Abstract: Disclosed is a turbine or compressor component with an integrated cooling channel, in particular a turbine blade, and a method for producing the same. The aim of the invention is to ensure an improved estimation of the service life of the component and furthermore, if possible, also increased safety during operation and increased service life, even in the presence of constantly variable thermal and mechanical stress. To achieve this, the cooling channel of the component is subjected to internal pressure during a pressure impingement phase, said internal pressure being at a level sufficiently high that it causes the at least semiplastic deformation of the wall regions delimiting the cooling channel.

Abstract: A wall element having at least one cooling channel formed therein, the wall element presenting an inside surface and an outside surface, the channel comprising a hole and a diffusion portion, the hole opening out at one end in the inside surface, and at the other end in a diffusion portion where it forms an orifice, the diffusion portion flaring around said orifice and being defined by a bottom wall and a side margin. Said bottom wall presents a first plane portion into which the hole opens out, and a second plane portion situated in front of the first plane portion, said first and second plane portions being inclined in the thickness of the wall. The oriented angle of inclination of said first plane portion is less than the positive oriented angle of inclination of said second plane portion.

Abstract: An air-cooled turbine blade and methods of manufacturing the blade are provided. The blade includes a suction side flow circuit formed within its interior and defined at least by an interior surface of a convex suction side wall, a pressure side flow circuit formed within the blade interior and defined at least by an interior surface of a concave pressure side wall, and a center flow circuit including a first section and a second section, the first section disposed between the suction side flow circuit and the pressure side flow circuit, and the second section in flow communication with the first section and a plurality of openings of a leading edge wall and defined at least partially by an interior surface of the leading edge wall.

Abstract: Methods are provided for modifying an airfoil internal cooling circuit that include a flow path configured to direct air through the airfoil in a direction and the airfoil having a leading edge, a trailing edge, and a first and a second wall therebetween, each wall having an inner and an outer surface, the inner surfaces defining a cavity and having features forming at least a portion of the internal cooling circuit. The methods may include the steps of forming a pilot hole through the airfoil first and second walls at a predetermined location, forming an insert hole based on the predetermined location, the insert hole enveloping the pilot hole and configured to receive at least a portion of an insert configured to modify the internal cooling circuit flow path, placing the insert into the insert hole, and bonding the insert to the airfoil first and second walls.

Abstract: A method for manufacturing a cooling microcircuit in a blade-outer-air-seal is provided. The method broadly comprises the steps of forming a first section of the blade-outer-air-seal having a first exposed internal wall, forming a second section of the blade-outer-air-seal having a second exposed internal wall, and forming at least one cooling microcircuit on at least one of the first and second exposed internal walls.

Abstract: The present invention relates to a cooled blade forming an upstream guide vane element for a turbomachine, wherein the airfoil comprises a longitudinal cavity with a first opening at one end and a second opening at the other end, a tubular sleeve being housed in the cavity with a first end in the first opening and a second end in the second opening, first spacers on the side of the first end and second spacers on the side of the second end of the sleeve making a space between the outer face of the sleeve and the wall of the cavity, the blade being arranged so that the sleeve is inserted into the cavity through the first opening. The blade is characterized in that the first spacers are secured to the sleeve and the second spacers are secured to the wall of the cavity of the airfoil. The invention makes it possible to mount the sleeve despite an accentuated curvature of the profile of the airfoil.

Abstract: A multi-part cast component for a turbine engine includes a first component section having a main body portion including at least one cooling flow passage section, and a second component section having a main body including at least one cooling flow passage section. The first and second component sections are joined along a parting line to form a turbine engine component with the at least one cooling flow passage section of the first component section aligning with the at least one cooling flow passage of the second component section to form a cooling flow channel.

Abstract: A fluid flow machine blade (1) is provided on the outer contour of the airfoil (4) with a thermal barrier coating (41). In this context, quite purposefully, only part-regions of the airfoil have the thermal barrier coating, while well-defined second part-regions of the airfoil (42, 43, 44) are realized purposefully without thermal barrier coating. In particular, along the trailing edge (46) of the airfoil, a region (42) is realized without thermal barrier coating. In further embodiments of the invention, regions of the airfoil (43, 44) which lie adjacent to foot-side (21) or tip (31) platforms of the blades are realized without thermal barrier coating.

