Patent ID: 8579723

Claim:
A golf club head comprising: a clubface for striking a ball, the clubface comprising a contact face and face grooves, and a metallic skin covering the contact face and interior surfaces of the face grooves, wherein the metallic skin on the interior surfaces of the face grooves has a surface roughness Ral of not more than 0.20 micrometers, and the metallic skin on the contact face is roughened by blasting abrasive to have a surface roughness Raf of more than 0.20 micrometers and not more than 0.55 micrometers, wherein the cross-sectional area of each of the face grooves is not less than 0.08 sq.mm and not more than 0.45 sq.mm and the sidewalls of each of the face grooves are inclined at an angle θ 2 of not less than 3 degrees and not more than 30 degrees, and wherein the clubface further comprises auxiliary grooves, said metallic skin covering the interior surfaces of the auxiliary grooves, the auxiliary grooves have a depth of from 0.005 to 0.025 mm and a width of from 0.10 to 0.50 mm, the auxiliary grooves each have sidewalls inclined at an angle θ 1 of from 40 to 70 degrees with respect to the normal direction to the clubface to become wider toward its opening at the clubface, the auxiliary grooves are substantially parallel each other, and the distance P 1 between the widthwise center lines of the auxiliary grooves is not less than 0.30 mm and not more than 0.70 mm.