Despite all the precautions you might take when draining your hot melt adhesive system (HMS), with careful cleaning of hoses and nozzles and thorough flushing each time you exchange hot melts, blockages are always a risk. These occur due to a build-up of old adhesive in the melt tank itself, or the connecting Hoses and Guns. They can also arise from dirt and sediment from old glue/cardboard dust/product restricting the flow of adhesive and eventually causing a blockage.
But why do these blockages occur, and is there anything you can do about it? Fortunately, preventing or minimising the number of blockages is fairly straightforward. Read on to find out more.
The Most Common Causes Of Hot Melt Blockages
The most common cause of HMS blockages is a lack of maintenance or preventative steps. With repeated use, and especially when HMS units are drained in order to exchange one hot melt for another, residue starts to build up around the sides of the tank. At the same time, valves, hoses and nozzles can become plugged with dirt and contaminant particles.
If you suspect a blockage and your HMS unit hasn’t been serviced, cleaned or rebuilt in some time, the problem is probably due to one of the following:
- The melt tank has been left on and the adhesive has cooked and jellified, creating a hard, impermeable barrier around the inside of the tank and Pump infeed.
- Carbon from contaminant particles and sediment has built up and is blocking the tank filter. (This can be resolved by removing the filter for either cleaning or replacement)
- Degraded (carbonised, cooked, black lumps of it etc.) adhesive, or char, has been sucked up the pump and become lodged in the hose or nozzle.
- The glue gun in-line filters have become blocked and need changing.
- The dispenser nozzle is blocked with degraded adhesive. (Because it’s the last point in the system, the build-up eventually blocks it.)
Preventing And Resolving Blockages
In many cases, blockages can be prevented by cleaning and replacing the all filters at regular intervals (check with your manufacturer of the timings), and submitting your hot melt dispenser for professional cleaning and rebuilding every 12 months, depending on the intensity of use. It’s always easier to take preventative action to avoid blockages rather than remedying one once it’s occurred. A blockage can cause frustrating downtime and damage your equipment, but even bad blockages can usually be fixed quickly with the right equipment and cleaning process. So if you suspect a blockage, or would like to find out more about maintaining your HMS equipment for optimum efficiency, please contact our technical team.