Process of machining scroll member by using non-rotary cutting tool

A process of machining a scroll member of a scroll compressor which has a base plate and a scroll wall extending from the base plate in a direction substantially perpendicular to the base plate, by using a non-rotary cutting tool comprising (a) a generally cylindrical shank portion, and (b) a generally semi-cylindrical body portion which is coaxial with said cylindrical shank portion and which has an outer circumferential surface constituted by a rake face and a semi-cylindrical surface, wherein said semi-cylindrical body portion has a cutting edge which is defined by an edge of said rake face and which is covered with a diamond coating,

• said process comprising:
• a step of moving at least one of said non-rotary cutting tool and said scroll member relative to the other in such a direction that permits the scroll wall and the base plate to be machined without rotating said cutting tool, while holding said rake face substantially perpendicular to said direction;
• and
• a step of cutting both a flat horizontal surface of the base plate and a vertical surface of the scroll wall at the same time by said cutting edge having a side cutting edge portion and an end cutting edge portion which are contiguous and intersecting perpendicularly with one another where the side cutting edge portion contacts the vertical surface and the end cutting edge portion contacts the horizontal surface at the same time during the cutting step;
• wherein said side cutting edge portion of said cutting edge has a high degree of parallelism with respect to an axis of said cylindrical shank portion such that an error in said parallelism is not larger than 3 μm, and said end cutting edge portion of said cutting edge has a high degree of perpendicularity with respect to said axis of said cylindrical shank portion such that an error in said perpendicularity is not larger than 3 μm, and
• wherein said rake face has a planar surface in a direction identical to that of said axis and a constant width throughout said cutting edge.