LEC MAGNETICS supports magnetic technologies capabilities for customers around the world in applying our technical know-how to provide initial and ongoing engineering and manufacturing support.

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Driving Cost Improvements Through Design
 
LECMAG are the perfect partner for innovative businesses looking to maximise performance, improve design and reduce costs. We have the expertise to tackle the most challenging of magnetic applications, working with clients to understand their project then design develop and produce a value adding solution.

Having the full package of services in-house gives us full control over costs and planning thereby ensuring we deliver projects on time and within budget. To find out on the sections below or contact us.

Typical magnetic applications

Our magnetic technology can be applied to a vast range diverse applications, some typical examples are list below:
Rotor assemblies for motors and generators
Loudspeakers
Magnetic pump couplings
Halbach arrays
Mass spectrometers
Magnetic clamping assemblies
Sensing and switching assemblies
Position sensing (rotary and linear)
Linear actuators
Hard drives
Door security
 Magnetic couplings
Magnetic levitation systems
Security tag removal systems


A wealth of in-house resources

We provide a range of in-house value adding resources and services:
Design consultation
Prototyping and validation
3D CAD design
3D FEA (Finite Element Analysis)
Field testing and monitoring
Magnetic stabilisation
Micron accurate machining
Rotor balancing
Mechanical and magnetic testing
Just in time delivery and stock holding


Ensuring the right material for your project

We offer a comprehensive range of material types and can recommend the optimum choice for your application:
Neodymium Iron Boron (NdFeB)
Samarium Cobalt (SmCo)
Iron Chrome Cobalt (FeCrCo)
Ferrite/Ceramic
Alnico
Compression Bonded
Injection Moulded
Flexible Magnets
Soft ferrites (transformer ferrite)
Powdered irons
Electromagnets
Magnetic assemblies


A wide choice of value adding finishing operations

We provide a range of specialist finishing operations to give your product the competitive edge:
Automated gluing
Ultraviolet light curing
Ultrasonic plastic welding
 Insert moulding
Rubber over-moulding
Powder or paint coating
Silk screen printing
Chemical etch printing
 Laser printing

Custom Magnet and Magnetic Assembly Engineering and Design

When you combine LECMAG’s accumulated knowledge and experience combined with new innovations and technology you get the best magnet and magnetic assembly design and engineering assistance in the marketplace. LECMAG utilizes 2D and 3D magnetic simulation packages to design engineered-to-order magnetic assemblies and magnet solutions for a wide range of applications, including:
Medical Devices and Equipment
Aerospace and Defense Programs
Sensor triggering
Thin Film Deposition and Magnetic Annealing
Metal working
Fixturing and Work-holding
Electro Mechanical Devices
Various Holding applications
Various Material Handling Devices
Toque and Linear Couplers

Commitment to Technology and Design for Manufacturability

Custom Magnet and Magnetic Assembly Engineering and Design

Custom Magnet and Magnetic Assembly Engineering and Design

The professionals at LECMAG understand that our customers are not always certain about the existence or feasibility of a magnetic solution. To that end, LECMAG leverages its technical assets, including computer simulations with 2D and 3D FEA and Boundary analysis software to validate design concepts, thereby reducing product development time and expense, and ensuring manufacturability of the finished product. By utilizing simulation software, a tentative solution can be generated, forwarded, and discussed with your design team. After preliminary models are reviewed, an informed decision can then be made on how or whether to proceed.

Reverse Engineering

LECMAG industry expertise and in-house capabilities allows us to reverse engineer an existing magnet or magnetic assembly to improve performance, enhance service life, quantify and qualify older designs, and reduce costs. These capabilities include:
Vast accumulated knowledge base
Hysterisigraph used to quantify the magnetic characteristics of the magnet
Simulation Software
Performance benchmarking of the application
Chemical analyses

Design Pitfalls
During the design phase of your project, it is important to consider the complexities associated with designing with magnetic materials. Not only is the magnetic performance of the magnet important, but also how the magnet will be integrated into the final solution.

