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Wang, Peter

Publications and source records attributed to Wang, Peter.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Printed Metal Molds for Mainstream Automotive Production

The main focus of this work was to evaluate additive manufacturing of metal molds, with significantly reduced cost and/or procurement lead time, for production of large composite components for mainstream (> 100k units/yr) automobiles. A two-component large tool with conformal heating channels was designed, optimized, printed, machined, and tested in production. The resulting analysis indicates that large scale AM is suitable for manufacturing complex geometry large scale metal molds.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Optimization of prefabricated component installation using a real-time evaluator (RTE) connection locating system

Prefabrication promises to industrialize the construction industry. By constructing elements within a manufacturing environment, producers can better control quality and maximize production efficiency. Since the major adoption of prefabrication, a wide variety of prefabricated components have been produced for varying applications such as new construction and exterior wall retrofits. While the production processes of these prefabricated components have seen much innovation, the installation process has remained relatively unchanged for decades. To innovate the installation process with modern technologies, a real-time evaluator (RTE) has been developed to reduce the installation cost of prefabricated components by reducing installation time, decreasing rework, and improving accuracy. The RTE uses developed software solutions with off-the-shelf hardware to assist erectors in completing an installation by measuring the real-time positions of connections and prefabricated components, providing installation guidance through a graphical user interface, and monitoring the accumulated installation errors. An overview of the RTE and proposed workflow is presented. A connection locating system that guides users in expediting the installation of connections is introduced. Laboratory experiments were conducted to determine the accuracy improvement and time savings of the RTE in installing connections for prefabricated components. RTE enabled a time saving of up to 37% compared to traditional connection installation methods using handheld measurement tools.

Hayes, Nolan↗
DOE OSTI2024

The g-code file

The slicing process for additive manufacturing (AM) involves many steps, including slicing the object to be printed and fitting toolpaths to each resulting layer. The toolpaths define the trajectories that the machine must follow during printing to construct the object. Once the slicing is complete and all toolpaths have been found and properly planned, this data must be transferred to the 3D printer in a way the printer can use to construct the object. This is achieved by exporting a file, usually a g-code file, from the slicing software. The g-code file is a text-based file that contains instructions for the machine, controlling the system and defining the motions for each toolpath. The file, which often contains thousands of lines of code, is mostly composed of numbers that command positions for axis motions. This chapter will outline the contents of a g-code file, discuss various commands and their implementation, then provide example codes and files for object construction.

Roschli, Alex↗
DOE OSTI2024

Toolpath considerations for hybrid additive manufacturing

Hybrid additive manufacturing combines both additive and subtractive manufacturing processes to fabricate geometrically complex, dimensionally accurate parts that are difficult to make using either additive or subtractive manufacturing alone. Industrial applications for hybrid additive manufacturing include direct manufacturing (building whole parts), feature addition (adding onto existing parts), and remanufacturing or repair operations. To coordinate the additive and subtractive processes, computer-aided manufacturing (CAM) software must generate distinct toolpaths for each process. Each application requires different considerations and inputs when generating the toolpaths. For example, when building a part with an internal cavity that would otherwise be unmanufacturable due to reach or access limitations, a CAM must determine which layer(s) of deposition are appropriate to machine to create the internal cavity. This chapter explores the area of toolpath generation for hybrid manufacturing by discussing the necessary considerations that are unique to a hybrid process.

Feldhausen, Thomas↗
DOE OSTI2024

Planar slicing for nonextrusion AM processes

Extrusion-based AM processes, including material extrusion and directed energy deposition, construct objects by continuously depositing a relatively small amount of molten feedstock to a specific location. Nonextrusion AM processes, on the other hand, tend to form each layer by linearly or areally projecting either energy onto a vat of photocurable liquid or a binding agent into a bed of loose powder. Such systems vary significantly from extrusion-based AM processes but do share similarities. The general approach to path planning is the same, but nonextrusion processes typically favor the use of bitmap representations, instead of polygons, for pathing computation and do not use a g-code file to command the printer. In this chapter, a high-level discussion of these differences will be covered.

