Plastic Can

[durcan]

HI,
I am looking at using a plastic molded can to house some electrial parts. It is going to be used in a hot and humid enviroment, about 60 - 70deg C. I have to make sure that the can can't leak or any moisture enter the can. The dim of teh can would be 170mm x 175mm x 275mm, the top of teh can will have a aluminium lid on it.
I was looking at ABS? or Polyethlene? I need it to be a molded part if possible?

Thanks

 

[Demon3]

As you mention you need a plastic that can withstand water and high temperatures while at the same time retaining mechanical properties and acting as a barrier. I would go for polypropylene. It's very cheap, good mechanical properties, immune to water and a good barrier against water as well.

You mentioned PE. I would advise against that as its softening temperature is too low. I would not recommend ABS because the rubber in it will tend to degrade at the elevated temperatures that you mentioned. Nylons would be a poor choice too as they are very sensitive to water.

The only thing is to talk to the supplier to ensure that the PP grade you use contains suitable antioxidants that resist extraction by water. For example Irganox 1010 is the most common but a poor choice for applications in contact with water because it hydrolyses and is extracted.

Thermoforming is one option for making the cans as it's cheap. Injection moulding is better when you have really large production runs (over 100 000 parts for example) but the investment costs are high for injection moulding and low for thermoforming.

Ask a good supplier (e.g. Borealis for help)

 

[patprimmer]

I agree PP seems the best choice.

Bassel is another major supplier who might supply info.

PET will also be OK in water at 70 deg C, but will have a finite life due to hydrolysis.

It all depends on expected life, time exposed to both water and temperature and the consequence of some moisture permeating through the plastic and eventually forming condensation inside.



Regards

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[durcan]

That great guys thanks for your help.

I will contact a supplier and get there input,


regards

p