CCT specializes in cutting glass-filled materials.  The addition of glass to plastics is relatively common.  The glass fibers added come in several forms.  With FR-4/G-10 materials, the glass is in the form of a woven cloth.  Pressing these layers together with an epoxy resin yeilds a very strong and rigid, yet lightweight material.  Random glass-fibers added to a polyester resin adds strength to GPO materials.   Glass can also be added to polycarbonate, Torlon, Ultem, and a wide variety of other materials, improving their strength characteristics without changing insulation properties or other unwanted traits.  The one thing that the addition of glass does to any material is make it more difficult to machine.

Glass is abrasive.  It is, after all, made from sand.  When you cut it, it tends to powder rather than cut in the nice, neat spiral chips that most machine shops are used to.  Also, if you run coolant, the dust generated by cutting glass-filled materials mixes with the coolant and creates a slurry that can destroy pumps and must be removed from the liquid before it can be used again.  It also requires carbide tooling, which is much more expensive than high-speed steel cutting tools.

Most machine shops hate that, and rightfully so.  Most machine shops are set up to cut metals, and glass-filled materials behave completely differently.  Try to face the surface of a piece of Ultem 2300 the way you would surface aluminum, and the internal stress will turn the workpiece into a curved shape resembling a Pringle's potato chip.  Get too aggressive with a piece of G-11 and you will see that glowing tungsten isn't reserved for lightbulb filaments. 

Glass-filled plastics are also not homogenous.  FR-4 for example is made up of laminated layers of glass-cloth in an epoxy resin.  Waterjet FR-4, and you will see the layers separate from each other in a process called delamination.  It looks like the parts were chewed apart, rather than CNC cut.

Luckily, we aren't like most machine shops.  Our staff has decades of experience CNC cutting glass-filled materials, and we can do it cheaper, faster and better than almost anyone. 

Please contact us to see how we can help you.