Abstract: A turbine engine component, such as a high pressure turbine vane, has an airfoil portion and at least one coolant system embedded within the airfoil portion. Each coolant system has an exit through which a cooling fluid flows, which exit has at least one device for preventing deposits from interfering with the flow of cooling fluid from the exit. The at least one device may be at least one depression and/or at least one grill structure formed from elongated ribs.

Abstract: The ends of cooling air passages in turbine blades and/or vanes of a gas turbine engine are provided with turbulation promoters to enhance the cooling of such structures as inner and outer shrouds and the like to accommodate thermal loads thereon.

Abstract: A cooled turbine engine component is made by providing first and second pieces respectively having first and second surfaces. At least one circuit is formed in at least one of the first and second surfaces. A first plurality of apertures is provided in the first piece to form inlets to the at least one circuit. A second plurality of apertures is provided in the second piece to form outlets to the at least one circuit. A combination of the first and second pieces is assembled and integrated.

Abstract: A blade for a turbine engine is described, having a base body, made from a titanium alloy, with a first and a second component piece, which are connected in the connection region by means of a bonding process. A groove with a groove wall runs through the connection region, to prevent local concentration of tension, such that the above borders directly on the second component piece and forms therewith a connection angle greater than 70 degrees.

Abstract: A blade or a vane preferably used in a gas turbine engine, the blade or vane being formed of a metallic core or insert with a ceramic airfoil surface bonded to the metallic insert. The insert includes a series of concave and convex portions arranged along the outer surface, in which a plurality of hoop fibers are secured within a resin matrix to firmly secure the metallic insert to the ceramic airfoil body. Axial loads between the insert and the ceramic body are transferred to the hoop fibers. The hoop fibers are strong enough to resist extending in length that would permit the hoop fibers from sliding over the widest portion of the insert.

Abstract: A turbine engine component has an airfoil portion with a pressure side wall and a suction side wall and a cooling system. The cooling system has at least one cooling circuit disposed longitudinally along the airfoil portion. Each cooling circuit has a plurality of staggered internal pedestals for increasing heat pick-up.

Abstract: A method for manufacturing a turbine engine component comprises the steps of forming a first half of an airfoil portion of the turbine engine component and forming a plurality of microcircuits having at least one passageway on an exposed internal wall of the first half of the airfoil portion. The method further comprises forming a second half of the airfoil portion of said turbine engine component, and forming at least one additional cooling microcircuit having at least one passageway on an exposed internal wall of the second half of the airfoil portion. Thereafter, the first half is placed in an abutting relationship with the second half after the cooling microcircuits have been formed and inspected. The first half and the second half are joined together to form the airfoil portion.

Abstract: A turbine engine component has an airfoil portion with a suction side. The component includes a cooling microcircuit embedded within a wall structure forming the suction side. The cooling microcircuit has at least one cooling film hole positioned ahead of a gage point for creating a flow of cooling fluid over an exterior surface of the suction side which travels past the gage point. The cooling microcircuit is formed using refractory metal core technology. A method for forming the cooling microcircuit is described.

Abstract: A gas turbine airfoil (1) includes a pressure sidewall (15) and a suction sidewall (16), extending from a root to a tip and from a leading edge region to a trailing edge and having at least one cooling passage between the pressure sidewall (15) and the suction sidewall (16) for cooling air to pass through and cool the airfoil from within. One or several of the cooling passages (3) extend along the leading edge of the airfoil (1) and several film cooling holes (1,2) extend from the internal cooling passages (3) along the leading edge region to the outer surface of the leading edge region. The film cooling holes (1,2) each have a shape that is diffused in a radial outward direction of the leading edge of the airfoil (1) at least over a part of the length of the film cooling hole (1,2).

Abstract: A turbine blade with a tip squealer and method of rebuilding a turbine blade for a gas turbine engine. The blade is of the type including an airfoil having first and second spaced-apart sidewalls defining an interior void and joined at a leading edge and a trailing edge. The first and second sidewalls extending from a root disposed adjacent the dovetail to a tip cap for channeling combustion gases, and a squealer tip including at least one tip rib extending outwardly from the tip cap. The method includes the steps of removing the squealer tip, including the at least one rib tip, from the tip cap and adding new material to the tip cap to serve as a new squealer tip. A plurality of spaced-apart notches is formed in the new material between the leading edge and the trailing edge of the airfoil. At least one hole is formed in each notch communicating with the interior void of the airfoil for channeling cooling air from the interior void of the airfoil to thereby form a squealer tip.

