Method for manufacturing wet friction plate

A method for producing a wet friction plate that includes a friction material disposed along a circumferential direction on a surface of a core metal formed in a flat-plate ring shape,

• the method comprising:
• a friction material producing step of producing, as the friction material, a paper body impregnated with thermosetting resin, the paper body including an aggregate of numerous fibers to which a filler is added, the filler exerting a function as a friction adjuster and/or a solid lubricant, the friction material producing step including curing the thermosetting resin until the thermosetting resin is not completely cured to produce the paper body containing the thermosetting resin in a semi-cured state;
• a groove forming step of irradiating the friction material in which the paper body containing the thermosetting resin is in the semi-cured state with laser light that is displaced relative to the friction material, thereby to form a concave groove on a surface of the friction material;
• and
• a crushing step of pressing the friction material while heated to crush and deform the groove formed by the laser light, wherein the friction material is heated so that the thermosetting resin in the semi-cured state is completely cured, and the groove is deformed so as to create unevenness on side surfaces of the groove to increase a surface area of an inner surface of the groove as compared to a surface area of the inner surface of the groove before the crushing step.

A method for producing a wet friction plate that includes a friction material disposed along a circumferential direction on a surface of a core metal formed in a flat-plate ring shape,

• the method comprising:
• a friction material producing step of producing, as the friction material, a paper body impregnated with thermosetting resin, the paper body including an aggregate of numerous fibers to which a filler is added, the filler being one or more selected a group consisting of barium sulfate, calcium carbonate, magnesium carbonate, silicon carbide, boron carbide, titanium carbide, silicon nitride, boron nitride, alumina, silica, zirconia, cashew dust, rubber dust, diatomaceous earth, graphite, talc, kaolin, magnesium oxide, molybdenum disulfide, nitrile rubber, acrylonitrile-butadiene rubber, styrene butadiene rubber, silicon rubber and fluorine rubber, the friction material producing step including curing the thermosetting resin until the thermosetting resin is not completely cured to produce the paper body containing the thermosetting resin in a semi-cured state;
• a groove forming step of irradiating the friction material in which the paper body containing the thermosetting resin is in the semi-cured state with laser light that is displaced relative to the friction material, thereby to form a concave groove on a surface of the friction material;
• and
• a crushing step of pressing the friction material while heated to crush and deform the groove formed by the laser light, wherein the friction material is heated so that the thermosetting resin in the semi-cured state is completely cured, and the groove is deformed so as to create unevenness on side surfaces of the groove to increase a surface area of an inner surface of the groove as compared to a surface area of the inner surface of the groove before the crushing step.