How New EZAC® and HF Alloys Are Overcoming Traditional Temperature and Weight Limitations in Die Casting

This technical brief is based on the academic paper "Recent Zinc Die Casting Developments" by R. Winter and F. E. Goodwin, Sc.D., published by the North American Die Casting Association (2013). It is summarized and analyzed for HPDC professionals by the experts at CASTMAN.

Keywords

• Primary Keyword: Zinc Die Casting Developments
• Secondary Keywords: EZAC alloy, HF alloy (High Fluidity Zinc), Creep resistance, Thin-walled die casting, Hot chamber die casting, NADCA

Executive Summary

• The Challenge: Traditional zinc die casting alloys face significant limitations in high-temperature applications due to poor creep resistance and are often at a disadvantage to aluminum or magnesium in weight-sensitive applications due to zinc's higher density.
• The Method: The research highlights the development and commercialization of two new zinc alloys: EZAC® for high-temperature creep resistance and the HF (High Fluidity) alloy for casting ultra-thin sections.
• The Key Breakthrough: The EZAC alloy dramatically improves service temperature capabilities and mechanical strength, while the HF alloy's superior fluidity allows for casting sections as thin as 0.25 mm, enabling the production of zinc parts that can be lighter than their aluminum or magnesium counterparts.
• The Bottom Line: These new alloys expand the market for zinc die castings into new areas like high-temperature components, lightweight electronics, and complex decorative parts, offering significant cost and performance advantages over materials like sintered iron, stamped brass, and machined aluminum.

The Challenge: Why This Research Matters for HPDC Professionals

Die casting with zinc alloys has long been recognized as one of the most efficient and versatile methods for producing accurate, complex metal components, particularly through the high-productivity, low-cost hot chamber process. However, engineers have consistently faced two primary roadblocks.

First, the practical service temperature of zinc is limited. Like many materials, zinc's mechanical properties degrade significantly when used above half its absolute melting point. This phenomenon, known as creep, causes deformation under sustained load and has historically restricted zinc's use in higher-temperature environments.

Second, in an era where lightweighting is critical—especially in transportation and consumer electronics—zinc's greater density has been a traditional disadvantage compared to aluminum and magnesium. The minimum wall thickness for conventional zinc alloys is typically around 0.75 mm, limiting how much a part's weight can be reduced. This research addresses these long-standing challenges head-on.

The Approach: Unpacking the Methodology

To overcome these limitations, researchers focused on developing new alloy chemistries. The work was a collaborative effort involving multiple organizations, including the US Department of Energy (DOE), the International Zinc Association (ILZRO), the North American Die Casting Association (NADCA), Eastern Alloys, and Michigan Technological University (MTU).

The development of the EZAC alloy began with research to find a zinc-based alloy with improved creep resistance, focusing on compositions near the Al-Cu-Zn ternary eutectic. The development of the HF alloy was sponsored by the DOE and NADCA to create a zinc alloy with significantly improved fluidity. Both development paths involved rigorous laboratory testing, industrial casting trials to validate performance, and flow simulations to predict die-filling capabilities.

The Breakthrough: Key Findings & Data

The research resulted in the successful commercialization of two new alloys that extend zinc's capabilities beyond its traditional boundaries.

• Finding 1: EZAC® for High-Strength, High-Temperature Performance The EZAC alloy is a hot chamber die casting alloy with enhanced creep, tensile, and hardness properties. It is the strongest and hardest zinc die casting alloy available, with properties comparable to the cold-chamber-only ZA-27 alloy. The paper reports an impressive yield strength of 393 MPa (57 ksi) and a hardness of 120 Brinell. Its first successful application was a prototype crankshaft for a lawn trimmer (Figure 1), which passed rigorous cyclic and heat testing that other zinc alloys could not. This demonstrates its potential to replace more expensive materials and processes like sintered iron and metal injection molding (MIM) in applications requiring high strength and wear resistance.
• Finding 2: HF Alloy for Ultra-Thin, Lightweight Parts The HF (High Fluidity) alloy was developed to address the challenge of weight. It exhibits 40% greater fluidity compared to Alloy 7, allowing it to reliably fill section thicknesses down to 0.25 mm (0.01"). This capability allows the HF alloy to produce parts that are lighter than equivalent parts made from aluminum or magnesium when mechanical property limitations are not critical. The paper highlights several innovative applications (Figure 2):
  • Smartphone Case: Flow simulations confirm that 0.3mm sections are possible, potentially eliminating costly machining required for pressed aluminum preforms.
  • LED Heat Sink: The alloy's ability to be cast with extremely thin fins creates a much higher fin surface area, providing superior heat dissipation performance.
  • Legacy Locket: Replaced stamped brass, allowing for greater design flexibility and the integration of hinges and clasps directly into the casting, reducing part count.

