There is provided a method of manufacturing magnetic head sliders comprising the steps of cutting a material block, which may be of sintered ferrite or ceramic material, to form a core block and slider block. A groove is formed in the core block, which is bonded to the slider block using techniques to provide a magnetic gap. Thereafter the core block is machined to form a plurality of head cores, followed by machining the slider block to form in parallel a number of sliders, which are lapped and then sliced into individual magnetic head sliders. To prevent particles of material from the magnetic head sliders from separating from the sliders and causing deleterious effects, such as head crashes, a heat treating process is employed in which the slider block and core block are treated for from 3 to 20 hours at a temperature of from 100.degree. C. to 150.degree. C., at an ambient air pressure of from 1.5 to 5 kg/cm.sup.2 and at a relative humidity of not less than 60%. In one embodiment the heat treatment is performed immediately following the step of cutting the material to form the core block and slider block. In another embodiment, the heat treatment is performed immediately prior to lapping the sliders.