+x

 

oekmont - 9/21/2018 3:52:04 PM

You have to enter the part from the sides with every cut. Never start in the middle of the part. Because while it cuts the initial hole, the water builds up pressure against the sides, wich then causes the damage. once the hole is established, the water just flows through the part, without building up that much delaminating forces. Holes can be drilled or better routed first, to give the water jet a starting point.
Laser cutting isn't a good option for carbon, as the fibre has an incredible high melting point and great thermal conductivity,  while the matrix is just the other way around. This means it's hard to cut through the fibres, and there is great thermal exposure to the resin near the cut, causing it to burn or degrade.

+x

 

malcsonar - 9/21/2018 4:15:50 PM

+x

 

oekmont - 9/21/2018 3:52:04 PM

You have to enter the part from the sides with every cut. Never start in the middle of the part. Because while it cuts the initial hole, the water builds up pressure against the sides, wich then causes the damage. once the hole is established, the water just flows through the part, without building up that much delaminating forces. Holes can be drilled or better routed first, to give the water jet a starting point.
Laser cutting isn't a good option for carbon, as the fibre has an incredible high melting point and great thermal conductivity,  while the matrix is just the other way around. This means it's hard to cut through the fibres, and there is great thermal exposure to the resin near the cut, causing it to burn or degrade.

Thank you - much appreciated.  That's a helpful description of what's going on with the delamination.  I think, though, the cutting house did pre-drill the holes, but we still ended up with delamination anyway...  All a learning process.  I'm convinced now that CNC is the way to go.

+x

 

Matt (Staff) - 9/24/2018 8:31:27 AM

+x

 

malcsonar - 9/21/2018 4:15:50 PM

+x

 

oekmont - 9/21/2018 3:52:04 PM

You have to enter the part from the sides with every cut. Never start in the middle of the part. Because while it cuts the initial hole, the water builds up pressure against the sides, wich then causes the damage. once the hole is established, the water just flows through the part, without building up that much delaminating forces. Holes can be drilled or better routed first, to give the water jet a starting point.
Laser cutting isn't a good option for carbon, as the fibre has an incredible high melting point and great thermal conductivity,  while the matrix is just the other way around. This means it's hard to cut through the fibres, and there is great thermal exposure to the resin near the cut, causing it to burn or degrade.

Thank you - much appreciated.  That's a helpful description of what's going on with the delamination.  I think, though, the cutting house did pre-drill the holes, but we still ended up with delamination anyway...  All a learning process.  I'm convinced now that CNC is the way to go.

Waterjet cutting really should be perfectly possible; 'bursting through' carbon sheet with a waterjet is a no-no but if you start from a pre-drilled hole then it should be no different to starting at the edge of the laminate. We supply hundreds of cut carbon fibre components to companies which are all done on waterjet. It might be worth checking with the waterjet company to make absolutely sure that all internal cuts were started from a pilot hole. I'm not a waterjet expert but there are a number of parameters (jet width, abrasive grit, sacrificial bed) which will all affect the quality of the cut. Set up correctly, you should get a near perfect edge.
CNC is of course also a great option. You've probably seen the video we produced on cutting carbon fibre sheet with a desktop CNC router, if not, take a look.