CNC trimming Kevlar

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    Default CNC trimming Kevlar

    First off Happy New Year to you all!!!!


    But as the new year beings so does the new challenges.

    I have being programming and machining for years on all types from foam to Titanium, composite materials have always being straight forward.....most time.

    I am now having to trim parts made from Kevlar and it is proving to be quite difficult. The parts along the trim line are extremely bally and are taking longer to deburr than they do to trim.

    Anyone machine this material before and have some tips on how best to trim it.

    Btw using a 5 axis Belotti Flu for trimming.



    Sent from my SM-G935F using Tapatalk

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    Default Re: CNC trimming Kevlar

    Kevlar is notorious for fuzzing and even the raw cloth can only be cut cleanly with special shears.You might not want to learn this but your best bet might be to send the job out to a shop that can water-jet it for you.



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    Default Re: CNC trimming Kevlar

    Quote Originally Posted by routalot View Post
    Kevlar is notorious for fuzzing and even the raw cloth can only be cut cleanly with special shears.You might not want to learn this but your best bet might be to send the job out to a shop that can water-jet it for you.
    Thanks for your reply.....we have have a water jet, a Flow Water Jet 4020 Mach 3. My problem is that it has to be 5 axis trimmed because of all the different cut outs plus one part is a tube with different slots and holes plus gooves going .45mm deep.

    These are 3d epoxy Kevlar parts and we are trimming after they have been cured.

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    Default Re: CNC trimming Kevlar

    Are the components wet laid and then post cured or prepreg?A green wet laid part will be a fuzzier part to trim than either of those.Here in Europe we use very little Kevlar largely because of this aspect of it's behaviour.With the exception of ballistics related applications its hard to think of good things to say about it.You might ask the suppliers if they can recommend a particular brand of cutter.



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    Default Re: CNC trimming Kevlar

    Quote Originally Posted by routalot View Post
    Are the components wet laid and then post cured or prepreg?A green wet laid part will be a fuzzier part to trim than either of those.Here in Europe we use very little Kevlar largely because of this aspect of it's behaviour.With the exception of ballistics related applications its hard to think of good things to say about it.You might ask the suppliers if they can recommend a particular brand of cutter.
    Yes it is both, one part is wet laid and the others is prepreg. And you are also correct about it application as I too am from UK.

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    Default Re: CNC trimming Kevlar

    I do not have a clue about it really. One of my big 3D printers uses Kevlar line for its Core XY drive system largely because of its strength and the fact that it will not stretch.
    Have you tried using a flame to get rid of the fuzz?
    The knots on the ends of these lines are dressed with a flame much like you would do with nylon line.

    Lee


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    Default Re: CNC trimming Kevlar

    Quote Originally Posted by LeeWay View Post
    I do not have a clue about it really. One of my big 3D printers uses Kevlar line for its Core XY drive system largely because of its strength and the fact that it will not stretch.
    Have you tried using a flame to get rid of the fuzz?
    Ha very good!! Thats exactly what one of my guys did......told my to leave and then stuck a flame along the edges. But this is not what I want them to be doing, we will have 450 parts of all different sizes with multiple trims,slots and holes, so need a correct cutter and process so as coming off machine as close as.

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    Default Re: CNC trimming Kevlar

    Hi Andy,

    We often machine composites, we also manufacture them. The tools you will need are expensive, and you need one kind to drill a hole and another kind to trim out a panel. Check out these tools that should do what you're looking for without burrs. But you need to follow the feeds and speeds on the site:

    https://store.osgeurope.com/en/produ...sg-d10-dia-hbc
    Or
    https://www.secotools.com/#article/m_7550

    These are compression cutters with two helices, you need to keep the cut line (cut depth/2) centre on the plane where the two helixes start. Half both the feed and speed and try out a part. If it goes well, you know what do to. When they cut, they press the cut part from both sides, so there is minimal to no fraying.

    Hope this helps.

    N

    Quote Originally Posted by AndyMcB View Post
    First off Happy New Year to you all!!!!


    But as the new year beings so does the new challenges.

    I have being programming and machining for years on all types from foam to Titanium, composite materials have always being straight forward.....most time.

    I am now having to trim parts made from Kevlar and it is proving to be quite difficult. The parts along the trim line are extremely bally and are taking longer to deburr than they do to trim.

    Anyone machine this material before and have some tips on how best to trim it.

    Btw using a 5 axis Belotti Flu for trimming.



    Sent from my SM-G935F using Tapatalk




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    Default Re: CNC trimming Kevlar

    Good luck. Two of aramid fiber's properties are resistance to abrasion and resistance to fire. That is why you will find it used in bulletproof vests, and both firefighting and auto racing apparels. That also makes it difficult to work with in composites, both pre- and post-cure. Pre-cure you need good, hard and sharp shears dedicated to the task. Post-cure you need a waterjet for the cleanest cut - most other tools are likely to leave fuzz. You can char the fibers, eventually, but it will be a slow process. This really comes down to part design - for aramid the mould should have been designed to eliminate post-cure trimming, or at least leave the trim where a little fuzz wouldn't matter. One other trick that can work in some circumstances - rewet the fuzz with either superglue or a thin epoxy drawn along the trim with a perpendicular blade edge such that it lays down and stays down. Again, that's another potentially slow post-op, difficult to maintain consistent QC, and dependent on the final result being acceptable.



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    Default Re: CNC trimming Kevlar

    Horrible material to router. As genixia says waterjet is the way to go. Are these your parts? Can you change the layup a bit??? One trick you can do is lay up carbon fiber about 1/2 on each side of the trim line. You don't really "cut" aramid as much as just 'shave' it, which, leaves the fuzz. The carbon fiber helps keep it stiffer while it shaves off.



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