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To solve the problem of thermal deformation during the cut-off process of polylactic acid (PLA) filter rods for heated tobacco products (HTPs), a vortex tube was added to the cut-off unit of filter rod maker to cool the cut-off knife. By numerical simulation, the preferable parameters of the vortex tube were determined: inlet pressure Pin 0.5 MPa, inlet air temperature Tin 26.85 °C, the air flow leaving the vortex tube is divided into hot and cold streams. When the hot end air pressure Phot is fixed at 0.07 MPa, the maximum cooling effect can be achieved. The vortex tube cooling was tested on an AF-KDF2 filter rod maker. The results showed that the temperature of the cut-off knife was lowered from 57.8 °C to 13.1 °C, the fibrous tail at filter's cut end was avoided, meantime, the running speed of the maker was increased from 50 m/min to 150 m/min. The roundness and circumference of the filter rods were stably within the specified limits. This technology supports the improvement of HTP quality. [ABSTRACT FROM AUTHOR]