Quality of the Blade
The quality of the blade is one of the leading issues when it comes to tiles chipping as they are being cut. If you have a blade that is reaching the end of its lifespan, it just doesn’t have that much diamond coating on the tip anymore, which means it won't cut properly. Instead, it is grinding its way through the piece rather than cutting, which causes chips.
Type of Saw
The type of saw you use is also directly related to whether or not it will chip your tiles. If you try and cut a 12-inch tile on a saw that is only designed to cut through 8 inch pieces at most, you will run into issues where the saw just doesn’t have enough horsepower to cut through the larger and thicker tile. Smaller tiles are meant to be used with small tiles, and while the tray might fit a larger tile, only cut the size that the manufacturer recommends.
A quick and easy solution to helping prevent chips is to protect the piece of tile with a piece of masking tape along the line that you need to cut. The masking tape will help hold the edges of the material together, such as in the case of porcelain tile, which is prone to chipping during cutting. Even with a good saw and a good blade, porcelain will sometimes chip, but masking tape is your secret weapon.
An old carpenter’s trick that also works for cutting tiles down to size is to include a piece of scrap tile. In essence, you place the piece of scrap material in the tray first, then put the actual piece in front of that piece so that they are butting up against each other. When you run the cut through the saw blade it will pass through the first piece and directly into the second and help avoid chipping any free-floating edges since the cut edges are reinforced by another scrap piece.