Abstract: Hollow fan blades for turbo fan gas turbine engines are formed of two separate detail halves. Each detail half has a plurality of cavities and ribs machined out to reduce weight. The floor and opposite interior walls of each cavity are machined simultaneously. The configuration minimizes the number of cutter plunge cuts for the internal cavities, and maximizes cutter size, in order to minimize the time required to machine them. These detail halves are subsequently bonded and given an airfoil shape in the forming operation.

Abstract: A method of reducing stress in a turbine bucket having an internal cooling circuit formed by a casting core having laterally extending support pins of square or rectangular cross section includes: (a) redesigning the support pins to have a round cross section; or (b) removing the cross-over holes between adjacent cooling passages.

Abstract: Methods are provided for modifying an airfoil internal cooling circuit that include a flow path configured to direct air through the airfoil in a direction and the airfoil having a leading edge, a trailing edge, and a first and a second wall therebetween, each wall having an inner and an outer surface, the inner surfaces defining a cavity and having features forming at least a portion of the internal cooling circuit. The methods may include the steps of forming a pilot hole through the airfoil first and second walls at a predetermined location, forming an insert hole based on the predetermined location, the insert hole enveloping the pilot hole and configured to receive at least a portion of an insert configured to modify the internal cooling circuit flow path, placing the insert into the insert hole, and bonding the insert to the airfoil first and second walls.

Abstract: A method for manufacturing a turbine engine component comprises the steps of forming a first half of an airfoil portion of the turbine engine component and forming a first cooling microcircuit having at least one passageway on an exposed internal wall of the first half of the airfoil portion. The method further comprises forming a second half of the airfoil portion of said turbine engine component, forming a second cooling microcircuit having at least one passageway on an exposed internal wall of the second half of the airfoil portion, and placing the first half in an abutting relationship with the second half after the cooling microcircuits have been formed and inspected.

Abstract: A turbine engine component has an airfoil portion with a leading edge portion. The leading edge portion includes a plurality of staggered holes for causing fluid to flow over a surface of the airfoil portion. A method for forming the leading edge portion using refractory metal core technology is described.

Abstract: An airfoil for a gas turbine engine, the airfoil includes a plurality of cooling air passages to supply cooling air to an external surface of the airfoil, the cooled surface of the airfoil having a critical temperature in which any cooled surface of the airfoil should not exceed, the cooling air passages having a coating applied within the passages, the coating being made of a material that has an oxidizing property such that the material oxidizes away and opens the passage to more flow when exposed to a temperature above the critical temperature. When the airfoil surface is not properly cooled by a flow passing through the passage, the material oxidizes away until the size of the passage increases to allow for the proper amount of cooling air to flow to cool the airfoil. Each passage is located in a different part of the airfoil that requires more or less cooling flow, and each passage will oxidize until the size of the passage is large enough to allow for the proper amount of cooling flow.

Abstract: An airfoil for a gas turbine engine blade includes a plurality of film cooling holes extending through its outer surface. The film cooling holes are formed by defining at least a first datum structure and a second datum structure, and then forming each film cooling hole at a location on the airfoil outer surface relative to the first and second datum structures. As a result, each film cooling hole has a centerline extending therethrough that forms a compound angle with respect to a tangent to the outer surface, and the distance between the centerlines of each film cooling hole is at least a predetermined minimum distance.

Abstract: A method for adjusting the airflow in a turbine component having a plurality of airflow holes. The method comprises the step of depositing an overlay metallic coating on the surface of the turbine component in a manner such that at least some of the airflow holes are partially filled such that the volume of the partially filled airflow holes is changed so as to adjust the airflow through the turbine component. Also provided is a turbine component having a plurality of airflow holes, at least some of the airflow holes being partially filled with the overlay metallic coating to change the volume thereof so as to adjust the airflow through the turbine component.

