Packaging / Foam expertise

[WinterDeere]

Not a tractor topic, but there's such a wide range of expertise here, I figured it'd be foolish not to ask: are there any folks here real knowledgeable on foam compression, stiffness, and preloading for packing? I have some 1U chassis height rack-mount electronics devices weighing 25 to 36 lb. each, and need to prepare them for international shipment. Chassis size is the usual 17" width (19" at mounting tabs) x 1.75" high for rack mounted hardware, with depths of 16" and 24" for the two respective weights listed above.

I'm figuring 2 units per box with foam surrounds and coardboard separators, and setting the boxes onto pallets like books on a shelf. That means the weight of the product will be sitting on the foam surround, such that we need to get the density of the foam right in order to support the product weight.

If the orientation is such that the product is standing up on the face panel of the rack chassis, that's a footprint of 19" x 1.75" = 33.25 sq.in. for either product, and relative pressures of 0.75 and 1.08 psi for the two product weights.

If we need to keep foam pressure consistent between the two product types, I could set them on their sides and hit 0.84 to 0.89 psi on both products, but they'd take up more pallet space and the delicate "ears" of the rack chassis would be facing down, unless removed prior to shipping.

I'm not totally confident on choosing the right foam density for this job, but schedule and costs make it relatively important to get this right off the bat. If anyone here has experience in this type of packaging, I'd appreciate some advice, or at least confirmation of my material selection. I can do math, but I have no real experience in choosing packing foam without a lot of trial and error.

 

[MossRoad]

Good luck.

When we used to receive oddly sized machines and fixtures, many times it was bolted to a skid in the bottom of the cardboard box. Then, it seemed, they'd put a plastic bag on each side of the object and fill it with expanding foam. That would expand and compress around each side of the object, but not so much it would push out the sides of the cardboard box. If it was really tall, then they'd do two lifts, requiring 4 bags on each lift. On the top they'd just use one bag and I'm not really sure how they got it even with the box top, but it was.

When it arrived, we'd slit the cardboard down two opposite corners, remove the box, and pull off the plastic bags full of foam.

But then, they knew what they were doing and I don't know what kind of expanding foam they used.

 

[LittleBittyBigJohn]

For international shipment you also need to look at whether or not your pallets will need to be heat treated. We have to use heat treated pallets with a certification mark (IPPC) that can be tracked back to the time, date, location, and company that did the heat treating. Something to do with making sure bugs don't get transported with the wood.

Depending on quantity I would ask a packaging company local to your area about the foam and cartons.

My thoughts though, for the little they are worth. With this being basically a cube I would think you should be able to use sheets of PE foam and design your carton to pack them tightly. I personally wouldn't be as critical of the density of foam as long as it's got some spring but not a huge amount. Nesting your bundle of product tightly with quality corrugate will likely mean more than the density of the foam. It sounds like you are going to have several cartons stacked on each other anyway so you would have to consider total weight of the stack if you were going to do calculations like that. We use 1.7lb 2" thick 4x4 corner pads for an 80ish lb cabinet here and it does a great job. But the foam is expensive. Also be mindful of abrasion to the finish of your product from the foam. If the carton is snug enough it shouldn't be an issue. But if you think it will be, sometimes we will use what equates basically to a trash bag around the product before it goes into the carton and that usually solves the issue.

We also do test shipments when we design our packaging. We ship across the country to a contact, they photograph and inspect, then ship it straight back. Then we make a determination on if the packaging protected well enough or not and re-design if necessary. But it doesn't sound like you have the time for that.

 

[WinterDeere]

When we used to receive oddly sized machines and fixtures, many times it was bolted to a skid in the bottom of the cardboard box. Then, it seemed, they'd put a plastic bag on each side of the object and fill it with expanding foam.

Yep, this is what I do for larger or oddly-shaped objects. Essentially a custom wood cradle to which the item bolts down, then framing around the cradle to support the next box stacked atop, if stacking boxes, prior to spray-foaming it all in place. But in this case the items are essentially rectangular boxes, and so thin that spray foaming isn't going to work as well... it'd tend to bulge the box out on the large face. Pre-cut foam, or even just corrugated liners, is usually the way to go here.

