Grain size effects on magnetic properties and core process of recording head Ferrites

A study has been made which correlates grain size with magnetic properties so that the proper range of grain size in ferrite materials can be determined for recording head applications. The effects of Ni-Zn and Mn-Zn ferrite grain size on 1) initial permeability, 2) loop, 3) density of ferrites, and 4) core processing, e.g., lapping and glass bonding, are described. Both experimental results and published research indicate that highly densified ferrites having larger grains are desirable for recording head applications. ASTM grain size Nos. 8-9 are therefore recommended for Ni-Zn ferrite R/W heads.