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New NdFeB Grades and Assembly Techniques

Over recent years NdFeB has seen a significant increases in the performance of grades in terms of both energy and temperature capabilities. With advances in metallurgy and production techniques, it is now possible to have production parts in N52 (52 MGO with a maximum working temperature of 80°C) and N50M (50 MGO & with a maximum working temp of 100°C). Further work is being done in labs to create grades of N53 and N55 and as soon as these reach production standards HSMAG will offer them to customers.

Using magnets with such high energy values creates other problems, such as safe handling and assembly. Again further development work has been done in this area to make the assembly of NdFeB easier. Now many smaller motors can be assembled onto the rotor and then magnetised with the appropriate fixtures in-situ.

New NdFeB Grades and Assembly Techniques

TESTING MAGNETS AND MAGNET ASSEMBLIES

HSMAG excels at testing magnets and assemblies.

Our state-of-the-art testing capabilities include:

  • Helmholz coil testing – measures total flux of individual magnets
  • Hall probes used to measure field in Gauss. Custom test stands to measure axial field on Traveling Wave Tubes
  • Axial field profile for measurements on assemblies
  • Custom testing and custom fixtures as required by application
  • High resolution testing of Br as a function of temperature to 10 ppm resolution in % change in Br /°C

Raw Material Testing

  • Vibrating Sample Magnetometer (VSM) – takes open circuit BH measurement from room temperature up to 1000°F.
  • BH testing using hysteresigraph – used to quantify raw material bulk properties. Characterizes the material’s ability to resist demagnetization.

We can test from 100°C to 300°C

Composition analysis is one of the standard process control methods used to produce metal products like steel and titanium alloys. However, the rare earth magnet industry does not typically use composition analysis to control the manufacturing processes.

Alternatively, we control our processes by measuring and monitoring magnetic properties, which we have found to be both more accurate and more relevant.

Although accurate composition analysis for rare earth alloys is difficult to do, we can provide that service (by subcontracting the analysis to a qualified laboratory). If required, we will quote composition analysis as a separate line item.

MAGNETIC CIRCUIT DESIGN

Magnetic circuits, comprised of permanent magnets and ferromagnetic return paths, can be designed with a wide variety of air gaps and magnetic flux density levels. Of course the performance of the magnetic systems is highly dependent upon the flux density in the air gap.

Gauss’s Law for Magnetism

The total flux of any closed region within a magnetic circuit must always be conserved; meaning the total flux leaving this region must equal the total flux entering this region. The net magnetic flux out of any closed surface is zero. Therefore magnetic monopoles do not exist. This flux conservation principal, also known as Gauss’s Law for Magnetism, is expressed mathematically as follows:

(1)

 

Ampere’s Law

Ampère’s circuital law relates the integrated magnetic field around a closed loop to the electric current passing through the loop. The line integral of magnetic field H around a closed circuit bounding a surface A is equal to the current flowing across A, which can be written as:

(2)

 

The following is a very simple magnetic circuit consisting of one rectangular permanent magnet with two steel components on each side. The magnetization direction of the permanent magnet is oriented from left to right.

HISTORY OF PERMANENT MAGNETS

People have been fascinated with the phenomenon of magnetism since ~600 BC. An ancient Greek philosopher observed that lodestone (magnetite) can attract iron. The ancient Chinese were credited with inventing the compass, which had great impact on human history and global exploration. The first written reference to compasses used in Chinese navigation dates to 1086, and it was later used by European mariners. However, the compass was used centuries earlier for spiritual and religious purposes. The ancient compasses were built using lodestone, a natural permanent magnet, which aligns itself with the Earth’s magnetic field.

In the last 100 years, various permanent magnets have been developed and have achieved great commercial success. From ferrite, Alnico, SmCo5, Sm2Co17 to Nd2Fe14B magnets, the maximum energy product, (BH)max, has been increased from a few MGOe to over 50 MGOe, as is shown in the following figure.

permanent-magenets-history

 

Historical information about the maximum energy product of permanent magnets

Can You Really Erase Your Hard Drive With A Magnet

We are often asked if we sell magnets that will erase hard drives. This is not one of our target applications, and most of our engineers report that they prefer a sledge hammer to a magnet when looking for external forces to disable the storage device. Magnets often distort more than erase the data.

