Micro magnets are magnets that are very tiny. Most of them made in Neodymium Iron Boron, SmCo, Alnico, Ferrite. If you have some cases that need some custom neodymium magnets (SmCo, Alnico, and Ferrite are acceptable).
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Micro neodymium magnets – or tiny neodymium magnets, precise neodymium magnets – are neodymium magnets that usually have a size below 2 mm (5/64 inch) or are even smaller.
To simplify the communication of technical subjects, we categorize the most miniature magnets into two tiers of dimensions:
• Small magnets (Little magnets): 1.00 – 2.00 mm (3/64 – 5/64 inch)
• Micro magnets (Tiny magnets): 0.20 – 0.99 mm (200μm-990μm,1/64 – 1/32 inch， )
Micro neodymium magnets have more and more popular applications in various industries. They include consumer electronics, automobiles, medical devices, etc. It is because the overall precision of manufacturing technologies is advancing steadily. As a result, it’s possible to build more and more compact designs. And micro neodymium magnets can help scale the overall product dimensions down.
More and more micro neodymium magnets are offering functions that were impossible before. One example worth mentioning is Minimally Invasive Surgery (MIS). For example, coronary arteries are only 3 – 4 mm in diameter. And the appropriate magnet diameter is 1.35 mm or smaller than that.
Features of Micro Magnets
Custom micro magnets are tough to make, and it’s difficult to find supply information. If you search on some major B2B websites, those results are usually for small magnets of quite a few millimeters, not micro magnets.
• Across the country, only several magnet manufacturers can produce such tiny magnets with unique shapes – like drilling a hole in a micro magnet, or the form is irregular (like the picture below).
As a custom neodymium magnet supplier, Osenc takes micro magnets as one of our most important focuses. We can produce micro magnets with different materials. Like Neodymium Iron Boron, Samarium Cobalt, Ferrite, and Alnico.
Lots of people use the same measurement unit as regular magnets. Both of them are mm. For example, people can describe the disc magnet as 5*5mm. Block magnet as 5*6*9mm. (Please note the last number is magnetic direction)
But in the scientific research, scholars like use μm to measure magnets. like in the paper “A micro electromagnetic actuator with high force density” （Yue Wang）
Minimum Dimensions of Micro Neodymium Magnets
Osenc can produce micro magnets with the dimensions below as a custom magnet supplier.
• Minimum block: 0.2*0.2*0.2 mm
• Minimum disc: 0.2*0.2 mm
• Minimum tube: 0.38*0.14 *2 mm
• Tolerances: between +/- 0.005mm and +/- 0.020 mm
• Minimum hole diameter: 0.10 mm
The giant thin magnet we made is 50*50*0.2mm (This is a big challenge)
Neodymium magnets are graded based on the strength of their magnetic field. A number indicates the grade of a neodymium magnet. A more significant number indicates a stronger magnetic field.
Neodymium magnets have different grades, ranging from N35 to N55, and they also have high-temperature grades for special applications, like H, M, SH, EH, and AH.
You can refer to our introduction to neodymium magnet grades. It will be helpful for you to determine which grade is the most appropriate for you.
Besides the technical possibilities about which grades we can offer, we recommend choosing micro neodymium magnets of the top grades – N52, N54, and N55.
• The sizes of micro magnets are tiny. Therefore, if you choose magnets of lower grades, they may not be able to offer magnetism at an optimum level.
• Second, magnets of lower grades are more difficult to process and more likely to get damaged during applications.
For these reasons, micro magnets of the top grades are more logical choices than lower grades.
Neodymium magnets are sensitive to the working environment. The humidity and even other corrosive elements can cause them to corrode quickly.
To improve the durability of neodymium magnets, we will need to apply a layer or even multiple layers of coatings on their surfaces. Meanwhile, this will also make the magnets more resistant to scratches and other types of damage.
Osenc offers custom neodymium magnets with several different types of coatings. Like nickel, zinc, epoxy, parylene, etc. Each of them has its unique properties and benefits.
Please refer to neodymium magnet coating to pick the most appropriate coating for your magnets.
The dimensions of micro neodymium magnets are already tiny. Therefore, they need to have high precision to function properly. For this reason, customers have to consider the tolerance of different coatings. We must avoid the issue that the coating ruins the magnets’ precision.
In some cases, the thickness uniformity of the coating needs to be appropriate. Somewhere thick and somewhere thin. This is not because the coating service providers deliberately make defective products but because of the nature of such coating techniques.
Don’t hesitate to get in touch with us if you have strict requirements on the roughness and tolerance of the magnet surface.
Costs for Micro Neodymium Magnets
People are curious why micromagnets are more expensive than ordinary magnets. The production of miniature magnets consumes much less material than ordinary magnets.
Is it the manufacturer who makes a high profit?
No, here are three reasons why miniature neodymium magnets cost more.
Hard to Process
Micro magnets are harder to produce mostly because they are too small to handle properly. They will require special fixtures and additional attention. Cutting and coating are the biggest challenges. It can take more time to adjust and finetune machines. In some extreme cases, it takes us 7 hours of manual work before we can produce the first qualified micromagnet.
Most of the procedures require manual processing for the magnets, resulting in lower productivity. This also adds to the production cost.
Micro magnets have a dramatically higher defective rate during production. Sometimes, we have to produce 800 – 2,000 pieces in order to obtain 50 qualified magnets. Their raw material is N52, N54, or N55, which are expensive.
Most of the defective magnets usually occur when workers are setting up and finetuning the machine. Micro neodymium magnets are too small and brittle. Even if the processing force is slightly higher, the magnets will be defective or even damaged.
Production facilities for regular magnets cannot be used for micro magnets. Their tolerance will be more than acceptable. So, we need to use some special instruments. And we also have a Quadratic element measure to check the dimensions and make sure the product reaches the customer’s requirements.
Excellent Skilled Workers
Many procedures for producing micro magnets are actually manual work. Automatic machines have made great progress, but they still cannot produce some precision custom magnets. Human workers are still more flexible to suit the needs of precision work.
With our continuous efforts, Osenc has been expanding our capacities to deliver a wider range of micron magnets, and now we can process 0.2 mm magnets.
Osenc always provides long-term-stability products, which have high quality. We have achieved great development in this field.
Our products, especially our deep-hole thin magnetic rings are widely used in watches, clocks, micro-motor, meters, optical communication, and other fields.
Also, we can make a new design according to the customer’s drawing and request. Lots of customers are satisfied with our best techniques in magnetic tubes, magnetic cylinders, columnar magnets, magnetic pipe, hole magnets, magnetic ducts, pipe magnets, tube magnets, Cylinder magnets, deep hole magnets, etc.
In the medical device industry, minimally invasive surgery (MIS) and medical micro robot have always had higher and more requirements for micro magnets. They require smaller sizes than other industries. Because they have no choice.
For example, in the MIS, the diameter of human coronary arteries is only 3 to 4 millimeters. That means the magnet diameter should be 1.35 or less. otherwise, catheters containing magnets risk injuring the blood vessels.
In the subretinal injection studies (Like: A Magnetically Navigated Microcannula for Subretinal Injections, Samuel L. Charreyron), the magnet is a very tiny tube magnet, just 400 μm OD, 270 μm ID, and 2mm length.
Where to buy?
You can buy these micro magnets from Osenc.
Osenc has an advantage on the tiny magnets. If you would like to purchase some micro magnets, don’t hesitate to contact us.
We offer lots of micromagnets to research institutes, universities, and companies.