The accepted composition for this now-commercial NADCA-listed alloy is detailed in Table 1.

Practical Implications for Your HPDC Operations

• For Process Engineers: The HF alloy's ability to fill sections down to 0.25 mm can reduce material consumption and potentially shorten cycle times. The fact that EZAC is a hot chamber alloy means you can achieve superior mechanical properties without sacrificing the high productivity associated with the hot chamber process.
• For Product Designers: This research opens new doors. Designers can now confidently specify zinc for applications previously limited by high operating temperatures (using EZAC) or strict weight requirements (using HF). The fluidity of the HF alloy, as demonstrated in the locket and shot glass examples (Figure 2), allows for the casting of fine details, logos, and integrated features, reducing assembly complexity and cost.
• For Die Design & Simulation: The success of these alloys, particularly HF, underscores the importance of predictive engineering. The paper explicitly notes that "Flow simulations show that 0.3mm section thicknesses are possible for typical smartphone case sizes." This highlights the critical role of simulation in validating designs for thin-walled applications, ensuring die fill, and optimizing the casting process before cutting steel.

Paper Details

Recent Zinc Die Casting Developments

1. Overview:

• Title: Recent Zinc Die Casting Developments
• Author: R. Winter, F. E. Goodwin, Sc.D.
• Year of publication: 2013
• Journal/academic society of publication: 2013 Die Casting Congress & Tabletop, North American Die Casting Association (NADCA)
• Keywords: Zinc die casting, EZAC, HF alloy, creep resistance, high fluidity, thin-wall casting

2. Abstract:

Recent developments in new applications for zinc diecastings are reviewed, including the increased usage of two new alloys that have extended zinc's capabilities: the EZAC® high temperature capability alloy and the HF ultra-thin section alloy. These alloys have essentially overcome the service temperature and density limitations traditionally associated with zinc die castings. Opportunities for cost and energy savings are identified in selected applications. Other zinc die casting technical developments will also be reviewed.

3. Introduction:

Die casting with zinc alloys is an efficient and versatile production method for complex metal components, utilizing the high-productivity hot chamber process. A key limitation is creep, which occurs at temperatures above half the absolute melting point of zinc (73°C). Another disadvantage, particularly in transportation, is zinc's high density compared to aluminum and magnesium. This paper introduces two new alloys, EZAC and HF, designed to overcome these respective limitations in temperature and density.

4. Summary of the study:

Background of the research topic:

The study is based on the need to expand the applicability of zinc die casting by addressing its inherent weaknesses. For high-performance applications, creep resistance at elevated temperatures is a major hurdle. For markets dominated by lightweight materials, zinc's density has been a barrier.

Status of previous research:

Previous efforts to improve creep resistance in zinc alloys had been made. The paper references work on ACuZinc 5, which had casting issues. The development of the EZAC and HF alloys builds upon a foundation of research sponsored by organizations like ILZRO, the US Department of Energy, and NADCA.

Purpose of the study:

The purpose is to introduce and review the developments and applications of two new zinc die casting alloys, EZAC and HF, which significantly extend the performance capabilities of zinc castings.

Core study:

The paper details the properties, development history, and commercial applications of the EZAC and HF alloys. For EZAC, it focuses on its superior mechanical properties (strength, hardness, creep resistance) and its ability to replace materials like sintered iron. For the HF alloy, it focuses on its enhanced fluidity, which enables the casting of ultra-thin sections, leading to lightweight parts that can compete with aluminum and magnesium.

5. Research Methodology

Research Design:

The development of the alloys involved a combination of alloy chemistry research, laboratory testing, and industrial production trials. For the EZAC alloy, research focused on the Al-Cu-Zn ternary eutectic with additions of Cr and Ti. For the HF alloy, development centered on creating a composition with maximum fluidity.

Data Collection and Analysis Methods:

Data was collected through mechanical property testing (yield strength, hardness) and performance testing in real-world applications (e.g., the lawn trimmer crankshaft). Fluidity was measured using laboratory methods (Ragone fluidity test) and validated in industrial casting trials. Flow simulations were also used to predict die-filling capabilities for thin-walled parts.

Research Topics and Scope:

The scope is limited to the review of two new zinc die casting alloys, EZAC and HF. It covers their development, key properties, and examples of commercial or prototype applications that demonstrate their unique capabilities.

6. Key Results:

Key Results:

• The EZAC alloy is a hot chamber alloy with superior creep, tensile, and hardness properties, comparable to the cold-chamber ZA-27 alloy. It has a yield strength of 393 MPa and hardness of 120 Brinell.
• The HF alloy has 40% greater fluidity than Alloy 7, allowing it to be cast in sections as thin as 0.25 mm (0.01").
• The HF alloy enables the production of zinc parts that can be lighter than aluminum or magnesium parts when mechanical strength is not the limiting factor.
• Both alloys have been commercialized and are enabling new applications for zinc die casting in medical, safety, electronics, and consumer products, often replacing more expensive materials or processes.

