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Industrial box without adhesive but with tape

by Butters
Tags: adhesive, industrial, tape
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Butters
#1
Jun13-14, 10:44 AM
P: 28
I'm thinking of reducing adhesive consumption in box assembly which has to hold ~7 kg. The assembly process consists of product insertion, glue application on box ends and tapping along the gap (nothing extraordinary here).
My question is: Why does a box even need adhesive if it gets tapped externally which I believe to withstand the weight?
There're two narrow strips of glue on both ends of the box. Initial idea is to reduce the size of those strips but I don't see the point in using adhesive at all when it has tape applied instantly.
I'd like to do some calculations regarding the issue. I think that shear force plays a key role in this case. How should I carry my theoretical calculations?
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AlephZero
#2
Jun13-14, 10:56 AM
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This is guessing without a drawing of the joint, but the glue probably transfers the load in shear over the whole glued area. A tape joint would carry the whole load through the tape, in between the two parts that are taped together. That might be OK in theory, but if the tape was damaged if would probably tear apart completely.

I guess the real purpose of the tape is to stop the glued joint being pulled apart through rough handling of the box, not to carry the load.
Butters
#3
Jun13-14, 12:36 PM
P: 28


This is basically how it looks. How do I resolve my shear forces?

256bits
#4
Jun14-14, 10:05 AM
P: 1,472
Industrial box without adhesive but with tape

Glue was probably included due to the fact that a lot of people do a crappy job in taping a box shut. They will overlap the sides with a half-inch, tape the folded flaps, and cut the tape allowing only another half inch of overlap on the other side. And without pressing the tape down so that it will definitely be adhering to the cardboard, they then expect the box to be able to be transported to destination without incident.
A box poorly taped on the bottom will spill its contents when picked up. A box with a poorly taped top will have the flaps separate from the tape and become undone. The flaps where they meet the edge of the side have to be tightly taped so that the flaps do not shift with respect to one another loosening up the tape. It doesn't hurt to tape the edges of the flaps to the side for extra stress management.

The glue will aid anybody or his monkey to be able to properly close the box and secure the flaps, with hope that the box and contents will remain as one unit during transportation. You want the box to arrive at the destination looking as good as it did when it left your place, which will impress the receiver.

As long as any crushing, puncture, or mishandling cannot be traced to you, then your liability has been reduced, in regards to returned or refused damaged goods.

So you can teach a course in how to tape a box properly, impressing the use of more tape up the sides from taping the flap crack, and with additional taping the flap-edge if necessary.

Rather than just looking at saving a penny per box on glue, you might want to investigate the handling of the box, the number of times it changes hands from send off to being received, and the state of the box when it arrives, and the state of the contents upon arrival. Boxes are thrown, upended, stacked, put upside down, dropped, squished. Theoretical calculations should take some aspect of those conditions into consideration.
Butters
#5
Jun14-14, 11:34 AM
P: 28
I've seen the automated process which does gluing and tapping. Don't think any misalignment of the tape is even possible. However, I liked the idea about liability and I do agree that this won't probably save a lot.
Anyhow, I'd still like to know how to apply some theoretical calculations in the case, i.e. knowing adhesive and cardboard parameters how do I find weight a box could withstand?
NascentOxygen
#6
Jun15-14, 01:29 AM
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The glue gives the box structural rigidity. The tape serves as a backup should part of a glued joint be overstressed.
AlephZero
#7
Jun15-14, 10:06 AM
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Quote Quote by Butters View Post
Anyhow, I'd still like to know how to apply some theoretical calculations in the case, i.e. knowing adhesive and cardboard parameters how do I find weight a box could withstand?
It's probably not worth the effort to even try. Cardboard is an anisotropic material. The basic design concept of a cardboard box only "works" because of nonlinear behavior of the structure. And the answer will depend very much on what is inside the box. For example if the contents are supported by polystyrene pieces that effectively form a "frame" along the edges of the box, with rigid connections at the corners, that is a very different situation from a the weight of the contents pressing over the whole of the cardboard surface.

Just find something like the postal regulations for packages in the relevant countries, and follow the guidelines. The "7 kg contents" is irrelevant, if a 150kg gorilla working as a mail handler stands on your box to reach something else.


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