Thread-forming STI (screw-thread insert) taps produce cleaner, stronger, and more accurate threads than STI taps that cut threads. Also called chip-free taps, they press against the sides of a hole to form threads as they are rotated into the hole. They don't produce chips, which eliminates the need to clear chips from the hole and prevents threads from being deformed during tapping. STI taps create an oversized thread inside a hole so a helical-coil screw thread insert can be inserted in the hole. The insert distributes the load across the length of the threads and improves the threads' strength when a fastener with a standard screw thread size is installed in the hole.