Industry research was one of the first reasons the American Foundry Society was established in 1896—marked by a meeting of foundry delegates to come together for the “presentation and discussion of papers on interesting subjects,” according to an article written by Howard Evans in 1896 encouraging metalcasters to attend. This research and technology transfer remains a foundational aspect of AFS, which funds and monitors various projects through principal research conducted by AFS committees, as well as through cross-industry partnerships.

Currently, the Society is directly supporting 17 active projects in various stages of development, from recently approved to nearly complete. Following is a synopsis of the projects and their status.     

Determining the Effect of Boron in Gray Iron

Principal Investigators: Dr. Laura Bartlett and Dr. Simon Lekakh, Missouri Univ.  of Science & Technology

The project is being monitored by the AFS Cast Iron Division.

The use of boron containing ultra-high strength steel parts has been ever increasing in Europe and North America since 2007. All that steel is now making its way into the scrap supply with unintended quality control consequences to gray iron foundries. The other source of boron in gray iron melts can come from fresh furnace linings. Although boron is known to be a powerful carbide stabilizer, it may also counteract the effects of pearlite stabilizing elements like Cu and Mn, resulting in “soft” pearlitic castings. It is debated what is the “safe” level of boron in gray iron castings or what effect boron has on the microstructure and mechanical properties. Conflicting reports exist because the synergistic effects of boron and pearlite stabilizing elements such as Cu and Sn, and other minor elements, such as N and Ti, have not been considered. 

Ongoing Results and Status: At the lower CE levels, which are most common in industry, there were no harmful effects observed of boron in class 30 or class 40 iron. In contrast, harmful effects of boron were observed in class 20 gray iron or at high CE levels.

This project is in the final reporting phase and results have been published in AFS Transactions under paper # 22-134.

Effect of Ceramic Sand on Cast Iron Mechanical Properties

Principal Investigator: Dr. Scott Giese, University of Northern Iowa

The project is being monitored by the AFS Cast Iron Division. 

Due to the OSHA respirable silica rule under enforcement in the foundry industry today, many foundries are considering changing from silica sand to a ceramic sand/media to alleviate the issue. Many questions are associated with this change, but one that is of primary importance is understanding the effect, if any, in microstructure and the associated mechanical properties that might accompany the use of the ceramic sand/media.

The purpose of this project is to evaluate the effect of ceramic sand/media on the mechanical properties for Class 30 iron and 80-55-06 ductile iron.

Ongoing Results and Status: During the previous quarter, the principal investigator completed gray iron heats for baseline silica and ceramic aggregate and prepared mechanical and metallographic specimens for testing. Plans for the current quarter include complete testing of the mechanical specimens and analysis of the metallographic specimens for graphite morphology and ferrite/pearlite ratio for both the baseline silica and ceramic aggregate.

PVD Coatings to Aid Release for Permanent Mold Castings

Principal Investigator: Dr. Stephen Midson, Colorado School of Mines

The project is being monitored by the Aluminum & Light Metals Committee. 
Aluminum often strongly solders to uncoated steel dies when cast in permanent metal molds. To address this problem, metalcasters use lubricants, which often need to be applied to the die prior to the production of each casting. For high-pressure diecasting, organic lubricants are sprayed onto the die, while for permanent mold casting, ceramic coatings and graphite are used. Although the application is necessary, they cause various problems, such as reducing the quality of the castings and the creation of costly housekeeping issues. In addition, they are expensive and add to the cost of the casting.

The purpose of this project is to develop and utilize a laboratory test that can provide a quantitative measurement of the impact of different PVD coatings on the level of adhesion and force required to extract long cores from aluminum coatings.

Ongoing Results and Status: During the previous quarter, the project testing equipment was fabricated, and core pins have been purchased and machined to meet specific testing dimensions. Plans for the current quarter include initial testing of molten aluminum, coating designed pins for preliminary trials, and obtaining experimental alloy for project trials.

Lost Foam Casting Molds Produced Using Additive Manufacturing

Principal Investigator: Marshall Miller, Tesseract4D

The project is being monitored by the AFS Lost Foam and Additive Divisions.

Tooling constructed of T6061-T6 is considered expensive and requires special programing software and skilled programmers. The purpose of this project is to determine the applicable metal additive manufacturing method and material for medium- and high-volume production considering material durability, material costs, cycle time, equipment costs, and skill level required for production as compared to conventional methods.

Ongoing Results and Status: Castings were poured during the previous quarter and the data was analyzed. Project is currently in the reporting phase, with results expected to be published in AFS Transactions.

Lost Foam Casting Molds Produced Using Polymer FDM & SLA Additive Manufacturing

Principal Investigator: Marshall Miller, Tesseract4D

The project is being monitored by the AFS Lost Foam and Additive Divisions. 

