Say Goodbye to Clogged Nozzles: Maintenance Tips for Hot Melt Systems
In any hot melt system, the adhesive dispensing nozzles are the final and critical point of contact before application to the substrate. Hot melt glue nozzle performance directly dictates the quality of the bond and the efficiency of your production line, with a clogged or partially blocked nozzle often leading to spoiled products and materials, as well as production delays. Implementing a consistent cleaning and maintenance routine for your hot melt nozzles is, therefore, a core part of operational best practice in most assembly lines. Read on as we discuss how to keep your adhesive dispensing nozzles in great condition and maintain a consistent adhesive flow.
Regular hot melt nozzle cleaning: why it’s important
The main reason why it’s important to keep your nozzles clean is to maintain a consistent and unimpeded flow of adhesive. Over time, even high quality and well formulated adhesive can begin to cure or char within the nozzle, especially during idle periods or system cool downs. This buildup restricts the flow of adhesive, causing stringing, inconsistent bead sizes, or completely blocking the nozzle in some cases. Regular cleaning removes its accumulation before it can cause a blockage. Proactively doing this prevents unexpected line stoppages, and makes sure that the adhesive is applied exactly as specified.
How to identify clogged hot melt glue nozzles
A fully clogged nozzle is fairly obvious to diagnose. Normally the dispenser shuts down at this point. However, there are several early signs of a blockage that, if addressed early, could prevent a major system failure. Keep an eye out for these key indicators.
1) Inconsistent bead profile: the most common sign of an impending blockage is a change in the shape or size of the adhesive bead. The bead may appear thinner than usual, wavy, or intermittent.
2) Adhesive stringing: when the nozzle exit is partially blocked, it can prevent a clean cut off, causing fine filaments of adhesive to form as they are pulled from the nozzle.
3) Increase system pressure: a partial nozzle blockage will force the hot melt adhesive machine’s pump to work harder to push the adhesive through the nozzle, which is often indicated by rising system pressure readings.
4) Visible residue: visually inspecting the nozzle tip may reveal charred particles or cured adhesive building up around the orifice.
Best practices to prevent clogged nozzles
There are several steps you can take to maintain your adhesive dispensing nozzles to prevent blockages. But first, always wear the appropriate personal protective equipment (PPE), including heat resistant gloves and safety glasses, before handling hot components. Power the system down and release pressure according to the manufacturer’s guidelines before attempting maintenance.
Then, perform the following after every shutdown:
v External cleaning: while the nozzle is still warm, use a silicone spray and a nonabrasive brush or cloth to wipe away any external adhesive residue.
v Nozzle purge: before shutdown, purge a small amount of adhesive through the system. This helps to clear the nozzle of any material that might otherwise cure inside it as it cools.
Avoid using metal probes or hard metal objects to clear a blocked nozzle orifice, as this can easily scratch or damage the precision machined opening, permanently altering its flow characteristics. If a manual cleaning tool is needed, use only soft metal or a manufacturer-approved implement.
Another best practice is to use high quality adhesives, as the formulation of the adhesive itself is a fundamental factor in preventing blockages. Premium adhesives are formulated for better thermal stability, making them less prone to charring and degradation at normal operating temperatures. Using an adhesive with poor thermal stability could create a rapid buildup of contaminants within the hot melt tank and hose, which inevitably find their way into the hot melt nozzles. Investing in a good adhesive will reduce the rate of char formation in your system, as well as extending the time needed between cleanings, and protecting your equipment from premature wear.
What next?
If you have attempted to clean the nozzles yourself and there is still a full or partial blockage, get in touch with the team at Adhesive Laundry today. We specialise in fully restoring hot melt equipment to optimal working conditions, and can restore even heavily soiled and blocked equipment. Contact us today for a quote on 01480 271800 or send us a message by clicking here.