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Question and Answer

Gluing Systems

by Staff

August-September, 2012
What routine maintenance should be performed on a cold glue or hot melt system?
A cold glue system should be completely flushed from pump to valve at least four times per year or whenever changing the type of glue being used. Fill a five-gallon bucket with clean water and run the entire five gallons through the system. Make sure all glue lines are open and to speed up the process, remove the internal components of the glue valves (spring, plunger and nozzle). When re-introducing glue, make sure to open all glue lines so a consistent flow of adhesive is coming through the lines.

The frequency of cleaning cold glue filters depends on the type of glue and the filter mesh size. Check the filter once per week to make sure there isn’t too much build up and adjust the frequency based on the condition of the filter.

Hot melt systems require unique flushing or purging. When changing types of adhesive, add to the system a hot melt purging compound based on the manufacturer’s specification and purge the system until the compound is completely through all the lines in the system. Add the new hot melt to the tank once the purging compound has cleared out all of the old hot melt adhesive. Do not leave hot melt systems on when not in use. The glue can become charred and clog the filters, glue hoses and guns if overheated.

How can a gluing / QA system save money?
The payback on a glue system can be measured in several ways:

  • Glue systems that are old or have not been properly maintained can create costly downtime; whereas a new system with newer technology can run problem-free. Costly trouble-shooting time incurred with an old system can be eliminated, and new systems have easy maintenance capabilities designed into them, such as water-flushing at the manifold.
  • High-speed cold glue systems can replace glue wheels for side seam gluing on a carton. Mechanical glue wheels are cumbersome to clean; require a thicker viscosity adhesive; use costly spare parts and if not set properly, can create defects where the carton is stuck together due to glue ‘sling’. A high-speed cold glue extrusion system can apply glue on the opposite side of the carton (4th panel), creating similar results to a glue wheel without the drawbacks of glue pots.
  • New technology allows glue systems to monitor carton length and can identify potential machine jams due to overlapped or doubled cartons. This saves run time, reduces carton waste and increases overall throughput.
  • Systems have become more intelligent, requiring less operator input which reduces makeready time. Programming a new job can be done in a matter of a couple minutes, allowing the machine to produce more cartons. New systems also have better diagnostics to help quickly identify where a problem could be occurring.
What quality assurance options are most often used on a folder-gluer?
Quality assurance requirements have become standard for folding carton buyers. Glue detection, which identifies cartons that could be stuck together or fall apart from not enough glue, almost is mandatory. Mix inspection is equally, if not more, important to prevent the wrong carton from potentially being shipped to the end user. Jam detection also is important. Quality assurance systems can detect jams much quicker than mechanical switches and can stop the machine much sooner, which can reduce downtime and prevent possible machine damage.

How fast does a gluing system operate – cold and hot?
In order to get the best performance out of your glue system, you first need to make sure maintenance is performed on the system, use a glue that machines well (it’s not all about cost per pound), set the height of the glue valve to the manufacturer’s specification and program your distances accurately (there are a few more tricks, but that’s in the advanced course). With this criteria in place, cold glue systems can operate over 650 MPM with a +/- tolerance of 2mm at the start and end of a glue pattern.

An electric-operated hot glue system can operate over 500 MPM with a +/- tolerance of 3mm at the start and end of a glue pattern.

InsideFinishing would like to thank W.H. Leary for its assistance with this article. For more information, visit www.whleary.com.