Macdonald, Eric↗
DOE OSTI2024

Travels, optimizations, and ordering

With all the necessary build pathing in place from the preceding steps, the final task is to organize the build pathing via directionality, ordering, and connectivity. Directionality controls closed-loop pathing by deciding whether construction occurs clockwise or counterclockwise. Ordering determines whether construction occurs outside-in or inside-out, by manipulating what path types will be printed first. Connectivity links all the pathing together, which is achieved through the insertion of travels. Connectivity has numerous approaches, but only the most common will be addressed in this chapter. In addition to these manipulations, other considerations, such as spiral pathing and unique cases for infill, will be discussed.

Borish, Michael↗
DOE OSTI2024

Off-axis and nonplanar slicing

Traditionally, slicing processes have assumed a horizontal plane that moves up the Z axis to produce layers. However, through relatively straightforward modifications, this process can be extended to allow planar slicing at any angle and along any axis in a process referred to as off-axis slicing. Additionally, more advanced pathing solutions are moving away from planar approaches entirely by printing directly on non-flat surfaces. Both of these alternative approaches to slicing, as well as some common issues associated with them, are discussed in this chapter to provide a foundation for more advanced pathing solutions.

Borish, Michael↗
DOE OSTI2024

Toolpath considerations for 5-axis systems

There have been many studies that show how additive manufacturing (AM) has been able to improve the performance of a component, reduce manufacturing costs, or minimize lead times. As the adoption of AM significantly increased, so did the complexity of designs for AM. Many designs require advanced systems, and in response to this, there is an increasing number of systems now capable of additional degrees of motion. 5-axis systems, which include two rotary axes, are becoming more common in the additive manufacturing community. These systems are capable of depositing material on a nonplanar surface and lend themselves to many industrial applications, further extending the design space for AM. However, computer-aided manufacturing (CAM) for AM has been dominated by 3-axis slicing software that do not typically accomodate 5-axis motion. This chapter introduces 5-axis motion and presents the unique considerations that need to be accounted for when generating toolpath trajectories for 5-axis systems.

Feldhausen, Thomas↗
DOE OSTI2024

Mechanical systems and kinematics

Kinematics is the study of how motion is achieved without reference to the forces that create the motion. This includes the basic structures of all robotic systems, such as links and joints, as well as their mathematical representations. This chapter will provide a brief overview of the types of motion used in additive manufacturing (AM) systems, as well as the mathematical equations that govern them. Rotations are explained using both Euler rotations and quaternions. Combined rotation and translations are shown using homogeneous transform matrices. The robot Jacobian, which relates joint velocities to the end effector translational velocities, is explained with an example calculation. This section will give the reader the basic mathematical foundation in kinematics that is necessary to understand the mechanical underpinnings of path planning for AM systems.

Wang, Peter↗
DOE OSTI2024

Toolpath considerations for DED: Arc and laser welding

Directed energy deposition (DED) is a form of additive manufacturing that uses localized melted metal, similar to traditional arc welding, to construct an object. In comparison to polymer systems, metal systems can exert additional control over the build process through manipulation of the pool of melted metal, called the “melt pool.” This is especially important to maintain appropriate layer heights and create high quality builds. Additionally, metal systems allow site-specific control of the printed part, which enables advanced construction techniques that would otherwise not be possible. However, both of these types of control require support from the slicing software and, potentially, sensor feedback. This chapter will discuss these control processes and their basic implementation in a slicing program. The processes described here lay the foundation for more advanced solutions, particularly sensor feedback, that will be discussed later.

