Die Casting Congress & Tabletop

October 20-22, 2020
Virtual Event

Tuesday October 20

Printable Schedule

Modeling and Simulating the Die Casting Process

9:00 am – 10:30 am CDT

Session Chair: Rob McInerney

 

NADCA Research & DevelopmentWater Analog Experiments and Simulation of Vacuum High-Pressure Die Casting of Aluminum

Nicole Trometer, Xuejun Huang, Emre Cinkilic, Alan Luo (The Ohio State University); Larry Godlewski, Eben Prabhu (Ford Motor Company)

High-pressure die casting (HPDC) of aluminum alloys is widely used to make lightweight structural and powertrain components. However, a common defect associated with these parts is air entrapment, which has a negative effect on the performance of these components. The application of vacuum in HPDC process can reduce the air entrapment and increase the soundness of the parts. Water analog experiments were conducted, using a servo motor and a linear actuator to replicate the slow and fast shots in HPDC cavity fill. A vacuum chamber was added to the setup to evaluate the efficiency of vacuum and obtain the optimal process conditions for vacuum HPDC. The experiments showed the air bubbles escaping from the fluid and the fluid being sucked up by negative pressure during injection. Cavity fill simulations were performed using MAGMASOFT® and compared with water analog experimental results. These results suggest that using a vacuum in HPDC process can reduce entrapped air in cast parts.

 

Intensification Feeding Analysis of High Pressure Die Casting Process

Siming Ma, Chuanghua “Joshua” Huang, Yeou-Li Chu, Patrick Cheng (Ryobi Die Casting)

A simplified modeling approach, Intensification Feeding Ratio Modeling (IFRM), was developed to quantitatively analyze the intensification feeding ratio in high pressure die casting process. The intensification feeding ratio is defined as the intensification feeding volume percentage that is normalized by the corresponding concerned local casting volume. A typical geometric model was employed to analyze the intensification feeding ratio into a cylindrical boss through a thin plate, which was associated with geometry parameters such as the boss radius, height, the plate length and thickness, as well as with die casting process parameters such as initial solid fraction, initial die temperature and intensification pressure. Both thermal shrinkage feeding (due to casting solidification) and deformation feeding (due to deformation of molten metal under intensification pressure) were analyzed in the IFRM. The pressure and velocity fields along the feeding path were calculated based on Darcy’s law combined with Blake-Kozeny model. With the IFRM approach, extensive numerical investigations were carried out. The numerical results match the process development experiences on the foundry floor. Notably, the results showed that among different geometry parameters the casting wall thickness is the most effective parameter that influence the intensification feeding ratio to a heavy boss. The numerical analysis also revealed that the intensification feeding ratio is very responsive to the increment of intensification pressure when the pressure is below 10 MPa, but much less responsive when the pressure is over 30 MPa. This finding is very valuable and intuitive for overall die casting process design.

 

American Metalcasting ConsortiumComputational Modeling and Visualization of Industrial Furnaces

Tyamo Okosun, Mosquera Salazar, John Estrada, Kyle Toth, John “Jack” Moreland, Chenn Zhou (Purdue
University Northwest)

Furnace operations are among the most capital and energy intensive parts of multiple industries. Economic and environmental pressures from energy consumption constantly drive research to improve the furnace operation efficiency and energy efficiency. This paper presents research conducted for various types of furnaces outside of the die casting industry utilizing computational fluid dynamics (CFD) modeling and visualization to provide useful tools and recommendations on heating and melting practices. In addition to informing efficient operations, the same computational modelling and visualization tools have also been used for training. Furnace simulations to be presented will include the blast furnace (used in ironmaking), the reheat furnace (used in steelmaking), and various types of boilers. The paper will also present initial work on a virtual training tool being developed for furnace operations within the die casting industry.

 

Optimizing Die Casting Quality

10:45 am – 12:15 pm CDT
Session Chair: David Blondheim

 

Brancaleon American Metalcasting ConsortiumSpecifications and Standards Development for Enhanced Casting Performance thru Development of Alloy Properties versus Casting Section Thickness

Paul Brancaleon (North American Die Casting Association)

The chemistry and section thickness of a die casting can cause large variations in the mechanical properties of die cast components. There is a strong need to understand these variations in properties in order to maximize the properties and minimize the weight to develop optimum casting designs. Therefore, the objective of this work is to use production die castings of specific aluminum alloys and remove as cast specimens of various thicknesses. In this paper we report on the extensive measurements of mechanical properties of the various cross section thicknesses of each of the alloys to meet these goals.

 

Using Sphericity Calculations to Identify the Source of Porosity in Aluminum Castings

Dani Barna, Branden Kappes, Stephen Midson, Doug Nychka (Colorado School of Mines)

Porosity in aluminum die castings can come from a number of origins, including entrapped gasses, dissolved hydrogen, and shrinkage porosity. At present it is challenging for die casting engineers to determine the origin of porosity in die castings, and so difficult to identify the process changes necessary to reduce the porosity. CT scanning is a relatively new analytical technique that allows engineers to view the size and spatial distribution of porosity within die castings, but at present it provides little-to-no information on the origin of the pores. This project is an initial attempt to use sphericity calculations to determine the origin of pores, based on the fact that gas pores should be more spherical in nature than shrinkage pores. This project measured pores in an aluminum casting using CT scanning, and utilizing a discrete mathematical approach counted the number of voxels within each pore that are surface voxels and volume voxels, to gain an estimate of the sphericity value of each pore in the casting. Charts will be displayed that show the spatial distribution and size of each of the pores, which have been color coded to demonstrate the degree of sphericity. Based on this preliminary work, it appears that gas pores have sphericity values between 0.4 and 0.75, while shrinkage pores have smaller sphericity values closer to 0.2.


