Cut composites

[GilPolymers]

Hello,

I have long fibre reinforced composites samples with 10 x 50 x 2 (mm).
Composites have a thermoplastic matrix and glass fibres.
I'm trying to cut those composites in smaller samples of 5 x 5 x 2 without change their morphology.
I tried to cut those with a saw but the result was not so good, then I try to cut with a surgical knife but it was to hard, the 3rd attempt was using the same surgical knife but heated, it was nice but probably changes the polymer's morphology, finally I mad just some superficial cuts I put the composites in liquid nitrogen and I try to break them but the result was not the best.

someone has a better idea?!

Thanks in advance!

Pedro

 

[MechanicalChef]

What type of saw are you using?

A wood blade will cause splitering. You'll want to use a diamond blade, or a blade with cemented-carbides. The type of blade used to cut ceramics.

like this:

http://www.made-in-china.com/image/4f0j00FcaQLfEtFTjVM/Diamond-Jigsaw-Blade.jpg

or

http://www.toolstation.com/images/library/stock/webbig/69765.jpg

 

[GilPolymers]

Thanks "mechanicalchef",

I'll try something similar but I'm afraid that this blade can "kill" my specimens... I tried a usual blade to cut metals...

If someone has more ideas, they will be welcome!

thanks,

 

[SWComposites]

"tried to cut those with a saw but the result was not so good" - what do you specifically mean by "not good"? please describe in detail.

what type of saw/blade are you using? band saw? jig saw? table saw with circular blade? hacksaw?

what type of thermoplastic? melt temperature?

a diamond coated circular saw blade should work just fine. If is a low melting temp thermoplastic you might need to use coolant.

 

[GilPolymers]

The problem is that I need to analyse those samples in SEM and I want to get the structure intact. The thermoplastic has a melt temperature around 150 ºC so this is not the problem! I just want to make sure that the composite's structure or the polyemer's microscopy do not change.

Anyway thanks for your hint.

 

[wes616]

In lieu of a saw, use a diamond tipped cut off(grinding) wheel. You're basically trying to sand through the laminate.

Wes C.
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[Compositepro]

Composites are most commonly cut with abrasive tooling. The abrasive grit should be fairly fine and sharp. Abrasive cut-off blades are often used. There are diamond blades where the grit is imbedded in metal and this is not very suitable but can still work. Water cooling is usually required so that the matrix resin doesn't soften and become gummy. This will just generate more heat and a bad cut. Fiber pull-out on the back side of a cut is a problem that can be avoided with several techniques. Rotate the part so the saw is always cutting into the part, use a backing plate, or cut very slowly.

 

[GilPolymers]

Thanks Mr Super Composite "CompositePro"

I'll follow your ideas...

Thanks for the others suggestions too,

Regards

Pedro