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Jeffrey Damour

If you unwind and rewind rolls of material, you most likely must decide on the best type of core holding for your converting operation. That is, how you hold the core of your material roll for unwinding or rewinding. There is a multitude of core holders from which to choose. Here are the most common types:

Air shaft – a deflated air shaft is inserted into a core. It is then inflated with compressed air to activate a core gripping mechanism.

Main Advantages:

·      Easiest to use

·      Works well for high tension (torque requirement) applications

·      Good for heavy rolls

Main disadvantages:

·      Most expensive

·      Custom manufactured with longer lead-times

·      Can be heavy for handling

Dual air chuck – dual air chucks are similar to air shafts but utilize two, short, independently inflated air chucks mounted on a thru shaft.

Main advantages:

·      May be lighter weight than an air shaft

·      Cost effective, usually stocked

·      Easy to use

Main disadvantages:

·      Must move air chucks for varying web widths

·      Must be inflated independently (two places, instead of one)

·      Less torque for lighter tension applications

Tandem air chuck – Tandem air chucks are similar to dual chucks but they can be inflated in one position because they use pneumatic tubing between chucks.

Main advantages:

·      Air chuck advantages (above) but faster roll loading and unloading with one inflation point

·      Less expensive than air shafts

·      May be faster delivery than a custom air shaft

Main disadvantages:

·      Must be moved in and out for varying web widths

·      Less torque than air shafts

·      More expensive than dual air chucks

Dual mechanical chucks – mechanical chucks lock cores in place without the use of air. They are very similar to their air chuck counterparts, but no air required.

Main advantages:

·      No air required, may be useful for specific applications

·      Some designs are “torque sensitive” meaning they work GREAT for HIGH torque applications where tension may be very high

·      Cost effective

Main disadvantages:

·      May be harder to load and unload than air chucks

·      Core dust may affect operation

·      Minor diameter to expanded diameter range does not allow for a lot of core size variance.

Chuck (air or mechanical) and end plug – This type of core holding arrangement can use air or mechanical chucks and a “dummy” end plug. The end plug is a cone shaped device that simply supports one end of the core while the chuck supports the opposite core end. The chuck delivers the torque to lock the core in place.

Main advantages:

·      Cost effective

·      Simple

·      End plug includes a core stop flange for core alignment in the unwind or rewind

Main disadvantage:

·      Half the torque output, compared to dual chucks

·      Not well suited for wide widths, large diameter rolls and / or high web tension

Core cones – the simplest of all core holding methods. This system uses two cone shaped, serrated cones that are pressed into each core end to hold and lock the core in place.

Main advantages:

·      Extremely cost effective

·      Great for crushed cores

·      Very simple to use

Main disadvantages:

·      Least operator friendly

·      Limited to certain core sizes

·      Cone must be removed to load and unload