Magnetic materials, unlike common commercial materials that have ASTM classifications, are difficult to manufacture and to fabricate and present a special set of challenges. Therefore, it becomes incumbent upon the design team to take special care when creating a custom solution for your application. Common design challenges with Magnetic Materials:
Are typically environmentally unstable (Highly reactive and prone to oxidation). Common coating and plating solutions usually do not translate to magnetic alloy.
Will gain or lose magnetic field relative to the operational temperature fluctuations necessitating the need to design for magnetic performance through a temperature spectrum.
Can experience irreparable harm at extreme temperature exposures. This harm is irrecoverable and represents an effective partial or total demagnetization of the magnet.
Challenging to fabricate because conventional machine tools and machining methods are not feasible.
Challenging to design because the magnetic field density and resulting force are not linear relative to distance.
Magnetic fields can create hazards for personal and some electronic equipment.
Common methods of component integration and retention such as; tapped holes, shoulders, through holes, staking, and tapers are expensive to employ. The integration of a magnet into a sub-assembly requires a functional knowledge base when designing an integration scheme.
Are MAGNETIZED. This seems obvious, but magnetized magnets and sub-assemblies present a unique set handling and integration problems. The issue can range from protecting the operators to demagnetizing of the magnet itself. This aspect must be accounted for early in the design phase.

Commonly requested specifications attributed to conventional materials, such as aluminum, steel alloys, plastic, etc., are usually challenging to implement with magnets and magnetic materials. These specifications, usually indicated on a drawing by default, may add cost and complexity when manufacturing a magnet or magnetic assembly. It is important to review the relevance of these industry standard features and specifications when designing and specifying a magnet or magnetic assembly.

Magnetic Concept Validation

The first step associated with the design and manufacture of a custom magnet or magnetic assembly is concept validation. During the early phases of a project, our engineering staff examines the specific parameters of your custom application to determine the viability of a magnetic solution.

Initial consultations explore two basic questions:

Does a magnetic solution for the given application exist?
Can the proposed custom magnet or magnetic assembly design concept be manufactured in a cost effective manner while meeting the performance criteria?

This process involves design exchanges between team members, drawing reviews, first order software simulations, and geometry mock-ups of the assembly. All of these activities are vital to ensure the intended design concept can consistently yield desired performance characteristics.

Concept Validation and Design for Manufacturability

Once a design concept is deemed viable (i.e., a magnetic solution does exist), focus turns to the manufacturing process. Even the best design concept is of no value if it can’t be manufactured to specification within existing budgetary guidelines. During this stage of the validation process, our engineering team can also explore how design variables may influence performance characteristics and ease of manufacture.

Reverse Engineering

Our industry expertise and in-house capabilities also allow us to reverse engineer an existing magnet or magnetic assembly to improve performance, enhance service life, quantify and qualify older designs, and reduce costs. These capabilities include:
Vast accumulated knowledge base
Hysterisigraph used to quantify the magnetic characteristics of the magnet
Simulation Software
Performance benchmarking of the application
Chemical analyses

Deliverables and Next Steps

Magnetic concept validation produces supporting documentation that empirically proves the viability of the proposed magnetic solution. With this information in hand, we can confidently progress to the design and manufacturing phases, armed with data that verifies the viability and feasibility of your project. Although concept validation may seem like time consuming exercise to those unfamiliar with our industry, the process is central to the development and fabrication of custom magnets and magnetic assemblies.

Oftentimes the magnet alloy is the most costly part of an assembly and optimizing the magnet volume used yields financial savings. By validating and optimizing a magnet design for an application using simulation software, LEC Magnetics can offer significant cost reductions. Concept validation can also significantly shorten design, prototype, and manufacturing lead times, leading to reduced product development costs.

If you have an application that may require a custom magnet or magnetic assembly, partnering with an engineering oriented vendor offers the best chance of successfully completing your project on time, on budget, and on spec. To learn more about magnetic concept validation, or to discuss your project, send us EMAIL.

Generator Magnets – Magnets for use in Permanent Magnet Generators

All Permanent Magnet Generators (in fact all Generators) work using the principles of Faradays Law and Lenzs Law.

A voltage (electromotive force or back emf) is induced (generated) inside a copper coil winding as a changing magnetic field passes through (cuts through) the winding. The magnetic field must be changing in magnitude (and ideally also in direction). The back emf, when the winding is part of a closed electrical circuit is used to create an induced current (the electrical load affects the magnitude of the current e.g. light bulb, charging battery, etc).

Lenzs Law states that the induced current direction is such that the magnetic field created by the induced current opposes the original change in magnetic field. Hence the minus sign in the below Faradays Law:
E=-NA (dB/dt) where
E is the induced voltage (back emf)
N is the number of turns in the copper coil winding
A is the coil cross sectional area
dB/dt is the rate of change of magnetic field strength with respect to time

The direction of induced current could also be explained by Fleming’s Right-Hand Rule.

