Abbott Furnace Company’s team of furnace experts has written technical papers on metal brazing, sintering, continuous belt furnace techniques and operation, and other topics related to powder metallurgy and the powder metal industry.
To request the full technical paper, please complete the form on this page; a member of the Abbott Team will send you the requested paper.
Effect of Particle Size Distribution on the Physical Properties of Binder Jetted 17-4PH Stainless Steel as a Function of Print Axis
NANNA L. BUSH
Pennsylvania State University- Penn State Dubois
NATHAN HIGGINS
FreeForm Technologies
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
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 distribution on the physical properties of the components and directions in which they are printed remains an area of investigation.
In this work, 17-4PH Stainless Steel powder of varying particle size distributions were used to print tensile bars with their axes oriented in the x, y, and z directions. Particle size distributions, physical testing, densities, and electron microscopy were completed to better understand the printing process.
optimization of the de-bind and sintering cycles of binder jetted 17-4 components
X-Ray Computed Tomographic Study of Density Gradients within Binder Jetting and the Influence of Printer Design and Printing Parameters on Ballistic Ejection
JACOB P. FELDBAUER
Pennsylvania State University- Penn State Dubois
NATHAN HIGGINS
FreeForm Technologies
DUSTIN B. GILMER, PH.D.
University of Tennessee
PEEYUSH NANDWANA, PH.D.
Oak Ridge National Laboratory
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
Binder Jet Additive Manufacturing (BJAM) is a versatile powder bed technique that uses a binder deposited using ink jetting to form complex components. Ballistic ejection occurs during the application of the binder to the powder bed layer during the binder jet printing process. The momentum of the binder droplet impacting the powder bed results in a disturbance of the powder layer. This disturbance of the particles in each layer causes inconsistencies in the density and bonding during the sintering step of the process, resulting in a localized disruption in the uniformity of the material properties.
The printer design and the parameters used to print influence the size and momentum of the binder droplet. The influence of these parameters will be reviewed to minimize ballistic ejection during printing and improve the quality and uniformity of the printed components. We use X-Ray computed tomography to study the differences in 17-4 steel parts as printed in the green state. This information will be critical for understanding the evolution of inhomogeneity in sintered components and their role in material properties.
JEREMIAH KAHLE, GLENN RISHEL
Pennsylvania State University- Penn State Dubois
NATHAN HIGGINS
FreeForm Technologies
DUSTIN B. GILMER, PH.D.
University of Tennessee
PEEYUSH NANDWANA, PH.D.
Oak Ridge National Laboratory
BRIAN SMITH, STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
Binder jetting is quickly becoming recognized as one of the most desirable methods for producing high-volume additively manufactured components and developing new printed material. Although this technique has been available for two decades, the optimal time to de-bind and sinter components remains an area that is not well understood. Better understanding must be developed of optimal de-binding for the full advantage of this method to produce high-volume components to be realized.
Through time stop studies, components of 17-4 material of varying thickness will be analyzed for lubricant removal and degree of sinter. By understanding the de-binding steps as a function of time, the optimal time for de-binding and sintering as a function of the components thickness can be determined. This information can then be used to optimize the binder jet process, advance production rates, reduce cost, and improve product quality.
Application of Additive Manufacturing to Deliver Incremental Production of Conventional Powder Metal Components without Compaction Tooling
HOPE SPUCK
Pennsylvania State University- Penn State Dubois
MATTHEW J. HOLCOMB, PH.D.
Grid Logic
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
The conventional powder metal industry has always struggled with distributing the cost of compaction tooling and the need to maintain a competitive price of the final product. The result has historically limited the order size to high volume orders.
Although additive manufacturing of metal components has become more accepted. Additive techniques, such as laser powder bed fusion and traditional binder jet printing, have been focused on the production of small spherical particle sizes and materials that are less susceptible to oxidation, like 316 and 17-4. This has prevented the application of AM as a low volume process to complement the conventional press and sinter production of traditional powder metal chemistries and parts.
Recently, a new approach to additive manufacturing has provided a technique for the printing of conventional powder metal chemistries and particle size distributions. Using an FC-0208 powder, the physical properties and processing requirements will be reviewed to assess the application of this printing technique to expand the market for conventional press and sintering manufacturing.
A REVIEW OF LUBRICANT REMOVAL SYSTEMS AND THE LATEST TECHNOLOGY
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
Whether a component is produced through binder-jet additive manufacturing, metal injection molding, or conventional press and sintering, lubricant removal continues to be one of the most common issues in sintering. As with all technologies, new forming techniques have resulted in the development of new lubricants. The result is the need for more understanding and process development in lubricant removal. A review of the “old rules of thumb,” current solutions, and where the lubricant removal technology is headed will help to lay out a roadmap for dealing with this issue today and into the future.
FURNACE OPTIMIZATION: MEETING THE NEED TO REDUCE COSTS
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
Reducing operating costs is a major focus of part producers, and the continuous brazing furnace is one area where there are opportunities to reduce cost. Typically, production requirements and the chemistry of the brazing process dictate the operational characteristics and costs during normal production. However, significant savings can be achieved by optimizing the furnace parameters when the furnace is not producing parts. This paper calculates the impact of various approaches and describes when each approach is most appropriate.
STAINLESS STEEL BRAZING
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
Atmosphere integrity and control are key to successfully brazing stainless steel components. Due to the very high affinity that stainless has for Oxygen at high temperatures, the presence of Oxygen or moisture in the furnace will oxidize the surfaces to be brazed and result in a defective braze. Vacuum furnaces and Humpback furnaces have been the traditional systems used to braze stainless steel because of their ability to ensure an Oxygen-free atmosphere with a very low dew point. However, both furnace technologies bring issues that result in higher operational costs, increased maintenance costs, and other process-related costs that can be avoided by using straight-through continuous belt furnace technology.
