Question PVC foam?

Hello zusammen,

even if I love Delrin/Acetal/POM material the most, now I'm searching a cheaper/easier material to produce a waterproof box for electronic components. I search for board of 20mm thickness and black color as minimum.

As I understand, the PVC foam is a quite good candidate, below the information that I've collected about it:

density of PVC foam = from 0.5 to 0.7 gr/cm3
density of PVC hard = from 1.3 to 1.4 gr/cm3 (really similar to POM-C)
stable bis 90° temperature

Also, Forex and/or Foamex are just commercial names for the same PVC foam material.

Here the question:
what is the PVC Hart or, more often, Hartschaum that I usually find on ebay.de? It's high or low density PVC?

Sometimes I've found also "Forex Hartschaum" as description. Since Forex is not "hard" this definition makes me crazy...

properties of pvc

Hartschaum is a foam material (Schaum => German word for Foam)
Hart PVC is most likley high density meaterial.

If the images have enoupg resolution you can spot the difference by looking at the edges:
foam shows tiny bubbles (poriferous)
Hard PVC will show filled material

@drilldevil:

thank you, I know that page. My problem is with german vendors: they use the word "PVC Hartschaum" and "Forex" interchangeably (and no info at all about density!)

@speedo:

thanks to you too. So you confirm me that "Hartschaum" is always a foam. But... what about density? When I read "Hartschaum" can I deduct that we're talking about the typical Forex density (around 0.6 gr/cm3)?

Hi,

julius wrote: Here the question:
what is the PVC Hart or, more often, Hartschaum that I usually find on ebay.de? It's high or low density PVC?

Sometimes I've found also "Forex Hartschaum" as description. Since Forex is not "hard" this definition makes me crazy...

"Hart" is the solid material whereas "Hartschaum" is the foam material. Even though both include "Hart" Hart and Hartschaum have 2 very different meanings and Forex is correctly called "Hartschaum" because it is a foam.

We Germans like to put words together - so in English Hartschaum may be best translated to "rigid foam". And we do not just call it "Schaum" because "ordinary" Schaum is usually associated with something very soft like e.g. a sponge.

Both materials are very nice to machine - but you should prefer the solid material whenever stiffness and the appearance of the cutting edges are important.


Edit: the density of the foam material depends a lot on Manufacturer and thickness with thin sheets usually having much higher densities than thick ones. If you need to know for sure you need to ask the vendor.

Christian

Hi Christian,

now I understand that PVC Hartschuam doesn't necessarily means Forex or Foamex (or Sintra and other commercial names - with well known density). So one has to ask always to the vendor...

It seems to me that "Forex" material is good when you don't care about surfaces quality, precision and so on.

Unfortunately there is no way here in Germany to get a 19mm-thick board in other color than... white!
In England you can get it here (but too big plate for me!)

the question ist: must it be pvc or can it be something else e.g. pe 500 /pe 1000 this material u can get in a lot of different colors (white, light grey, black, yello, red, orange, green, .......)

drilldevil wrote: the question ist: must it be pvc or can it be something else e.g. pe 500 /pe 1000 this material u can get in a lot of different colors (white, light grey, black, yello, red, orange, green, .......)

My around 10x6x1.8cm box should be placed under the seat of a motorcycle. So the material should:

- absorb minimum amount of water/humidity
- be easier to machine than POM-C (higher feed rate)
- be a little cheaper than POM-C
- maintain a minimum dimensional stability (to keep gaskets in their place as minimum)
- be temperature resistant in the range of [-20, +90] (air coming from the motor is sometimes hot, expecially in summer)

As said before, I don't care about surface quality since the box will stay in an hidden place, but... the white color of Forex-19mm is honestly orrible!
ehehhehe...

PE 500 will meet my requirements? (I will google for it this evening anyay)

PE 500 seems a good material:

- density is around 0.93 g/cm3, between PVC Hartschaum (0.7 g/cm3) and POM-C (1.42)
- very low water absorption
- resistant to very low temperature (below -100°)
- not so resistant to high temperature (70° bis 90° - depends on the type)

The curios thing is that PE300, PE500 and PE1000 have a little variation on density, but the chemical and physical properties are different.

Now I'm trying to buy a little piece but it's not easy: all vendors sells only big boards. 1 meter breite/lange as minimum.

Try here

there are lot of smaller peaces available!

frankjoke wrote: Try here

there are lot of smaller peaces available!

I know them, I bought some POM-C there.
But at the moment they have only white PE-500, black or green are not available.
On the other hand, on ebay.de there are only PE-300 boards available.
I'm googling, googling, googling...

perhaps you can try here and find what you want. thats a german producer and vendor.

Try a local sign making company, they may be glad to get rid of off cuts.

drilldevil wrote: perhaps you can try here and find what you want. thats a german producer and vendor.

Sehr interessant...
Their Tekalon A 500 is the PE-500 that I need. I will try to contact them even if I think they are not selling small boards.

hale2160 wrote: Try a local sign making company, they may be glad to get rid of off cuts.

Oh God! Another night on Google!
(A joke, thanks for the suggestion)