Archive for the ‘Finishing/Converting’ Category

Tolerance for Scrap in Load

March 13, 2018

Andrew asks,

I had a customer ask me how much scrap they should tolerate in their product (slots/cutouts/etc). We aim for 100% scrap removal, but this is not always possible. So my question to you is if there an industry standard for this?

The answer is it’s what the customer demands or will tolerate. There is really no industry standard that I’m aware of for the amount of scrap allowed in a load. In the past customers were much more tolerant of “some scrap” in the load. However, as packing lines have become highly automated the amount of scrap a customer will tolerate has continued to decrease. Today many customers and brand owners have zero tolerance for stray scrap. Even a single piece of slot or glue tab scrap can result in costly downtime on an automated packing line. The customers don’t want the downtime, nor do they want to pay their employees to remove the scrap. In some cases with “hands-off” lines there may not be anyone to monitor the incoming boxes and remove stray scrap before it stops the line.

So we have to do our best to eliminate the scrap before it gets to the strapper or unitizer. We need to make sure our tooling is properly designed and the equipment is setup to optimize cutting and scrap removal. On the folder-gluer we need to make sure the slot knives and heads are sharp, properly adjusted and not damaged. The same goes for the tab knives and hand-hole devices as well.

On the diecutter we need to make sure the cutting die is designed and rubbered properly to provide a clean cut and proper scrap ejection. Make sure all rubber is in good condition and that the cutting die rule is not broken or damaged. If there is any impacted scrap in the cutting die, remove it and investigate the rubbering in that area. Also make sure the anvil covers are in good condition and even across the cylinder.

There are rotary diecutter stackers on the market that are specifically engineered to provide superior scrap removal even when running behind the industries fastest diecutters. These stackers are designed to remove scrap before it makes it to the stacking hopper and eliminate the labor involved in manual stripping or scrap picking. The saving in labor and returned product can have a very positive impact on your bottom line.

You’re correct, even though our goal is 100% scrap removal it can be difficult to make sure that one tiny piece of slot doesn’t make its way into the finished product. Sometimes it can become a battle between the customer and the boxmaker as to how much is too much.

Let’s toss these two questions out to our readers. We would like to know your thoughts and experience.

  1. If the customer and boxmaker agree on an acceptable amount of scrap when the order or contract is signed, will/does it help elevate issue down the road?
  2. I know there is an ongoing battle to control costs and offer the customer the best possible competitive price, but can a premium be charged to guarantee zero scrap loads?

— Ralph

Assembled Corrugated Blank Tolerances

February 23, 2018

Kevin asks,

Is there an industry-standard tolerance that would be applied to the assembled dimensions (Length, Width, Depth) of a 2pc carton?  I would question whether multiple processes should lead to alternate tolerances when compared to a single process 1-piece carton.  I would also wonder how carton size would play into the tolerance and if there are any steadfast rules and/or guidelines throughout the industry.

The particular carton I am trying to apply tolerance to is a 2pc Partial Overlap Top, HSC bottom where the width panels are die cut and the other scoring off of a press and then offset stitched within the length panel for reference.  I am trying to hold +/- 1/8” on all dimensions now.  These tend to be around 76 x 32 x 50” with 2” POL.

According to the Joint PMMI/FBA publication PMMI B155-TR2.2-2011,  the tolerance of a RSC panels are +/- 1/16 inch per panel with an overall blank tolerance of +/- 1/8 inch for both length and width. Also, I believe there is a TAPPI publication of dimensional accuracy which may make reference to tolerance.

Slot depth should be within 1/8 inch from the center line of the corrugator score. Slots should also be centered within 1/16 inch of the aligning scores.

No allowance is given for carton size, caliper, substrate or complexity of design in this specification.

I haven’t found any reference to multiple piece cartons which would lead me to believe that there would be an additional allowance for a multi-piece carton.

So, based in this information, it would make sense that the overall assembled dimensions (interior and exterior) should be within, and controlled by, the +/- 1/8 inch overall tolerance of the RSC or die-cut blank.

One other note to toss in here. While the PMMI/FBA publication above may note that +/- 1/8 inch over all is acceptable, today’s customers are typically demanding something closer. With today’s drive and anvil technology +/- 1/16 inch (1/8 total) may generally be considered the norm, but more and more customers are demanding closer tolerances and expecting little to no variation.

— Ralph

Bake a cake in a box

January 31, 2018

Stan asks,

We have a customer who wants to bake a cake in our corrugated box. We use recycled paper from XXXXXXXXXX Mill in XXXXXXX. We also have a letter of ‘No Objection’ from Health Canada. Do you foresee any problem or restriction on this method of cake preparation?

Assuming you have some type of suitable and accepted barrier coating the only other concern would be heat. I assume that they are planning to bake in a conventional or convection oven. Since cakes typically bake at 350 degrees F you shouldn’t have to worry about the 451 degree combustion point of the paper.

If a microwave oven is to be used then there may be a few concerns about the paper and what comes into direct contact with it. A mass resting against paper in a microwave can cause temperatures to reach a point significant enough to cause scorching and even combustion of the paper. (I’ve ruined enough bags of pop corn to prove this point)

I’m not sure how the AIB may play into this if the products are to ship into the United States.

Let’s toss this one out to the readers and see what knowledge they have to share.

– Ralph

Manufacturer’s joint tolerance

January 31, 2018

Kenny asks,

I am new to the AICC family and I have a question I hope you can help me with. I have a customer that is asking questions about the tolerances on an RSC box, specifically the glue joint gap dimension. As I understand from the FBA Handbook, a box maker has 1 board thickness of tolerance after machining. To be even more clear, for a C flute box, a box maker has approximately 3/16” total, that a gap can deviate from where it is designed from (3/32” from Center on both sides).

Well welcome to the family Kenny.

The tolerance as I have always understood it (for fishtail) is no more than 3/16 variance overall from the score line to the end of the flap regardless of the thickness of the sheet. Nor should the gap width at any point of the manufacturer’s joint be less than 1/16 inch in width, again regardless of substrate thickness.

However, with automated packing lines, customers may require a tighter or more consistent tolerance.

This is a battle that has been going on since Hector was a pup and always seems to be a topic for discussion.

– Ralph