Recent advances in furnace design and atmosphere control have made it possible for stainless steel to be brazed in straight through continuous belt furnaces. This technological step permits continuous processing at lower operational costs, less maintenance, and higher yields than realized with traditional brazing systems. Oxygen levels of less than ten ppm and dew points as low as –85ºF are common in a state-of-the-art straight-through continuous belt brazing furnace. Adopting this technology by some of the leading producers of brazed components is allowing the industry to become more competitive.
COMPARING FURNACES USING A DETAILED OPERATING COST MODEL
JOHN R. HADDOCK
Abbott Furnace Company
A decision on what furnace to buy is usually based on several factors, but the price is typically the most dominant. However, an examination of the total operating costs for a furnace shows that the initial purchase price is, in fact, one of the least important elements. A detailed operating cost model has been developed into which appropriate furnace operating cost assumptions can be inserted. The paper highlights experience with the model and provides examples and insights into the most critical factors affecting the real costs of purchasing and operating a furnace.
STEAM TREATING: ENHANCING THE SURFACE PROPERTIES OF METAL COMPONENTS
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
Steam treating is the controlled oxidation of metals to produce a thin layer of oxide on the surface of a component. This process can be used to provide a component with increased corrosion resistance, better wear resistance, increased surface hardness, an attractive surface finish, and, in the case of porous materials such as powder metal, seal the part porosity and increase the density.
ADVANCES IN POWDER METAL SINTERING TECHNOLOGY
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
The traditional powder metal process often referred to as “press and sinter,” is constantly driven to change by an industry goal of entering new markets through substitution and developing innovative products for new applications. Although much advancement has been made in the area of compaction, new materials and sintering technology continue to broaden the applications and improve the overall quality and competitiveness of powder metal components.
PASTE OR PREFORMS; THE BRAZER’S QUESTION
KEN ALLEN
Bellman-Melcor, Inc.
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
There is a spirited debate among manufacturers involved in copper brazing in controlled atmosphere furnaces. Which form of filler metal is better to use; paste or preforms? This paper addresses the relative advantages and limitations of paste and performs.
Furnace brazing differs from hand brazing and many types of open-air brazing in that the filler metal must be pre-placed on the part. Furnace brazing is done in a controlled atmosphere brazing furnace. This furnace type uses a stainless steel mesh belt that carries the product through a heated muffle containing the furnace atmosphere. The furnace atmosphere is typically neutral to reducing in nature. The atmosphere in the furnace usually contains significant amounts of Hydrogen and Nitrogen that allow high-temperature brazing to be accomplished without oxidation or minimal to no flux.
A copper braze paste consists of copper powder blended into a neutral suspending agent. The product is a semi-solid consistency, somewhat similar to toothpaste.
A preform is a solid piece of copper (or any braze alloy) pre-engineered to provide an exact volume and shape to accommodate a particular part or application. Preforms made from wire include rings, ring segments, wire segments, and four-slide fabrications of limitless geometries. Preforms manufactured from flat stock include washers, shims, and a wide variety of stamped configurations.
GASSING UP TO GET THE RIGHT ATMOSPHERE
AKIN MALAS
BOC Gases, A Linde Group Company
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
In a continuous sintering furnace, one of the most important variables in achieving a successful process is control of the atmosphere. From the initial installation and start-up of the furnace to its maintenance throughout its life cycle, the process atmosphere demands an attentive eye in order to produce powder metal parts that are well sintered, meet the specification and have no defects. Starting with the source of the atmosphere gases and working through the components of the furnace, the atmosphere integrity must be verified before any parts can be processed. As the furnace ages, issues will arise that affect the integrity of the atmosphere and, ultimately, the quality of the product. Continual preventative maintenance and troubleshooting techniques will maintain the integrity of the process atmosphere. An understanding of the causes, diagnostic techniques and solutions to the many atmosphere problems that may compromise the atmosphere integrity, will enable a furnace operator to run an efficient and profitable process.
This paper focuses on the important parameters of the furnace and its atmosphere that affect the integrity of the sintering process, and gives guidance on how to approach and solve the problems they may cause.
A REVIEW OF THE FUNDAMENTALS OF STAINLESS STEEL BRAZING IN CONTINUOUS STYLE, CONTROLLED ATMOSPHERE BRAZING FURNACES
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
The use of continuous style, controlled atmosphere brazing furnaces to braze stainless steel is becoming more common as the aerospace and automotive producers increase the use of stainless steel components on existing designs and explore new designs. Although much of the metallurgy and thermodynamics of Iron, Chrome, Nickel, and their compounds are well understood, a review of the application of the fundamentals to the current practices and equipment technology can help with improved product quality, expanded applications, and the optimization of costs for a net improvement in competitiveness.
TROUBLESHOOTING CONTINUOUS CONTROLLED ATMOSPHERE BRAZING FURNACES
STEPHEN L. FELDBAUER, PH.D.
Abbott Furnace Company
Controlled atmosphere brazing furnaces of the continuous type are some of the most common furnaces used in brazing. The goal of a brazing furnace is to provide a time, temperature, and atmosphere relationship that is accurate, repeatable, and economical in meeting the requirements of the brazing process. Although the general operation of this equipment is fairly straightforward, the troubleshooting that can often accompany a brazing issue can be frustrating.
This paper provides a step-by-step methodical approach for troubleshooting the furnace and identifies what steps need to be taken to address any problems.
