January 27

Improved Powder Compaction Through Use of Advanced Binders and Lubricants
Neal Kraus, Hoeganaes Corporation

Binder-treatment of premixes is extremely effective in improving part-to-part consistency, weight variation, powder flow, and overall cleanliness.  As part geometries become more complicated and faster filling speeds are desired, additional benefits of binder-treatment can be realized.  More recent studies have shown exceptional filling behavior and higher stroke rates when converting to precision bonded products.  When combined with advanced lubricants, higher densities can be achieved with lower ejection forces and excellent surface finish.

Additive Manufacturing of Refractory Grid Structures—Historical Overview
Juha Kotila, EOS Finland

The developments on laser beam properties of additive manufacturing equipment have enabled reaching higher and higher laser beam intensity levels. These high beam intensities have made possible to process materials with very high melting temperatures, e.g. refractory metals. Most of these materials are difficult or impossible process in conventional manufacturing methods to include thin walled sections, internal cavities or structures with significant weight savings.

This presentation will focus on historical overview on development done on requirements and performance on both AM machines and process features needed to produce AM tungsten grids for X-ray guiding applications during the last 12 years. Practical examples of properties of refractory materials processed are given. In addition the performance of freeform, solid refractory metal components in their final intended use will be given.

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February 24

Material Options for Improved Dimensional Consistency
Roland Warzel, III, North American Höganäs Co.

Powder Metallurgy (PM) enables the manufacturing of high-volume components with near net shape capability. The required tolerances on PM components continues to tighten at the same time as the complexity increases. To minimize secondary machining steps, highly repeatable dimensional consistency is required. The dimensional consistency can be influenced by several factors with the material composition playing a large role in the tolerances which can be achieved. In this presentation, factors which influence dimensional consistency will be reviewed. Solutions which allow for increased precision will be presented.  

Development of a Surface Roughness Measurement Sample and Its Use in Sinter-Based Metal Additive Manufacturing
John Reidy, Desktop Metal

Rapid advancements have been made with metal Additive Manufacturing (AM) technologies based on both melt-based and sinter-based processes. The result is the need to develop a simple metal part that can account for most of the surface roughness conditions that evolve on different planar surfaces during processing. For example, processes based on fused filament fabrication (FFF) yield different surface roughness conditions on the top and bottom faces as well as along the planes in the z-direction. At the same time, processes that involve the spreading of a layer of powder followed by the application of either binder, laser or e-beam, can have subtle variations in surface roughness on different planar faces. Focusing on the extrusion-based FFF process, this investigation discusses  the efforts to design a new part with 10 surfaces that can address the majority of the surface roughness variations on different planar orientations.

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March 24

Lightweighting Material and Process Options for Automotive Applications—Focus on PM Aluminum
Chaman Lall, MPP

Mobility vehicles powered by hydrocarbon fuels are subject to regulation by Federal emission standards that are aimed to reduce greenhouse gases. Because of the high number of automotive vehicles in use globally, they present the greatest threat to the environment. The automotive industry has developed strategies to improve fuel efficiency- one of those being the reduction of vehicular mass. One approach is the utilization of low-density materials such as the alloys of Al, Mg and Ti. This presentation aims to provide an overview of light weighting options using these materials, with a specific focus on the powder metallurgy (PM) technology as applied to the processing of aluminum alloys.  An new alloy developed presents an opportunity to reduce mass by 50%; this alloy has a yield strength of about 300 MPa, and a tensile elongation of about 2%.  The technical and economic feasibility of various paths to vehicular mass reduction will be reviewed.

Evaluation of AM Technologies in MIM Applications
Joe Strauss, HJE Company, Inc.

