{"id":5657,"date":"2026-07-19T13:47:57","date_gmt":"2026-07-19T05:47:57","guid":{"rendered":"https:\/\/www.semiconductorcutting.com\/?p=5657"},"modified":"2026-07-19T13:48:00","modified_gmt":"2026-07-19T05:48:00","slug":"ndfeb-magnet-grinding-polishing","status":"publish","type":"post","link":"https:\/\/www.semiconductorcutting.com\/ja\/ndfeb-magnet-grinding-polishing\/","title":{"rendered":"NdFeB\u30de\u30b0\u30cd\u30c3\u30c8\u306e\u7814\u524a\u30fb\u7814\u78e8 \u2014 \u30b9\u30e9\u30a4\u30b9\u5f8c\u306e\u5b8c\u5168\u306a\u30ef\u30fc\u30af\u30d5\u30ed\u30fc"},"content":{"rendered":"

NdFeB magnet grinding and polishing is the finishing stage that converts a sliced magnet block into a dimensionally precise component ready for coating and assembly. Slicing gets the magnet close to final dimensions \u2014 but “close” is not close enough for motor lamination stacks, precision sensors, or direct-drive generators where parallelism tolerances of \u00b12 \u03bcm and surface roughness below Ra 0.5 \u03bcm are standard requirements.<\/p>\n\n\n\n

This page covers the complete NdFeB magnet grinding and polishing workflow: the process sequence from sliced blank to finished magnet, surface quality requirements by application, double-sided lapping equipment selection, and key parameters for achieving tight TTV control.<\/p>\n\n\n\n

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The NdFeB Post-Slicing Workflow Overview<\/h2>\n\n\n\n

NdFeB magnet grinding and polishing follows a fixed sequence. Each stage removes a defined amount of material and delivers a specific surface condition to the next operation.<\/p>\n\n\n\n

Sliced blank \u2192 Rough grinding \u2192 Double-sided lapping \u2192 Fine polishing \u2192 Coating\n<\/code><\/pre>\n\n\n\n
Sliced blank condition:<\/strong> Wire saw slicing produces Ra 0.5\u20131.5 \u03bcm surface roughness and TTV (total thickness variation) of 5\u201315 \u03bcm across a typical 50 \u00d7 25 mm magnet. For many applications, this is insufficient \u2014 motor magnets require TTV \u2264 5 \u03bcm, and sensor magnets require TTV \u2264 2 \u03bcm.<\/p>\n\n\n\n
Rough grinding:<\/strong> Removes slicing damage and brings the magnet to near-final thickness. Typically 50\u2013150 \u03bcm removed per face using resin-bonded diamond wheels. Output: Ra 0.3\u20130.8 \u03bcm, TTV 3\u20138 \u03bcm.<\/p>\n\n\n\n
Double-sided lapping:<\/strong> Processes both faces simultaneously on rotating lapping plates with abrasive slurry. Achieves tight parallelism (TTV \u2264 1\u20132 \u03bcm) and consistent thickness across a full production batch. This is the step that determines dimensional accuracy for assembly.<\/p>\n\n\n\n
Fine polishing:<\/strong> Optional for applications requiring Ra < 0.1 \u03bcm. Used for sensor magnets, precision assemblies, and magnets going into high-frequency servo applications where surface condition affects eddy current losses.<\/p>\n\n\n\n
Coating:<\/strong> Ni, Zn, or epoxy coating applied after polishing. Surface condition at the end of lapping directly affects coating adhesion \u2014 rough or contaminated surfaces cause premature coating failure.<\/p>\n\n\n\n
\u306e \u30de\u30b0\u30cd\u30c3\u30c8\u30b9\u30e9\u30a4\u30b7\u30f3\u30b0\u30de\u30b7\u30f3<\/a> upstream determines how much material needs to be removed in grinding. Diamond wire slicing produces shallower subsurface damage than ID saw or blade cutting, which reduces the grinding stock required and shortens finishing cycle time.<\/p>\n\n\n\n
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Surface Quality Requirements by End-Application<\/h2>\n\n\n\n
NdFeB magnet grinding and polishing targets vary significantly by application. Over-specifying surface quality wastes cycle time; under-specifying causes assembly problems downstream.<\/p>\n\n\n\n
\u5fdc\u7528<\/th>Ra Target<\/th>TTV Target<\/th>Parallelism<\/th><\/tr><\/thead>
EV traction motor magnets<\/td>\u2264 0.8 \u03bcm<\/td>\u2264 5 \u03bcm<\/td>\u2264 10 \u03bcm<\/td><\/tr>
Servo motor magnets<\/td>\u2264 0.4 \u03bcm<\/td>\u2264 3 \u03bcm<\/td>\u2264 5 \u03bcm<\/td><\/tr>
Wind turbine generator magnets<\/td>\u2264 1.0 \u03bcm<\/td>\u2264 8 \u03bcm<\/td>\u2264 15 \u03bcm<\/td><\/tr>
Precision sensor magnets<\/td>\u2264 0.2 \u03bcm<\/td>\u2264 2 \u03bcm<\/td>\u2264 3 \u03bcm<\/td><\/tr>
Speaker magnets<\/td>\u2264 1.5 \u03bcm<\/td>\u2264 10 \u03bcm<\/td>\u2264 20 \u03bcm<\/td><\/tr>
Medical \/ MRI magnets<\/td>\u2264 0.1 \u03bcm<\/td>\u2264 1 \u03bcm<\/td>\u2264 2 \u03bcm<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
For most motor magnet production, the governing specification is TTV rather than Ra. A magnet that meets Ra but has 8 \u03bcm TTV will create uneven stack height in a laminated assembly, producing air gap variation that reduces motor efficiency and generates vibration.<\/p>\n\n\n\n
NdFeB Magnet Grinding and Polishing: Double-Sided Lapping Equipment<\/h2>\n\n\n\n
Double-sided lapping is the core equipment in NdFeB magnet grinding and polishing. The workpieces are loaded into carrier plates between two horizontal lapping plates rotating in opposite directions, with abrasive slurry flowing between plate and workpiece. Both faces are lapped simultaneously, producing matched parallelism that single-sided grinding cannot achieve.<\/p>\n\n\n\n
Three machine sizes cover the production range from R&D to mass production:<\/p>\n\n\n\n
13B-6LY\/P \u2014 R&D and Small Batch Production<\/h3>\n\n\n\n