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Kevlar project. Question

Vlad The Impaler

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#1
I have some kevlar panels I need cut along the lines seen in photos. Water Jet seems to be the way to go and local shop wants to do the job for me however google says the water will degrade the ballistics of the kevlar.


True or false?
How else to cut the stuff? I have cut some but without flexibility the sheers cannot get any further then a few inches.
Kevlar1.JPG
Kevlar2.JPG
Kevlar2.JPG
 

Uglytruth

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#2
Used to make sharp edge cutting dies. Man it was hard on them. I assume this is it or very small quantities. Everything you do I doubt if you get a sharp crisp cut. Lasering? Scalloped blade in a band saw? Modified paper cutter? Metal sheer with almost no clearance? Cutoff grinding wheel?

How to Cut Kevlar Fabric
By Michael Longhurst
eHow


Kevlar is a strong and lightweight organic fiber. (Image: kevlar carbone image by serge simo from Fotolia.com)

How difficult is it to cut a fabric strong enough to stop bullets? It can be pretty tough. But like many things in life, having the proper tools available can make the job much simpler. For cutting Kevlar, there are purpose-built carbide or ceramic shears available either online or at high-end hardware stores that cater to the needs of engineering and aerospace industries. If the scale of the job is small enough, a nice pair of sewing scissors or a heavy-duty utility knife will usually work in a pinch -- but don't expect the blades to maintain their sharpness for long.

Things You'll Need
  • Scissors or Kevlar shears
  • Sand paper
  • Utility knife

Determine the scale of the job. If simply trying to cut out a few small patches of lightweight Kevlar for one-time-use application, it would be most timely and economical to buy a pair of scissors or a few blades for a utility knife with a view to disposing of them afterward. For a bigger job or for continued use, a high quality pair of Kevlar shears can be purchased for between $40 and $80, as of 2011, depending on the design and quality of the shear. An ordinary pair of scissors can also be converted into Kevlar shears by roughing up the blades on a disc sander. To accomplish this, take turns holding each blade of the scissors perpendicular to the disc sander and then draw it across the disc.

Measure the size of Kevlar piece to be cut.

Cut the Kevlar like any other fabric, using scissors or Kevlar shears. Good shears will leave a very clean paper-like cut that won't need any touch-up work. If there is any Kevlar fuzz along the edges of the cut, sand off with 220-grit sandpaper or remove with a utility knife.

Tips & Warnings
  • Do not use Kevlar shears to cut fiberglass. The edge of the shears will be worn down very quickly, and fiberglass already cuts easily enough with even a poor pair of scissors.
 

Joe King

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#4

Vlad The Impaler

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Might be some info in here that could help. Hughes Helicopters - Development of effective machining and tooling techniques for kevlar composite laminates.

Whatever you cut it with, clamping the the kevlar plates between sheets of plexiglass might help to minimize the fraying.
...and have you tried any kind of nibbling tool?
NO as any tool I use needs to be as thin as the cut it's making. I think what I need is a super sharp blade on a weighted length if steel and a press to press it down onto a steel platform. I just don't know what the tool might be called.

My question really is will a water jet cutter ruin the kevlar? The Shop tells me now. Google says yes.
 

Uglytruth

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http://www.fremontcuttingdies.com/

How many do you need? 1 or 100 or 1000? That will determine the way forward. You might have to buy a die but if low quantity is needed they will both make your die & cut your parts.
 

Joe King

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NO as any tool I use needs to be as thin as the cut it's making.
What does a box cutter blade do to it? Is it possible to score the surface with one? Even just a little bit?
...and what does an angle grinder do to it?

My question really is will a water jet cutter ruin the kevlar? The Shop tells me now. Google says yes.
If it's good enough for the military, I'm sure it would work for your application too.

U.S. Military Mine Resistant Ambush Protected (MRAP) vehicles being used in Iraq and Afghanistan are withstanding the impact of bullets and blasts from explosives better because of waterjet cutting technology and other technology from ArmorStruxx of Lodi, Calif.

Mine Resistant Ambush Protected vehicles are a new class of heavy military vehicles designed for frontline transport.

They are fitted with armor plating to protect their occupants. The armor plating is made of Kevlar, some of which is hybridized with S-glass, mounted to ballistic-grade aluminum or to hard steel armor plate. ArmorStruxx produces custom armor panels for these vehicles with waterjet systems from Flow International (www.flowcorp.com).

When fabricating the armor panels, ArmorStruxx produces the Kevlar armor material on site and cuts the composite material to size from 5-ft. by 10-ft. master panels. It also cuts mounting holes for various armor panels that are installed on the vehicles.

The shop does this fabrication on its seven IFB waterjet machines that have 87,000-psi cutting and use Dynamic Waterjet technology, and on one IFB machine that has 60,000-psi cutting.

All ArmorStruxx’s Flow waterjets run three shifts per day, seven days a week, and at the peak of its production ramp last month, the shop was shipping 35 vehicle sets per day to support two different MRAP vehicle platforms.

“The waterjet has proven to be the ideal cutting tool, especially in cutting the Kevlar composite material for the MRAP vehicles,” Joe Felts, vice president of operations for ArmorStruxx, said.

“This material quickly dulls any other type of cutting tool, and the abrasive waterjet machines cut continuously through the composite material, which is significant for our operations,” he added.
 

Uglytruth

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Good but I think those are "high performance" models at that pressure, not run of the mill water jet cutting.
 

Zed

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#11
Are they laminated with epoxy resin? What are the panels? Core material etc? Solid kevlar? If its laid up with a decent resin then water should have no real impact on its properties.
 

Vlad The Impaler

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#14
Yes, they don't really tell you anything much. The layup could be anything, do you know what the resin used is? Do you want an answer or do you want to piss about in your normal dick head way?
I had my answer several posts ago. I don't know if they have resin in them. Look at them, they are not flexible. What you can see from the photos you can tell as much as I can.
 

southfork

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#15
How about a diamond blade on a dremel tool, i used that to cut thru tile and glass, or perhaps they make a carbon blade