eNewsletter

April 2009

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NIST research shows that magnetism plays a key role in iron pnictide superconductors’ crystal structure. (Iron is purple; arsenic is yellow; calcium is green.) Only if the iron’s magnetism is taken into account do calculations of the distance between these crystal layers match up with lab measurements. Magnetism’s importance to their physical properties make it a likely factor in the iron pnictides’ ability to superconduct, say team members. Credit: Yildirim, NIST

The team has found strong evidence that magnetism is a pivotal factor governing the physical properties of iron pnictides, a group of materials that conduct electricity without resistance at temperatures of up to 56 K (-217°C). Iron pnictides are composed of regularly spaced layers of iron sandwiched between other substances. And although –217°C might sound pretty cold, they are the first class of materials found to superconduct at that high a temperature since the discovery of copper-based superconductors more than two decades ago.

“Without considering magnetism, for example, the calculated distance between iron layers, a distance that has been thoroughly measured, comes out to be wrong,” said Yildirim, of NIST’s Center for Neutron Research. “However, provided that we consider magnetic spin in our calculations, we can explain almost all of the iron pnictides’ structural and dynamic properties.”

Yildirim gave an invited talk* at the March meeting of the American Physical Society, where he presented theoretical evidence demonstrating how magnetism controls basic aspects of iron pnictides as the position of the atoms, the materials’ phase transition, i.e. the sudden changes in the structure with temperature, and—probably, Yildirim says—their superconducting properties.

“Determining the mechanism of superconductivity in iron pnictide systems is very important in solving the long-standing mystery of the high temperature superconductor phenomena in general,” Yildirim said. “Once we have such an understanding of this strange phenomenon, we can then make predictions and design new materials with even higher superconductivity temperatures.”

For more on Dr. Yildirim’s work, see www.ncnr.nist.gov/staff/taner/highlights.htm.

* T. Yildrim. Competing magnetic interactions, structural phase transition, and the unprecedented giant coupling of Fe-spin state and the As-As interactions in iron-pnictide. Presented at the March Meeting of the American Physical Society, March 17, 2009.

Payton Planar Magnetics Introduces a Line of Low Profile High Power Transformers for Processor Power
The demand for low profile, high efficiency, low input voltage with low output voltage with high current, is driving the need for high performance planar transformers to be used in the power stage of microprocessor power.

The demand for high current required to power the faster microprocessors requires the power magnetics to be very small so they can be placed near the processors in order to minimize the losses. The P/N 3013336 is 20.5 mm by 19.5 mm by 10 mm at 200 watts. The output is 2.4 Vdc at 85 amps. The topology is Full H Bridge with Synchronous current doubler. The total power losses are 3.3 watts with 45°C temperature rise. The efficiency of this magnetic is 98.4 percent. This example is 4:1 transformer. Other models are available.

Allegro MicroSystems, Inc. Introduces New 12 V Hot Swap Controller
Allegro has released a new 12 V hot swap controller with power good indication. The ACS761 is a highly integrated Hall-effect current sensor with an integrated charge pump, gate driver and multiple levels of load fault protection. Hot swap control and short circuit protection are provided in a single IC without the need for an external shunt resistor. The resistance of the ACS761 internal current conductor is typically 1.5 mΩ, resulting in substantial power savings relative to shunt resistor based hot swap solutions without a reduction in sensing accuracy. The ACS761 is a further enhancement on the ACS760, a Hall-effect based hot swap controller with 240 VA protection. The ACS761 includes the following architecture enhancements:

• Fixed Over Current Fault Threshold - Set internally to 40 A
• Inclusion of PGOOD and PGOOD pins - Provides feedback to host system that the 12 V supply is enabled and eliminates external system logic components.

Allegro’s ACS761 combines Allegro Hall-effect current sense technology with an integrated charge pump, FET driver, and a hot-swap controller. The integrated protection in the ACS761 incorporates three levels of fault protection, which includes a Power Fault with user-selectable delay, an Overcurrent Fault threshold with user selectable delay, and Short Circuit protection, which disables the gate of an external pass FET in less than 2 µs. These faults are indicated to the host system via the Fault pin and are cleared upon reasserting the chip enable pin to the high state.

