Improving competitiveness through technological development: six AFS development projects aimed at improving quality, reducing cost and shortening lead-times are profiled.

In this era of multi-national manufacturing organizations, new business models are molded based on technological capability to meet market needs. As technology continues to expand, the metalcasting industry has aggressively pursued innovations to meet constantly evolving requirements for improved quality, reduced cost and shorter lead-times.

Two strategic challenges to maintain the industry's vitality and economic well being are complimentary. One challenge is outward focused--to improve design methods for new markets while maintaining current markets. The other challenge focuses inward--to improve operating efficiencies through fundamental understanding for accurate simulation and real-time control.

Six AFS development projects addressing both challenges are highlighted below. The research discussed is funded by AFS, the Defense Logistics Agency (DLA) through the American Metalcasting Consortium (AMC), the U.S. Dept. of Energy (DOE) Office of Industrial Technology through the Cast Metals Coalition (CMC), the United States Council for Automotive Research (USCAR), and the NASA Marshall Space Flight Center through the Auburn Univ. Solidification Design and Control Consortium (SDCC).

Project 1: Optimized Sand Core Blowing

Background: A software process design tool will help guide tooling and process decisions to make sound sand cores, reduce scrap and potentially lessen resin requirements and tooling wear, The modeling of air-blown sand cores was not technically feasible because of several numerical difficulties, including the need for a fully three-dimensional, transient solution.

With the large density difference between sand and air, it is necessary to model these "fields" separately. Closure models are required for interphase drag and wall interactions. Finally, dense-particle-regime techniques need to be developed as the cavity fills with sand.

Goal: A multiphase particle-in-cell technique was developed into a software tool useful for engineering sand core tooling design and for optimization of the core-blowing process.

Approach: The NASA Marshall Space Flight Center supported the SDCC at Auburn Univ. with funding to Arena Flow. General Motors conducted critical validation of the model predictions with additional parametric coefficients determined at Auburn Univ.

Results: Ashland Specialty Chemical Co., announced at CastExpo '02 its intention to distribute the software developed by Arena Flow to aid foundry engineers with the design of core-blowing molds and optimization of the overall process (Fig. 1). This will improve core quality, minimize waste, cut design lead times, optimize the core-blowing machine parameters, reduce tool wear, reduce resin requirements and enable fully integrated modeling of sand core castings.

Project 2: Tooling Advisor

Background: The ability to produce tooling from material removal and additive processes has given rise to new methods to produce tooling from digital geometry representations. A tooling designer must make decisions involving geometric reasoning coupled with other requirements based on production needs, cost constraints and individual shop capabilities.

Goal: The AFS Tooling Methods and Materials Div. recognized an opportunity to use information technology to guide decisions, since there are an unprecedented number of tooling choices currently available. Furthermore, the widespread use of digital representations of geometry permits the development of a computer consumable knowledge base. A buyer can make decisions that are more informed by quickly exploring different tooling production options and their likely outcomes with a computer simulation.

Approach: The project is concurrently developing a windows-based user interface, multiple databases (rapid tooling capability and conventional machining capability) and a core-reasoning engine as illustrated in Fig. 2.

Results: This limited release web-accessible tool will soon be available to commercial engineering and procurement personnel. Purdue Univ. will present more information during the Tooling Methods and Materials Div. panel at the AFS 107th Casting Congress in Milwaukee April 26-29.

Project 3: Information Technology

Background: AFS received a grant from the DOE to better assess the long-term implications of information technology on the metalcasting industry. The objective of this study is to identify more efficient systems utilizing knowledge management, to increase integration within the supply chain, to capture tacit and explicit knowledge, and to improve metal casting quality and consistency.

Four topics were identified:

* casting standard technical exchange protocol;

* information technology capitalization;

* web-based solidification failure analysis diagnostic tools;

* commercialization of academic process modeling knowledge.

Goal: During the past decade, academic knowledge in many government-sponsored research projects has been increasingly captured as physics-based models. However, the development of this software into a useful engineering tool for designers is beyond the primary mission of a university. Therefore, the return of this government investment has gone unrealized in the commercial sector.

Approach: Champions were identified for each topic and commissioned to discuss the current status and recommendations to address the full potential of implementing these technologies.

Results: The highest priority identified is to establish a Metalcasting Software Advisory Board composed of three distinct groups, each with a specific function. The core perspective panel will provide the board with concepts and approaches that have worked in other venues. The industry stakeholders will be equally divided among users and software providers. Finally, government delegates will identify opportunities from emerging technology and leveraging resources.

