High impact Plastic Shims

[JCasper]

What makes a high impact plastic shim, "high impact"? I have not found any ASTM standand that differentiates between high impact and non-high impact shim properties. Any help would be greatly appreciated.

 

[MintJulep]

And you won't. "High Impact" is one of those meaningful sounding but actually meaningless terms.

Figure out what material properties you actually need for whatever you are doing and look at the actual material properties defined using actual engineering units to identify a material that will work for you.

 

[Tmoose]

"high impact" seems to enjoy some level of technical credibility for a few different types of plastic with a little rubber thrown in.

PVC per ISO

http://www.iso.org/iso/catalogue_detail.htm?csnumber=36965

HIPS = High impact polystyrene per many suppliers
BASF

http://www.plasticsportal.net/wa/plastics-supplier/hips.htm

http://www.britannica.com/EBchecked/topic/265242/high-impact-polystyrene

I know folks who report they have had good success using plastic shims to align machinery (under motor feet, etc), but I have a hard time beleiving there will not be some creep in response to bolt clamping forces over time, resulting in loosening. I would be reluctant to use anything but stainless steel.