It is a common problem for manufacturers of stone kitchen and bathroom countertops that their CNC machine leaves visible lines after profiling the edge of marble or granite, resulting in a finish that is not as glossy as desired.
The lines are inevitable in profiles with a large flat section such as the ‘T’ profile but also in all other profiles more or less. The visibility of the lines depends on different factors. One is the stone itself, regardless of whether it is natural stone such as granite and marble or artificial (engineered) stone. CNC diamond tools are another important factor in the finishing result. With brand new diamond tools, the lines are minimal, but will eventually develop lines that are noticeable and unacceptable to most stone makers and their customers.
On some profiles and stones, it is possible to limit the lines to a minimum by running the buffing wheels back and forth 3-4 times and changing the Z value up and down by a minimal amount (0.005mm) for each pass, which might not be enough. be possible to do with each profile.
Another option is to manually run a 400 grit pad after the CNC has run all the metal wheels and before the polishing wheels. That helps keep the polishing tools in good shape, but it’s additional manual work that disrupts the normal workflow on the CNC machine.
Regular polishing of profile diamond wheels with the proper polishing stones will help keep lines to a minimum.
There are also special tools called line breakers and line breakers, to name a few, that can result in a better finish.
If you compare the hand polishing process to the way the CNC machine works on a profile, then you can recognize where these lines come from and why they are hard to get rid of. In the CNC machine, the tool rotates in the same direction as the movement of the machine. There is no cross movement of the tools and the movement of the CNC machine.
Just see what happens when you hand grind, the tool rotates along with the motion you make with your hand. That movement is what removes the lines and that’s not possible with a CNC machine until someone designs a machine head that works the same way as hand grinding. It is doubtful that this is even possible.
You really can’t compare a “T” or “V” profile produced on a CNC to a profile polished by hand or with an in-line polishing machine. The CNC profile is never that shiny and will need to be touched up by hand if you want a high quality finish.
TIPS: If your CNC machine is equipped with a saw gearbox, you can get an adapter made to connect standard magnetic squeegee polishing tools to run on the T-profile. As long as your CAD-CAM-CNC software allows you to program correctly , especially the entry and exit of the tools are essential to avoid blocking the machine. The result is almost perfect, but the arris or pencil round still needs to be finished off by hand afterwards.