This study investigated the feasibility of producing a MIM-like part via metal AM technologies, specifically Binder Jetting, Material Extrusion, Metal Jetting, and Photopolymerization of metal-loaded photopolymers. These new AM technologies are of interest to MIM companies as they leverage much of the knowledge base of MIM and, in some cases, use similar powders.  These AM technologies have the potential to enable the production of MIM-like parts at production volumes not possible by MIM. 
The outcome of this study was that these technologies claimed the ability to produce candidate parts and the resulting cost structures were feasible for low production numbers.
This current portion of the study will examine actual parts made by these various technologies and evaluate their abilities to achieve tolerances, surface finishes, and densities.

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April 28

Mix Solution for High Green-Strength and Green Machining
Roland Warzel, III, North American Höganäs Co.

A new mix system that provides increased green strength has been developed. By achieving a high green strength, it is possible to reduce the formation of green cracks during part ejection and handling which provide the possibility of reducing green scrap. Another potential opportunity with high green strength is the ability to facilitate green machining. This mix system has been developed to provide high strength together with good fillability and ejection characteristics. In this study, the performance of this newly developed mix system is evaluated and compared to the common industry lubricant amide wax.  This new mix system is shown to increase the green strength by up to 60%  in a FC-0208  material system compared to premixes based on amide wax. This increase in green strength will also be shown to provide opportunity for a robust green machining solution. 

Processing of Tungsten Heavy Alloy by Extrusion-Based Additive Manufacturing
Animesh Bose, Desktop Metal

Tungsten heavy alloy (WHA) is a class of liquid phase sintered composite material that consists of predominantly tungsten (typically 90 wt.% or more) grains dispersed in a matrix of two or more elements chosen from Fe, Ni, Co, and Cu. Due to its unique combination of properties including high density, strength, hardness, toughness and good corrosion resistance, these alloys have found numerous applications in diverse industries such as counter weights, sporting goods, kinetic energy penetrators, radiation shields, vibration dampening devices, etc. bound metal deposition (BMD) is an additive manufacturing (AM) technology that has its roots in metal injection molding (MIM) and a freeform material extrusion process of fused filament fabrication (FFF). The process is capable of rapid prototyping and low volume serial production of complex shaped parts. This paper reports on the preliminary investigations in the processing of a WHA composition using the BMD process.

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May 26

Understanding the Factors Influencing PM Dimensional Change to Improve Part Consistency
Neal Kraus, Hoeganaes Corporation

One of the most desirable attributes of PM processing is the near net-shape that is possible with compacted parts.  To optimize this technology, one must understand the factors that affect dimensional change through sintering in order to minimize the amount of additional processing (sizing, machining) that must be applied.  This work aims to show basic factors that influence dimensional change in the most common PM alloys and offers possible solutions to improve both part-to-part and lot-to-lot consistency.  Alternative alloys, advanced powder solutions, and enhanced processing options are applied in a production setting to reduce the need for secondary processing steps.

3D Printing for Production: Reducing Variation of Binder Jet 3D Printed Parts
Andrew Klein, ExOne

Among the metal 3D printing technologies, binder jetting is becoming recognized as the technology with the best value proposition to produce production quantities of parts. The low cost of powders, high speed of printers and ability to leverage industry standard furnaces all make the printing process attractive for production applications. One of the challenges associated with the binder jet process is that fine, cohesive powders need to be spread into thin layers across a wide powder bed. Any variation in green density that occurs during the spreading and printing process will cause variability in final part tolerances from the sintering furnace. This presentation will discuss the methods and techniques used on binder jet 3D printers to minimize variation and improve the sintered part accuracy of parts produced using binder jet 3D printing.

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June 23

Advancements in Continuous Processing of Soft Magnetic Components
Stephen Feldbauer, Abbott Furnace Company

With the electrification of our world ever growing, the application of soft magnetic components is rapidly increasing.  A novel new approach was developed to produce soft magnetics in a continuous process that is more efficient and cost effective.  Here the process along with the underlying science will be reviewed explaining why these developments are such an important innovation for the powder metal industry.

