China Neodymium And Ferrite Magnets Manufacturer & Supplier 
Neodymium bar magnets, a common shape of rare earth neodymium magnets, are widely used in sensors, electronic devices, motors, adsorption devices, and experimental teaching due to their strong magnetic force and regular geometric shape. Many people are concerned about one question when purchasing or designing magnets: How long can neodymium bar magnets be?
In theory, neodymium magnetic materials can be cut into very long bar shape, as long as there is sufficient raw material and the equipment supports processing. However, actual production is affected by many factors.
First, in terms of materials, long strips are prone to internal stress during the sintering and cooling process, which can cause warping, cracking, and even high scrap rates, so materials of this size are rarely produced.
Secondly, the material itself is hard and brittle, with poor bending resistance. Once neodymium bar magnets become too long, they are prone to breakage during transportation, installation, or use.
The accompanying image shows a 200mm length neodymium bar magnet.
Furthermore, the longer the bar magnet, the weaker the magnetic force in the middle area. If the length exceeds a certain proportion, a “magnetic dead zone” may occur.
In actual industrial applications, the conventional maximum length of neodymium bar magnets is generally controlled between 100mm and 200mm.
When a project requires neodymium bar magnets exceeding 200mm in length, it is recommended to use multi-segment splicing or metal reinforcement (stainless steel wrapping around the magnet).
Although neodymium bar magnets can be customized to various lengths, their actual “usable length” is not necessarily better the longer it is. Instead, it is important to strike a balance between magnetic performance, structural strength, manufacturability, and cost. For most applications, selecting bar magnets within the 50–150mm length range offers both convenient installation and reliable performance.
Recommended neodymium bar magnet size:
Large neodymium magnet block 5.91 inch F150 x 50 x 20 mm