Abstract: A method for repairing defects in a gas turbine component that comprises a substrate and an existing coating on the substrate. The article includes cooling holes having a predetermined air flow requirement and an outer shaped portion and an inner metering portion. The method comprises removing the existing coating and recoating the surface of the article with a nonoriginal coating. After the nonoriginal coating is applied onto the component, the cooling holes that meet a predetermined inspection criteria are reworked to remove the excess nonoriginal coating deposited in the outer shaped portion of the cooling holes. The reworking is done by receiving an electrode, having only a shaped portion with a preselected shape, in the outer shaped portion of the cooling holes thus restoring the cooling holes to the predetermined air flow requirement.

Abstract: A manufacturing system and manufacturing method for adjusting the performance of manufacturing operations or steps in manufacturing components having three-dimensional external structural characteristics. An embodiment of the system broadly comprises: (a) a plurality of manufacturing operations for processing a component having three-dimensional external structural characteristics; (b) at least one analytical device for analyzing at least one characteristic of the component after the performance of one or more manufacturing operations to generate a component data set; (c) at least one data storage device for storing the generated component data sets and for providing at least a relevant portion of accumulated component data; and (d) a communication mechanism for transmitting at least a relevant portion of accumulated component data to one or more manufacturing operations so that the performance thereof can be adjusted in response to the transmitted portion of accumulated component data.

Abstract: A thermally loaded component has at least one cooling passage for the flow of a cooling fluid passing through it. In the region of a bend, at least one diverter device for the integral capturing of the flow of the cooling fluid is provided within the cooling passage. The diverter device comprises, over the height of the cooling passage, two diverter parts which are spaced apart from one another. The diverter maybe cast with a notch therein so that during cooling, the diverter breaks into separated portions proximate the notch.

Abstract: An article such as a hollow gas turbine blade has an internal cavity therein with an inlet and outlet. The outlet has an outlet minimum transverse dimension of from about 0.009 inch to about 0.012 inch. An aluminiding source powder has a minimum particle size of greater than about 0.0015 inch and not greater than about 0.005 inch. The aluminiding source powder is a mixture of from about 5 to about 15 percent by weight of a metallic aluminum-containing powder and from about 85 to about 95 percent by weight of a ceramic powder. The aluminiding source powder is flowed into the internal cavity through the inlet, and the article is heated with the aluminiding source powder in the internal cavity to a temperature of from about 1750° F. to about 2000° F., and for a time of from about 2 hours to about 12 hours, to deposit an aluminum-containing coating on the internal surface of the internal cavity. The aluminiding source powder is thereafter removed from the internal cavity through the inlet.

Abstract: A method of manufacturing a composite structure uses a layer of an insulating material (22) as a mold for forming a substrate of a ceramic matrix composite (CMC) material (24). The insulating material may be formed in the shape of a cylinder (10) with the CMC material wound on an outer surface (14) of the cylinder to form a gas turbine combustor liner (20). Alternatively, the insulating material may be formed in the shape of an airfoil section (32) with the CMC material formed on an inside surface (36) of the insulating material. The airfoil section may be formed of a plurality of halves (42, 44) to facilitate the lay-up of the CMC material onto an easily accessible surface, with the halves then joined together to form the complete composite airfoil. In another embodiment, a box structure (102) defining a hot gas flow passage (98) is manufactured by forming insulating material in the shape of opposed airfoil halves (104) joined at respective opposed ends by platform members (109).

Abstract: An airfoil (30) having a continuous layer of ceramic matrix composite (CMC) material (34) extending from a suction side (33) to a pressure side (35) around a trailing edge portion (31). The CMC material includes an inner wrap (36) extending around an inner trailing edge portion (38) and an outer wrap (40) extending around an outer trailing edge portion (42). A filler material (44) is disposed between the inner and outer wraps to substantially eliminate voids in the trailing edge portion. The filler material may be pre-processed to an intermediate stage and used as a mandrel for forming the outer trailing edge portion, and then co-processed with the inner and outer wraps to a final form. The filler material may be pre-processed to include a desired mechanical feature such as a cooling passage (22) or a protrusion (48).

Abstract: A turbine blade airfoil assembly includes a cooling air passage. The cooling air passage includes a plurality of impingement openings that are isolated from at least one adjacent impingement opening. The cooling air passage is formed and cast within a turbine blade assembly through the use of a single core. The single core forms the features required to fabricate the various separate and isolated impingement openings. The isolation and combination of impingement openings provides for the augmentation of convection and film cooling and provide the flexibility to tailor airflow on an airfoil to optimize thermal performance of an airfoil.

