关键词: 磁性附着体, 固位力, 磁通量

Abstract:

Objective This study aims to evaluate the retentive force and magnetic flux of magnetic attachments after repeated insertion–removal cycles. The correlation of retentive force and magnetic flux was also observed. Methods A Magfit EX600W(n=5) was selected as retentive device for this study. The retentive force of the magnetic attachments after 2 500, 5 000, and 10 000 times of insertion–removal cycles was obtained through a universal testing machine. Magnetic fluxes at three positions (P1, upper surface of the magnet; P2, lower surface of the keeper; and P3, lateral side of the magnetic attachment set) were measured using a Gauss meter. Results The initial retentive force of the Magfit EX600W attachment was(3.361±0.137) N. The retentive force significantly decreased to (3.109±0.160) N, (2.666±0.195) N, and (2.224±0.231) N after 2 500, 5 000, and 10 000 refitting cycles, respectively. However, no significant difference was observed among the increased magnetic flux at the three positions after refitting cycles. Moreover, the retentive force and maximum magnetic flux leakage showed strong negative correlation. Conclusion The retentive force decreased because of the refitting cycles. However, insertion–removal cycles had no significant effect on magnetic flux.

Key words: magnetic attachment, retentive force, magnetic flux