For the segment SmCo magnet, Sm2Co17 are needed much more than SmCo5, due to higher cost and lower magnetic properties of SmCo5 magnet. The production technology especially the milling process is different between SmCo5 and Sm2Co17. For SmCo5 magnet, the wet milling or ball milling is used to make the raw materials to become powder, but this technology has some disadvantages including low efficiency, low consistency between batches, and then high cost generated. In machining the arc process, the magnet is easy to magnetize partially and the surface of the arc magnet becomes dirty. Jet milling is used to produce powder for Sm2Co17 magnet. Normally the arc shape is machined by EDM wire cutting with lower accuracy and tolerance about +/- 0.1 mm, and sometimes the molybdenum wire trails are left on the radius surface. The shape grinding is an alternative to grind the R surface to get tight tolerance and fine smoothness.
The sealless magnetic drive pump and coupling is another main application market for SmCo segment magnets. The SmCo arc magnets or loaf magnets are assembled on the impeller contained by hermetically sealed housing and outside the housing. Due to the high magnetic properties of Sm2Co17 segment magnets, the attraction of the drive magnet and the impeller magnet enables the full torque of the motor to be passed onto the impeller. This mag-drive pump design eliminates the need for the shaft sealing, and then avoids corrosive chemical fluids or gases to escape or leak and then cause harm to operators and environment. There are many famous manufacturers of magnetically-driven pumps or couplings in the world like Iwaki, Pan World, Sundyne, Magnatex, DST Dauermagnet-SystemTechnik, etc.
