BACKGROUND OF THE INVENTION
The present disclosure relates generally to additive manufacturing and objects formed therefrom and, more specifically, to forming an additively manufactured object having an improved surface finish without post-manufacturing processing.
Additive manufacturing is a technology that enables "3D-printing" of components from various materials, such as metallic material. In additive manufacturing processes such as direct metal laser melting (DMLM), an object is built layer-by-layer by leveling a powder bed and selectively fusing predetermined portions of the powder bed using a high-powered laser. After each layer is fused, additional powder is leveled and the laser fuses the next layer, thereby fusing it to the prior layers to fabricate a complete object buried in the powder bed. At least some known additive manufacturing processes form components that have a rough surface finish, and that may be finished in a post-manufacturing process to reduce the surface roughness of the component. However, post-manufacturing processes may be time-consuming and costly to execute. In addition, many additively manufactured components include internal side walls that define cooling channels in the component, for example, and the post-manufacturing processes are generally physically incapable of improving the surface finish of the internal side walls.
BRIEF DESCRIPTION OF THE INVENTION
In one aspect, a method of additively manufacturing an object is provided. The method includes providing an additive manufacturing system configured to operate using at least one build parameter, and forming the object using the additive manufacturing system. The object is formed with the at least one build parameter having a value within a predetermined threshold such that the object, as manufactured, has a surface finish of less than about 5 microns Ra.
In another aspect, an object additively manufactured by a process is provided. The process includes the steps of providing an additive manufacturing system

configured to operate using at least one build parameter, and forming the object using the additive manufacturing system. The object is formed with the at least one build parameter having a value within a predetermined threshold such that the object, as manufactured, has a surface finish of less than about 5 microns Ra.
BRIEF DESCRIPTION OF THE DRAWINGS OF THE INVENTION
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
FIG. 1 is a block diagram of an exemplary additive manufacturing system;
FIG. 2 is a comparison view of internal channels within additively manufactured objects that are formed using non-optimized build parameters and optimized build parameters; and
FIG. 3 is a flow diagram illustrating an exemplary method of additively manufacturing an object.
Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of the disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of the disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein.
DETAILED DESCRIPTION
In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms "a", "an", and "the" include plural references unless the context clearly dictates otherwise.

"Optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about", "approximately", and "substantially", are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
Embodiments of the present disclosure relate to forming an additively manufactured object having an improved surface finish without post-manufacturing processing. More specifically, the additive manufacturing system described herein is operable using at least one build parameter such as, but not limited to, laser power, layer thickness of powder bed material, hatch distance between adjacent laser scan vectors, and particle size of the powder bed material. The systems and methods described herein include operating the additive manufacturing system using optimized build parameters each having a value within a predetermined threshold. It has been found, without being bound to any particular theory, that objects formed using the optimized build parameters have a surface finish of less than about 5 microns Ra, as manufactured. The improved surface finish is not limited to an exterior surface of the object, but rather is realized on side walls that define internal channels within the object as well. As such, objects formed using the optimized build parameters have an improved surface finish without post-manufacturing processing, such that the objects may be finished and certified for service in a faster and less costly manner.

FIG. 1 is a block diagram of an exemplary additive manufacturing system 100, such as a direct metal laser melting (DMLM) system. In the exemplary embodiment, additive manufacturing system 100 includes a build chamber 102 and a moveable build platform 104. An object 106 is fabricated within build chamber 102 on top of moveable build platform 104, as will be explained in further detail below. Additive manufacturing system 100 further includes a laser melting device 108 and a controller 110. In one embodiment, powder bed material 112 is deposited within build chamber 102 and a pulsed laser beam 114 generated by laser melting device 108 melts powder bed material 112 to manufacture object 106.
In addition, additive manufacturing system 100 includes a gas source 116 in flow communication with build chamber 102. In one embodiment, gas source 116 facilitates forming an inert atmosphere within build chamber 102 for use during the additive manufacturing process. For example, the inert atmosphere may be formed from a gas such as, but not limited to, helium, argon, hydrogen, oxygen, nitrogen, air, nitrous oxide, ammonia, carbon dioxide, and combinations thereof.
In operation, the form and the material buildup of object 106 are determined as a function of design data embodied in a data file 118. Data file 118 may be in any form that enables additive manufacturing system 100 to function as described herein. For example, data file 118 may be a computer aided design (CAD) file or scan data. In some embodiments, the CAD file or scan data is converted into a different file format, such as a stereolithographic or standard triangle language ("STL") file format. The STL format file is then processed by a slicing program to produce an electronic file that converts the three-dimensional electronic representation of object 106 into an STL format file that includes the object 106 represented as two-dimensional slices. The layer information generated from this process is transmitted to controller 110, and controller 110 controls the operation of moveable build platform 104 and laser melting device 108, for example, and also controls the supply of powder bed material 112 into build chamber 102, to facilitate manufacturing object 106.