Horseshoe Magnet

Plus the sledgehammer can be worked into your cardio for the day and the greater satisfaction of smithereens and bits from the bytes that persecuted one for so long with that hour glass and the incessent locking up and I volunteer to help someone because I obviously have some pent up frustration with Windows!!! Thanks for the humor and the link.

With stories abounding of identity theft aided by information lifted from discarded storage devices, you want devices you no longer plan to use to have no usable information when they head out the door. Here’s how to wipe them clean.

Why Erasing Files Is Not Enough

Sure, you could erase the contents of the drive, but keep this in mind: the act of erasing a file does not remove it from a storage device.

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Magnetic Domains

magdom1
1. Magnetic moments in neighboring atoms are held parallel by quantum mechanical forces.

2. These atoms with these magnetic characteristics are grouped into regions called domains. Each domain has its own North pole and South pole.

A Domain is the smallest known permanent magnet. About 6000 domains would occupy an area the size of the head of a common pin.
A domain is composed of approximately one quadrillion (1,000,000,000,000,000 or 1015) atoms.

magdom4

3. In unmagnetized ferromagnetic materials, the domains are randomly oriented and neutralize each other or cancel each other out. However, the magnetic fields are still present within the domains!

magdom9

(These diagrams show domains as small cubes or squares – kind of a micro view.)
Here is a sample of unmagnetized iron, showing its domains in random magnetic orientations (x is arrow away from you = South Pole, dot is arrow toward you = North Pole)

magdom10
This shows the magnetic field around that sample of unmagnetized iron with its groups of domains, like those noted above, with random orientations. As you can see, this sample has multiple North and South poles where the magnetic field lines exit and enter the material.

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Samarium-Cobalt Magnet

samarium-cobalt-magnet

Samarium-cobalt magnets (SmCo5) are powerful magnets rare earth magnets composed of samarium and cobalt. These are brittle magnets and hence prone to crack and chipping. Samarium cobalt magnets can be used for high temperature applications.

Features
Following are the features of samarium cobalt magnets:
• High magnetic properties
• Good thermal stability
• Resistance to corrosion
• Resistant to demagnetization

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Rare Earth Magnets

rare-earth-magnetsMade from alloys of rare earth elements, rare earth magnets are strong permanent magnets. As they are stronger than ferrite or alnico magnets, the magnetic field produced by them are also higher.

Applications
Some of the common applications of the rare earth magnets are :
•They are used in computer hard drives.
• Rare earth magnets also find their utility in high-end speakers.
• Useful in experiment with diamagnetic levitation.
• Helpful in the study of magnetic field dynamics.
• They are also studied for a superconductor levitation.
Based on the applications and properties earth magnets are of two types:
• Neodymium Magnet
• Samarium-Cobalt Magnet

Process of Making Rare Earth Magnets
Rare Earth Magnets The rare earth magnets are made by using different process involving various stages. The popular stages of the production of rare earth magnets are:

• The first stage is the manufacture of rare earth element alloys.
•The metal alloy is then finely powdered.
•The next step involved is pressing of powder either isostatically or pressing through die process.
• The particles so pressed are oriented.
• Sintering of the element is done accordingly.
• The shapes are then sliced into desired shapes and sizes.
• The coating is done thereafter.
• After finishing the above tasks, the finished shapes are magnetized.

Graphical Representation
Below is the graphical representation of making earth magnets:

About Rare Earth Elements
Rare elements consists of group of seventeen elements having atomic numbers 21, 39, and from 57 to 71. The elements having atomic numbers between 58-71 are called as lanthanide. As these elements have strong affinity for the non metallic elements due to which they are used for producing alloys which are used in metallurgical industries. They occur in low concentration in the nature. However in certain minerals, where they occur as mixtures, they occurred in high concentration.