Figure Name List:

• Figure 1 - EZAC net shape insert molded crankshaft prototype for lawn trimmer.
• Table 1 - Composition Range of the HF Alloy
• Figure 2. Examples of applications developed with the HF alloy

7. Conclusion:

The development of the EZAC and HF alloys allows the usage of zinc die castings in applications that were previously not possible. The EZAC alloy overcomes traditional temperature limitations with its enhanced creep resistance and strength. The HF alloy overcomes the density limitation by enabling the casting of ultra-thin, lightweight sections. These innovations open up new competitive opportunities for zinc die castings.

8. References:

• 1. J.M Benson, D. Hope, and F.E. Goodwin, “Development of a Creep Resistant Hot Chamber Die Casting Zinc Alloy", Proceedings of the 104th Metalcasting Congress, 2000, North American Die Casting Association.
  2. F.E. Goodwin, “Update on Zinc Die Casting Research & Development”, Die Casting Engineer, 2003, North American Die Casting Association
  3. R. Winter, "EZACTM – High Strength, Creep Resistant Zinc Die Casting Alloy”, Die Casting Engineer, March 2011, North American Die Casting Association.
  4. F.E. Goodwin, K. Zhang, A.B. Filc, R.L. Holland, W.R. Dalter and T. M. Jennings, “Development of Zinc Die Casting Alloys with Improved Fluidity: Progress in Thin Sections of Die Casting Technology," Proceedings of 111th Metalcasting Congress, May 15-18, 2007, Houston, TX, North American Die Casting Association
  5. F.E. Goodwin, A. Filc, D. Liu and B. Lehenbauer, “Further Work on the New High Fluidity Zinc Diecasting Alloy”, Proc. 113th Metalcasting Congress, April 7-10, 2009, Las Vegas, NV, North American Die Casting Association.

Conclusion & Next Steps

This research provides a valuable roadmap for enhancing component performance through advanced material selection in zinc die casting. The findings offer a clear, data-driven path toward improving strength, increasing service temperature, and reducing component weight.

CASTMAN is committed to applying cutting-edge industry research to solve our customers’ most challenging technical problems. If the problem discussed in this white paper aligns with your research goals, please contact our engineering team to discuss how we can help you apply these advanced principles to your research.

Expert Q&A:

• 1. What are the main limitations of traditional zinc die casting alloys that the new alloys address? Traditional zinc alloys are limited by creep (deformation under load) at elevated temperatures and by their high density, which can be a disadvantage in lightweight applications. According to the paper "Recent Zinc Die Casting Developments," the EZAC alloy addresses the temperature and creep limitations, while the HF alloy addresses the density limitation by enabling ultra-thin wall casting.
• 2. What makes the EZAC alloy suitable for high-temperature applications? The EZAC alloy has "enhanced creep, tensile and hardness properties." The paper states it has "dramatically improved creep performance" and has demonstrated the potential to increase the practical service temperature. Its success in a lawn trimmer crankshaft prototype, which passed rigorous testing involving a combination of cyclic loading and heat, validates its high-temperature capabilities.
• 3. How does the HF alloy enable the production of lightweight parts? The HF alloy has "40% greater fluidity compared with Alloy 7." This high fluidity allows it to be cast with section thicknesses down to 0.25 mm (0.01"). As stated in the paper, "The ability to reliably fill much thinner sections allows the HF alloy to produce lighter weight parts than Al and Mg when mechanical properties limitations are not critical."
• 4. Can the HF alloy be used for applications requiring heat dissipation, like electronics? Yes. The paper highlights an LED lighting fixture as a key application. It states that because zinc alloys like HF can be cast with very thin fins, they can achieve a "much higher fin surface area" in a given design envelope. This allows them to provide "superior performance to even copper alloys" for heat dissipation where the limiting factor is the transfer of heat from the fin surface to the surrounding air. This is supported by the "LED heat sink" example in Figure 2.
• 5. What are some examples of materials that can be replaced by these new zinc alloys? The paper suggests several replacement opportunities. The EZAC alloy is a potential candidate to replace "sintered iron, and/or metal injection molding" due to its combination of low-cost net-shape processing and high mechanical properties. The HF alloy was used to replace "stamped brass" in the legacy locket application shown in Figure 2, and has the potential to replace "pressed Al preform" used for smartphone cases.

Copyright

• This material is an analysis of the paper "Recent Zinc Die Casting Developments" by R. Winter and F. E. Goodwin, Sc.D.
• Source of the paper: https://www.researchgate.net/publication/343322977
• This material is for informational purposes only. Unauthorized commercial use is prohibited.
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