Time / Temperature Packaging Trial

By bjackman
Published: January 12th, 2011

Have there been any time temperature studies conducted on injection molded parts for packaging and shipping. I have looked all over including government transportation web sites. We have a customer that wants us to run our parts through a chamber at 110C for 6 hours to see if the heat has any effect on the product – specifically to warp. The part is a 10 percent glass filled nylon. The idea is to simulate exposure time in a trailer during peak summer hours. Does this sound realistic?

Thanks

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This is a 'spec' that came

Submitted by bill4012 on January 12, 2011 - 1:53pm.

This is a 'spec' that came from folks in the US shipping parts south. It's a lot more common than you'd think to have a trailer full of parts baking in the sun in the middle of august in a freight consolidator's lot (or a Custom's Impound lot) for a few days in Arizona

The trick to this test is NOT to put them into a pre-heated oven. Put them in 'as packed'. Then as bill states, pull them out periodically to see what if any warp has occurred.

I experienced a disaster of plastic cooling grates that were flat as a pancake when we shipped them but when unpackaged in Puerto Rico they looked like potato chips. Came from sitting in an international freight container for a few days in Houston in July. we had to re-mold everything using low stress techniques to keep them flat. Ooops.

You should have less trouble with GF material. But you'll have to try it first.

Bill

Yes, it does. How else would

Submitted by bill28 on January 12, 2011 - 8:38am.

Yes, it does. How else would you determine residual stress in a part? If the material was transparent, i.e. polystyrene, polycarbonate, PET, etc. a simple polarized light box would highlight the molded in stresses.

All you are trying to do in this accelerated temperature-time test is to see if annealing the parts causes warping.

In my past I was a lab rat, having run many tests like this. To be completely scientific, you would need to remove samples at set intervals & compare them to a control set at room temperature. This way you can see exactly how long it takes to warp. If your process was correct, the warping should be minimal.

Something else to consider, are the parts to be tested & shipped in an as molded or conditioned status?

I hope this helps.