Project 4: Iron Fatigue Design Properties

Background: Design engineers generally rely on axial fatigue data to optimize component geometry and mass since failures occur at more highly strained regions found around notches, fillets and other natural geometric discontinuities. Older cast iron fatigue data is not used in modern fatigue life determination analysis because samples are not axially loaded (rotating beam testing) and infinite life is determined.

Goal: Under the guidance of the AFS Gray and Ductile Cast Iron Research Committees, the ASTM grades of austempered ductile iron, ductile iron, compacted graphite iron and gray iron have been selected. These grades have been divided into subcategories based on other important characteristics such as cast section size and heat treatment.

Approach: Support from the DOE Office of Industrial Technology of the current phase allows twenty-two materials to be tested for axial fatigue data. The Cast Iron Research Committees also are seeking strain-life data for austempered ductile iron, ductile iron, compacted graphite iron and gray iron.

Results: Without appropriate strainlife fatigue data (Table 1), cast iron is virtually "invisible" to designers. A robust database will provide manufacturers the confidence needed to explore cast iron in conceptual design trade-off studies.

Project 5: Permanent Mold Casting Aluminum 535 Alloy

Background: Aluminum-magnesium alloy 535 is susceptible to hot tearing and poor fluidity when poured in metal molds. However, it exhibits good strength and elongation coupled with good corrosion resistance after cooling. It also does not need to be reheated for solution heat treating prior to aging, which is required by other aluminum alloys.

Goal: The alloy's good as-cast mechanical properties and excellent corrosion resistance can expand automotive, marine and military applications, if the hot tearing and poor fluidity obstacles can be overcome.

Approach: Casting fluidity was studied by tilt pouring plate and direct pouring spiral castings in specially designed permanent molds. The hot tearing resistance was studied by pouring ring, cup and constrained rod castings in specially designed permanent molds.

Results: Aluminum-magnesium alloy 535 can be successfully cast in a preheated gravity permanent mold at approximately 392F (200C) without hot tearing and have adequate fluidity when poured with a metal superheat of 90-180F (SO-100C). The hot tearing mold designs show different degrees of sensitivity, but all are effective in showing the susceptibility of alloy 535 to hot tearing (Fig. 3).

Additions of grain refiners improved the hot tearing resistance. Grain sizes ranging from 250-470[micro]m are achieved by individually adding 0.05% titanium, 0.085% boron, 0.2% zirconium, 0.5% scandium or 0.1% strontium. A combination of 0.05% titanium and 0.010% boron is also an effective grain refinement addition.

Project 6: Quality Improvement System

Background: Some foundries use an internal defect code system to characterize casting failure analysis. This is a detriment to clear, concise and efficient communication among metalcasters with there customers. A need exists to maintain a common structure to organize photographs, literature, case histories and process parameter data relating to all potential unwanted casting solidification features (defects). This knowledge will form a useful database to seek different solutions to eliminate a particular undesirable solidification artifact.

Goal: The casting defects classifications were updated into various specific standardized codes to include new processes such as lost foam casting. These standardized codes are used on a web-based site to promote the understanding of the basis for solidification artifact formation to improve quality.

Approach: The AFS Research Board funded this project to motivate foundries to use a standard classification system to describe casting defects for more effective failure analysis and to provide an internal tool for continuous training of personnel.

Results: The website is currently available at www.4ebasic.com. The site also provides services to foundries interested in developing solidification defect databases for analysis and training.

For More In formation

A comprehensive list of on-going developmental projects can be found at wwww.afsinc.org/research/index.html.

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Table 1

Strain-Life Data Necessary for Design Analysis

Material Characterization
 Material Grade Designation
 Microstructure
 * Graphite Characterization
   (ASTM A-247)
 * Matrix Characterization
   Alloy Chemistry
   Processing History

Monotonic Properties
 Testing Procedure & Methods
 * Hardness
 * Ultimate Tensile Strength
 * 0.2% Offset Yield Strength
 * % Elongation
 * % RA
 * True Yield Strength
 * True Fracture Strength
 * True Fracture Ductility
 * Strain Hardening Exponent
 * Strength Coefficient
 * Modulus of Elasticity

Cyclic Properties
 Testing Procedures & Methods
 Cyclic Stress Strain Behavior
 * Cyclic Strain Hardening Exponent
 * Cyclic Strength Coefficient
 * Cyclic Yield Strength
 Fatigue Life
 * Fatigue Ductility Coefficient
 * Fatigue Ductility Exponent
 * Fatigue Strength Coefficient
 * Fatigue Strength Exponent