Tooling constructed of T6061-T6 is considered expensive and requires special programing software and skilled programmers. The purpose of this project is to determine the applicable FDM (fused deposition modeling) polymer additive manufacturing and SLA (stereolithographic additive) method and material for low- and medium-volume production considering material durability, material costs, cycle time, equipment costs and skill level required for production as compared to conventional methods.

Dimensional Tolerance Assessment Using 3D-Printed Sand Casting Process

Principal Investigators: Jiten Shah, Product Development; and Tyler Nooyen, Waupaca Foundry, Inc.

The project is being monitored by the AFS Additive Manufacturing Division. 

The use of the 3D-printed sand (3DPS) casting process is growing in the production environment, and the initial feedback is comparable to precise sand casting processes. The adoption of 3DPS is seen mainly with the hybrid approach, where the mold is made with the conventional green sand process and the complex core assembly is redesigned with a three-piece consolidated core using 3DPS. Very little is studied and known in the public domain about the dimensional tolerances achieved with this toolingless, precision sand casting process, especially the potential of achieving much better true position and internal feature tolerances.

The purpose of this project is to identify and provide guidelines for improved dimensional tolerances with 3D printed sand iron castings to design engineers.

Results and Status: Overall results show that 3D-printed molds and cores achieved tighter dimensional tolerances relative to traditional chemically bonded sand molds and cores. The dimensional tolerance improvement was one grade according to ISO 8062.  The three-piece 3D-printed mold and cores performed better dimensionally than conventional six-piece traditional sand molds and cores; however, other factors such as de-sanding, core handling, and coating of the mold post operations may have contributed to these results. Further research is needed to quantify the root cause of the dimensional variability for 3D sand printing since a potential for automating the de-sanding process exists to likely reduce variability further. Results also establish a potential for adjusting the core’s geometry to be closer to a nominal dimension in order to account for any possible shrinkage with the printed molds and cores.

Dynamic Testing and Analytics From Working Green Sand Systems

Principal Investigators: Dr. Sam Ramrattan and Dr. Lee Wells, Western Michigan University

The project is being monitored by the AFS Molding Division. 

Foundry engineers have long known that baseline standard green sand properties tests provide limited information for green sand control. The purpose of this project is to provide a statistical model demonstrating the ability of newly developed “dynamic” green sand control tools to augment standard tests and effectively detect near real-time process shifts affecting casting quality. The tests and strategy will reveal the influence of advanced oxidation bentonite treatment on green sand stability, scrap rate, energy signature, dimensional stability, and labor per shipped unit at a working green sand foundry.

Ongoing Results and Status: During the previous quarter, data was received and analyzed from partnering foundries. Plans for the current quarter are to continue to analyze received data and begin reporting phase.

Iron Casting Life Cycle Analysis

Principal Investigators: Dr. Greg Keoleian and Dr. Daniel Cooper, University of Michigan

The project is being monitored by the AFS Cast Iron Division. 

Limited life cycle inventory data are available to characterize the energy and environmental performance of ductile iron cast products for the automotive industry and other sectors. The data is used by industry and other analysts to inform material selection and design decisions. Consequently, the ductile cast iron industry is missing the opportunity to compare the energy and environmental performance of their components against equivalents.

The purpose of this project was to develop a Life Cycle Analysis (LCA) model to characterize the energy consumption and greenhouse gas emissions for cast ductile iron parts and wrought steel equivalents.

Ongoing Results and Status: With the aid of 11 U.S. ductile iron foundries, representing 26% of annual U.S. ductile cast iron production excluding ductile iron pipe, thorough and updated life cycle inventory data for ductile iron was successfully generated. An analysis of the data revealed that the environmental impact of ductile iron could be significantly reduced by improving casting yield via mold design, increasing recycled content, decarbonizing electricity supply, and improving melting furnace efficiency.

The inventory data was also compiled into an easy-to-use Excel-based model that allows users to vary a multitude of parameters to best represent their foundry’s process. Afterwards, it calculates the total life cycle energy consumption and greenhouse gas emissions for a hypothetical automobile component and compare its total life cycle impact to generic aluminum and steel equivalents. Using this model, real-world casting conversion case studies illustrated that ductile iron parts with a casting yield above 50% likely have lower life cycle impacts than steel or aluminum equivalents.

The final report is undergoing peer review by the steering committee. It will be presented at the 2023 Metalcasting Congress, and the results will be published in AFS Transactions.

Disposable, Wireless Sensor Systems for Integration Within Molds and Cores

Principal Investigators: Dr. Eric MacDonald, University of Texas at El Paso; and Jerry Thiel, University of Northern Iowa

The project is being monitored by the AFS Additive Manufacturing Division. 