Abstract: A cooled turbine engine component is made by providing first and second pieces respectively having first and second surfaces. At least one circuit is formed in at least one of the first and second surfaces. A first plurality of apertures is provided in the first piece to form inlets to the at least one circuit. A second plurality of apertures is provided in the second piece to form outlets to the at least one circuit. A combination of the first and second pieces is assembled and integrated.

Abstract: A method for fabricating a turbine engine blade. The method includes providing a resistance welding system, and welding a metering plate to the turbine engine blade using the resistance welding system.

Abstract: A thermally highly loaded machine component (10), which is protected from overheating by film cooling, is provided with conical cooling passages (30) of circular cross section. The cooling passages are designed so as to be divergent from the cold-gas side (13) toward the hot-gas side. The conical cooling passages, as compared with cylindrical passages with regard to the mass flow of cooling medium (35) fed through the cooling passages, are substantially less dependent on the pressure ratio between the cold-gas side (13) and hot-gas side (14) of the component. The straight conical cooling passages of round cross section throughout may be produced in a very simple manner by laser drilling, with a convergent cutting beam being used for the machining.

Abstract: A method for forming a channel within a coated, metal-based substrate is described. In one technique, a channel-forming material is first deposited on the substrate, followed by the deposition of a bonding agent, such as a braze. One or more coatings can then be applied over the substrate. In one embodiment, the channel is formed when the channel-forming material is subsequently removed. In another embodiment, the channel is formed due to the lack of adhesion between particular channel-forming materials and the overlying bonding agent. Related articles are also described, e.g., gas turbine components which include protective coatings and a pattern of cooling channels.

Abstract: Method for manufacturing a vane (1) to a gas turbine component intended for guiding a gas flow. The vane (1) is produced by casting, and an internal hole (3) for coolant is then cut out of the cast vane (1). The vane (1) is provided with a starter hole (5), either during casting or once casting is completed, following which the internal hole (3) for coolant is cut out of the vane, proceeding from the starter hole. A method is also disclosed for manufacturing a gas turbine component including a plurality of vanes (1) for guiding a gas flow. The gas turbine component is cast in such a way that it includes the vanes and an internal hole (3) for coolant is then cut out of each of the vanes.

Abstract: A method of diffusion bonding three metal work pieces to form a fan blade, where each workpiece has a flat surface and an excess portion larger than a predetermined size needed to produce a finished fan blade; longitudinally extending slots are provided to interconnect the flat surfaces of the excess portions of the work pieces; the work pieces are assembled into a stack with the flat surfaces in mating abutment and the stack is evacuated from one end of the stack through the slots; heat and pressure are applied across the thickness of the work pieces to diffusion bond the work pieces together to form an integral structure; the excess portions with the slots are then removed.

Abstract: A device and a method are for producing a blade including two outer walls and at least one cavity between the outer walls, for a turbine. An outer mould and several cores are used in forming the outer walls and the at least one cavity of the blade. At least one of the cavities is divided into two channels by a middle segment. One channel is located between the first outer wall and the middle segment, while the other channel is located between the middle segment and the second outer wall. Two cores which are separate from each other are used accordingly. This provides a simple and economical means of reducing the thickness of the outer wall.

Abstract: A method of manufacturing a gas turbine engine fan blade (10) comprises forming three metal workpieces (50,52,54). A metal slab (30) is upset forged at both ends (32,34) to produce a metal block (40) with increased thickness (42,44) extending from opposite surfaces (36,38). The metal block (40) is cut in an inclined path to form two of the metal workpieces (50,52). The metal workpieces (50,52,54) are assembled into a stack (56) so that the flat surfaces (38,42,46,48) are in mating abutment. Heat and pressure is applied across the thickness of the metal workpieces (50,52,54) to diffusion bond the metal workpieces (53,52,54) together to form an integral structure (100). The integral structure (100) is hot creep formed and superplastically formed to produce the required aerofoil shape and the thickened end is machined to form the blade root (26). The method enables thinner metallic workpieces with better microstructure to be used and increases the yield of metallic workpieces.

Abstract: Apertures in airfoils for use in a hot gas path of a turbine are formed from the interior of the airfoil to the exterior in circumstances where line-of-sight access from locations external to the nozzle is inhibited or prohibited. A water jet nozzle head is disposed in a cavity within the airfoil and angled at the desired inclination to cut an angled hole through the airfoil wall using a water jet and abrasive material contained in the water. A protective device, e.g., a backstop or shield, is provided on the outside of the nozzle to prevent damage to other portions of the nozzle from the water jet which would otherwise impinge but for the protective device.

