A method for manufacturing a tool head of a rotary cutting tool , the tool head having a front end and a rear end between which a centre axis (C) of rotation and a peripheral envelope surface extend, the method comprising: - forming at least a first part and a second part from a powder composition, wherein the powder composition is a hard metal composition or a cermet powder composition, wherein the first part comprises a first joining surface and wherein the second part comprises a second joining surface, the first joining surface being configured to be brought into contact with the second joining surface, wherein the first part further comprises a first outer surface portion configured to form a first portion of the peripheral envelope surface of the tool head , and wherein the second part further comprises a second outer surface portion configured to form a second portion of the peripheral envelope surface of the tool head , - forming at least one groove in the first joining surface and at least one corresponding groove in the second joining surface, wherein the at least one groove of the first joining surface is configured to face the at least one corresponding groove of the second joining surface when the first joining surface and the second joining surface are brought into contact, comprising forming the at least one groove as a curved groove, - assembling the parts into a shape of a tool head by bringing at least the first and second joining surfaces into contact to form an interface , so that at least one pair of facing grooves forms a channel extending in the interface , the channel having an inlet opening in the rear end of the tool head and an outlet opening in the front end and/or in the peripheral envelope surface of the tool head , and the channel being curved in a plane parallel with the centre axis, - joining the assembled parts in a sintering operation to form the tool head . - forming at least a first part and a second part from a powder composition, wherein the powder composition is a hard metal composition or a cermet powder composition, wherein the first part comprises a first joining surface and wherein the second part comprises a second joining surface, the first joining surface being configured to be brought into contact with the second joining surface, wherein the first part further comprises a first outer surface portion configured to form a first portion of the peripheral envelope surface of the tool head , and wherein the second part further comprises a second outer surface portion configured to form a second portion of the peripheral envelope surface of the tool head , - forming at least one groove in the first joining surface and at least one corresponding groove in the second joining surface, wherein the at least one groove of the first joining surface is configured to face the at least one corresponding groove of the second joining surface when the first joining surface and the second joining surface are brought into contact, comprising forming the at least one groove as a curved groove, - assembling the parts into a shape of a tool head by bringing at least the first and second joining surfaces into contact to form an interface , so that at least one pair of facing grooves forms a channel extending in the interface , the channel having an inlet opening in the rear end of the tool head and an outlet opening in the front end and/or in the peripheral envelope surface of the tool head , and the channel being curved in a plane parallel with the centre axis, - joining the assembled parts in a sintering operation to form the tool head . <EOS>