The North American Die Casting Association (NADCA) has sponsored the research to create a new zinc alloy for thin wall applications. The alloy was developed by the International Lead and Zinc Research Organization (ILZRO). This alloy, also known as the HF alloy (HF for high fluidity), has 40% higher fluidity than Zamak 7 – the previous commercially available zinc die casting alloy of highest fluidity.
The cell phone company HTC saw an opportunity to decrease machining time and cost for producing the case of their HTC One V Windows based cell phone. The two-piece set (front and back) of the case was being machined from forged 6000 series aluminum blanks. The time to machine the forged aluminum set was 20 minutes. With the dimensional capability of the HF alloy, the machining time was estimated to be 2 minutes which provided a huge incentive to convert to die cast HF zinc alloy.
The front and back components (figure 1 & 2) of the case were designed as die castings utilizing the HF zinc alloy. This alloy has higher yield strength and ultimate strength than the 6000 series forged aluminum alloy as well as the ability to be cast to the desired wall thickness of 0.4 mm (slightly less than 0.016 inch). Dies for the two castings were designed for a 4-slide zinc die casting machine to accommodate undercuts and other details of the configurations not achievable with current aluminum and magnesium die casting alloys. Based on computer simulation which showed acceptable flow and fill analysis, die sets were fabricated.
Converting the HTC cell phone case front and back to die cast zinc alloy HF from machined aluminum forgings provides large cost and energy savings. Based on a production level of one million cell phones per month, the cost savings for machining is $720,000 per year.
Information on this alloy (Tables below) has been transferred to the industry through the NADCA Product Specification Standards for Die Castings document. Additionally, ILZRO is providing design assistance to companies for proper implementation. The benefits of technology include:
- Casting of thinner walls
- Fill of more complex geometries
- Minimization of scrap due to lack of fill
- Shorter cycle times
- Higher productivity
- Enhanced energy efficiency
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General Motors Sales In China Reach New Record
The Los Angeles Times (12/6, Hirsch) reports, “Imagine a world where Buick outsells Chevrolet. It’s called China. Buick is the top seller for General Motors’ Shanghai GM venture. November sales in China for the Buick brand reached 70,172 vehicles, a 17% gain from the same month a year earlier. The Regal sold 9,204 units, almost 10 times the volume it sold in the US last month.”
The Detroit News (12/6, Burden) reports, “GM said it has sold 2.59 million vehicles in China through the first 11 months of the year. Last year, the company sold nearly 2.55 million vehicles in the country. The automaker said sales in China by GM and joint ventures are up 10.4 percent through the first 11 months of 2012 compared to the same period in 2011.”
Bloomberg News (12/6) reports, “GM had said it plans to invest as much as $7 billion in the five years to 2015 in China. GM China President Bob Socia said Nov. 30 the company’s priority next year is to boost Cadillac sales. The automaker’s Cadillac deliveries rose 8.4 percent last month to 3,260 units, led by the SRX sport utility vehicle at 2,082 units.”
Michigan Becomes the 24th Right-to-Work State
Michigan Governor Rick Snyder yesterday signed two bills enacted by the Michigan Legislature which makes it unlawful for employees to be required, as a condition of continued employment, to become union members or pay any fees or dues to a union. Senate Bill 116 applies right-to-work (“RTW”) provisions to private sector workers. HB 4003 precludes compelled union membership or the payment of any fees or dues by public sector employees to a union as a condition of employment, with the exception of police or fire department employees subject to interest arbitration under Act 312, and State Troopers.
Want to Learn More About Semi-Solid Slurry Forming of Alloys? Check Out NADCA’s Newest Publication!
Semi-solid metal processing has been known for many years to have several benefits that could change the way the industry produces metal parts. The focus of the exploitation of the technology in the early years has been on forming semi-solid metals by the thixocasting route. In the last decade, however, the focus has been shifted to a more cost effective and less complex forming route, called rheocasting. During the attempts to commercialize a rheocasting process in the die casting industry, it has been found that the needs to modify the current processes, machines, and dies have prevented prompt interests and collaborations from the industry.
A new forming approach called semi-solid slurry forming has been applied. This process involves producing semi-solid slurries at a low solid fraction so that they can simply be poured into a shot sleeve.
NADCA’s new publication, Semi-Solid Slurry Forming of Alloys by Jessada Wannasin, covers a historical introduction to the subject and then moves to the formation of the slurry, its fundamentals and its practice. In addition forming processes are addressed as well as characteristics and benefits of the cast products. This publication also provides insight into the intimate relationship among processing, structure and properties, and also shows how relative processing costs influence processing route to be chosen.
Semi-Solid Slurry Forming of Alloys is now available for purchase at the price of $40 for Corporate Members, $60 for Individual Members and $80 for Non Members. To purchase this publication please visit www.diecasting.org/publications; publication #217.
Please contact the NADCA publications department at firstname.lastname@example.org if you have any questions.