Glue joints vs. stitch joints. What are the benefits of each type of manufacturing joint and which is stronger? Often I am told glue joints are stronger because glue penetrates and bonds the liners. Are there any test results that support this?
The intended use and environment that the container is going to be used in are key factors in selecting glue or staples for your manufacturer’s joint. For the majority of uses, glue is the preferred method because it provides a higher strength in most cases. Glues also enhances productivity because, in the case of a flexo folder-gluer, you can print, fold, glue and stack or bundle in a single operation while stapling would require a second operation. In applications where gluing is a second operation, it can typically be accomplished at production speeds far greater than stapling.
So why use staples? Well, they still have their purpose. Staples are often preferable for containers that are subject to high levels of moisture or exposure to outdoor elements and temperature change. These types of containers are typically coated with materials that repel water such as wax and other weather resistant coatings. Glue usually does a poor job of bonding these types of materials.
Both methods have their disadvantages too. As mentioned above, glued joints can be more susceptible temperature and moisture changes and may not adhere well to some printed or coated surfaces. Glued joints take a little longer to set, but since they are going through a stacking to compression device that’s usually a non-issue.
Staples may have a few more disadvantages. They are typically not desirable for use with food products and can complicate the recycling process. Staples can also scratch or damage products inside of the container, though this is more likely in manual than automatic operations. They can also create a bit more of a safety risk especially if they are not properly installed.
Here are some documents that provide additional information.