Surface finishing using magnetorheological (MR) fluid is useful to finish small but not too small workpieces such as those in a few millimeter scale. However, due to the high surface hardness, this finishing process does not seem to be suit for applying to a hard disk slider. In this work, a preliminary study is performed on the finishing of the hard disk slider surface with a mixture of an MR fluid and diamond powder. During a wheel type MR finishing process, centrifugal force is found to be a major factor to cause a reduction in material remove rate (MRR), which is supported by a theoretical model. To facilitate this founding, the rotational speed of tool is confined to 500rpm while a rectilinear alternating motion with the mean speed, which is equivalent to the rotational speed, is additionally applied to the workpieces. As a consequence, MRR of about 2 times of the sole rotational case is obtained. This paper shows that MR finishing process can be used to polish a hard material in millimeter scale efficiently by controlling the speeds of the tool and the workpiece.