Clamp position accuracy directly affects mould protection and flash control. Start from the purpose: for indication alone, a 0.1 %FS rod-type sensor suffices; for closed-loop control, aim for 0.05 %FS or better and prefer a non-contact principle.
Then consider space and environment — draw-wire sensors suit tight platen gaps, while magnetostrictive sensors win on life where vibration and oil contamination are severe. Finally match the output signal to the controller to avoid extra transmitters introducing error.