Cooling

Temperature Reduction How Does Lowering Temperature Help Reduce Adhesive Curing? Adhesive curing is a problem. Burnt hotmelt adhesive application compromises performance and can damage the entire system. It's as frustrating as it is common. The good news is: there is something that can be done about it! Since excessive heating is the root cause of curing, lowering adhesive temperature during production stoppages can be a good approach. Ultimately, this saves time and money by preventing prolonged production downtime and reducing waste product.

Heated Adhesive Does Not Like to Sit Idle

Adhesive application systems are typically switched on and off together with the entire machine, so they are ready to apply adhesive when production starts. However, when the line stops – for instance due to tooling changes – the adhesive application system also remains idle. Of course, operators aiming for continuous production, especially if they do not know exactly how long the stoppage will last, may prefer to keep the adhesive at process temperature for a while when it is not in use. But there is a problem: melted adhesive begins to degrade when it remains idle unused for an extended period. The first signs of degradation are adhesive stretching and color change. The adhesive's viscosity increases, its pressure drops, and consequently adhesion is compromised. Additionally, if adhesive filters become clogged, all alarm bells should sound: adhesive is about to burn! This process is known as adhesive curing, cracking, or carbonization. Curing Causes Production Stoppages This is no secret: burnt adhesive loses bonding quality and product is wasted! Curing also clogs application heads and hoses. As a result, production comes to a standstill – this time due to the adhesive application system! Minor adhesive curing can be removed by flushing the system, but rinsing everything is not always possible. In the worst case, irreparable damage occurs to components. This means significant quality and time loss. What can be done to prevent this? Adhesive can be protected by lowering the temperature when the adhesive application system is not in use but should not be completely shut down.

When Does Temperature Reduction Make Sense?

If the adhesive application system is not needed for more than 30-45 minutes, it is recommended to lower the adhesive temperature by at least 20-30°C from the current process temperature. This both protects the adhesive and allows it to return to working temperature in just a few minutes at any time. Those few minutes are worth their weight in gold. Cleaning and even replacing the entire adhesive application system due to cured adhesive is only a fraction of the cost in terms of time and money! The advantages are at your fingertips: better quality, increased process reliability, and longer machine operating time. For overnight or longer stoppages, the adhesive application system can of course be completely shut down.     *Robert Seiferth has headed the technical advisory hotline for 12 years, providing solutions to technical problems for customers from various sectors. Robert Seiferth* Technical Customer Manager Robatech Germany