So a generator requires a magnetic field that changes with time (e.g. magnets on a rotor) and copper windings (coils other electrically conductive materials other than copper could be used but copper windings are used as standard) positioned to have the changing magnetic field passing through the windings. The magnets may pass the open face of the coil windings, or they may pass through the centre of the windings.

Be aware that the voltage generated is a.c. (alternating current) it has positive and negative signal of a possibly sinusoidal nature / waveshape. As the magnetic field increases in magnitude dB increases (positive); as the magnetic field reduces in magnitude dB starts to reduce (negative) hence positive and negative voltage signal. If you require a d.c. voltage you will need some form of rectifier circuit (e.g. full wave rectifier) and possibly also some form of smoothing (e.g. capacitor). In more complex generators, the a.c. voltage is cleaned and then a new 50Hz mains voltage is created. We do not get involved in such generator circuitry design.

Generator designs can be such that more than one electrical phase can be generated in different windings (e.g. three phase windings). This is achieved by clever placement of the windings and magnets relative to each other and is design specific.

There are literally hundreds of designs of permanent magnet generator. It is assumed that people designing generators are suitably qualified (e.g. electrical and electronic engineers, design engineers, etc).

Quick rules for electricity generation using permanent magnet generators:
The generated voltage is an alternating voltage (alternating current) with positive and negative voltages. For a dc current you will need rectification and perhaps also smoothing.
Ideally have a -N-S-N-S- type of arrangement with the copper windings.
More turns in the winding gives a higher N giving more voltage generated.
Faster movement (e.g. faster rotation) reduced dt giving more voltage generated.
Stronger magnets give more magnetic field output (B) giving more voltage generated.

If your design can incorporate more winding coils they could be connected in series to give extra voltage (but be careful to connect in the correct sense otherwise the coils may possibly cancel each other out; and also be aware of placing the coils at different positions could give different electrical phase angles which may or may not be desirable for your application) or they can possibly be connected in parallel for higher current capability (same voltage as a single coil). It depends on the design as to what is required.

We do not design generators we merely provide technical support on the magnet materials to use and also we manufacture and supply the magnets that could be used in generators and we would also supply the magnetic assemblies used in generators (to customer designs).

What magnet shapes are best for permanent magnet generators? This depends entirely on your design. Sometimes the magnets are arc segments. In other designs the magnets are blocks, discs, trapezoids, rings, etc. There is no fixed magnet size or shape that is best for permanent magnet generators.

Can we supply magnets for use in Wind Turbines?

Yes. A wind turbine is a generator that uses wind as the power source for turning the wind turbine blades to turn the rotor. Some designs are very large and the magnets are sometimes best supplied as sub-assemblies; other designs are smaller and the magnets can be supplied as single piece blocks. Again, it really depends on the design as to what is required for size and shape. Often the customer has a design in mind and requires our technical support to verify the correct magnet choice, coating type, assembly procedure, cost reduction, etc. We can produce and supply magnets and magnetic assemblies for wind turbines and can provide relevant technical support on magnetic material choice.

Magnetic Rotor Assemblies

LEC Magnetics can design, produce and supply Magnetic Rotor Assemblies to customer requirements.

Whether it is a simple rotor asssembly for low cost low speed use or a high specification magnetically balanced rotor with mechanical balancing, LEC Magnetics can produce and supply high quality magnetic assemblies for your application.

Magnetic Balancing – some applications require the back-emf (generated voltage) in each phase to be of equal magnitude (to keep the power electronics simpler and lower cost). To allow this, it is possible for the magnetic output of each magnet to be measured and then the magnets can be assembled onto the rotor so that the total magnetic field each phase will see is as equal as possible. This is called magnetic balancing (or magnetic tuning).

Magnetic Rotor Assemblies

Magnetic Rotor Assemblies

High Speed rotors – in some applications the magnets need additional sleeving to assist in holding the magnets in place. We work with customers, often using their designs, to ensure the magnets stay on the rotor at all times.

Mechanical balancing – high speed rotors often require mechanical balancing to limit bearing damage, internal stresses and strains, noise, etc. We can balance the rotors to meet customer requirements.

Assembling – we can either assemble fully magnetised magnets onto the rotor. Or we can look to assembly unmagnetised magnets onto the rotor and magnetise afterwards in situ (if the design allows post-assembly magnetising to be feasible).

Machining – sometimes, especially for adding sleeves to rotors or when the air gap from rotor to stator is very small, the assembly outer radius needs to be precision ground. We can do this (but be aware that this may possibly affect the magnetic balancing – if you require more information on this effect please contact us).

Magnetic rotor assemblies include:- motors, generators, high speed actuators, wind turbines, magnetic pump couplings, printer rotors, direct drives, etc.

