Hi IOPP Members, I started sharing some of my knowledge and experiences in the adhesive/hot-melt equipment industry with other professionals in related industries. As a result, I started creating troubleshooting tips for Adhesives and Hot Melt Equipment. I will be covering some of the most common problems when using adhesives and hot melt equipment, the causes of those problems and solutions to prevent those problems in the future. I will be posting on here every other week with a new topic. Please feel free to reply with any feedback or your own thoughts & experiences related to the topic. I also attached the PDF if you want to print it out.
Hot Melt Troubleshooting Blog #2: Topic – Don't Lose Money from Box Pop-Opens
When you're running adhesives on fast packaging lines, you may experience a flap popping open from time to time. Even worse, you may have shipped a product to your end user and found that the boxes you shipped them popped-open when they arrived, Ouch! This can be extremely costly for your company, now your customer must ship the product back to you, you have to re-package the product, you're behind on schedule, and doing double the work. That is worst case scenario, sometimes pop opens may not seem like a big issue if it is only happening a few times here and there. It can be very costly to stop your lines for one box, pay your employee to seal the box again and get your line back up to speed. It is easy to blame your glue; keep in mind the glue is not intelligent enough to choose to work on one flap and not the other. Pop-opens can happen for a variety of reasons, my goal is to outline my experiences with boxes popping-open and how you can prevent losing money due to pop-opens in the future.
Scenario 1: Less Glue = More Savings
It is common for manufacturers to save money through stitching their hot-melt onto their boxes and/or move to smaller orifice nozzles, this can make the glue cool faster than it should and only penetrate on flap, see (fig 1.). These are two easy ways to cut down on the amount of glue you are using, however if it is not tested properly, you may run into costly problems into the future. If you are experiencing pop-opens, you might be using too little adhesive and costing you more than the perceived savings. Solution: When changing the amount of glue you are using, Consult with your glue rep and quality team to make sure that you do the right testing to ensure you have 100% fiber tear and your box will hold up once it gets to the end user. NOTE: Do not change over all your lines to using less glue, begin with one batch or one line and test those boxes before converting the rest of your lines.
Scenario 2: Inconsistent Compression
If you are having random flaps pop open after compression, you may not be getting enough compression on your box. I see this happen often in industries that package bottles and the box flaps are on the side. There is nothing for the flap to compress against on the top flap where the bottle neck is at and will often cause a pop-open if the adhesive doesn't set up fast enough. One way to tell if you're not getting compression is if glue is not on the flap and only on the spot where it was dispensed, this failure mode is referred to as an adhesive failure, see (Fig 1.). Solution: Have your mechanic add more compression time to your box so your glue has time to form a bond, increase the amount of compression, or consider testing a higher tack hot-melt that will grab the flap easier.
Scenario 3: More glue = Better Bond
It seems intuitive that if you put more glue on your boxes, your bond will be better. This is true up to a certain point. The more glue you use, the longer it will take for your hot-melt to set-up. This is because the glue keeps itself warm. If you are putting too much glue on, your box would have glue on the flap and where the glue was dispensed onto the box. This is referred to as a cohesive failure, see (Fig 2.) Solution: Switch to a smaller orifice nozzle or turn down the pressure to your solenoids. You might also try turning down the temperature in 5 degree increments to help the glue set-up faster.
Scenario 4: Lowering the Temperature Too Much:
It is very common for companies to lower their temperature in their hoses and guns to prevent charring. This however can lead to pop-opens if you turn the temperature too low. If the temperature is lower than the recommended operating temperature on the TDS, the adhesive can set prematurely before compression see (Fig 1.). Solution: Refer to your manufacturer's TDS and make sure that you are running your product within the recommended operating temperature. The warmer you run the adhesive, the slower the set-time, the colder the glue is, the faster it will set-up. Also, if you are running at faster line speeds, lower your temp. in 5°F increments, because your glue needs to set up faster.
(Fig 1.) Located in Attached PDF
Adhesive Failure: Refers to the state when your adhesive only penetrates on one of the substrate surfaces. This often occurs when adhesive is cooled before compression, you are using too little adhesive, or you have poor compression.
(Fig 2.) Located in Attached PDF
Cohesive Failure: Refers to the state when your adhesive remains on both substrates surfaces. This often occurs when you are using too much glue and/or your glue temperature is too hot and does not set during compression. This may also occur if your box is shifted during compression or before it has set up.
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Nick Woerner
Account Manager, ADQ Inc.
Whitestown IN
(317) 410-4440
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