Method of making a powder metal rotor for a surface

A method of making a powder metal rotor for a surface permanent magnet machine, the method comprising:

• filling an inner annular region of a disk-shaped die with a soft ferromagnetic powder metal;
• pressing the soft ferromagnetic powder metal in the die to form a compacted magnetically conducting segment;
• sintering the compacted magnetically conducting segment;
• filling discrete regions within an outer annular region of the die with a non-ferromagnetic powder metal so as to leave spaces between each discrete region;
• pressing the non-ferromagnetic powder metal in the die to form a plurality of compacted magnetically non-conducting segments;
• sintering the compacted magnetically non-conducting segments and the compacted and sintered conducting segment to form a composite powder metal disk having an inner annular magnetically conducting segment and outer annularly spaced magnetically non-conducting segments;
• and
• providing permanent magnets in the spaces between the magnetically non-conducting segments.

A method of making a powder metal rotor for a surface permanent magnet machine, the method comprising:

• filling a disk-shaped die in an inner annular region with a soft ferromagnetic powder metal and an outer annular region with a hard ferromagnetic powder metal;
• pressing the soft and hard ferromagnetic powder metals in the die to form a compacted powder metal disk;
• and
• sintering the compacted powder metal disk and magnetizing the hard ferromagnetic powder metal to form a compositc powder metal disk having an inner annular magnetically conducting segment and an outer annular segment of alternating polarity permanent magnets.