If you have a need for any type of magnetic assembly, LEC Magnetics can supply you.

Halbach Array Assemblies

LEC  Magnetics can design, produce and supply Halbach Arrays to customer requirements. We specialise more in the Halbach Array cylinders although we can assist in the supply of any Halbach Array design.

A typical Halbach Array design is the dipole (two pole) NdFeB Halbach Array cylinder where a ring of NdFeB magnets are assembled within a non-magnetic retaining ring to create a high magnetic field within the central air gap – the field lines being uniformly ditributed (homogenous) across the diameter of the air gap.

Halbach Array Assemblies

Halbach Array Assemblies

An example is a Dipole Halbach Array of Magnet Inner Diameter 30mm, Magnet Outer Diameter 95mm and Magnet Axial Length 40mm made using high strength NdFeB magnets (8 arc segments, each with a specific Direction of Magnetisation to pull magnetism around the ring shape of the magnetic assembly) which offers around 1T (10000 Gauss) right in the centre which drops to 0.6T (6000 Gauss) at the axial ends. Longer axial length units give slightly higher magnetic field output with increasing central axial section of more uniform high field output (the field will still drop towards the ends). Lengths of 100mm are possible in this example without the need to split the assembly into two or more axial sections. Higher homogeneity of field (uniformity of cross the diameter) is possible by using more arc segments.

The magnitude of magnetic field within the air gap can be modelled using our 3D Magnetic FEA software although the field can be crudely estimated since it is proportional to the natural logarithm of outer to inner diameter ratio times the Br of the magnetic material.

Higher fields in the central air gap are more easily achieved with smaller inner diameters (as the inner diameter increases the outer diameter can soon become too large to produce from single blocks of magnet).

Halbach Arrays can take many forms with many magnetic patterns. Linear Halbach Arrays are magnets in a row to have a magnetic pattern on the one side. Cylindrical Halbach Arrays can have magnetic fields on the inside our outside diameters. Varying pole numbers are possible, depending on the design. Halbach Arrays usually do not require ferromagnetic materials such as mild steel to carry magnetism – the magnets carry and add to the magnetic field within the magnetic circuit to allow for higher magnetic fields to be utilised in the application.

Typical applications for Halbach Arrays include motors, generators, food production, levitation, medical, R&D, University projects, etc.

Magnetic Coupling Assemblies

Magnetism can be used to push or pull other magnets, pull (attract) ferrous objects and even create eddy currents in electrically conductive metals such as aluminium or copper. Magnetism can be used to create forces and torques.

Magnets can be used to make assemblies that, when separated by an air gap (or effective air gap), will interact with each other. Such assemblies are said to be magnetically coupled. As such when you move, turn or rotate one assembly, it causes a movement turn or rotation on the other assembly.

Examples of such magnetic couplings are magnetic pump couplings and hysteresis drives.

Magnetic Pump Couplings tend to be of two design styles pancake and canister.

Magnetic Coupling Assemblies

Magnetic Coupling Assemblies

Pancake magnetic pump couplings comprise one half of the assembly having a disc-shaped plate at the end of a shaft onto which are placed magnets in a -N-S-N-S- arrangement (on a pcd to create a ring shape). The other half of the assembly is either another assembly (mirror-image) or a copper or just an aluminium disc or copper disc at the end of the shaft. The former (mirror-image assemblies) will align such that the North face of one magnet faces a South face on the other assembly) as one assembly is rotated, the other assembly will lag slightly (rotational displacement) creating a torque magnetically (the torque will increase as the lag angle increases until a peak torque is reached called Pull Out torque; the Pull Out torque is a function of the magnetic assembly design). The latter (magnets on a rotating disc facing an aluminium or copper plate) is used to create eddy currents in the aluminium or copper disc which then causes that disc to rotate and follow the rotating magnet disc a hysteresis drive or eddy current drive. The disc holding the magnets is usually ferromagnetic to give extra magnetic performance. The magnets used can be blocks, discs or arc shaped it depends on the design and performance characteristics required.

Canister magnetic pump couplings comprise of a can inside another can (a ring within a ring) the smaller can has magnets around its outer diameter in a N-S-N-S- arrangement; the larger can has magnets around its inner diameter in a N-S-N-S- arrangement. The magnets on the outer and inner cans interact magnetically and line up as you start to rotate one of the cans the two sets of magnets displace by an angle and the magnetic forces create a torque which forces the other can to follow in rotation (by a lag). As with the pancake versions the magnetic design is such that a peak torque exists (Pull-Out torque). The magnets used tend to be blocks or arc segments. The cans tend to be ferromagnetic to carry the magnetism between adjacent magnets to increase magnetic performance and torque production.