Relative to other forms of casting, sand casting provides a wide range of sizes, complexity, and types of metal alloys, and combined with additive manufacturing (AM), complex, reverse engineered geometries are now possible. One potential benefit for 3D printing-enabled casting is the design freedom necessary to introduce cavities for the housing of disposable wireless sensors in remote and traditionally inaccessible mold and core locations. Process variation (during molding fabrication and casting) has been the source of defects and delays in product delivery. Monitoring variations in the molding and casting process can support the prediction of product quality and provide valuable feedback to improve the process. The purpose of this project is to demonstrate the potential of wireless sensing for improving casting process quality and yield, identify failed castings, and validate casting simulations.

Ongoing Results and Status: This project demonstrated that sensors can be successfully embedded into 3D printed molds during printer interruption without disrupting the curing process. The sensors were able to relay data on temperature, humidity, and VOCs from three different environments (heated, refrigerated, and ambient). Results show that a combined metric of temperature and humidity provide a higher correlation between the calculated metric and the final mold flexure strength between the environments. Further research is needed to establish guidelines for monitoring temperature and humidity with mold storage to calculate minimum curing time for these specific conditions.

This report is currently undergoing peer review and is scheduled for presentation and publication at the next AFS Metalcasting Congress.

Low CRI, High CSR Coke Cupola Trials

Principal Investigators: Steve Hay, Hay Melting Solutions; and Bruce Blatzer

The project is being monitored by the AFS Melting Division. 

Higher CSR (coke strength after reactivity) coke has higher hot strength—implying that coke with those properties will travel farther down the cupola shaft, which can enhance metal temperature and carbon pick up. Furthermore, the stronger coke in the presence of heat and CO2 will better support the burden in the cupola. In addition, lower ash fusion temperatures of blast furnace coke imply a higher carbon pickup from such coke. Research is needed to determine if coke for cupola melting with a lower CRI (coke reactivity) and higher CSR can enhance performance and cost for cupola melting. The purpose of this project is to reduce coke per ton of iron melted with no change in melted iron properties and no detrimental changes in the melting operation.

Ongoing Results and Discussion: During the previous quarter, principal investigators were able to secure coke supply for testing, completed baseline testing, and finished 70/30, 50/50, and 100% replacement trials. Plans for the current quarter include analyzing results from previous quarter testing as well as performing a second set of testing of coke replacement for 100% blast furnace coke.

Quantifying Aluminum Casting Quality Through H Gas – (Phase 2)

Principal Investigator: Daniel Hoefert, Eck Industries, Inc.

The project is being monitored by the AFS Aluminum and Light Metals Division. 

Foundries producing gravity-pour aluminum castings have several gating concepts to choose from. Phase 1 (Quantifying Casting Quality Through Filling Conditions) compared three systems that provided different filling conditions ranging from tranquil bottom filling to semi-tranquil side filling to turbulent top filling. The results of the top- and side-filling gating systems repeatedly exhibited less shrinkage porosity and improved the general tensile properties over the bottom-filling system. While bottom filling did avoid turbulence and oxide films associated with buoyant bubbles and non-buoyant flow tubes, tranquil filling did not reduce the overall shrinkage porosity in the castings and did not improve tensile properties. However, other observations suggested that a relationship may exist between hydrogen gas levels in melts and subsequent interdendritic porosity. It also suggested hydrogen gas levels may reduce bubble formations.

The purpose of this project is to gain additional understanding regarding the solidification and filling dynamics associated with common defects such as porosity (micro & macro), bubbles, flow tubes, and hydrogen gas. 

Foundry Emissions Benchmarking Database

Principal Investigator: Craig Schmeisser, Mad River Strategies, LLC.

The project is being monitored by the AFS EHS Division.

The foundry industry has limited publicly-available information for comparative analysis of emissions associated with iron and steel foundries. The purpose of this project is to compile collected foundry emissions information and process information, as available, into a singular searchable database.

Ongoing Results and Status: During the previous quarter, reviews were completed of 178 of the 250 emissions tests received from participating foundries. Plans for the next quarter include addressing any issues the database has, finalizing the database, and preparing documentation for database instructions and limitations.

Digital Active Clay Measurement in Green Sand

Principal Investigators: Dr. James Springstead and Dr. Sam Ramrattan, Western Michigan University

The project is being monitored by the AFS Molding Division. 

Casting defects are consistently attributed to variations in green sand systems and limitations of the clay control methods for green sand. A better clay measurement technique is necessary to improve green sand systems. The purpose of this project is to create a novel, optimized method for the measurement of active clay in green sands that will be tested in multiple working foundries and is ready to be implemented as a standardized method.

This project was approved for funding last quarter and is just getting started.   CS

View the full article in the November/December 2022 digital edition.