For example, after a layer of powder bed material 112 has been processed as a result of being melted by pulsed laser beam 114, at least a portion of moveable build platform 104 may be moved (i.e., lowered) within build chamber 102. Thereafter, additional powder bed material 112 may be deposited within build chamber 102 and then processed using pulsed laser beam 114. Each time a subsequent layer of powder bed material 112 is deposited within build chamber 102, a recoater arm may be used to smooth the layer such that the layer forms a substantially planar surface within build chamber 102. The layer is then melted in each successive build cycle.
Powder bed material 112 is any material that enables additive manufacturing system 100 to function as described herein. In one embodiment, powder bed material 112 includes at least one of a nickel-based material or a cobalt-based material. Moreover, in one embodiment, powder bed material 112 is selected and utilized in build chamber 102 in accordance with at least one powder bed build parameter. Example powder bed build parameters include, but are not limited to, a layer thickness of powder bed material 112 deposited within build chamber 102 in each successive build cycle, and a particle size of powder bed material 112. In operation, a value of the powder bed build parameters are defined within a predetermined threshold to facilitate manufacturing object 106 having a surface finish of less than about 5 microns Ra.
For example, in one embodiment, the layer thickness of powder bed material 112 is defined within a range between about 35 microns and about 45 microns. More specifically, in one embodiment, the layer thickness of powder bed material 112 is about 40 microns. Moreover, in one embodiment, the particle size of powder bed material 112 is defined within a range between about 5 microns and about 45 microns.
As noted above, laser melting device 108 is operable to perform layer-by-layer and local fusing (i.e., melting or sintering) of powder bed material 112. In one embodiment, pulsed laser beam 114 is applied in a pulsed manner utilizing laser

welding build parameters including, but not limited to, a laser power used by laser melting device 108 during an additive manufacturing process, and a hatch distance between adjacent laser scan vectors of pulsed laser beam 114. In operation, a value of the laser welding build parameters are defined within a predetermined threshold to facilitate manufacturing object 106 having a surface finish of less than about 5 microns Ra.
For example, in one embodiment, the laser power used by laser melting device 108 when forming object 106 is defined within a range between about 285 watts and about 295 watts. Moreover, in one embodiment, the hatch distance between adjacent laser scan vectors is defined within a range between about 0.10 millimeters (mm) and about 0.12 mm. More specifically, in one embodiment, the hatch distance between adjacent laser scan vectors is about 0.11 mm.
Forming object 106 using additive manufacturing system 100, wherein additive manufacturing system 100 is operated with the values of the powder bed build parameters and the laser welding build parameters within predetermined thresholds, produces object 106 having a surface finish of less than about 5 microns Ra. In some embodiments, a finishing operation is performed on object 106 such that the surface finish of an exterior surface of object 106 is reduced to less than about 1 micron Ra. An example finishing operation includes, but is not limited to, shot peening the exterior surface of object 106. As such, the surface finish of object 106 is improved in a faster and less costly manner when compared to performing a finishing operation on an object additively manufactured using non-optimized build parameters.
FIG. 2 is a comparison view of internal channels within additively manufactured objects that are formed using non-optimized build parameters and optimized build parameters. In the exemplary embodiment, object 106 formed using optimized build parameters includes a first internal channel 120, and an object 122 formed using non-optimized build parameters (i.e., the object is formed using values of the build parameters outside the predetermined thresholds) includes a second

internal channel 124. First internal channel 120 is defined by a first side wall 126, and second internal channel 124 is defined by a second side wall 128.
As noted above, forming object 106 using optimized powder bed and laser welding build parameters produces object 106 having a surface finish of less than about 5 microns Ra. When forming object 106 having first internal channel 120 defined therein, the improved surface finish is likewise applicable to first side wall 126 that defines first internal channel 120. As such, surfaces and side walls disposed internally within object 106, and not physically accessible using traditional surface finishing means, are likewise formed with a surface finish of less than about 5 microns Ra. Alternatively, object 122 formed using non-optimized build parameters has a surface finish of greater than 5 microns Ra.
An exemplary technical effect of the systems and methods described herein includes at least one of: (a) forming an object having a surface finish of less than about 5 microns Ra, as manufactured; (b) forming side walls, disposed internally within the object, having a surface finish of less than about 5 microns Ra; and (c) reducing or eliminating the need for post-manufacturing surface finishing of the object.
Exemplary embodiments of an additive manufacturing system and method of additively manufacturing an object are provided herein. The systems and methods are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the configuration of components described herein may also be used in combination with other processes, and is not limited to practice with only an additive manufacturing system, as described herein.
Although specific features of various embodiments of the present disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of embodiments of the present disclosure, any

feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose the embodiments of the present disclosure, including the best mode, and also to enable any person skilled in the art to practice embodiments of the present disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the embodiments described herein is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