So one half of each coupling assembly is a drive (e.g. connected to a motor); the other half is driven. Often the driven half of the assembly is within a hermetically sealed chamber and is often connected to an impeller (fan blade) to push along (pump), stir or agitate the contents surrounding it. A canister can be inserted between each half of the assembly to separate the drive and driven parts. This makes magnetic pumps very useful for pumping along liquids or fluids which are chemically damaging or corrosive the driven part is sealed away within the harsh environment.

The Pull Out torque of the design needs to exceed the torque required to rotate the drive half of the assembly in the given application (e.g. pumping a thicker/viscous fluid would require more torque than pumping a thin fluid).

One factor to note is matching the motor turning the drive to the Pull Out torque. If the motor torque exceeds the Pull Out torque then if the driven assembly gets stuck (e.g. blockage in the fluid) then the motor can still turn (the assembly will cogg) but the motor will not burn out, protecting the motor if such a fault condition were to exist.

Which magnetic material to use and what shape? This depends on the customer application and the environment the magnets will be within. Often such designs as customised to the customer requirements. NdFeB allows higher torques, SmCo allows higher temperatures, ferrite allows lower cost, alnico allows high temperature stability, etc. Use of ferromagnetic materials (mild steel, ferritic stainless) can improve the magnetic circuit. The air gap between each half of the magnetic coupling assembly also impacts on performance (less gap should give more torque). We can work with you to get the most from your design. We have 3D FEA to model such designs. We can also produce your magnets and assemble them for you (giving you sub-assemblies to insert into your systems).
Applications include magnetic stirrers, magnetic pumps, magnetic drives, hysteresis drives, eddy current drives, etc.

If you require assistance with Magnetic Coupling Assemblies, Magnetic Pump Couplings, etc or would like to arrange a visit or would like quotations for the magnets and magnetic assemblies, please get in touch. LEC Magnetic can custom produce magnets and magnetic assemblies for you.

Hall Effect & Reed Switch Magnets for speed and position sensing using magnetism

Magnetic sensors interact with magnetic fields from electromagnets, solenoids and permanent magnets. They do not require any physical contact making them potentially highly reliable with long lifecycle due to no wear contactless position sensing. Magnetic sensors can work through most non-magnetic barriers (materials capable of having eddy currents would have limitations e.g. aluminium, copper).

Some of the magnetic sensors have a voltage induced in them e.g. Hall Effect devices in Gaussmeters the voltage is proportional to the magnitude of the applied magnetic field from the magnet. The magnitude of the applied magnetic field from the magnet is a function of the magnet size and shape and the magnetic material used (magnet type, magnet grade, temperature of the magnet).

Hall Effect & Reed Switch Magnets

Hall Effect & Reed Switch Magnets

Magnetic field sensors are used to give information relating to speed, position, movement, rotational angle, etc.

Magnetic field sensors include:-
Reed Switches
Hall Effect Devices
Giant Magneto Resistive Devices (GMR)
Variable Reluctance Devices (VR)

Reed Switch Magnets

Reed Switches are amongst the simplest of all the magnetic field detection devices. It consists of two thin ferromagnetic plates (usually nickel-iron or nickel-cobalt) called reeds within a glass ampoule (casing) which overlap each other except for a small gap between them so they are not quite touching.
When a magnetic field nears the reed switch, a magnetic field is induced within the reeds, magnetising them. Since they carry magnetism because they have high magnetic permeability, the two reeds magnetically attract each other closing the gap until they mechanically touch (when the applied magnetic field is strong enough to cause the magnetic pull to exceed the spring force trying to open them out). The reed switch is closed so, if in an electrical circuit, would allow current to flow through it. Reed switches close when the magnetic field is large enough they activate regardless of whether a North or a South pole is present. As soon as the magnetic field is reduced enough the spring force exceeds the magnetic pull force and the reed switch opens again and any electrical circuit is made open circuit.
A typical example is in security systems a magnet holds the Reed Switch closed when a window closed; when the window opens the magnet is taken away and the switch opens changing the electrical circuit and hence setting off the alarm.