Factors Affecting the Dimensional Variation in SS 17-4 PH Binder Jet Components
Venkat Roy, INDO MIM INC.

Additive manufacturing processes have provided an avenue to manufacture metal components with highest complexity and customized geometries. Although they are currently being utilized for low-volume production especially for tool making and prototyping, some of these processes are moving towards mass production, specifically the Binder Jetting (BJT) process which is relatively more scalable to mass production. At higher volumes, there will be dimensional variation in parts that are induced by the printing and as well as the subsequent processes. 

This paper aims to study the factors influencing the dimensional variation of SS17-4 PH parts printed using a binder jet printer. Test specimens with different geometries will be printed across the build-box at different conditions and the variation in dimensions will be reported upon necessary post-printing processes like curing, depowdering, debinding and sintering. In addition to charting the sintered dimensional variation from the print location, the green condition variation will also be tracked to correlate its effect on sintered dimensions. The results from this study should also help in establishing critical process variables in the binder jet process and derive an estimate of the dimensional tolerance that can be achieved.

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July 28

Increased Productivity and Longer Tool Life in Machining High Strength Powder-Forged Connecting Rods
Bo Hu, North American Höganäs Co.

Powder-forged connecting rods for automotive applications require significant machining with multiple operations to provide precise dimensions and surface finish. Powder-forged connecting rods are commonly manufactured from copper steels with a conventional machining additive such as MnS. Recent developments in advanced machining enhancers showed the capability of advanced machining additives in improving machining for various as-sintered steels. Feasibility assessment in laboratory tests with powder-forged pucks indicated that the advanced machining enhancers have potential in improving the machining of powder-forged materials and achieving higher productivity. In this study, mass-production machining trials with actual connecting rods were performed in order to validate the performance of the advanced machining enhancer in improving the machining of high strength powder-forged materials. The results obtained from the production trials demonstrated the advanced machining enhancer could provide increased productivity by reducing the total machining cycle time 20 seconds. This was achieved in conjunction with a 100% increase in the tool life of the crank boring operation.  

3D Printing of Permanent Magnets
Kalathur Narasimhan, FAPMI, P2P Technologies

Lasers provide a unique opportunity to heat small area of powder ,typically 20 to 40 microns, and the melt cools rapidly  .The cooling rate is fast enough to form fine grained microstructure. In the case of hard magnetic materials this cooling rate allows the opportunity  for the formation of nearly single domain grains .In the case of melt spun Neodymium iron boron ,selective lase meting(SLM) can be used to make bulk magnet fully dense bodies which otherwise not possible by melt spun ribbons. Ribbons need to be crushed and blended with polymers to shape magnet bodies or hot formed to make dense magnets.

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August 25

Microstructure Development in Dual Phase Stainless Steel Parts Made by Laser Bed Powder Fusion
Thomas F. Murphy, FAPMI, Hoeganaes Corporation

Dual phase stainless steel alloys are characterized by a ferrite-martensite microstructure that is usually formed through a secondary heat treatment after creation of the part.  The heat treatment requires reheating the part into the ferrite-austenite region of the phase diagram, creating partitioning of the alloying elements into the two phases.  This is followed by rapid cooling, which transforms the austenite at high temperature to martensite.  It will be demonstrated that the as-built parts made by laser bed powder fusion do not have the dual phase microstructure because, when building parts by heating with the laser, the cooling rate experienced by the parts in the powder bed is too rapid for the alloy partitioning to occur and consequently, the dual phase microstructure is not transformed.  In order to create the desired two-phase microstructure, experiments are made with several heat treatments, which result in variations in the proportions of the ferrite and martensite phases after cooling.  The resulting differences in microstructure and alloy distribution are investigated with the corresponding changes in physical and mechanical properties caused by variations in heat treatment temperature.  

