On 9/11/12 6:45 PM, Geoffrey Smith wrote:
Folks,
Following the Peter Gottlieb post, it seems that a number of list members
have been "victims" of carriers that mishandled badly packed gear. I now
too often the heart ache of a broken handles and the handle through the box
wall, not to mention that rattling sound as a something rolls around in the
cabinet.
May I suggest that we pool our ideas on minimum packing requirements to be
posted as an article on say "ebay". Simple thing like no loose beans,
bubble wrap size for instrument weight, box wall thickness, preparedness to
pay for better packing ( there is no free lunch) etc. Forget insurance,
bad packing voids most policies and who can value the loss anyway.
There may be appropriate MIL standards? May be even a feedback score on
ebay if we all ask for it?
I notice that the experienced sellers can still pack test equipment with
recycled packaging and get the items from Europe, USA and Asia in the
condition it was advertised. Conversely I also note that the newer ebay
list-ers are more likely to have packing problems.
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.
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
