Page 356 - Design for Six Sigma a Roadmap for Product Development

326 Chapter Nine

■ Replace the subject by another substance.
■ Switch on/off the magnetic influence on the subject.

Example 9.25. Grinding the Inner Surfaces of Parts A ferromagnetic
medium with abrasive particles moved by rotating magnetic field can be
applied to polish the internal surface of a workpiece.
Old design

Part (1) Magnetic
field (2)
Magnetic
field
1 2

Part
Abrasive

An external magnetic field moves ferromagnetic abrasive particles inside a
part. The abrasive particles grind the part. (Disadvantage: The part walls
weaken the magnetic field.)
New design

Part (1) Magnetic
Magnetic field (2)
field 1 2

Part
Abrasive
Heating

It is proposed to heat the part to the Curie point temperature. The part
magnetic properties are removed to ensure that its metal does not weaken
the magnetic field. The grinding intensity is increased by the stronger mag-
netic field and the higher part temperature.