Highlights of Copper Development for Binder Jet: Porosity Control for Metal Filters, Nanoparticle Enhancements, Isostatic Pressing and Oxidation Control
Patrick Dougherty, ExOne

Binder jet additive manufacturing (AM) has a number of unique advantages compared to other AM techniques including more traditional microstructure , ability to handle a wider range of materials, and faster throughput which leads to much lower cost at production volumes. Pure copper is a high-value material due to its thermal and electrical conductivities, and recently also due to its antiviral properties in light of the COVID-19 virus. While the sintering process inherent to binder jet should make processing easier than with other AM techniques like EBM and DMLS, copper has its own unique challenges in the green state which have so far prevented fully dense binder jetting of copper. In this work, several techniques will be presented for enhancing the density and material properties of binder jet copper, as well as an application in which the unique aspects of copper can be to create a partially sintered, porous metal filter for airborne particulates.  

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September 22

Improvements in Parts Production Enabled by Full Cycle Closed-Loop Hydraulic Control
Heath Jenkins, Gasbarre Products, Inc.

The use of hydraulics in powder compaction has been a staple of the industry for many decades – enabling larger and more complex parts to be added to the scope of PM capabilities. Typical hydraulic press packages have retained mechanical functionality that yields decreased costs and increased simplicity. However, these mechanical features come with a downside by limiting the realization of the full benefits of closed-loop control throughout the compaction cycle. Today, advances in hydraulic control have enabled the full use of closed-loop control throughout the compaction cycle while limiting the cost/complexity impact. Discussion of these advances and the resultant capabilities improvements in terms of accuracy, repeatability, setup time, etc. will form the focus of this presentation.

Development of Dual Phase Steel for LPBF Applications
Kerri Horvay, Hoeganaes Corporation

As additive manufacturing (AM) expands into the structural and automotive parts market more suitable materials need to become available that are tailored to these applications. For this study, a dual phase (DP) steel was chosen because of its combination of high strength and ductility. Its microstructure consists of two phases: islands of hard martensite and a soft ferrite matrix. Currently, DP steel is used in various automotive components that are produced by conventional manufacturing methods. The mechanical properties of laser powder bed fusion (LPBF) test specimens are evaluated as well as heat treated properties to show the range that can be developed with a single alloy system. This provides greater flexibility to the end user by allowing one material to be utilized in a range of applications. Microstructures and porosity are evaluated for both gas and water atomized powders and discussed in relation to build parameters and the mechanical properties.

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October 27

Development of a Free-Sintering-Low-Alloy (FSLA) Steel for the Binder Jet Process
Thomas F. Murphy, FAPMI, Hoeganaes Corporation

Alan Lawley’s research in powder metallurgy covered a wide range of topics from atomizing to mechanical properties. Most noteworthy of his efforts was his work in alloy development. Professor Lawley was a strong believer in the relationship between microstructure, processing and properties as it relates to the performance of the material. As new PM processes (such as additive manufacturing) were developed, Professor Lawley helped design new alloys to take advantage of the relationship between the microstructure and the processing.  This paper builds on his work in dual-phase steels to develop an alloy for Additive Manufacturing; specifically, for the binder jet process.  This work describes a dual phase low alloy steel designed so that it exhibits enhanced diffusion at the sintering temperature leading to high densities. The alloy constituents are formulated, so that upon cooling from the sintering temperature, the transformation products allow the alloy to reach the required mechanical properties.  In addition, the microstructure of the alloy can be varied post-sintering, by heat treatment, to give a wide range of mechanical properties that are suitable for automotive components. This alloy, called FSLA (free-sintering low-alloy), was designed and implemented based on the previous work in conjunction with Professor Lawley and demonstrates his continued impact on the PM community.

