Method for producing multi-layered plastic mouldings made from a homogenous thermoplastic, in particular for producing optical components, on an injection moulding machine comprising - a plasticising unit with a plasticising screw, and - an injection mould supplied by the latter which comprises -- at least one pair of mould cavities (13, 15), a first cavity of which - pre-cavity - is intended for a premoulding and a second cavity-after-cavity - is intended for an after-moulding to be injected onto a premoulding, -- a distributor arranged downstream of the injection nozzle of the plasticising unit, which distributor connects the injection nozzle of the plasticising unit via two branch channels (23, 25) to the pre-cavity and after-cavity (13, 15) respectively, -- a controllable sealing device (24, 26) in the two branch channels (23, 25) respectively, and characterised by the following method steps: -- injecting the premoulding in the pre-cavity with a closed sealing device in the branch channel to the after-cavity, -- in the same injection stroke of the plasticising screw injecting the after-moulding onto a premoulding coming from an advance and sitting in the after-cavity with an opened sealing device in the branch channel to the after-cavity with the simultaneous cooling of the premoulding sitting in the pre-cavity, -- simultaneous charging of the pre-cavity and after-cavity (13, 15) at the end of the same injection stroke of the plasticising screw with pressure with opened sealing devices (24, 26) in the branch channels (23, 25) to the pre-cavity and after-cavity (13, 15) with the simultaneous cooling of the premoulding and after-moulding (14, 16), and -- further cooling of the premoulding and after-moulding (14, 16) and removal of the premoulding and after-moulding (14, 16) from the injection moulding tool during the withdrawal of the plasticising screw and the preparation of the plastic material for the following injection stroke of the plasticising screw. - a plasticising unit with a plasticising screw, and - an injection mould supplied by the latter which comprises -- at least one pair of mould cavities (13, 15), a first cavity of which - pre-cavity - is intended for a premoulding and a second cavity-after-cavity - is intended for an after-moulding to be injected onto a premoulding, -- a distributor arranged downstream of the injection nozzle of the plasticising unit, which distributor connects the injection nozzle of the plasticising unit via two branch channels (23, 25) to the pre-cavity and after-cavity (13, 15) respectively, -- a controllable sealing device (24, 26) in the two branch channels (23, 25) respectively, and characterised by the following method steps: -- injecting the premoulding in the pre-cavity with a closed sealing device in the branch channel to the after-cavity, -- in the same injection stroke of the plasticising screw injecting the after-moulding onto a premoulding coming from an advance and sitting in the after-cavity with an opened sealing device in the branch channel to the after-cavity with the simultaneous cooling of the premoulding sitting in the pre-cavity, -- simultaneous charging of the pre-cavity and after-cavity (13, 15) at the end of the same injection stroke of the plasticising screw with pressure with opened sealing devices (24, 26) in the branch channels (23, 25) to the pre-cavity and after-cavity (13, 15) with the simultaneous cooling of the premoulding and after-moulding (14, 16), and -- further cooling of the premoulding and after-moulding (14, 16) and removal of the premoulding and after-moulding (14, 16) from the injection moulding tool during the withdrawal of the plasticising screw and the preparation of the plastic material for the following injection stroke of the plasticising screw. -- at least one pair of mould cavities (13, 15), a first cavity of which - pre-cavity - is intended for a premoulding and a second cavity-after-cavity - is intended for an after-moulding to be injected onto a premoulding, -- a distributor arranged downstream of the injection nozzle of the plasticising unit, which distributor connects the injection nozzle of the plasticising unit via two branch channels (23, 25) to the pre-cavity and after-cavity (13, 15) respectively, -- a controllable sealing device (24, 26) in the two branch channels (23, 25) respectively, and -- injecting the premoulding in the pre-cavity with a closed sealing device in the branch channel to the after-cavity, -- in the same injection stroke of the plasticising screw injecting the after-moulding onto a premoulding coming from an advance and sitting in the after-cavity with an opened sealing device in the branch channel to the after-cavity with the simultaneous cooling of the premoulding sitting in the pre-cavity, -- simultaneous charging of the pre-cavity and after-cavity (13, 15) at the end of the same injection stroke of the plasticising screw with pressure with opened sealing devices (24, 26) in the branch channels (23, 25) to the pre-cavity and after-cavity (13, 15) with the simultaneous cooling of the premoulding and after-moulding (14, 16), and -- further cooling of the premoulding and after-moulding (14, 16) and removal of the premoulding and after-moulding (14, 16) from the injection moulding tool during the withdrawal of the plasticising screw and the preparation of the plastic material for the following injection stroke of the plasticising screw.