Archive for the ‘Uncategorized’ Category

Is there a standard for the number of people needed to feed an RDC?

August 3, 2022

Brad asks:

A recent safety question has come up.  Is there an industry standard for 1 vs. 2 employees required to manually fed rotatory converters?  We have a non-documented rule of thumb based of sheet size, single wall and double wall.  But I am looking for additional information to determine if what we are currently using fits within the standards of the industry.

I’ve asked Les Pickering for his input on this question. According to Les,

“There is no hard and fast rule, but I will outline the custom and practice.

Assuming it’s a machine like a 618 or an Emba…

  • A sheet width of 36” x 24” is a single person feeding operation.
  • If the sheet increases width to 40” x 24” it’s still a single person feeding operation.
  • If the sheet width is 36”, but the body increases to 30 or more inches, then it becomes a two-person operation as the sheet is more difficult to handle and its weight is heavier.
  • Usually anything over 40” becomes a two-person operation. This makes getting the weight of the bundle into the feeder manageable, maintains the speed up of the machine and creates a more ergonomic operation.”

We might also note that OSHA does not have a published standard on the amount of weight a person may lift. According to the U.S. department of Labor…

“OSHA does not have a standard which sets limits on how much a person may lift or carry. However, the National Institute for Occupational Safety and Health (NIOSH) has developed a mathematical model that helps predict the risk of injury based on the weight being lifted and other criteria. The NIOSH model is based on previous medical research into the compressive forces needed to cause damage to bones and ligaments of the back. The mathematical model is incorporated in the Applications Manual for the Revised NIOSH Lifting Equation, which can be found on the NIOSH website ( It should be noted, however, that this NIOSH document provides only voluntary guidelines”

— Ralph

Case Erector Issues, Finish and Metal

June 27, 2022

Hagan asks:

We recently had a customer contact us in reference to issues in their automatic food packing line which they think may be related to the boxes. They are concerned that the finished surface of some of the outer liners is too porous and causing the suction grippers to lose their grasp of the sheet. They also referred to the boxes causing jams as being “fuzzy”. Their second concern is that occasionally their inline metal detectors are rejecting boxes for metal shavings. This happens after the product has been loaded into the box. Therefore, the package and the contents are rejected and dumped.

We don’t test for smoothness in-house, but we have contacted our paper supplier and asked for them the to provide test results for the rolls in question. Below are the results they provided.


The porosity range between 12 and 28 seems to be quite a difference, but the supplier says that’s within TAPPI standards. We don’t have a good benchmark. With your vast background in the paper industry, do you believe the data provided above is in fact satisfactory results for both categories?

 As far as porosity goes that does seem to be a bit of a variance between Roll ‘J’ and Roll ‘E’. The porosity does, as we would expect, coincide with the smoothness. The smoother the paper the lower we expect to see the porosity. The plant I was responsible for typically ran an average of 350 smoothness and a minimum of 16 for porosity. Even with the range of your examples, they do seem to be in tolerance.

The smoother the liner the better the grasp the suction cups are going to have. I would think it would take a rather porous liner to allow enough vacuum loss to lose the grip. However, I don’t know what that number may be. As well, it would make sense that a surface which may be “fuzzy” could lead to vacuum loss and loss of grip before the box was completely open.

Occasionally we hear of a bit of metal finding its way into the paper. End users, especially food and pharmaceuticals, take this very seriously. I assume at the customer’s plant there are no metal detectors prior to final inspection. It’s unfortunate that it’s not being found until the product has already been packed. At that point the paper/box has been through so many operations that it is possible the metal could have been introduced to the paper nearly anywhere, the paper mill, shipping, converting, storage and even the packing process itself. You mentioned [in and off-line conversation] that your supplier, as well as your own operation, was looking into the metal issue, reviewing operational and maintenance logs, and samples would be sent out for analysis. That sounds like a very good action plan and hopefully it will result in identifying the source. Please follow up and let us know what results you receive.

This points out how important it is to maintain good operational, maintenance, and service records of our operations. Not only can it help us prevent or reduce unscheduled and/or unnecessary downtime, but it can also help diagnose quality issues and sometimes help us pinpoint the source of the issue. Ralph

Inside Cracking on Singleface

November 24, 2021

Fern asks:

I am curious if there is anything written regarding inside cracking on the singleface liner and how it doesn’t take away from the structural aspects of the box, or if there is an industry guideline that I can refer to.

Of course we do our best to eliminate it all together, but now we are working with more & more recycled liners (some heavily recycled) and shorter fibers, we continue to battle this.

You are not alone in this struggle.  And it’s becoming that time of year when this becomes common for many cold weather converters.

One thing we need to remember is that recycled paper gives up moisture much faster than papers made with virgin fibers. When relative humidity drops below 50% the normal board moisture content can plummet leading to a more brittle liner. And, the short fibers of recycled paper create a structure that is more brittle to begin with than long fibre virgin.

Many converters use and/or have experimented with different score profiles and for virgin and recycled paper. The more aggressive, or sharper the profile the more likely to crack the liner. While 4pt crease may be typical, 6 or 8 point can be used to distribute the pressure across the surface.

AICC published a White Paper on Score Cracking a few years back. Click here to download the White Paper. The White paper is free to AICC Members.

We have visited this topic many times in Ask Ralph. Type “Cracking Scores” or “Cracking liners” in the “Search Ask Ralph” field on this blog.

— Ralph

EPA PBT Compliance Request

November 24, 2021

We recently received a request from a customer to sign a form/letter stating that we were compliant with the new EPA regulations on PBT’s in the boxes we manufacture for them. Have you heard of any other box maker that have been asked to sign such documents?

They also reference compliance to RoHS requirements.

Regarding the PBT compliance, probably the best and most efficient thing to do is contact your suppliers and request a reply, in writing, to the questions your customer has asked, and/or a COA (Certificate of Compliance) for both the EPA and RoHS regulations. You may be able to collect this information from their Safety Data Sheets, but make for you have the latest official documents from them, and if possible, make sure they are original documents and not photocopies.

The chemicals referenced in the January 2021 EPS issued rule include Decabromodiphenyl ether (DecaBDE), Phenol, isopropylated phosphate (3:1) – (PIP 3:1), 2,4,6-Tris(tert-butyl)phenol (2,4,6-TTBP), Hexachlorobutadiene (HCBD), and Pentachlorothiophenol (PTCP).

Typically we don’t think you’re going to find the chemicals in the EPA description in the paperboard, inks, or starch adhesives used to make standard corrugated packaging. We don’t know the exact extent of the information your customer is asking for, but if you are shipping product to your customer on plastic pallets, with plastic strapping, or plastic wrapping, you may want to request information from your suppliers of those products as well.

We have had a few discussions on RoHS compliance previously in this blog. In the sidebar under “Search Ask Ralph” type RoHS and hit enter to find these articles.

Do any of our readers and followers have any information or experiences to share on this topic?

— Ralph