First, the bonded magnet
is isotropic, i.e. the strength of the magnetic field are the same (and have relation with shape), no matter which direction the magnets magnetized. But sintered magnet is anisotropic magnet, in the production process of sintered magnets, there is a procedure which called as magnetic field orientation, so only the direction of magnetization orientation can be magnetized and have high magnetic field strength, other direction can not be magnetized and there is no magnetic force. In theory, the remanence of isotropic magnet is only half of anisotropic magnet, because the energy product is proportional to the square of the remanence, so the anisotropic magnetic properties of anisotropic magnet is four times of isotropic magnet.
Secondly, because boned magnet contain adhesive, the actual density is only 80% of theoretical density, therefore, the magnetic performance of bonded magnets will decay around 30%. While the actual density of sintered magnet is close to the theoretical density, attenuation is very small.