Debasis Mechanical drilling - at two far terminal ends for crack-drill-arrest serves the purpsoes of : A: arrest of crack propagation during gouging or mechanical grinding and B: also serves as a compressive stress reliever at the two ends. This is a well proven technique - followed by most mechanical engineering crack repair approach in most industries. Some users, however, prefer to adopt modern technique of laser drilling specialized applications for ex: Ti or Ta type special alloys repair applciations- not as a routine practice in industry. This is finer improvement using laser beams for arresting crack propagation but essentially again serving the same purpose. Hope this helps you C.V.Srinivasan Nishi Engineres Pvt Ltd India August 30, 22007 E-mail: nishi@vsnl.com >Often during crack repair we adopt the procedure >ofcrack-drill-arrest method by drilling judicious drill hole >at the terminals of the crack to mitigate uncontrolled crack >propagation during crack gouging. Is there any alternate >method so far adopted by mechanical engineers in operating >plant besides this method ? May pl. share >regards