Method for manufacturing a composite part, comprising the following steps: preparing a stack of plies, said stack comprising a plurality of plies, each of which is made of a starting material, applying a vacuum bag to the stack of plies, and applying vacuum within the vacuum bag, and subjecting the stack of plies to a temperature and pressure cycle in an autoclave; wherein each of said plies is of laminate material comprising a resin matrix reinforced with a fibre material, wherein the matrix comprises a core layer of semi-crystalline thermoplastic resin having a melting point T f, and a pair of outer layers (12, 13) arranged on opposite sides of the core layer, each outer layer consisting of amorphous thermoplastic resin having a glass transition temperature T g, wherein the glass transition temperature T g of the amorphous thermoplastic resin is below the melting point T f of the semi-crystalline thermoplastic resin, in said plurality of plies, adjacent plies make contact with each other by means of the respective outer layers (12, 13) of amorphous thermoplastic resin, and the temperature and pressure cycle in an autoclave comprises: applying pressure in an increasing manner until a working pressure p w is reached, and rapidly heating the stack of plies until a working temperature T w which is above the glass transition temperature T g of the amorphous thermoplastic resin but below the melting point T f of the semi-crystalline thermoplastic resin is reached, keeping the stack of plies at the working temperature T w during a time period for compaction alone, and cooling the stack of plies, and releasing the pressure after the temperature has dropped below the glass transition temperature T g of the amorphous thermoplastic resin. preparing a stack of plies, said stack comprising a plurality of plies, each of which is made of a starting material, applying a vacuum bag to the stack of plies, and applying vacuum within the vacuum bag, and subjecting the stack of plies to a temperature and pressure cycle in an autoclave; wherein each of said plies is of laminate material comprising a resin matrix reinforced with a fibre material, wherein the matrix comprises a core layer of semi-crystalline thermoplastic resin having a melting point T f, and a pair of outer layers (12, 13) arranged on opposite sides of the core layer, each outer layer consisting of amorphous thermoplastic resin having a glass transition temperature T g, wherein the glass transition temperature T g of the amorphous thermoplastic resin is below the melting point T f of the semi-crystalline thermoplastic resin, in said plurality of plies, adjacent plies make contact with each other by means of the respective outer layers (12, 13) of amorphous thermoplastic resin, and the temperature and pressure cycle in an autoclave comprises: applying pressure in an increasing manner until a working pressure p w is reached, and rapidly heating the stack of plies until a working temperature T w which is above the glass transition temperature T g of the amorphous thermoplastic resin but below the melting point T f of the semi-crystalline thermoplastic resin is reached, keeping the stack of plies at the working temperature T w during a time period for compaction alone, and cooling the stack of plies, and releasing the pressure after the temperature has dropped below the glass transition temperature T g of the amorphous thermoplastic resin. applying pressure in an increasing manner until a working pressure p w is reached, and rapidly heating the stack of plies until a working temperature T w which is above the glass transition temperature T g of the amorphous thermoplastic resin but below the melting point T f of the semi-crystalline thermoplastic resin is reached, keeping the stack of plies at the working temperature T w during a time period for compaction alone, and cooling the stack of plies, and releasing the pressure after the temperature has dropped below the glass transition temperature T g of the amorphous thermoplastic resin.