Cutter combination for an electric shaver

A cutting device for an electric shaver comprising:

• an outer cutter and a plurality of inner blades, said outer cutter being made of a ferrous alloy comprising a first substrate of an Fe-Cr stainless steel and a first hardened layer formed on a side face of said first substrate, said plurality of inner blades being made of a ferrous alloy comprising a second substrate of an Fe-Cr stainless steel and a second hardened layer formed on a side face of said second substrate;
• said outer cutter formed with a plurality of openings for receiving hairs therethrough, said outer cutter being formed around each of said openings with a first polished contact surface, a first cutting edge, and a side surface of said first hardened layer, said side surface of said first hardened layer being adjacent to said first polished contact surface, an angle of said first cutting edge being defined between said first polished contact surface and said adjacent side surface of said first hardened layer to have an angle of 35.degree. to 90.degree.;
• each of said inner blades having a second polished contact surface, a second cutting edge, and a side surface of said second hardened layer, said side surface of said second hardened layer being adjacent to said second polished contact surface, an angle of said second cutting edge being defined between said second polished contact surface and said adjacent surface of said second hardened layer to have an angle of 35.degree. to 90.degree.;
• said inner blades being movable relative to said outer cutter in sliding engagement between said respective first and second polished contact surfaces for cutting the hairs by said second cutting edge in cooperation with said first cutting edge;
• said first hardened layer being formed on said first substrate so that an end face of said first hardened layer and an end face of the first substrate in cooperation define said first polished contact surface, and so that an edge of said first hardened layer forms said first cutting edge for said outer cutter;
• said second hardened layer being formed on said second substrate so that an end face of said second hardened layer and an end face of the second substrate in cooperation define said second polished contact surface, and so that an edge of said second hardened layer forms said second cutting edge for said inner blades;
• and
• wherein said first and second substrates have a Vickers hardness of at least 400 and said first and second hardened layers have a Vickers hardness of at least 700, and said first and second hardened layers have a thickness of 2 to 15 .mu.m.