Filling Machines with Screw Indexing

Filling Machines and Screw Indexing

Filling machines come in all different types and sizes.  From tabletop overflow fillers to fully automatic piston fillers, these packaging machines can fill free flowing liquids as well as thick, viscous products. Just as there exist a number of different principles for moving product into the bottle, there exist a number of different ways to move bottles through a filling machine.
While the most common types of indexing will use entry and exit gates or a simple starwheel, some packagers may prefer or even require screw indexing.  The preference may come from the fact that screw indexing can, in many circumstances, add speed to the packaging process.  For example, when using pin indexing, there will be a pause or delay as containers move out of the filling area before the next set of empty containers enter the fill area.  While this delay may be only a fraction of a second, those fractions add up over an entire production day.  Screw indexing allows for the continuous entry and exit of containers, with a pause only to complete the fill, thus reducing the time for each fill cycle.
In other cases, a unique bottle shape or material may call for a timing screw versus some other type of filling machine indexing.  An oval bottle may cause some issues in spacing or alignment when using pin indexing and guide rail.  In such a case, screw indexing may be necessary to ensure a consistent and reliable movement and fill.  Some containers made from softer materials may also be better suited to screw indexing to avoid marring or damaging during the indexing process.
In the video link above, screw indexing can be seen in the testing of a packaging line.  This packaging system uses a laning conveyor to move containers onto the main conveyor system.  From here, the main conveyor moves the containers into the filling machine and the timing screw can be seen indexing containers into and out of the fill area.  A servo motor stops the screw to allow the alignment of the containers under the fill heads.  Once the fill is complete, the screw turns again to allow the containers to move to the next packaging machine, here a spindle capping machine.
A single screw can work with a number of different containers, depending on the range in size and material.  In some cases, the screws may need to be changed out if a company is running a small bottle and an extremely large bottle on the same filling machine.  While such changeover will require some downtime, in many cases the downtime will not be significantly longer than the changeover for pin or starwheel indexing.
Just as the product being filled will have some bearing on the type of filling machine to be used, the package itself will have some bearing on the indexing type used on the filling machine.  Consult with a packaging professional to ensure that you have both the correct filling machine and the correct indexing type for your unique application.