Archive for the ‘Finishing/Converting’ Category

Trouble Stacking RSCs

July 14, 2022

Armando asks:

You know most RSC box styles when glue and strapped are not totally flat, due to the extra thickness of the glue flap. This adds some instability to the finished pallets and may prevent stacking.

To solve it we´ve tried to crush the glue flap, but if we do this, the scoring between the flap and the first panel, kind of disappears and it causes the box to fold in a weird way.

We´ve also tried alternating the directions of the bundles, and it helps in some styles, but some others, have the flap right in the middle and it’s difficult to avoid.

Do you have an idea how can we solve the problem without affecting the score?

Yeah, that’s a tough one and one that most plants encounter at one time or another. Unfortunately, there is no one-size-fits-all answer. Crushing the glue tab helps, but, as you mentioned, you sometimes get a soft crease at the glue tab fold. That typically may not be a big deal for manually set up boxes but can be a huge issue for case erectors. It helps with the center thickness issue, but it will never completely alleviate the problem. You still have the thickness buildup of the liners and the medium. The two folded scores on the on flat RSC also contribute to this issue. When it’s folded flat there is tension caused by the two panels at the score pressing against each other. This makes the folded box want to spring open. So, you are not only fighting thickness, but you are also fighting tension.

Try to keep the bundle or batch count as small as possible. The fewer in the bundle or batch the less deviation you’ll get, or at least the more opportunity you will have to compensate for it. And always try to interlock your layers.

When you have a center glue flap, whether running bundles or batches, interlock the bundles or batches of RSCs as much as possible. If you can overlap three lengths across your pallet you can build a pretty stable load. You just need to make sure your top layer is the center bundle that locks the two outer bundles in place as shown below.Offsetting layer stack


A chimney stack configuration (similar to the illustration below) may help as well. Again, keeping your bundles or batches as small as possible and interlocking the layers.chimney stack


Of course, shrink wrapping or cross-strapping will help keep them together during shipping. Most of the time the end user wants to rip all the shrink wrap off first thing. If they can cut the wrap and open on only one side, the rest of the wrap may hold the stack in place until it gets used down. That will probably require changing the customers procedures or habits. Sometimes it’s not practical… and sometime not possible.

— Ralph

Searching for Glossary of Industry Terms for US and UK

July 14, 2022

Ted asks:

I’m looking for a glossary of corrugated terms that we use in the United States. Everything to do with corrugated, containerboard, tooling, equipment and testing as much of a comprehensive list as we can compile. We’re working with a company in the UK and their design team is using terms that we’re unfamiliar with or can’t easily translate off the top of our heads. I want to compile a glossary of industry terms with brief definitions, much like a translation lexicon, so they can then add their term next to the relative definition. The goal is to streamline communications and make life easier for both groups.

I have an old Fiber Box Handbook that is the starting point but very incomplete. If you have something that you can send me or guide me to, it would be most appreciated.

Even here in the US we can have different terms for the same thing. Anilox roll and ink roll for example. So, communicating with someone in another country where, for example, ‘printing plates’ may be called ‘stereos’, can certainly be a bit of a task until you learn the lingo.

Below are a few links to some publicly accessible collections of industry terms that are a good source of information and hopefully will contribute to your project.

When you complete your glossary, I hope you will share it with us and our readers.

Glossary of Corrugated Material Terms (Pro Pac)

Packaging Terminology: A glossary of terms and definitions (GWP Group)

The Packaging School Glossary

— Ralph

RSC Tolerances for Case Erectors and Packers

May 27, 2022

Brian asks:

Do you have any printed information, such as TAPPI, PMMI, FBA, regarding tolerances for RSC’s that you can share with me?  We have a customer that purchased a box erector/packer/taper that sometimes jams up and they would like to know what the tolerances are for the boxes that we manufacture for them. Any help would be appreciated.

There are industry guidelines, but they are just that…guidelines. Tolerances can be customer specific and should be considered when estimating a job. Then you consider your capabilities. What tolerances can your equipment hold from feeder through counter-ejector? Probably not your case, but if you’re diecutting RSCs, what tolerance does your diemaker guarantee?

The FBA Handbook discusses these tolerances and provides guidelines for carton tolerances and may be purchased at (Store Products – Fibre Box Association).

The PMMI/FBA publication PMMI B155-TR2.2-2011, recommends that any RSC panel, when measured from scoreline to scoreline should not exceed ± 1/16” (1.5mm). It also recommends that the overall length of the blank should not exceed ± 1/8” (3mm). From specified size of course.

The PMMI document also recommends that slot depth should vary no more than ±1/8 (3mm) from the centerline of the slot (corrugator) score to the tip of the slot. Slots should also be aligned within 1/16” (1.5mm) of the centerline of the aligning (relative) score.

The PMMI/FBA publication PMMI B155-TR2.1-2011 offers some tolerances for the manufacturers joint (MJ) which, as we know, is most important to creating a square box. Measured at the flap (corrugator) scorelines, the MJ should not be less than 1/8” (3mm) or larger than ½” (12.5mm). Skew or fishtail should not exceed 3/16” (4.5mm), again when measured at the flap scores. At no point along the MJ should the opening be less than 1/16” (1.5mm) and the alignment of the flap scores should not exceed 3/16” (4.5mm) at the MJ.

TAPPI has a very wide range of documents and specification available to TAPPI members, but in reviewing the lists we couldn’t identify any document specific to RSC tolerances. (If anyone know of such a document, please shar ethe name with us.)

Now of course, case erectors and case packers are going to want the box as square as absolutely possible. Perhaps equally as important is the consistency in size. We can often compensate if we are consistent. It’s when sizes or tolerances jump around that it becomes difficult to keep an automatic line running.

We also have to be cognizant of tolerance stackup. If we look at the tolerances above, the overall blank length can vary ±1/8”. So that’s a total of 1/4″. Now let’s add in the manufacturers joint. According to the specs we can be as small as 1/16” and as large as 1/2”. Now, we rarely see the MJ vary this much, but it can happen. Then, there is fishtail to consider. Remember that these tolerances tend to stackup, a combination of MJ width variation and fishtail can cause nightmares for case erectors and packers. This is especially true if the stackup causes the flaps to come into contact with each other.

We reached out to a few case erector/packer manufacturers, but it was hard to get a ballpark reference because of the number of possible variables from the squareness and size of the box to the forgiveness of the product being packed.

— Ralph

Stitching Tolerance

December 30, 2020

Dave asks,

 We have an old foot pedal stitcher we manually stitch boxes with. Is there a standard spacing between staples that we must maintain?

Dave, this was a new one for me.  Took a bit of research using a number of resources, but this should address your question.

Singlewall: Starting and ending staples shall be 1 to 1½ inches from the flap score lines.  Intermediate staples shall be spaced no more than 2½ inches apart.

Doublewall: Starting and ending staples shall be double stitched no more than 1 to 1½ inches from the flap score lines.  Intermediate staples shall be spaced no more than 2½ inches apart.  For products weighting 100 lbs. or more spacing of intermediate staples shall be reduced to 1 to 1½ inches apart.

Triplewall: Starting and ending staples shall be double stitched no more than 1 to 1½ inches from the flap score lines.  Intermediate staples shall be double stitched and spaced no more than 1 to 1½ inches apart.

— Ralph