Predicting Quality of Cylinder Block Castings via Supervised Learning Method

Adam Kopper (Mercury Marine); Diran Apelian (ACRC, University of California – Irvine)

The process input data which materials processing operations can collect for each unit of production is extensive.  Large datasets have long been difficult to work with as computing power to execute analysis in a timely fashion was unavailable.  When troubleshooting by a small dataset, such as the last few hours of production, observations made on the measured parameters can be misleading.  Further, the great velocity at which the data is generated makes near real-time decision making unwieldy without a new set of tools with which to do the work.  Machine learning is opening doors to high-dimensional data analysis in material processing.  In this work, high-pressure die-casting (HPDC) is explored as an exemplar of high-volume materials processing.  HPDC process summary data from a full year of production data covering over 950,000 machine cycles is analyzed via supervised machine learning methods to successfully model the prediction of good parts and process scrap as determined by the die casting machine.  Additionally, the prediction of ultimate tensile strength via a classification method of extracted tensile bars is performed and the important features identified are discussed.  Supervised learning is found to be a useful tool for materials processing applications.

 

Metal Melting
1:15 pm – 2:45 pm CDT

Session Chair: Charles Monroe

 

NADCA Research & DevelopmentA Systematic Approach to the Evaluation of the Performance of Refractory Materials in Contact with Molten Aluminum

Jianyue Zhang, Xiaoming Wang (Purdue University); Emre Cinkilic, Alan Luo (The Ohio State University); Bob Cullen (Westmoreland Advanced Materials); Yeou-Li Chu, Patrick Cheng (Ryobi Die Casting)

Molten aluminum metal processing is critical to the production of high-quality die cast parts. These aluminum melting and holding processes also have a significant impact on the production costs, and ultimately on the profitability, of a die casting company. Refractory materials are used in direct contact with molten aluminum in various processing equipment including melting furnaces; holding furnaces; transfer ladles; and transfer launders and troughs.  There are several factors affecting the performance of refractories in contact with molten aluminum including: reactivity with the molten aluminum; thermal characteristics; and physical properties to name a few. Unfortunately, there are a very limited number of in-depth, systematic studies evaluating refractory performance as it relates to the type of aluminum alloy used in molten aluminum metal processes.  An even greater concern is that many die casters consider refractories as a “necessary evil,” and put very little thought into the selection of refractory materials. And often these decisions are based on the die caster’s “experience,” or a “vendor’s suggestion.” This results in the relinquishing of control of a very critical aspect of molten aluminum processing, which can have a significant effect on the quality and profitability of a die casting company.  This type of decision making also precludes the evaluation of new and innovative types of refractory materials.  Therefore, a systematic evaluation of the performance of refractory materials in contact with molten aluminum which encompasses theoretical study, in conjunction with laboratory testing and commercial production validation, to optimize refractory selection is truly needed by the die casting industry.

 

REMADE InstituteThermodynamic Modeling and Experimental Investigation of Refractory Materials Used in Aluminum Die Casting

Emre Cinkilic, Michael Moodispaw, Alan Luo (The Ohio State University); Yeou-Li Chu (Ryobi Die Casting); Paul Brancaleon (North American Die Casting Association)

Best PaperAl2O3-SiO2 based refractory materials have been traditionally used in aluminum melting and holding furnaces. However, the formation of corundum (hard, crystalline type of Al2O3) has been an issue for these refractories, causing increased downtime due to cleaning operations and reduced energy efficiency in melt processing operations due to the degradation of insulating properties of the refractories. In this study, the thermodynamic stability of common refractory oxides (Al2O3, SiO2, CaO, P2O5, ZrO2, and TiO2) and antiwetting components was investigated using CALPHAD (CALculation of PHAse Diagrams) modeling tools, in relation to major alloying/impurity elements (Al, Si, Mg, Cu, Fe, Mn, Zn etc.) in aluminum die casting alloys. Based on the thermodynamic simulations, three different refractory materials were selected for melt immersion experiments in atmospheric conditions to validate the simulation results and evaluate the corrosion properties of the refractories of different compositions. The study suggests that replacing SiO2 with moderate contents of CaO and using combination of Ba-based non-wetting agents as binder can improve the corrosion resistance of refractories significantly.

 

American Metalcasting ConsortiumThe Role of Advance Ceramics for the Development of Melting System for Titanium Alloys

Danny Portillo (University of Alabama at Birmingham)

On-demand melting systems are capable of suppling the amount of molten metal as needed by the downstream process. Titanium alloys are melted for commercial production in an inert atmosphere and using a cold crucible technique, typically made of copper, due to its reactivity. In comparison with other non-reactive alloys where a ceramic crucible can be used, melting in a cold crucible is slower and energy inefficient. These factors are important because they have an effect on the rate of molten metal production. Replacing the cold crucible with a ceramic crucible emerges as an option, but the chemical reactivity needs to be investigated. Classics ceramics such as alumina-silicate and more advanced ceramics such as zirconia and calcium-zirconate were tested using an induction equipment to rapid melt Ti-6Al-4V alloy in a vacuum atmosphere. The ceramic-alloy interface is analyzed to validate the materials’ ability to thermo-chemically withstand the titanium alloy in molten state. Findings indicate that advance ceramics have the potential to be used as a crucible for melting titanium alloys.




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