Four units of the MP-981 are mounted in a line for one gear with the fixing jig of the SUS400. When the gaps between the units and gear are 1 mm or more, two external units are operated but two inner units are not operated. But when the gaps are 0.8 mm, two inner units are operated. Why?
To come right to the point, it happens because the SUS400 is magnetic material. Please change it into non-magnetic material.
The tip of the MP-981 contains magnetism. The MP-981 detects the difference of the magnetism which is generated by the magnetic circuit between the unit and crests and troughs of the gear tooth. Therefore, when the ferromagnetic material is used for mounting the MP-981, the magnetism between the gear tooth become weak and the sensitivity will tend to be reduced. Generally, iron material is used as the fixing jig for the MP-981, but when several units of the MP-981 are used, the adjustment might be necessary to shorten the gap due to the magnetic affect.
The followings are the note on using the MP-981. For further information, please refer to the operation manual.
1. Use the ferromagnetic material for the detection gear Module: 1 to 3 or less, gear tooth width: 3 mm or more