The ACS761 is targeted at the computer/office automation market, most specifically for server applications. It is priced at $1.98 in quantities of 100,000 units and has an 8 to 10 week leadtime to market.

ProGrade Tube Magnets Separate Contaminants from Dry and Liquid Products
Eriez now offers ProGrade Tube Magnets in various strengths and lengths to remove ferrous contamination from both dry and liquid products. These tube magnets can be used as inspection tools or in areas where conventional grate magnets will not fit. Tubes can also be used for customers to fabricate custom grates for their own unique requirements.

The one-inch diameter (25 mm) magnetic tubes are available in lengths from four inches (100 mm) up to 24 inches (610 mm). They are used primarily to remove ferrous contaminants from liquids in tanks, as a quality control check of dry bulk materials or in various other application settings where a powerful, portable magnetic power source is needed.

ProGrade Tube Magnets are made from 316L stainless steel and have 0.25 x 20 UNC drilled and tapped ends. They are offered in three strengths, enabling customers to select the right degree of magnetic strength to suit their application needs.

Ceramic powered tube magnets remove medium to large tramp metal such as bolts, nuts and hand tools.

Rare Earth powered tube magnets remove small ferrous contaminants such as pins, staples and clips.

Xtreme Rare Earth powered tube magnets are best at separating out weakly magnetic fine ferrous contaminants.

New Linear Magnetic Encoders for Harsh Environments
New LM13 linear magnetic encoders bring big performance to small spaces and tough applications. Consisting of only a readhead and separate self-adhesive scale, the LM13 gives OEM designers an ultra-compact package that's well suited for industry's toughest applications in woodworking, metalworking, stone cutting, paper converting, packaging, plastics processing, laser/flame/water-jet cutting, chip/board production or assembly and packaging machinery. Magnetic sensing delivers dependability in applications too dusty, dirty, greasy or destructive for optical encoders.

Engineered for extreme service, LM13 encoders handle operating temperatures from -10°C to 85°C, providing waterproof sealing to IP68 and high resistance to shock, vibration and pressure. Frictionless operation eliminates wear, while reducing system inertia and hysteresis for high precision at high speeds and acceleration loads. LM13 encoders produce a digital, square-wave signal output to RS422, with customer-selectable resolution of 1, 2, 5, 10, 20, 25, 50, 125 and 250 µm. The encoder comes with bidirectional reference that can be actuated by a preset mark integrated into the scale, or by adding a reference sticker on top of the scale using the self-aligning installation tool.

Simple to install, the LM13 features integral go/no-go LEDs on the readhead, wide installation tolerances, and an applicator tool for the adhesive-backed scale. The scale is available either “cut to length” or in lengths up to 100 m in easy-to-handle coils.

The new Renishaw linear encoders join the proven family of RLS magnetic rotary/angle encoders designed and manufactured by Renishaw’s associate company RLS d.o.o.

As with all Renishaw products, a worldwide application support network and local inventory give confidence to system developers and OEM volume producers.

Magnetics 2009: New Sessions Announced
Magnetics 2009, a prestigious global forum featuring thought-provoking presentations, discussions, world-class training, business contacts and networking opportunities, will be held April 15-16 in Chicago, Ill.

Download Program here.

New Sessions!

Industrial Infrastructure: The Magnet Industry's Role in our Economy's Success
Ed Richardson, Sales & Marketing Manager • Thomas & Skinner, Inc.

X-Ray Vision of the Inner-Workings of Functional Magnetic Materials
Daniel Haskel, Advanced Photon Source • Argonne National Laboratory

The Magnetics Recording Industry: In Pursuit of Revolutions
Ed Murdock, Ph.D., President • ESM Consulting

The influence of magnetics can critically impact the economics and performance of your products and services. Knowing the current status of pricing, supply & demand and new technology developments are key factors for maximizing your return on investment in magnetics materials, assemblies, components and technologies.

In order to keep up with the changing magnetics marketplace, the 2009 program will feature numerous sessions designed to help end-users, product developers and application manufacturers optimize the economics of their investment in magnetic materials, components and products.

