# US 9,434,025 B2 · Laser drilling methods of shallow-angled holes > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,434,025 B2 - Document ID: US9434025B2 - Status: Granted - Kind: B2 - Application number: 13/185,959 - Filed: 2011-07-19 - Published: 2013-01-24 - Granted: 2016-09-06 - Earliest claimed: 2011-07-19 - Assignees: Pratt & Whitney Canada Corp. - Applicants: Amr Elfizy; Ghislain Hardy; Sylvain Cournoyer - Inventors: Amr Elfizy; Ghislain Hardy; Sylvain Cournoyer - Web page: https://patentgrep.com/patent/US9434025B2 ## CPC - B23K 26/389: {of fluid openings, e.g. nozzles, jets} - B23K 26/388: Trepanning, i.e. boring by moving the beam spot about an axis - B23K 2101/001: {Turbines} - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM ## Abstract A method for drilling a shallow-angled hole through a thermal barrier coated component includes a step of applying a pulse laser beam to drill a section of the hole substantially within a thermal barrier coating of the component in a direction substantially perpendicular to a top surface of the component. A further step is conducted to apply the pulse laser beam to further drill through a base metal of the component to complete the formation of the hole extending through the component. ## Claims ### Claim 1 A method for providing a hole through a metal component having a base metal and a thermal barrier coating applied to the base metal to form a top surface of the component, the method comprising: a) applying a pulse laser beam to the top surface of the component perpendicular with respect to the top surface to form a section of the hole substantially penetrating only the thermal barrier coating and leaving the base metal substantially intact, the section of the hole located within a boundary of a final perimeter of the hole; and then b) changing an orientation of the pulse laser beam to an angle of 20 degrees or less with respect to the top surface; and then c) applying the pulse laser beam with the changed orientation through the section of the hole partially formed in step (a) to drill through the thermal barrier coating remaining within the boundary of the final perimeter of the hole and through the base metal to provide the final perimeter of the hole, the final perimeter of the hole defining opposed acute and obtuse angles of intersection with the top surface. ### Claim 2 (depends on 1) The method as defined in claim 1 wherein a depth of each perpendicular drilling in step (a) is not greater than a thickness of the thermal barrier coating locally at a location of the hole. ### Claim 3 (depends on 1) The method as defined in claim 1 wherein step (a) is conducted with a depth of each perpendicular drilling free of damage to the final perimeter of the hole. ### Claim 4 (depends on 1) The method as defined in claim 1 wherein in step (a) the pulse laser beam is set with a spot size smaller than a minimum cross-sectional dimension of the hole. ### Claim 5 (depends on 1) The method as defined in claim 1 wherein step (a) is conducted by applying the pulse laser beam to more than one location within the boundary of the final perimeter of the hole on the top surface of the component, thereby reducing said residual thermal barrier coating material within the final perimeter of the hole. ### Claim 6 (depends on 1) The method as defined in claim 1 wherein the pulse laser beam is set with a first pulse frequency rate in step (a) and is re-set with a second pulse frequency rate in step (c), the first pulse frequency rate being higher than the second pulse frequency rate. ### Claim 7 (depends on 1) The method as defined in claim 1 further comprising the steps of (i) determining a gas pressure corresponding to a bending moment created by an assist gas jet on the thermal barrier coating just sufficient to create cracks between the thermal barrier coating and the base metal, and then (ii) injecting the assist gas jet into the hole being drilled during the pulse laser beam drilling, with a pressure of the assist gas jet lower than 100 psi, thereby limiting a bending moment created by the assist gas jet not greater than the determined pressure. ### Claim 8 (depends on 1) The method as defined in claim 1 wherein step (c) is conducted by applying shots of the pulse laser beam to strike the base metal until the hole extends through the component. ### Claim 9 (depends on 1) The method as defined in claim 1 wherein the pulse laser beam is set with a first pulse energy level in step (a) and is re-set with a second pulse energy level in step (c), the first pulse energy level being lower than the second pulse energy level. ### Claim 10 (depends on 1) The method as defined in claim 1 further comprising repeating steps (a), (b) and (c) to complete a plurality of holes extending through the component. ### Claim 11 (depends on 10) The method as defined in claim 10 comprising: determining a lowest gas pressure value at which injection of an assist gas jet into one of the holes being drilled during the pulse laser beam drilling initiates a crack occurrence in an interface between the thermal barrier coating and the base metal; and injecting the assist gas jet under a gas pressure into the respective holes being drilled during the pulse laser beam drilling, the gas pressure being lower than the determined gas pressure value. ### Claim 12 (depends on 11) The method as defined in claim 11 wherein the gas pressure is measured within a gas jet nozzle injecting the assist gas jet.