A I I + hole II II + hole III III + hole

B 20 30 40 – – –

C 15 25 35 – – –

D 15 25 35 – – –

E 20 30 40 – – –

F 20 30 40 – – –

G 20 30 40 – – –

Unit for B–G is mm.

M. Mori et al. / CIRP Annals - Manufacturing Technology 58 (2009)   331–334 333

Table 2

L18 orthogonal array and result of  analyses.

Analysis  model No. Control factor A B

C

D

E

F

G X (mm) Y (mm) h (db) S  (mm)

1 1 1 1 1 1 1 1 0.023 0.162 35.7 0.012

2 1 2 2 2 2 2 2 0.030 0.160 33.6 0.015

3 1 3 3 3 3 3 3