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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 even smaller.
In order to simplify the communication of technical subjects, we categorize the smallest magnets into 2 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 (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. This is because the overall precision of manufacturing technologies is advancing steadily. 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 not possible 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 very difficult to make, and it’s not easy 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 really micro magnets.
• Across the country, just several magnet manufacturers can produce such tiny magnets with special shapes – like drilling a hole in a micro magnet, or the shape is irregular (like the picture below).
As a custom neodymium magnet supplier, Osenc takes micro magnets as one of our most important focuses. Most of the micro magnets we can offer are made from neodymium, but we can also make them in SmCo, Ferrite, and Alnico.
For the dimensional identifications of micro magnets with regular shapes, we use the same formula as regular magnets.
But for micro magnets with irregular shapes, we always advise using technical sketches / drawings to communicate, in order to avoid misunderstanding.
Minimum Dimensions of Micro Neodymium Magnets
As a custom magnet supplier, Osenc can produce micro magnets with the dimensions below.
• Minimum block: 0.2 x 0.2 mm
• Minimum disc: 0.2 x 0.2 mm
• Minimum tube: 0.38 x 0.14 x 2 mm
• Tolerances: between +/- 0.005mm and +/- 0.020 mm
• Minimum hole diameter: 0.10 mm
The biggest 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. The grade of a neodymium magnet is indicated by a number. A bigger 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 usually recommend choosing micro neodymium magnets of the top grades – N52, N54, and N55.
• The sizes of micro magnets are very small. 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.
As for technical possibilities, Osenc can offer custom neodymium magnets with several different types of coatings. They include nickel, zinc, epoxy, etc. Each of them has its own unique properties and benefits.
Please refer to this page to pick the most appropriate coating for your magnets.
The dimensions of micro neodymium magnets are already very small. Usually, they require high precision to function properly. For this reason, we will also need to consider the tolerance of different coatings. We must avoid the issue that the extra layer of coating ruins the precision of the magnets themselves.
For some coatings, their thickness uniformity can not be properly managed. It’s common for such coatings have a bigger thickness somewhere and a smaller thickness elsewhere. This is not because the coating service providers make defective product deliberately, but it’s because of the nature of such coating techniques themselves.
Due to the limits of most regular coating techniques, we usually recommend Parylene coating for micro magnets. This coating has many excellent performances, which are important.
Costs for Micro Neodymium Magnets
Generally speaking, the costs of producing micro magnets are much higher than regular average magnets, rather than lower since they use fewer materials.
Material cost accounts for a larger percentage of costs for regular magnets. However, this accounts for a significantly smaller percentage of micro magnets, which serve more like solutions, and technical innovations.
Below are the 3 reasons why the costs of micro neodymium magnets are higher.
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 micro magnet.
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) has always had higher and more requirements for micro magnets. They require smaller sizes than other industries. Because they have no choice.
For example, human coronary arteries are only 3 to 4 millimeters in diameter, which requires a magnet diameter of 1.35 or less, otherwise, catheters containing magnets risk injuring the blood vessels.