Register Now!

Attend a Pre-Conference Workshop!

NEMA Publishes MW 1000-2008 Magnet Wire
The National Electrical Manufacturers Association (NEMA) has published MW 1000-2008. MW 1000 is the premier standards publication for general requirements, product specifications, and test procedures for magnet wire. It is frequently updated by NEMA’s Magnet Wire Section to meet evolving user needs and magnet wire manufacturing technologies.

The 2008 revision includes:

• New specifications for self-bonding magnet wire
• An additional appendix detailing formulas for deriving dimensional and performance requirements
• An expanded thermal endurance procedure to include testing information for a range of wire specimen sizes

“This standard is the essential resource for anything related to the use, manufacture, and packaging of magnet wire. With the inclusion of new material and clarifying information, MW 1000 is more valuable and user-friendly than ever,” said Sergio Peña Rojas, chairman of the NEMA Magnet Wire Section Technical Committee that produced the standard.

An electronic copy may be downloaded at no charge, or a hard copy purchased for $173, by visiting NEMA’s website at http://www.nema.org/stds/mw1000.cfm.

Cobham Rebrands Three Prominent Technology Design, Development and Testing Businesses
Three prominent technology design, development and testing businesses, ERA Technology, Culham Lightning and Vector Fields have been brought together under the new name of Cobham Technical Services - as part of a group wide re-branding program by FTSE 100 parent company Cobham plc.

Cobham plc has revenue of £1.5 billion and employs more than 12,500 people worldwide on five continents, with customers in more than 100 countries. In the past, individually branded business units have provided products and services to primarily aerospace and defense customers, many of whom have been unaware of the breadth of capabilities available to them from across Cobham. The unification of all businesses under a single unified brand is designed to make it easier for customers to understand the group and highlight the career opportunities available to current and future employees.

Cobham Technical Services brings together more than 250 people in three businesses operating in related consultancy and technology design areas.

ERA Technology, based in Leatherhead UK, started life as the 'Electrical Research Association', a cooperative organization undertaking research predominantly associated with electricity supply and use. Today, it offers leading-edge design, development and consultancy services but across a broader range of markets from electronics and communications systems, to antenna technology, safety and EMC and reliability engineering.

Culham Lightning of Abingdon UK, is dedicated to understanding the problems relating to the direct and indirect effects of lightning strikes. It provides consultancy and testing services to clients in aerospace and other sectors including wind power and oil and gas. The business has made significant contributions to lightning standards and best practices used in many applications, particularly aerospace.

Based in Oxford UK and Aurora USA, Vector Fields produces advanced design automation software for modeling and analyzing electromagnetic equipment and effects. Its virtual prototyping and optimization tools speed time to market in an exceptionally broad range of applications from communications products and systems, to motors, loudspeakers and particle beam machines.

“In an increasingly competitive and international marketplace, aligning three successful businesses under the name Cobham Technical Services is going to make it easier for our customers and employees to understand the breadth of capabilities and opportunities available to them from across Cobham,” said Paul McCarter, general manager of Cobham Technical Service. “This is an evolution of a successful growing business, with our great products and services now provided under the brand of a FTSE 100 company.”

More information: www.cobham.com/technicalservices

Outsourcing Magnetic Assembly Manufacturing in China: The Challenges and Pitfalls
Rising costs in the US is forcing companies to outsource the production of magnetic assemblies abroad, mostly to China. Although considerable savings are achievable, US companies face numerous difficulties outsourcing this critical function.

The Chinese manufacturing culture poses many challenges asides from language barriers. US companies face strong cultural resistance to accepted practices in the West. Despite China’s strides towards adopting Western manufacturing standards in principle, implementation on the factory floor may be vastly different in practice. We’ll review 10 key areas affected by this cultural challenge. We’ll dissect the thought processes behind the underlying principles that govern how and why manufacturers operate the way they do. Finally, we’ll review selection criteria that can be critical to finding the right assembly partner in China.

Read full article here.

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ISSUE INCLUDES:

• Research & Development
• Feature Articles / Columns
• New Magnetics Products / Technology
• Industry News

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