Plastic Products and Mold Design

Good day guys, please I need help in the getting a device that can actually measure the mass flow rate of melted plastic inside the mode, so that I can fully automate my machine with lesser error.

I initially use a the velocity of screw and to determine the flow rate of plastic into the mold, but any distortion in the machine timing will leads to trash and the machine really need strict monitoring, please if you can help, I will really appreciate it. Thanks