Troubleshooting Loose Caps on a Spindle Capping Machine

Most automatic capping machines, spindle cappers included, will be pre-set to run caps for a specific project before the machine reaches the production floor.  The packaging equipment manufacturer will "dial in" the machine to work with the cap or caps to be used, leaving only minor adjustments when changeover from one cap to another is necessary.  Sometimes, however, a spindle capping machine will simply stop consistently sealing bottles, leaving the packager with numerous loose caps upon output.  On most occasions, simple adjustments can correct this problem, but making the wrong adjustments can often exacerbate the issue.  The following is a quick checklist for the operator of the spindle capper to follow if loose caps become an issue.

 

 

The incorrect placement of the spindle wheels on the cap as it passes through the packaging machine is one cause of untightened caps.  If the spindle wheels sit to high or to low on the cap, the amount of torque will change and affect the tightness achieved by the capping machine.  As a general rule, each spindle wheel will contact the cap at the midpoint as it passes by, meaning a slight decline will exist for each set of spindle wheels from the entrance to the exit of the capper.  The slight decline between spindle sets accounts for the portion of the tightening that will be done by the previous set of spindles.  Even having the placement of the spindle wheels off on one set of disks can result in loose caps.  

 

Of course, if the spindle wheels are spaced too wide, the disks will get no traction on the cap and loose caps will result.  Set the disks too narrow and the squeezing and pressure applied to the caps can also lead to unreliable results.  Fortunately, making corrections to spindle wheel placement is a simply task.  The operator of a spindle capper can simply turn the machine off and slowly move a bottle and cap through the disks to ensure that each set of disks is at the proper height and width.  Adjustments are normally made with simple hand wheels or knobs.

 

 

Even after the spindle wheels are positioned correctly, they can still be the cause of inconsistent capping.  The speed of the spindle wheels can be set using a speed pot, allowing the operator to turn the speed up or down with a simple dial.  If spindle wheels are moving too slow, they may simply not turn the screw cap enough to complete the necessary tightening.  Scars and scrapes on the cap may also be evidence of a speed setting that is too high.  An operator should make small adjustments to the speed of the disks to attempt to resolve the capper issues.

 

 

If loose caps continue to exit the capping machine after the spindle wheels have been adjusted, the stability of the bottle may be the issue.  Gripper belts are used to keep the bottle steady as it passes through the bottle capper, with some tall or oddly shaped bottles requiring a double set of belts.  If the belts are not properly positioned, the consistency of the capping process can be compromised.  Gripper belts set too high on the bottle can squeeze or crush the neck, and as a result caps will seem to be tightly placed on the bottle, until the pressure from the neck is removed.  Setting the gripper belts too low will usually result in crooked caps, which at times can lead to cross threading or less than tightly sealed bottles. 

 

Like the spindle wheels, setting the gripper belts too tightly against the bottles can crush or squeeze the bottles, leading to loose caps and setting them too wide will simply cause bottles to rock or shake as they pass through the capper, leading to a multitude of issues.  Simple knob adjustments will allow the operator to fine-tune the placement of the gripper belts on the bottle.

 

 

If issues persist after adjustments to both the disks and the belts, the spindle wheels themselves should be checked for wear and tear.  The disks on the spindle capper will need to be replaced occasionally, and wear and tear can be accelerated if the wheels are not properly aligned.  Environmental issues, product, product fumes and other factors may also lead to the breakdown of the rubber disks and keeping an extra set of disks on hand is always a good idea.

 

In most cases, making either one or a combination of these adjustments will correct the problem of excessive loose caps.  If the issue is not resolved after making these adjustments or changes, we welcome anyone with a spindle capper to contact LPS toll free at 1-888-393-3693 for assistance.