Lexan 223R-701

[remj]

Currently using Lexan 223R-701 on a product with .080" wall. Looking for a material with similar mold parameters that would be stronger & not fail upon impact. Any suggestions or contact info of vendors that you can supply me.

Thanks

 

[Demon3]

Good luck, polycarbonate has the best impact resistance there is. My advice is to go to

http://www.matweb.com

(free), look up your PC grade and then find a PC with higher impact resistance, if it exists. You can search at matweb and screen by polymer type and properties.

Chris DeArmitt

"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill

 

[patprimmer]

Yo say the wall is 0.080" thick. How uniform is this, what is the flow path length, what is the melt flow type, ie is it CD grade or extrusion grade or something in between.

Regards
Pat
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[patprimmer]

Opps. is it exposed to ANY chemicals before it is impacted and fails.

Regards
Pat
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[remj]

Wall thickness is uniform. Flow path length is about 7". There is an open void in the middle & at the corners of that area is where we found failure with impact. I added some ribs to strengthen those areas to avoid breaking again. I think concern now is the wall thickness areas being too thin, although we have not seen any failures in any of those areas.

 

[patprimmer]

Seeing as you seem unwilling or unable to provide data on the grade of Lexan I did your research for you this time.

223R is an easy flow mould release UV stabilised grade.

I would try a medium viscosity non mould release grade and I would not use UV stabilisers unless the environment of us required it.

From a wild guess based on your description of the part, it sounds like your problem is at a weld line. Weld line strength can often be improved by eliminating additives and improving the vents in the area of the weld line. Melt temperature and consistency, mould temperature, gate size, hold up time and pressure and injection speed can all have an influence on weld line strength.

You have not commented on my question about exposure to solvents. I cannot do your homework for you on that one.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[remj]

Thanks for the info. There is no exposure to foreign solvents. Your generous info on the mold parameter options will be forwarded to my molder to see if there are any improvements they can provide.

I'll check into the med flow material too. Thanks

 

[Demon3]

It is a little known fact that the impact resistance of PC is much better for thin parts. That's the way they always quote it, for this walls. Once the part is thicker, the impact resistance goes way down.

I'm not sure how much ribs will improve impact resistance. It may be more effective to design your whole round with no sharp edges to avoid stress concentrations.

Chris DeArmitt

"Knowledge has no value except that which can be gained from its application toward some worthwhile end."
Think and Grow Rich - Napoleon Hill