CTF: Critical to Function - Designation for a parameter (other than a “Cpk” parameter) that is critical to WD product function, is subject to SPC, may be required to meet a minimum Cpk criterion, must meet a Mean Centering requirement if applicable, and may be called out in an associated IP or WD internal PMP. Depending upon the Cpk requirement, a CTF parameter shall be designated as one of CTF-0, CTF-1, or CTF-2. See section 6.3.5 and Table 6.3 for the criteria for all Critical Parameters. The legacy “CTF” flag shall be interpreted as CTF-1. For new drawings derived from existing, find and convert all “CTF” to “CTF-1.”
CTC: Critical to Control - Designation for a parameter that is critical to WD product function, is subject to SPC, and may be called out in an associated IP or WD internal PMP. A CTC parameter may also be a TCTF, but may not also be a PF, CTF-x or Cpk parameter.