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Air Shafts: Not Recommended for Roll Handling

Roll handling equipment is utilized to assist machine operators with loading and unloading rolls of material into and out of converting machinery. Roll handing equipment is also used to assist with moving, storing and packaging rolls. Basic concepts for accomplishing this may be to grip the roll of material by the outside diameter, in a clamping device, for instance or gripping the inside diameter of the core on which the roll is wound. This tech tip discusses the latter method of gripping a roll by the core.

Air shafts and chucks are very common in the converting industry. They are used to grip roll cores and deliver torque to a core in the rotational direction. Gripping the inside diameter of the core on which a roll of material is wound allows brake torque (unwind) and drive torque (rewind) ultimately be delivered to the web in the form of web tension.

Air shafts and chucks are specifically designed to grip a core and apply torque to that core in the rotational direction. Again, for unwinding and rewinding applications. Air shafts and chucks should not be used for roll handling applications and here’s why:

  1. Air shafts and chucks inflate and deflate. Roll handling equipment typically lifts rolls of material off the floor to allow moving and orienting. Consider the consequences if the air shaft suddenly deflated, inadvertently, while suspending a roll of material in the air.
  2. Air shafts are designed to supply torque in the rotational (radial) direction. Roll handling devices require torque be delivered to the core in the axial direction. Air shafts are simply not designed to supply large amounts of torque in the axial direction. Cores may just slip off the air shaft as the roll of material is being lifted. Long term effects may damage the air shaft.
  3. A mechanically locking device specifically designed to properly grip the core on which a roll of material is wound is the best choice for roll handling when using this method of roll handling. Mechanically locking teeth do not use air pressure to operate, so loss of air pressure is not a concern. Properly designed core gripping teeth will supply enough torque to the roll core to allow the roll material to remain suspended and allow roll orientation.

Jeff Damour
Converter Accessory Corporation

**DISCLAIMER - A great deal of time has been invested in the development of our weekly tech tips. To the best of our knowledge, they are accurate. It is up to the user to verify all results.


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