Although a few versions exist, the most commonly used is of the above description which is called a SPST-NO (Single Pole Single Throw Normally Open Reed Switch).
One issue with reed switches is how they are rated. Reed Switch Suppliers use an Ampere-turn rating (A-t) for activating their reed switches (due to their using electromagnet coils with a certain number of turns and an applied current). In the Magnetic Industry the units are Gauss, Tesla or perhaps even Oersted (units of magnetic field used for magnets). The units are not easily interchangeable. A very rough guide is:-

B(Gauss)=0.4 x pi x NI(Ampere Turns) / L(cm) x 1.2(safety factor)

Where L is derived from the coil that the Reed Switch manufacturer uses. The coil may perhaps be a standard coil known as a Narm 1 coil that has a length, L, of 1.039 cm if the coil length is not known, using L=1.039 is a good estimate to consider using.

Simplified rough guide (assuming L=1.039cm)
B(Gauss)=1.451 x NI(Ampere Turns)

However, changing the reed switch terminal lengths, bending the terminals and altering the direction from which the magnetic is brought towards the Reed Switch can all affect the above rough guide. So the Gauss value is shown to be anything from 1 to 3 times the NI value (some Reed Switch companies even suggest up to 10 times). So perhaps testing with sample magnets beforehand may be advised if the Reed Switch company only offers Ampere turn data.

Sometime a magnet is offered with the Reed Switch this is fine. However the trigger positions for the Reed Switch may not be ideal for your application, in which case you may be able to change to another magnet type or magnet size to change the operation zone of the Reed Switch. If you have a magnet of known size, known material type and known material grade and you know how far the Reed Switch is from the magnet before it activates, it is often relatively easy to work out a new magnet shape for activating at a different distance away from the magnet.

We will give Gauss values (1 Gauss = 1 Oersted = 0.0001Tesla) and have assumed 1A-t~1.451Gauss (bearing in mind the A-t to Gauss conversion may need altering to suit your application).

Hall Effect Magnets

Hall Effect devices usually have three connections a Vcc (dc power supply positive terminal), Ground (dc power supply negative, zero or ground) and Vo (dc output voltage).

Hall Effect devices differ to Reed Switches in that they are more sensitive to the magnitude, direction and polarity of the magnetic fields being applied. Gaussmeters uses Hall Effect devices to operate.

The Hall Effect device is a semiconductor which has an electrical current flowing through the semiconductor – a voltage is created (Hall Voltage) when a magnetic field is perpendicular to the active element of the semiconductor. The Hall Voltage is proportional to the magnitude of the perpendicular magnetic field. The magnetic field causes the charge carriers, electrons and holes in the semiconductor to move to one side of the semiconductor, creating a potential difference across the semiconductor which is the Hall Voltage. Usually, Hall Effect devices output zero voltage output when no magnetic field is applied.

Some Hall Effect devices only work when a South Pole of a magnet face them; others only work with a North Pole facing.

Hall Effect devices are sensitive to the angle of the magnetic field relative to the active element of the semiconductor. When the field is perpendicular, maximum voltage is possible, as the angle reduces from 90 degrees, the Hall Voltage will fall by a ratio of the sine of the angle (sine90=1, sine60=0.866, sine45=0.707, etc).

Ideally the voltage output is linearly proportional to the applied field strength. The voltage is also linked to the perpendicularity of the applied field – a Sine (angle) relationship exists e.g. maximum output when the field is 90 degrees to the semiconductor active element. Some electronic chips have multiple Hall Effect Devices to allow measurement of North and South Magnetic fields. Some Hall Effect chips contain more than one device and allow applications such as 3D field mapping to be possible. Other chip variants also exist e.g. some Hall Effect Devices allow temperature correction.

Some Hall Effect devices give an output of half the supply voltage when no magnetic field is present then increase of decrease the voltage depending on whether a North or South magnetic field is applied.
Some Hall Effect devices have trigger levels to provide a digital high or low to give clean digital switching they are often known as Hall Effect Switches.
Some Hall Effect devices have trigger levels to provide latching ability linked to a digital high or low output to give clean digital switching (staying on one state with a North and not changing state until a South is applied) they are often known as Hall Effect Latches.
Some Hall Effect devices have Schmitt triggers built into them to help avoid “chattering” when the device is near its trigger value to change state.

Sensor Magnets, electromagnets and solenoids could all be used to trigger magnetic sensors such as Reed Switches and Hall Effect devices. The choice of magnet is determined by the actual application and the environment of the application. Temperature, distance and location of the magnet, presence of other magnetic field sources and the presence of any ferromagnetic materials all need taking into account. Sensor Magnet Selection

To activate a Reed Switch or Hall Effect device requires selecting the correct size, shape and grade of magnet for the application (to give the required magnetic field strength at the distance away from the magnet). If you have a magnet that works but you need to change how your application is activated, we can assist you.

