A Heli-Coil tap chart is a chart indicating the appropriate tapping tools and procedures for cutting threads to receive a particular size of Heli-Coil screw thread insert. A tap is a tool used to cut threads into a hole so that a screw, bolt or other threaded fastener can screw into that hole. Heli-Coil inserts screw into tapped holes before the threaded fastener. The fastener then screws into this insert to better secure the fastener.
When a company manufactures a product out of a softer metal, such as aluminum, any threads it taps into this metal are softer as well. Stanley Engineered Fastening makes Heli-Coil screw thread inserts out of a very hard stainless steel. By first screwing this hard insert into a tapped hole, and then screwing a fastener into the insert, manufacturers can offset some of the thread strength loss associated with using a softer metal. Heli-Coil screw thread inserts are helpful in industries that require both strength and lightness, such as automobiles and aerospace.
Stanley Engineered Fastening also manufactures an array of tools for its Heli-Coil inserts, including pneumatic, electric and hand tools for installation. Additionally, the company manufactures specialized taps for its inserts, gauges to check that holes for proper tapping and insert-removal tools.