On 9/11/12 6:45 PM, Geoffrey Smith wrote:

Packaging is a very complex science...

We had an incident a couple years ago where a piece of not-quite-flight
prototype hardware was packed in a standard foam filled shipping case;
hand carried on the plane with a second seat, etc.  It slipped when
getting it out of the minivan at the destination and he caught it
between his knees and the bumper and it slid to the ground.

Some of the shock sensors on the package tripped.

Since this is
a) a million dollar piece of gear
b) essentially a rehearsal of the delivery of the real deal a few months
later

There was a LOT of official attention.

Here's what I learned:

1. we put shock sensors that were WAY too sensitive on the package (if
   your device can take a 50g shock, and you put 10g shock sensors on, all
   you get is aggravation, not useful information)  given the actual
   fragility of the part.
2. Nobody actually knows how much packaging is right, without a lot of
   research.  It is CERTAINLY not a simple "use X inches" of foam or
   something like that.  You need to know the "spring constant" of the
   packing material and then calculate the forces when it's dropped (from
   some specified height) and figure out what the peak acceleration is.
   there's a whole science to this.

As you can imagine, it turns out that foam can be too stiff or too soft,
and that the appropriate foam density and thickness is dependent on both
the mass of the thing being supported and the expected loading.

the previous guidelines we had of "ensure 4" of foam" and stuff like
that were basically worthless, and we'd just been lucky in the past.

People who design shipping packaging for things like computers actually
build test packages and instrument them,because, basically, it's an
empirical design problem.  (there was a an interesting case of someone
shipping an iPhone recording accelerations via various shippers a couple
years ago)..  The iPhone maxes out way too low, but you could easily
build a suitable tester with an Arduino and some off the shelf
accelerometer shields.. Or, if you're being paid to do this, you spend
$600 and buy the calibrated recording accelerometer and do some tests.

Take home message:  packaging is non trivial. A simple: "pack it in two
boxes with X inches of crumpled paper or peanuts" isn't going to work.

Historically, at work, we've had reasonably good luck with the "foam in
place" scheme where they squirt a expanding foam into plastic bags
around your stuff (if you've rented test equipment, you know what I'm
talking about).    But I suspect there's a whole art to picking a foam
density and box size that this works for, most of the time.

In general, this will wind up with a box that is MUCH larger than you
think.  When you're shipping a 50k network analyzer, a few hundred bucks
extra in shipping for dimensional size penalties isn't a big deal.  When
you're shipping a $100 surplus widget, perhaps it is.

Jim wrote:

You also need to pay attantion to what parts of the item can bear how
much loading, and from which directions -- knobs, connectors, and
many handles can't bear much, for example -- and design the packaging
to route loads around these features to other parts of the item that
can bear them.  That's what all the carefully folded cardboard and
die-cut foam in engineered pakaging do.

There is no substitute for a basic understanding of the physics
involved and the properties of available packing materials.  The
mistake I see most often is that the contents of a box are not
immobilized by the packing.  When the box is in motion and then
stopped abruptly, the item has a running start to smash into the
inside of the box and whatever stopped it.  Sometimes there is enough
packing material to fill the space in the box but it just isn't stiff
enough (e.g., light open-cell foam), and sometimes there isn't enough
packing material so there is air space inside the box.  Frequently,
both.  The buffer material for a 50 to 100 pound item needs to be
considerably stiffer than most people think.

That said, it's not rocket science.  Large-bubble bubble wrap,
wrapped TIGHTLY around the item in at least two directions until
there is at least 4" on all sides of the item, is a very good start
for anything up to about 100 pounds (6" on all sides is better by the
time you get to 100 pounds).  You may need to use sheets of styrofoam
insulation, heavy cardboard, or plywood to make sure loads will not
bear on fragile parts of the item.  The bubble wrap must be taped up
very tightly so the wrapped item feels like a monolith bursting at
the seams, then put into a box rated for the weight of the item.

All internal space in the box must be filled with packing -- the
bubble wrap, applied as described, will make a rounded shape, so
peanuts or something else must be used to fill the gaps to the square
corners of the box (I hate peanuts, so I generally use rolls of
bubble wrap, pieces of styrofoam building insulation, etc.).

Finally, the entire contents should modestly overfill the box -- you
should have to compress the packing to get the box shut.  When you
do, USE TAPE FREELY.  Do not depend on tape-to-box adhesion -- wrap
wide (at least 2"), strong tape all the way around the box
(fiberglass filament tape is excellent), lapping the tape over itself
the entire length of the longest side to form a tape band all the way
around the box.  Wrap tape all three ways around the box (all three
axes).  For smaller boxes, you can wrap once per axis, in the middle
of the box.  For larger boxes, you need to use two or even three of
these loops per axis, spaced out along the box.

You can also build up most of the buffer with styrofoam building
insulation, if you prefer.  I still like to use an inch or two (all
sides) of tightly-wrapped bubble wrap as the innermost layer.

All of this is not exactly free, and takes a bit of time -- I often
use a whole roll of bubble wrap, sometimes more, and half a roll or
more of tape, for a benchtop instrument or a boatanchor radio.  Plus
a good, sturdy box.  But I have never once had an item damaged in
shipping, since long before there was an eBay.

Best regards,

Charles

I avoid styrofoam insulation because:

It is too rigid and therefore transmits shocks to the object.
Once crushed, it provides no further protecrion.

-John

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On Tue, Sep 11, 2012 at 6:45 PM, Geoffrey Smith geoffsmithoz@tpg.com.auwrote:

You might link to this.  Then add a little bit that is instrument specific.
.../guidelines/how_to.htmlhttp://www.ups.com/content/us/en/resources/ship/packaging/guidelines/how_to.html

Chris Albertson
Redondo Beach, California