Rotary Knife Cutoff

Cut-to-length process using rotary knife cutter and "recipe" storage to create flexible automation solution.


A web of material is fed into the machine by a prime mover. The machine must cut the web into regular length pieces or follow a programmed “recipe” of different lengths depending on production requirements. The cutter speed must be synchronous to the web speed while the cutter is engaged with the web.
Roll Feed Rotary Knife Cutoff Application


Rotary Cutter application

The EMAX 1-1/2 axis controller is selected for this challenging master/slave application. A servo motor is connected to the rotary cutter via a precision gearbox and, a line encoder with measuring roller is positioned to ride on the web of material. The touch-screen operator interface connects directly to the EMAX and is used for programming the cut length, cut length “recipe”, diagnostics and error messages. An application program for the EMAX controller was developed using the Emerald Motion Language (EML) PC software to create the following sequence:

  • The seal/cut drum is positioned so the knives are horizontal and clear of the web of material for machine threading.
  • The web prime mover starts running and the servo makes the first trim cut.
  • An electronic cam in the EMAX controller, driven by the line encoder is used to control the motion of the rotary cutter.
  • When a multi-length cut “recipe” is programmed the EMAX uses powerful switch cam instructions to seamlessly execute a series of electronic cams to change the motion of the rotary cutter to cut the various lengths.
  • When the programmed number of cut pieces or “recipe” of pieces is completed the rotary cutter stops clear of the web and the EMAX signals the prime mover to stop.

Additional Application Features

  • Touchscreen operator interface for “recipe” programming, batch count, parameter entry, diagnostics and error messages.
  • Control of the web prime mover motor.
  • Multiple “recipes” are stored in the EMAX memory and quickly selected using the operator interface.

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