For international shipment you also need to look at whether or not your pallets will need to be heat treated.

Yeah, this is all new to me! My first time doing a palletized export on my own, without a third party intermediary. Thankfully customer is in Taiwan, who have pretty loose standards. It seems any pallet of any age and origin will pass, as long as it has the IPPC's ISPM 15 heat treat marking.

I'm going to go check my pallet inventory later, to see what markings are on these we already have. I usually just re-use pallets received with our component orders, I always seem to have more coming in than going out, so I just save the nicest for re-use and burn the junkers. If I have a bunch with heat treat markings on them, I'll set them aside for this job, but I could also buy a few new pallets for this job if I need to. Heck, I could even buy plastic "international" pallets, if I really wanted to splurge.

Shipment would fit onto a single pallet, but customer has asked to have it split up onto 3 or 4 pallets, for reasons I honestly don't understand... perhaps insurance limitations due to high value.

Depending on quantity I would ask a packaging company local to your area about the foam and cartons.

I might. The last time I shipped this product, I just bought a few hundred feet of the 1/2" x 4" foam expansion joint material masons use when pouring patios, and it worked well. I used two layers of that around the perimeter of the part, and corrugated liners on the large flat faces. But in that case, I was only shipping domestically in smaller batches, it was someone else's problem to repackage and palletize for export.

My thoughts though, for the little they are worth. With this being basically a cube I would think you should be able to use sheets of PE foam and design your carton to pack them tightly.

That's basically the plan. I just want to avoid buying a truckload of foam that's going to be too soft and just squash to zero when I place it around these things in the box, or compress so badly that it blows the bottom out of the box when someone tips it off the pallet. I think the way to avoid that is choosing a foam with higher stiffness and aiming for maybe less than 10% compression under static load. That way a 5g shock in transit will compress the foam maybe 50%, but removing the load will only ever push the box wall out 10% of the foam thickness (e.g. 0.2" bulge for 2" thick foam).

I've been buying stuff packed in foam my whole life, and used to laugh at the idea of "packaging engineers", when I heard that was actually a major. Now I realize there's actually some serious art and science to this stuff.

We use 1.7lb 2" thick 4x4 corner pads for an 80ish lb cabinet here and it does a great job. But the foam is expensive.

Good reference point numbers. And yeah, this stuff ain't cheap, when you're buying it by the acre!

Also be mindful of abrasion to the finish of your product from the foam. If the carton is snug enough it shouldn't be an issue. But if you think it will be, sometimes we will use what equates basically to a trash bag around the product before it goes into the carton and that usually solves the issue.

These chassis are all aluminum with a mix of clear conversion coating and black anodize. Not totally impervious to abrasion, but at least not a super-fragile painted finish.

We also do test shipments when we design our packaging. We ship across the country to a contact, they photograph and inspect, then ship it straight back.

That's a great idea, but in this case I'd be concerned it only increases the probability of damage to a relatively expensive order (40 pieces ~ $700k). Just arranging for insurance on these shipments is a huge deal, as our regular inland policy doesn't cover this amount. Even a simple "test shipment" would probably cost me a few thousand dollars, round trip.

Since items are shipped under Ex Works terms, it becomes the customer responsibility as soon as I load it onto a truck here, and they insure it from their end. The customer is also a repeat customer, so I don't have much concern with them trying to claim false damages.

 

[LittleBittyBigJohn]

That's basically the plan. I just want to avoid buying a truckload of foam that's going to be too soft and just squash to zero when I place it around these things in the box, or compress so badly that it blows the bottom out of the box when someone tips it off the pallet. I think the way to avoid that is choosing a foam with higher stiffness and aiming for maybe less than 10% compression under static load. That way a 5g shock in transit will compress the foam maybe 50%, but removing the load will only ever push the box wall out 10% of the foam thickness (e.g. 0.2" bulge for 2" thick foam).

