Sintered NdFeB is brutally hard and brutally brittle — more like carving glass than cutting steel. You cannot forge, bend or roll it into shape. Instead, big sintered blocks are sliced, ground and drilled down to the exact shape on the drawing, using tools that are even harder than the magnet itself: diamond.
Cutting
Blocks and rods are sliced into thin wafers and segments with diamond blades or diamond wire, running fast with coolant. Several methods exist — blade slicing for flexibility, wire saws for high volume, and laser or spark cutting for complex shapes. The coolant matters: cutting generates heat, and heat is the enemy of magnetism.
Grinding
Grinding is where the final dimensions and smooth surfaces come from. Diamond wheels grind the faces, edges and bores to size, with coolant keeping the surface from overheating. A ground magnet is accurate to fractions of a millimetre.
Drilling
Drilling is the riskiest step, because brittle magnets shatter easily. Special machines and careful feeds drill the holes for screws and mounting, and tiny precise holes are made with ultrasonic tools that hammer abrasive into the surface instead of pushing a drill bit through.
Why it matters
Machining turns a plain block into the finished part in your motor, sensor or assembly. Two cautions: a freshly machined surface rusts within hours, so parts are washed and coated quickly, and every tighter tolerance adds cost — design for the loosest fit your application allows.
One practical detail: parts are usually machined before they are magnetized. A magnetized block would attract steel swarf like a fridge door attracts notes — chips would stick to every surface and ruin the finish.
Read on: coatings explained → · machining tolerances →