What does your adhesive application system do when production comes to a standstill? For example, because you are retrofitting the plant. Or if no adhesive application is needed at all for a product. Do you switch off the adhesive application system completely? Naturally, you want to resume production as quickly as possible after the shutdown. Therefore, you may prefer to leave the adhesive at processing temperature, especially if you do not know exactly how long the interruption will last.
But there is one problem: If the melted adhesive is heated up for an extended period of time without being used, it starts to decompose. Thread pulling and discoloration of the adhesive are the first signs. The adhesive becomes more viscous, the adhesive pressure decreases, and ultimately the adhesive bond suffers. If the adhesive filters are then also clogged, all alarm bells should ring: The adhesive is about to burn! The process is known as adhesive coking, cracking, or charring.
You are familiar with that: Burnt adhesive no longer adheres and you produce scrap! Charring also clogs the application heads and hoses. Production is at a standstill, this time because of the adhesive application system. Minor adhesive charring can be eliminated by flushing the system, but it is not always possible to flush everything out. In the worst case, irreparable damage is caused to the components. A huge loss of quality and time.
What can you do about it? Take care of the adhesive and lower the temperature if the adhesive application system is not being used but you do not want to switch it off completely.
If your adhesive application system is not needed for more than 30-45 minutes, I recommend lowering the adhesive temperature by at least 20-30 °C of the current processing temperature. This can be done manually or automatically. This protects the adhesive, but it can be heated back up to operating temperature in just a few minutes at any time. From my experience as a technical account manager of many years, I can assure you that those few minutes are worth their weight in gold. It is only a fraction of what cleaning or even replacing an entire adhesive application system due to charred adhesive will cost you in time and money! You can only gain: in quality, in process reliability, and in the longevity of your system. Overnight or for extended interruptions, you naturally switch off the adhesive application system completely as usual.
What is your experience? Do you lower the adhesive temperature during downtime? Why not? Write a comment, we are interested in your opinion!