The foam shouldn't compress at all in the carton. Think of it more as a bumper to absorb the impact from an outside force. Not to cushion internal movement of the product itself. The packaging should be sung enough that the product inside should not be able to gain any inertia relative to the packaging (the part shouldn't move in the box). What you are looking for is basically if you were to whack the carton with a stick it would provide enough flex to let the carton dent so the packaging does not damage the product, but not so much that the stick makes it to the product inside.

 

[WinterDeere]

The foam shouldn't compress at all in the carton. Think of it more as a bumper to absorb the impact from an outside force. Not to cushion internal movement of the product itself. The packaging should be sung enough that the product inside should not be able to gain any inertia relative to the packaging (the part shouldn't move in the box). What you are looking for is basically if you were to whack the carton with a stick it would provide enough flex to let the carton dent so the packaging does not damage the product, but not so much that the stick makes it to the product inside.

I think you're probably right. That was already my plan for sides and top. But for some reason, my gut was telling me I wanted some amount of compression of the foam placed under the part, to absorb shock loads in transit.

 

[Richard001]

You may also want to put on your shipment, as you are using pallets, "DO NOT STACK"

Richard

 

[WinterDeere]

You may also want to put on your shipment, as you are using pallets, "DO NOT STACK"

Richard

Yep... always! In fact, we sometimes include cones on top of the pallet to prevent stacking, on more expensive or delicate items. Also, BOL will always state non-stackable, and we pay a premium based on that.

BTW, I looked at the pressed wood pallets, which are ISPM-exempt, and likely more stable for a single use application like this, than those flimsy plastic pallets. Attractive at $30/each at 5 pieces, versus heat-treated wood export pallets at $50/each, not that $100 total difference matters all that much.

 

[anomad]

I've been buying stuff packed in foam my whole life, and used to laugh at the idea of "packaging engineers", when I heard that was actually a major. Now I realize there's actually some serious art and science to this stuff.

A Swedish friend of mine is one of those engineers. There is a little more to it than chucking something in a box like your Amazon robot at the fulfillment center - LOL.

I'm not much help with your packing... But in the agency I retired from we shipped a lot of computers and electronics in pelican cases (or the equivalent).

 

[LittleBittyBigJohn]

I think you're probably right. That was already my plan for sides and top. But for some reason, my gut was telling me I wanted some amount of compression of the foam placed under the part, to absorb shock loads in transit.

My experience is only with furniture like items. If there are internal components in your shipment that shock loads would damage, I'm sure there would be other packaging considerations.

 

[MossRoad]

We often got crates with shock sensors on them. Rarely were they not tripped. We'd make note of it, contact the vendor for approval to unpack, then proceed. Rarely was the item damaged.

 

[WinterDeere]

In this case, the item is relatively impervious to shock loads. There are some .125" thick aluminum mounting ears on the chassis, which could be bent if they suffered an impact, but the arrangement of foam around each item in the box will prevent that from happening due to normal in-transit shock loads. The rest of the assembly could likely be dropped off a building without damage, assuming it didn't land on one of the input or output connectors.

Twice in my career, I've had a customer or shipper drop one of our large systems off a loading dock. I remember one in particular totally sheared the welds and fasteners on the double-wide 19" rack into which it was built, leaving the whole rack look like a leaning parallelogram. Because that customer was overseas and we knew it would be months to get a new rack shipped out there with a technician to transplant all the hardware, we told the customer to just try powering up the system. Surprisingly, it all worked just fine! I think they ran that leaning tower of amplifiers for 3-4 months, prior to us coordinating a repair, with the customers usage schedule.

 

[dstig1]

We have a small group of packaging engineers at work. Depending on what they are working on they can do shaker tests, drop tests, corner impacts, etc. The shaker tables can be programmed for everything from "UPS domestic ground shipping" to MilSpec blah blah and everything in between. They have pallet sized versions of those and some small ones.

A lot of times their findings are about quality stuff. Like one product after their shipping cycle it was wearing a hole in the bottom of the bag where there was a bit of a sharper edge, so they added a small cardboard or foam bit there to solve that so customers didn't open it to a hole in the bag. It was a storage bag in addition to shipping protection, so we wanted it to be in good shape.

And yes, i am aware i did not answer your question