A slot milling disc for cutting slots or grooves of a uniform width in a work piece, the slot milling disc comprising • a disc body (31, 41), an outer peripheral surface of which is provided with a number of cutting edges, • attachment means configured to allow rotary preventing attachment of the slot milling disc to a rotatable mounting shaft, and • at least one flushing fluid channel having a confined cross-section and extending within the disc body from an inlet opening located in a central part of the disc body and configured to be connected to a source of flushing fluid to at least one outlet opening (22, 23) in the peripheral surface of the disc body, wherein the at least one flushing fluid channel comprises • an inner channel portion extending from the inlet opening towards the peripheral surface and ending before reaching this, • at least one outer channel portion (28, 29) extending from the inner channel portion while changing direction of the flushing fluid channel in such a manner as to be inclined in a direction towards a cutting edge and extending to the at least one outlet opening (22, 23), wherein the cutting edges are provided by separate cutting inserts being mounted in insert seats arranged at the peripheral surface of the disc body, characterised in that the inner channel portion is part of a channel portion extending all the way to the peripheral surface and which has then been plugged by means for plugging, and in that the entire slot milling disc is made in one piece with the exception of the means for plugging and the cutting edges, the cutting edges being wider than a thickness of the disc body in order to ensure clearance of the disc body from the work piece in a slot during cutting, and designed to cut a slot in a work piece with a width of 1.5 - 8 mm. • a disc body (31, 41), an outer peripheral surface of which is provided with a number of cutting edges, • attachment means configured to allow rotary preventing attachment of the slot milling disc to a rotatable mounting shaft, and • at least one flushing fluid channel having a confined cross-section and extending within the disc body from an inlet opening located in a central part of the disc body and configured to be connected to a source of flushing fluid to at least one outlet opening (22, 23) in the peripheral surface of the disc body, wherein the at least one flushing fluid channel comprises • an inner channel portion extending from the inlet opening towards the peripheral surface and ending before reaching this, • at least one outer channel portion (28, 29) extending from the inner channel portion while changing direction of the flushing fluid channel in such a manner as to be inclined in a direction towards a cutting edge and extending to the at least one outlet opening (22, 23), wherein the cutting edges are provided by separate cutting inserts being mounted in insert seats arranged at the peripheral surface of the disc body, characterised in that the inner channel portion is part of a channel portion extending all the way to the peripheral surface and which has then been plugged by means for plugging, and in that the entire slot milling disc is made in one piece with the exception of the means for plugging and the cutting edges, the cutting edges being wider than a thickness of the disc body in order to ensure clearance of the disc body from the work piece in a slot during cutting, and designed to cut a slot in a work piece with a width of 1.5 - 8 mm. the inner channel portion is part of a channel portion extending all the way to the peripheral surface and which has then been plugged by means for plugging, and in that the entire slot milling disc is made in one piece with the exception of the means for plugging and the cutting edges, the cutting edges being wider than a thickness of the disc body in order to ensure clearance of the disc body from the work piece in a slot during cutting, and designed to cut a slot in a work piece with a width of 1.5 - 8 mm.