polycarbonate against Retarder (cleaning agent)

[dogbural]

Hi,

Now I am facing an issue that polycarbonate sheet/panel experience cracking.
First thing I would suspect is the cleaning agent.

Do you have information if the retarder based cleaning would chemically attack the polycarbonate?

example of cleaning agent as attached.

thanks
MK

 

[Pud]

What's in it? What does it retard? The only thing guaranteed not to attack PC is water.

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[btrueblood]

What Pud said. If that retarder is any kind of petroleum distillate, then yes, it will likely attack polycarbonate.

 

[dogbural]

I am still getting more information. I will share once this info is available.

 

[dogbural]

by the way, another cause of cracking is the stress.
The polycarbonate sheet is mounted and fastened with bolt/ or countersunk screw.
It seems that the crack most of case happened near there.

Is there any way to measure or visualise the existing stress?

Polarised light? Compare the stress level before and after being mounted?

 

[dogbural]

also, would the material property change depending on cutting method?
Water jet cutting against CNC router ?

I do see water jet might produce a small indent due to water jet stream.

 

[btrueblood]

Yes, polycarbonate can be examined under polarized light and stresses correlated to fringes seen. Generally, not a good idea to use a countersunk screw on PC or any other plastic. Yes, a waterjet can be used to cut PC, but you need to confirm with the cutter that only water will be used. Any method of cutting can create stress risers - even a cleanly drilled hole is a stress riser, and even a molded hole is a stress riser...

 

[Pud]

Any pics of the cracks in question?

Politicians like to panic, they need activity. It is their substitute for achievement.

 

[dogbural]

thanks btrueblood, would you be able to share any literature showing that countersunk screw is not a good option on PC?

Pud, this is only photo I can share.

 

[Pud]

Countersunk screws are a no-no in any plastic. There is only effectively a line contact which gives high local stress which will initiate a crack or best case (say, in ABS), a drop-off in fastener tension (creep).



Politicians like to panic, they need activity. It is their substitute for achievement.

 

[btrueblood]

What Pud said. BTW, he is more of an expert in plastics than me.