Polyurethane Foam Testing and Controlling the Foaming Process

[mlthompson]

Does anyone have any advice/experience for foam testing or proven control methods to control the foaming process? We do 36 hour testing to check for foam hardness, but we would like to develop test methods that will give us results at 3 hours. Also any advice for process related testing would also be helpful.

 

[somerqc]

Re: Polyurethane Foam Testing and Control the Foaming Process

Mike,

Ironically, I did work in the polyurethane foam business (although it has been ~ 6 years since I left).

There were a number of tests that were conducted on the foam (depending upon grade). These were conducted from 24 to 72 hours depending again on the grade (some grades required at least 72 hours to fully cure and be "safe" to test).

All testing was conducted based on ASTM established testing protocols for density and hardness (I don't remember the exact numbers though)as well as flammability(i.e. Bell Helicopter test). You can probably look the ASTM standards up and easily find them (neither of them are difficult to conduct either).

I still have connections in the polyurethane foam industry (the company I worked for is USA based). Message me with the company you work for, it may be the same company. If so, I may be able to connect you with my connection who has been in the quality field in polyurethane foam for over 20 years. If not, he may still be able to help you out to some degree (obviously not as much as if he were with the same company)

John

 

[qualeety]

if you are producing moulded foam (foam with skin), as long as you crush the foam right after the production (compressing 90% of the original height or applying negative pressure in the vacuum chamber), the hardness does not change much from 3hr to 24 hrs to 48hrs.

However, if you are testing a core piece or slab foam, you need to do a linear regression between time and hardess...

Please note, you have to do a linear regression for every density and every hardness...which can be tedious and time consuming....also, whenever you change your suppliers of tdi, mdi or polyol, you have to verify your linear regression model...not all chemicals are interchangeable without a hickup or two.

 

[mlthompson]

Can you elaborate some more on your statement that hardness doesn't change from 3 hr to 48 hrs? How much change do you define as "not much"? Also what test methods do you use?

What you've said is interesting I would like to discuss these details and of process control methods if you are willing? My email is [email protected].

 

[somerqc]

Mike,

I will check with my contact concerning the "molded" foam requirements. However, they have switched to using CO2 instead of isocyanates for some time now so the testing may be different.

I know the isocyanate allowable exposure levels (and pollution release standards) are so stringent here that they were forced to reduce usage of "standard" chemicals.

 

[qualeety]

Can you elaborate some more on your statement that hardness doesn't change from 3 hr to 48 hrs? How much change do you define as "not much"? Also what test methods do you use?

What you've said is interesting I would like to discuss these details and of process control methods if you are willing? My email is [email protected].

I am no longer in foam manufacturing business but i used to be a process engineer for a slab foam line and a quality engineer for a moulded foam line.

For moulded foam, there were two different specs/testing methods:

Ford - measures forces required to compress 25%, 50% and 75% (?) of the initial thickness

GM - measures thickness when compressed with fixed load.

we used Instrons as a testing equipment for above requirement.

Due to Just-in-time delievery, we could not cure moulded foam 48hrs. We have done extensive testing to prove to GM/Ford/Chryster and others that the foam hardness did not change much from 3hrs to 48hrs, provided you crush the foam correctly. (this is another story ) Once we demonstrated our findings, we tested the foam without waiting 48hrs. I don't recall "how much it changed" but we did not have to adjust the spec to account for a curing time.

Also, all moulded parts are condition in the condition room prior to testing (temp and humity).

As for a slab foam, that is another story.

i sent you an e-mail...feel free to call me

 

[qualeety]

Mike,

I will check with my contact concerning the "molded" foam requirements. However, they have switched to using CO2 instead of isocyanates for some time now so the testing may be different.

I know the isocyanate allowable exposure levels (and pollution release standards) are so stringent here that they were forced to reduce usage of "standard" chemicals.

Are you using CO2 to blow the foam?..hmmmm, if i recall, you must add water to create CO2 and control density of the foam....****, my brain hurts now...