We can help you specify the required magnet and we can produce and supply stock and custom produced magnets (to all the magnet material types, grades and coatings we currently offer).

SENSOR MAGNET SELECTION – SIZE GUIDANCE

Magnetic field drops off quickly the further away the sensor is from the magnet.
To gain more field at the sensor, reduce the distance from magnet to sensor if possible.
To gain more field at the same distance increase magnet diameter.
To gain more field at the same distance increase magnet height (gain does plateau off with increasing height works well for thin magnets).
To gain more field at the same distance increase magnet Br (i.e. select a stronger magnet grade or even a stronger magnetic material if feasible).

Magnetic Material Instructions

These instructions should be made available to all staff members who come into contact with or who process magnetic materials in any form.

When handling magnetic materials, especially made from the high-energy material NdFeB, the following points must be observed:

1. Magnets can attract one another at significant distances. With larger magnets this results in a risk of injuries.

2. All sintered permanent magnets are hard and brittle. When they come together with any force, they can split into many sharp parts due to the strong magnetic attractive force. Appropriate safety measures must be taken (safety gloves, safety goggles).

3. The magnetic fields surrounding a permanent magnet on all sides can affect and even destroy sensitive electronic and mechanical measuring equipment. Please observe sufficient distance (e.g. greater than 2 m) from equipment of this type (including computers, screens, disks, credit cards, etc.).

4. Wearers of pacemakers must avoid magnetic fields at all costs!

5. During air transport of magnetised materials, the relevant IATA regulations must be observed (no magnetic fields are permitted to penetrate the packaging – it may be necessary to provide magnetic shielding).

6. Please do not process magnets in environments at risk of explosion. Sparks may be produced when moving magnets.

7. When processing rare earth magnetic materials in particular, please note that the dust and chips produced from grinding are self-igniting and can burn at high temperatures. Never work dry and take the relevant safety precautions before processing. Avoid breathing in the dust.

8. High-energy magnets, especially those made from NdFeB, must be stored in a dry place as this material has a high affinity with oxygen. Even unprotected use in a damp environment can result in corrosion and ultimately in the destruction of the magnets. The galvanic coatings on NdFeB magnets as corrosion protection must not be damaged. Even minor cracks can result in corrosion.

9. No permanent magnetic materials may normally be subjected to any type of hydrogen atmosphere or radioactive radiation. This can result in destruction.

10. Observe the maximum usage temperature for the relevant material. In general the magnetic properties decrease with an increase in temperature.

11. In addition, there are no known negative effects of magnetic fields on the human body. It can be assumed that persons who are allergic to ceramic or metallic materials will also be allergic to magnetic materials.

We would be happy to provide any advice you need for more complex queries.

Custom Special Magnets

– Different Shape, Different Size, Different Grades, Different Coatings, etc.

-We can produce custom magnet shapes and sizes.
-We can produce custom magnetic assemblies.
-We can produce magnets to different grades and temperature ratings.
-We can produce made-to-order bespoke magnets to customer requirements.
-We can produce magnets with different coatings.
-We can produce magnets with different dimensional tolerances.
-We can produce and supply NdFeB, SmCo, Alnico, Ferrite, Compression Bonded, Injection Molded, Plastic, Flexible and FeCrCo magnets.
-We also produce and supply Electromagnets, Electro-permanent magnets, Solenoids, Soft Ferrites and Powdered Irons
-We do this by quotation, working with the customer to ensure they have the best product for their application with full technical support including 3D FEA magnetic analysis where applicable.
-Custom magnets = Bespoke Magnets = Made to Measure Magnets = Made to Order Magnets = Customer Design Magnets = Non-Standard Magnets = Special Magnets. Custom Special Magnets

Although we stock a wide range of magnets, magnetic materials and magnetic assemblies, we understand that we do not always have exactly what you would require.

However, because LEC Magnetics is a permanent magnet and permanent magnet assembly manufacturer and supplier, we can produce special shapes, sizes, grades and finishes for all the magnet materials and magnetic assemblies.

LEC Magnetics has ISO9001 and also has a factory in China for magnet and magnetic assemby production with ISO9001, ISO14001 and TS16949.

Small production runs or continual high volume call offs are all possible. Sample magnets are the same quality as mass production magnets.

If you see the right size of magnet but in the wrong grade or finish, we can supply the magnet to your requirements. If you have a drawing or details of what you require, simply contact us. If you require prices or datasheets for the magnet grades available, please contact us.

