It is Usually Always a Clog
The most common reason for your hot glue system acting up is because of a clog. Clogs are common because you are working with glue, which is sticky and chars over time. Below are some of the most common technical calls we receive, with the solution…and you guessed it, it’s usually always a clog.
Pump is not pumping
There are several reasons as to why your pump can stop up. Honestly, it is usually dirty oily air in your shifter. However, when it is not your shifter it is usually a clog. If your shifter is running fine, but it sucked something up into the hydraulics of the pump, the pump shifter will be stopped in the top position, unable to shift down. That is because you probably have some char or debris in your hot glue reservoir and while pumping, you sucked something up into the ball check valve. You have now clogged up your pump and need to send it in for a flush and clean. Another potential issue could arise if your pump is running but sluggish. If your pump is running mush slower than it used to, it is probably because you haven’t changed out your tank filter and it is clogged. The tank filter is located on the side of the tank and filters all glue before it runs into the hoses. If that filter is not regularly changed (every 500 – 1500 hours depending on how clean your glue is) then that clog can cause pressure to back up into the tank and not allow your pump to run at full capacity.
Gun is not firing
If your gun is not firing at all, it is probably your solenoid valve. However, if your gun is firing every other time or randomly, it is probably due to a clog in your in-line filters. The in-line filters filter the glue from your hoses into your gun. These filters are there to help filter our char or debris that was missed by the tank filter or that has built up in the heated hose. If the filter screens are not changed regularly, they will get clogged up and not allow for your gun to fire properly. For example, if you need to increase air pressure in order for your gun to fire, it is probably the in-line filter clogged up. Another clog can happen in the gun manifold itself. Typically, this is only in multi-module guns. If you have a multi-module gun and the last module in the line is not firing, there is probably a clog in the manifold.
Module Drips
If your module is constantly dripping glue, then you have a clog in your module. This is most common in air open, spring close modules. A piece of char will get stuck in the seat and not allow the piston to seal tightly, causing the glue to drip out. A clogged module will need to be replaced with a new module.
Nozzle keeps clogging
This one is fairly straight-forward. If your nozzles keep clogging there are a few solutions. First, you can change out your in-line gun filters. They are probably not clean and not filtering the glue through the gun. You can also increase your nozzle diameter. If you are running small hole nozzles such as .010 or .012 diameter, try a .014 or .016 and you will start to see less clogging. However, that will lay down a little more glue, so keep that in mind when reviewing your glue usage.
The best way overall to reduce the number of clogs in your hot melt systems is to do preventative maintenance. That means cleaning your tank every month or every quarter, depending on how many shifts your tanks are running. Universal Systems makes Purge Plus tank cleaner and we sell them in a 5-gallon pail so that you are set for at least 2 – 3 cleanings. Additionally, change out your tank filters and in-line filters. These 3 tips are the most inexpensive way to keep your hot melt system running smoothly.
Not All Glue Melts Well Together
One of the most common customer service calls we receive has to do with adhesives that get mixed together and then create a mess inside the melter tank. It is important for any packaging line operator to understand that not all glue is made equal, which means they might not mix well together. Especially when operating at high heat with high demand.
Know Your Adhesive
There are two main types of adhesives that you could be using in your tank: ethylene-vinyl acetate (EVA) and polyolefin. EVA is a copolymer adhesive, most commonly used in the paper, packaging, and assembly industries, as they bond to a variety of cellulosic materials and have a wide range of formulation. Polyolefin is used mostly at low application temperatures and works best in spray or film form. The best thing to do is keep the adhesive information so that you do not accidentally order the wrong type of adhesive and mix them together. When EVA and PVA are mixed together and heated, they create a thick gelatin formulation that will destroy your melter pot. This is not something that can be cleaned out, even with the strongest of cleaners.
Clean & Purge Your Tank
It is imperative, whenever starting a new batch of adhesive to thoroughly purge and clean your tank, hoses and guns. Removing all remanence of previous adhesive build up. This will prevent any clogs or char from filtering through your adhesive system and causing any unnecessary adhesive mixing. Universal Systems offers a cleaner called Purge Plus™ that, when heated to the correct temperature within your tank, will remove all of the old adhesive and char.
For more information on Universal Systems SE or our Purge Plus™ cleaner, please contact us at (800) 848-5018 or email us at sales@ussefl.com.