Planning:
A coordinated and systematic process to assure that the overall course and direction of the organization are well thought out, sound and appropriate. It becomes the roadmap for achieving and sustaining the High-Performance Organization.
We will discuss:
•    Team formation
•    The elements
•    The process
High Performance Organizations:
We will see that in these organizations Managers become leaders, Committees become Teams, Employees/Volunteers become Team Members, and Problems become Opportunities.
We will discuss:
•    How they differ from other organizations
•    Barriers to achieving High-Performance.
•    The need for High-Performance individuals
•    How they are sustained