Method for measuring wear rate

A method for measuring a wear rate of a first consumable part having a wear surface exposed to an environment causing the first consumable part to wear out and a non-wear surface parallel to the wear surface of the first consumable part and exposed to an environment without causing the first consumable part to wear out, and measuring a wear rate of a second consumable part having a wear surface exposed to an environment causing the second consumable part to wear out and a non-wear surface parallel to the wear surface of the second consumable part and exposed to an environment without causing the second consumable part to wear out, the method comprising:

• arranging the first consumable part and the second consumable part such that the wear surface and the first non-wear surface of the first consumable part as well as the wear surface and the non-wear surface of the second consumable part are arranged to be parallel to each other along a same axis;
• thermally coupling a first non-consumable part with the first consumable part, the first non-consumable part being made of the same material as the first consumable part and having a first non-wear surface and a second non-wear surface, both the first and second non-wear surfaces being parallel to each other and exposed to an environment without causing the first non-consumable part to wear out;
• thermally coupling a second non-consumable part with the second consumable part, the second non-consumable part being made of the same material as the second consumable part and having a third non-wear surface and a fourth non-wear surface, both the third and fourth non-wear surfaces being parallel to each other and exposed to an environment without causing the second non-consumable part to wear out;
• arranging the first non-consumable part and the second non-consumable part such that the first non-wear surface, the second non-wear surface, the third non-wear surface and the fourth non-wear surface are arranged to be parallel to each other along a same axis;
• irradiating a low-coherence light beam to the first consumable part and the second consumable part orthogonally to the wear surface and the non-wear surface of the first consumable part as well as the wear surface and the non-wear surface of the second consumable part, receiving reflection light beams of the low-coherence light beam from the wear surface and the non-wear surface of the first consumable part as well as the wear surface and the non-wear surface of the second consumable part, and measuring a first optical path length of the low-coherence light beam that travels forward and backward within the first consumable part in a thickness direction thereof and a second optical path length of the low-coherence light beam that travels forward and backward within the second consumable part in a thickness direction thereof;
• irradiating a low-coherence light beam to the first non-consumable part and the second non-consumable part orthogonally to the first non-wear surface, the second non-wear surface, the third non-wear surface and the fourth non-wear surface, receiving reflection light beams of the low-coherence light beam from the first non-wear surface, the second non-wear surface, the third non-wear surface and the fourth non-wear surface, and measuring a third optical path length of the low-coherence light beam that travels forward and backward within the first non-consumable part in a thickness direction thereof and a fourth optical path length of the low-coherence light beam that travels forward and backward within the second non-consumable part in a thickness direction thereof;
• and
• calculating a wear rate of the first consumable part based on a ratio between the first optical path length and the third optical path length and calculating a wear rate of the second consumable part based on a ratio between the second optical path length and the fourth optical path length.