A cutting part of a cutting insert may include a first surface including a corner, a first side, a first region, a second region and a third region. The first region may be located along the corner and the first side. The second region may be located at a more inner part than the first region. The third region may be located at a more inner part than the second region. A boundary between the corner and the first side may be a first point. A boundary between the first region and the second region may be a second point in a cross section that passes through the first point and is orthogonal to the first side. An imaginary straight line passing through the first point and the second point may be a first imaginary straight line. The first imaginary straight line may intersect with the third region.

A cleaned component having a polycrystalline structure, a method and apparatus for cleaning a leached component to form the cleaned component, and a method for determining the effectiveness of cleaning the leached component. The cleaned component includes a leached layer that has at least a portion of by-product materials removed. The by-product materials were deposited into the leached layer during a leaching process that formed the leached layer. The apparatus and method for cleaning includes a tank, a cleaning fluid placed within the tank, and at least a portion of the leached layer immersed into the cleaning fluid. Optionally, a transducer emits ultrasonic waves into the leached layer. The method for determining the effectiveness of cleaning includes cleaning the leached component to form the cleaned component, measuring one or more capacitance values of the cleaned component, repeating the cleaning and the measuring until achieving a stable lower limit capacitance value.