Use of Advanced Premix Solutions to Increase Dimensional Consistency
Julie Campbell Tremblay, PMT, Rio Tinto Metal Powders

The use of copper, nickel and molybdenum is widespread in the powder metallurgy industry. While molybdenum is generally prealloyed given its limited impact on compressibility, copper and nickel are very often admixed. The use of fine admixed additives can lead to segregation during packaging and transport and result in part-to-part variations that affect dimensional stability. Various solutions were developed to minimize segregation and improve part-to-part stability. Advanced premix solutions like organic bonding, diffusion bonding and conditioning improve resistance to segregation with the intention of improving part-to-part stability and therefore obtain better dimensional control. Examples will be discussed.

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November 17

Toward the Improvement of Dimensional Control in FeCuC Steels
Elena Bernardo, AMES (Spain)

Sintering in the presence of a liquid phase is still a challenging production method. This work offers a new insight into the dimensional stability of FeCuC steels through the use of Cu in the form of a master alloys (MA). The composition and melting ranges of different MAs have been tailored with optimized Mn, Si and Ni contents in order to promote liquid formation below 1120 ºC. Dimensional behavior of the Cu-based MAs is performed through dilatometry trials and compared to plain Cu when admixed to Fe powders and different C contents between 0.2 and 0.8 wt.%. A comparison of the TRS, UTS and hardness values is also here presented. The particular interest of these new designed MAs lies in a decreased Cu-swelling effect and better tolerances without endangering the mechanical properties. Both the composition of the MA and the amount of C seem to play the main role in the dimensional stability of these steels. 

Effect of Atomization Method and Post-Processing Treatments on the Microstructure and Mechanical Properties of Ti-6Al-4V Alloys Manufactured via Laser Powder Bed Fusion
Leandro Feitosa, Sandvik Machining Solutions AB

Due to the rapid development of AM technologies, special attention is necessary towards reducing processing defects and achieving dense and homogenous materials. In this work, the assessment of Ti-6Al-4V powders fabricated via two of the mostly developed atomization processes, advanced plasma atomization (APA) process, which uses plasma torches to melt and atomize the metal wire feedstock, and electrode induction melting gas atomization (EIGA) is thoroughly carried out. Following production of parts by laser powder bed fusion (LPB-F) and post-processing treatments, which includes stress relief and hot isostatic pressing (HIP) treatments, the resultant mechanical properties at room temperature are reviewed. Microscopy study aimed to detect and discuss the level of microstructural damage and texture and their influence on the performance of pre and post heat-treated parts to obtain optimal parameters to achieve superior properties. A comparison is made between the effect of these stages and traditionally cast and HIPed Ti-6Al-4V alloys.

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December 22

Low Alloy Water-Atomized Steel Powder to Produce Pump Parts Using LPBF
Amin Molavi Kakhki, Rio Tinto Iron and Titanium

Low cost water atomized (WA) powder as feed material for laser powder bed fusion (LPBF) additive manufacturing (AM) can reduce manufacturing cost significantly. To verify the effect of WA powder on AM, a WA low alloy steel powder, was developed specifically for AM and its performance in AM was tested at KSB. Various samples were printed to study the effect of scan speed, layer thickness and hatch distance on surface finish and relative density of the printed samples. Results showed that a combination of printing parameters can result in 99.2% or more relative density. Furthermore, tensile test bars were printed using the optimum printing parameters and then heat treated. Mechanical properties measurements showed that the printed and heat treated samples have equivalent mechanical properties to the standard grade (ASTM A105, DIN 1.0460). The results were used to produce pump parts which are presented in the paper.

Sinter-Hardening of PM and AM Parts
W. Brian James. FAPMI, PMtech

Sinter-hardening has proven to be a process with a number of advantages for the production of cost effective  PM parts with good high mechanical properties. The response of parts to sinter-hardening depends on a number of factors including powder composition, alloying method, sintering parameters, density etc.This presentation will review some of the advantages of sinter-hardening and the influence of the important factors to consider to achieve high quality and consistent parts. The significant contribution of professor Alan Lawley to the field will also be presented.  Processes integrating 3D printing and sinter-hardening will also be discussed.

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