Sensitivity and Stability in NLP: Approximation

This invention relates to mold apparatus for injection molding plastic bonded magnets. The apparatus comprises body means having a molding cavity and gate. The body means includes a magnetizing device composed of a support of non-magnetic material having one or more permanent magnets contained therein and a non-magnetic wall portion interposed between each magnet and the cavity. The wall portion defines at least a portion of the cavity and the permanent magnet is disposed relative to the cavity such that at least a portion of the magnetic field therefrom enters the cavity through the wall portion. The support is of a strength to withstand the pressures of molten plastic in the cavity without the permanent magnet being present therein. The permanent magnet itself is so constructed and is of a physical strength inadequate to withstand such pressures. The support, therefore, isolates the permanent magnet from the molding pressures which could damage the magnet if directly applied thereto.