Abstract: A process and a device for coating a temperature-stable component with a thermal protection layer (15), in which the temperature-stable component has a surface (12) which is to be coated with the thermal protection layer (15) and at which there is at least one cooling-passage opening (1) which is connected to a cooling passage running inside the component. During the coating a mass flow (10) emerges through the cooling-passage opening (1), the coating takes place by a coating mass flow (11) directed onto the surface (12) which is to be coated, and the mass flow (10) emerges through the cooling-passage opening (1) and the coating mass flow (11) include an angle &agr;≠0°.

Abstract: A method for fabricating a rotor blade for a gas turbine engine facilitates reducing operating temperatures of a tip portion of the rotor blade. The method comprises forming an airfoil including a first sidewall and a second sidewall connected at a leading edge and a trailing edge to define a cavity therein, wherein the first and second sidewalls extend radially between a rotor blade root and a rotor blade tip plate, and forming a first tip wall extending from the rotor blade tip plate along the first sidewall, such that at least a portion of the first tip wall is at least partially recessed with respect to the rotor blade first sidewall to define a tip shelf that extends from the airfoil trailing edge towards the airfoil leading edge. A second tip wall is formed to extend from the rotor blade tip plate along the second sidewall.

Abstract: A method of forming a curved cooling channel into a gas turbine component such as a turbine blade uses an electrode in the form of a helix. The electrode is driven to rotate around the central rotational axis of the helix and axially along the central rotational axis. A turbine blade for a gas turbine component is provided with at least one helical cooling channel.

Abstract: An airfoil includes internal cooling air passages arranged in a serpentine manner with one or more radially outward and radially inward extending passages. The passages are in fluid connection through turns of approximately 180°. The turns near the platform of the airfoil connecting a radially inward extending passage with a radially outward extending passage are realized by a root turn defined by the passage sidewalls, which extend radially inward to the radially inner end of the root section of the airfoil, and by an end plate attached to the radially inner ends of the walls.

Abstract: A method is for producing a turbine blade, in particular, a gas turbine blade, comprising a head, a foot, and a blade section, in addition to an internal canalization system, including individual channels through which coolant gas can pass along a flow path within the turbine blade. The turbine blade also includes a throttle device which influences the passage of the coolant gas without impairing the flow of the coolant gas in the intake area. The throttle device is located in the rear section of the flow path, and is positioned upstream of the exit openings.

Abstract: An airfoil for a gas turbine engine including an inflection that facilitates enhancing film cooling of the airfoil, without adversely affecting aerodynamic efficiency of airfoil is described. The airfoil includes a generally concave first sidewall and a generally convex second sidewall joined at a leading edge and at a trailing edge of the airfoil. A plurality of cooling openings extend between an internal cooling chamber and an external surface of the first sidewall. One cooling opening extends from the cooling chamber into the inflection at a relatively shallow injection angle with respect the airfoil external surface.

Abstract: An airfoil for a turbine nozzle assembly of a gas turbine engine includes an outer side wall, an inner side wall, a leading edge extending from the outer side wall to the inner side wall, a trailing edge extending from the outer side wall to the inner side wall, a concave surface extending from the leading edge to the trailing edge on a pressure side of the airfoil, a convex surface extending from the leading edge to the trailing edge on a suction side of the airfoil, an outer cooling slot, an inner cooling slot, and at least one middle cooling slot formed in the concave side of the airfoil adjacent the trailing edge.

Abstract: A component for use in a flow path of a gas turbine engine. The component includes a body having an exterior surface mountable in the gas turbine engine so the exterior surface is exposed to gases flowing through the flow path of the engine. The body has a cooling hole extending through the body to the exterior surface for transporting cooling air from a cooling air source outside the flow path of the engine to the exterior surface of the body for providing a layer of cooling air adjacent the exterior surface of the body to cool the surface and create a thermal barrier between the exterior surface and the gases flowing through the flow path of the gas turbine engine. The cooling hole is defined by an elongate annular surface extending through the body of the component and terminating at the exterior surface of the body. The hole has a length, a maximum width less than about 0.