Method of forming blisters in a film web, which is moved intermittently in a conveying direction, the method comprising the following steps: a) providing a moulding device comprising a first moulding tool and a second moulding tool, which has a multiplicity of mould recesses, wherein the first and the second forming tool (12, 14) clamp a portion of the film web between them in a moulding position, wherein the moulding device also comprises a compressed air device, which is actuated to form the blisters when the first moulding tool and the second moulding tool are arranged in the moulding position, b) providing a multiplicity of temperature sensors, which are integrated in the first or the second moulding tool (12, 14), c) providing a heating device comprising a multiplicity of heating elements (30, 32) for heating the film web, wherein the heating device is arranged upstream of the moulding device with respect to the conveying direction, d) arranging a portion of the film web in the region of the heating device and actuating the heating device to heat the portion of the film web, e) arranging the heated portion of the film web in the moulding device between the first and the second moulding tool (12, 14) and actuating the moulding device, in order to arrange the first moulding tool and the second moulding tool in the moulding position, f) using the multiplicity of temperature sensors for measuring a corresponding multiplicity of actual temperature values (T IST) of the portion of the film web and comparing the actual temperature values (T IST) with a setpoint temperature value (T SOLL), wherein the measuring of the actual temperature values (T IST) is performed when the first moulding tool and the second moulding tool are arranged in the moulding position, and g) adjusting the heating output of at least one of the multiplicity of heating elements (30, 32) if a deviation of one or more measured actual temperature values (T IST) from the setpoint temperature value (T SOLL) has been established in step f). a) providing a moulding device comprising a first moulding tool and a second moulding tool, which has a multiplicity of mould recesses, wherein the first and the second forming tool (12, 14) clamp a portion of the film web between them in a moulding position, wherein the moulding device also comprises a compressed air device, which is actuated to form the blisters when the first moulding tool and the second moulding tool are arranged in the moulding position, b) providing a multiplicity of temperature sensors, which are integrated in the first or the second moulding tool (12, 14), c) providing a heating device comprising a multiplicity of heating elements (30, 32) for heating the film web, wherein the heating device is arranged upstream of the moulding device with respect to the conveying direction, d) arranging a portion of the film web in the region of the heating device and actuating the heating device to heat the portion of the film web, e) arranging the heated portion of the film web in the moulding device between the first and the second moulding tool (12, 14) and actuating the moulding device, in order to arrange the first moulding tool and the second moulding tool in the moulding position, f) using the multiplicity of temperature sensors for measuring a corresponding multiplicity of actual temperature values (T IST) of the portion of the film web and comparing the actual temperature values (T IST) with a setpoint temperature value (T SOLL), wherein the measuring of the actual temperature values (T IST) is performed when the first moulding tool and the second moulding tool are arranged in the moulding position, and g) adjusting the heating output of at least one of the multiplicity of heating elements (30, 32) if a deviation of one or more measured actual temperature values (T IST) from the setpoint temperature value (T SOLL) has been established in step f).