WE CLAIM:
1. A method of additively manufacturing an object, said method comprising:
providing an additive manufacturing system configured to operate using at least one build parameter; and
forming the object using the additive manufacturing system, wherein the object is formed with the at least one build parameter having a value within a predetermined threshold such that the object, as manufactured, has a surface finish of less than about 5 microns Ra.
2. The method as claimed in claim 1, wherein the at least one build parameter is a laser power of a laser melting device in the additive manufacturing system, and wherein forming the object comprises forming the object using the laser power defined within a range between about 285 watts and about 295 watts.
3. The method as claimed in claiml, wherein the at least one build parameter is a layer thickness of powder bed material, and wherein forming the object comprises forming the object using the layer thickness defined within a range between about 35 microns and about 45 microns in each successive build cycle.
4. The method as claimed in claim 1, wherein the at least one build parameter is a hatch distance between adjacent laser scan vectors, and wherein forming the object comprises forming the object using the hatch distance defined within a range between about 0.10 millimeters (mm) and about 0.12 mm.

5. The method as claimed in claiml, wherein the at least one build parameter is a particle size of powder bed material, and wherein forming the object comprises forming the object using the particle size defined within a range between about 5 microns and about 45 microns.
6. The method as claimed in claiml further comprising performing a finishing operation on the object such that the surface finish on an exterior surface of the object is reduced to less than about 1 micron Ra.
7. The method as claimed in claim6, wherein performing a finishing operation on the object comprises shot peening the exterior surface of the object.
8. The method as claimed in claiml, wherein forming the object comprises forming the object from a powder bed material including at least one of a nickel-based material or a cobalt-based material.
9. The method as claimed in claiml, wherein the object includes an internal channel formed therein, the internal channel defined by a side wall, and wherein forming the object comprises forming the object with the at least one build parameter having the value within the predetermined threshold such that the side wall has a surface finish of less than about 5 microns Ra.
10. The method as claimed in claiml, wherein providing an additive manufacturing system comprises providing a direct metal laser melting system.

11. An object additively manufactured by a process comprising the steps of:
providing an additive manufacturing system configured to operate using at least one build parameter; and
forming the object using the additive manufacturing system, wherein the object is formed with the at least one build parameter having a value within a predetermined threshold such that the object, as manufactured, has a surface finish of less than about 5 microns Ra.
12. The object as claimed in claiml 1, wherein the at least one build parameter is a laser power of a laser melting device in the additive manufacturing system, and wherein forming the object comprises forming the object using the laser power defined within a range between about 285 watts and about 295 watts.
13. The object as claimed in claiml 1, wherein the at least one build parameter is a layer thickness of powder bed material, and wherein forming the object comprises forming the object using the layer thickness defined within a range between about 35 microns and about 45 microns in each successive build cycle.
14. The object as claimed in claiml 1, wherein the at least one build parameter is a hatch distance between adjacent laser scan vectors, and wherein forming the object comprises forming the object using the hatch distance defined within a range between about 0.10 millimeters (mm) and about 0.12 mm.
15. The object as claimed in claiml 1, wherein the at least one build parameter is a particle size of powder bed material, and wherein forming the object comprises forming the object using the particle size defined within a range between about 5 microns and about 45 microns.

16. The object as claimed in claimll further comprising performing a finishing operation on the object such that the surface finish on an exterior surface of the object is reduced to less than about 1 micron Ra.
17. The object as claimed in claiml6, wherein performing a finishing operation on the object comprises shot peening the exterior surface of the object.
18. The object as claimed in claimll, wherein forming the object comprises forming the object from a powder bed material including at least one of a nickel-based material or a cobalt-based material.
19. The object as claimed in claiml 1, wherein the object includes an internal channel formed therein, the internal channel defined by a side wall, and wherein forming the object comprises forming the object with the at least one build parameter having the value within the predetermined threshold such that the side wall has a surface finish of less than about 5 microns Ra.
20. The object as claimed in claiml 1, wherein providing an additive manufacturing system comprises providing a direct metal laser melting system.