The example shapes shown on the right give a brief idea of what is ideally required as a minimum specification – the shape and dimensions of the magnet, any tolerances required for the magnet dimensions, the Direction of Magnetisation (DoM), the magnet material and grade and finally we would need to know the quantity or quantities. A drawing may not be necessary at all times – the mmA indication tells us the Axis in which the magnet is magnetised. Instead of using mmA or inchA (inches version rather than mm), it is also acceptable to use (A) after the dimesnion aligned with the DoM. If any details are unknown or unclear we would work with the customer to clarify the specification. Sometimes the Direction of Magnetisation (DoM) is shown by an arrow which points to the North Pole of the magnet. Please note that we follow the Magnetics Industry convention on magnetic poles (which is the correct scientific definition) – the North Pole of a magnet would point to the geographic North Pole of planet Earth (meaning planet Earth’s geographic North Pole is actually a Magnetic South Pole due to the convention of unlike poles attracting). The Magnetics Industry uses this definition when magnetising magnets.

Custom Magnetic Assembly Manufacturing

Since 2006, LEC MAG has offered in-house manufacturing capabilities to take your prints and specifications for an engineered to order magnetic assembly or custom magnet from the drawing board to the production floor. From quick turn prototypes to large volume production runs, we have the equipment, technical expertise, strategic relationships with key vendors, and trained personnel to needed to manufacture custom magnets and magnetic assemblies to meet your specific application.

Unlike many of our peers who have eliminated their manufacturing capability and rely on distribution type sales to reduce overhead, we understand the customer’s need to present a finished print and specification to a vendor with a capacity to deliver highly engineered magnetic solutions.

Custom Magnet and Magnetic Assembly Manufacturing

Custom Magnet and Magnetic Assembly Manufacturing

When researching new potential vendors to manufacture your custom magnet or magnetic assembly, it is important to remember that typical details, appropriate for common commercial materials, such as aluminum, steel alloy, brass, etc., are usually challenging to implement with magnets and magnetic materials and that these specifications indicated on a drawing, are often ignored by most magnet distributors.

The operational performance of a magnet material can be very challenging to predict. The magnet material used for your custom application may experience one or more of the following challenges:
Environmentally unstable (Highly reactive and prone to oxidation)
Gain or lose magnetic field relative to the operational temperature fluctuations
Can experience irreparable harm at extreme temperature exposures
Challenging to fabricate because conventional machine tools and machining methods are not feasible.
Challenging to design because the magnetic field density and force are not linear relative to distance.
Magnetic fields can create hazards for personal and some electronic equipment.
Magnet alloy is difficult to machine, so common methods of retainment such as tapped holes, shoulders, through holes, and tapers are expensive to employ.

If your potential vendor is not alerting you to these common manufacturing challenges during the quotation phase, you may be entering into a partnership with an order taker rather than finding a vendor capable of serving as your advocate, protecting your project from the common pit-falls experienced with magnetics manufacture. LEC Magnetics will provide a quote as per your drawing, observing the indicated details and specifications, and/or open a dialog, questioning the potential issues.

Custom Magnetic Assembly in-house manufacturing capabilities

Custom Magnetic Assembly in-house manufacturing capabilities

Quality Management System (QMS)
ISO 9001-2008 Production Manufacturing Facilities
Coordinate Measurement Machines and Video Inspection System
Magnetic testing equipment for measurements of Field Density and Field Strength
Hysteresisgraph for magnetic characteristic measurement
Variety of associated equipment for Electronic and Magnetic Performance evaluations

Equipment and Services
CNC Turning and Milling Machines
Sinker and Wire EDM
High Energy Magnetizers
Blanchard and Surface Grinding
ID and OD, and Centerless Grinding
Production and Precision Cut-Off Equipment
Sheet Metal Fabrication and Metal Joining Equipment
Coating and Plating
Painting
Powder Coating
Encapsulation
Clean Assembly Area

LECMAG Service

The LEC Magnetics service department ensures continuous optimal operation of the magnet systems delivered around the world. This includes commissioning delivered systems as well as magnet inspections, both for ensuring the quality of the products and for obtaining or retaining quality certificates. We also remove undesirable magnetism from equipment and tools. This can all be done on-site, so we are happy to come to you if you prefer.

Our engineers are experts in performing magnet calculations, which we use to develop magnet systems with optimal magnetic characteristics. We also use this knowledge to perform 2D or 3D magnet calculations for third parties.

All services can also be provided on-site. Please feel free to contact LECMAG with any questions you may have concerning these services.