Rare elements find their application in glass, ceramic, lighting, and metallurgical industries. These elements have properties of exhibiting light when heated with oxides due to which they are used in cored carbon arcs. Rare earths also find their application in the petroleum industry as catalysts. Some of the rare earth elements like Yttrium aluminum garnets (YAG) are used in the jewelry trade as artificial diamonds.

Latest Research
As per latest research in dissimilar crystalline environment rare earth ions compete with one another and undermine the magnetic performance of the highest performance magnets. These findings also pointed the need for specialized atomic engineering of the material – manipulating the rare-earth local atomic structure to fully utilize the rare-earth contribution in next generations of magnets. This research will perhaps help the manufacturers to manipulate the rare earth ions atomic structure to improve the performance of earth magnets in future.

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Magnetism in Space

The study of the magnetism found in the planets and the sun of our solar system has been a very exciting field during the last 100 years.

Earth

Of course, trying to understand the magnetism within our own planet earth has been going on for a very long time, and only recently (within the 1990s) has a reasonable model been made which closely mimics how the magnetic field is created and how it changes over time. Recently, it has been determined that the core of the earth’s core rotates about 0.3 to 0.5% faster than the crust, which may have an effect on the magnetic field generated. There are also models of the expected strength and direction of the magnetic field seen on the surface of the earth at various locations. But there is more to the Earth’s magnetic field than what we can measure at various locations on its surface. There is also the effect the earth’s magnetic field has on the solar wind coming from the sun. The solar wind is what the stream of particles created by the sun is called. It travels as fast as 1.7 million miles per hour (800 km/sec) and goes out in all directions from the sun! When special eruptions occur on the sun, we can measure the effects on Earth about 52 hours later. Several scientists have been studying the strength of the magnetic field of the earth out in the space around our planet, and have been able to obtain a good understanding of its shape and how it varies over time. Did you know that the aurora borealis (“Northern Lights”) is caused by the Earth’s magnetic field and its interaction with ionized particles? Amazing stuff, isn’t it?

Sun

Sun_flip_magnetic_pole

Studying the sun, especially the sun spots and the massive flares and eruptions happening on the surface of it, has shown that magnetism plays a major role in the life of our star. The sun goes through an 11 year cycle of sunspot activity. Actually, it’s a 22 year cycle, because at the peak of the activity is when the magnetic field created within the interior of the sun flips, just like the magnetic field of the earth has flipped in the past. That’s what creates the sunspots, just like the odd magnetic poles that are created when the earth is partway through its field reversal. Here are some great sites which describe the studies going on. Did you realize that the scientists are able to measure the strength of the magnetic fields on the sun by carefully measuring the absorption lines seen in the color spectrum from the light from the sun, in the areas of the solar flare. When the light is exposed to a strong magnetic field, the spectrum lines will begin to split into two or more lines! The amount of the split is proportional to the strength of the magnetic field. This is called the Zeeman effect. The next flip should happen in late Summer / early Fall of 2013.

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Magnets for Pain Relief

Introduction

Magnets have not been proven to work for any health-related purpose, yet static, or permanent, magnets are widely marketed for pain control. This fact sheet provides basic information about magnets for pain, summarizes scientific research, and suggests sources for additional information.

Key Points
##Scientific evidence does not support the use of magnets for pain relief.
##Do not use magnets as a replacement for conventional medical treatment or as a reason to postpone seeing your health care provider about any health problem.
##Magnets may not be safe for some people, such as those who use pacemakers or insulin pumps, as magnets may interfere with the devices. Otherwise, magnets are generally considered safe when applied to the skin.
##Tell all your health care providers about any complementary health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.

About Magnets

A magnet produces a measurable force called a magnetic field. Static magnets have magnetic fields that do not change (unlike electromagnets, which generate magnetic fields only when electrical current flows through them). Magnets are usually made from metals (such as iron) or alloys (mixtures of metals, or of a metal and a nonmetal).

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