Borish, Michael↗
DOE OSTI2024

Toolpath considerations for extrusion: Pellet, filament, concrete, and thermoset

There are a variety of extrusion and deposition-based processes for additive manufacturing, such as fused deposition modeling (FDM), fused filament fabrication (FFF), and directed energy deposition (DED). These processes can use a variety of materials, including thermoplastic pellets, thermoplastic filament, thermoset, concrete, metal wire, metal powder, and more. For all these processes and materials, the underlying toolpath strategies for 3D-printing an object are the same: the object to be printed is sliced into layers, then the layer is optimally fit with toolpaths of a given width, based on specific user settings. However, based on the specific process being used, additional modifiers and toolpathing strategies may be employed to maximize the capabilities of the process and successfully construct an object. This chapter explores the different pathing considerations and additional strategies to be employed in extrusion processes that use thermoplastics, thermosets, and concretes.

Roschli, Alex↗
DOE OSTI2024

Closing the Loop

Like all research, the concepts of exactly what a slicer should accomplish, and how, continue to evolve. The development of next-generation slicing is already underway, and this chapter introduces several related topics. This includes a new slicing paradigm driven by network connectivity, called “slice on demand.” This paradigm enables additional capabilities such as closing the loop with sensor feedback, experimental system support, and connectivity to simulation and visualization software, all of which are also discussed. Each of these concepts represents future opportunities for slicing software and supports the growing expectations of additive manufacturing technology.

Borish, Michael↗
DOE OSTI2023

Advanced Manufacturing Workflows for Tokamak Internal Components

The project aim was to create a new advanced manufacturing workflow for the design and creation of an internal component in a fusion device, enabling a low-cost, rapid design and fabrication cycle. As a result, two demonstration components were manufactured, and mechanical properties for two feedstock materials were tested in the context of fusion device conditions. This work shows a technological scoping toward future manufacturing of complex components in topologies relevant to magnetic fusion devices via additive manufacturing.

42 ENGINEERING↗
DOE OSTI2023

1. Introduction to Additive Manufacturing

Additive manufacturing (AM) is the process of constructing an object by adding layer upon layer of material in specific locations, to build the object into its final shape. There are many different AM processes that can be used to add layers of material, such as extrusion, material jetting, and sheet lamination. All of the AM processes are a form of digital fabrication because the object to be constructed must first be modeled with a computer. The modeled object must be converted into machine instructions that an AM system can use to construct the object. This chapter serves as an introduction to the many different AM processes. Subsequent chapters will explore the intricacies of creating machine instructions for the AM processes introduced here.

Macdonald, Eric↗
DOE OSTI2023

10. Path Modifiers

Toolpaths for additive manufacturing are typically broken into three types: closed-loop, open-loop, and space-filling. Each of these toolpaths serve a specific purpose and are often used in combination to construct an object. The standard implementation of each toolpath commands a constant motion speed and extrusion rate throughout the length of the path. The 3D printer will then make any necessary adjustments during interpolation of the motion, such as accelerating and decelerating when traversing a corner. However, sometimes more finite control and additional pathing can be needed to ensure the successful printing of a path. This chapter will outline path modifiers and how they can be used to enhance the printability of a toolpath by modifying parameters or adding segments.

Roschli, Alex↗
DOE OSTI2023

9. Support, Raft, Brim, and Skirt Pathing

The previous chapters discussed the primary path types in additive manufacturing: perimeter, inset, skeleton, skin, and infill. In addition to those distinct primary path types, regions of primary paths can be assigned secondary path types: support, raft, brim, and skirt. Support paths are used to enable the printing of features that would otherwise have nothing underneath to print atop, such as overhangs. Raft paths are used to level the build plate and provide a flat surface on which to construct the object. Brim toolpaths are used to increase the footprint of the object to improve bed adhesion and reduce first layer delamination. The last path type, the skirt, is used to prime the extruder at the start of the print. These four types of path regions are created using a combination of closed-loop, open-loop, and space-filling toolpaths. This chapter will discuss how to find and generate the pathing for each region.

Roschli, Alex↗
DOE OSTI2023

8. Open-Loop Toolpath Generation

Open-loop paths, as opposed to closed-loop paths, have start and end points that are at different locations. Open-loop paths, commonly called “skeletons,” can be generated through multiple approaches. Most approaches utilize a shape's medial axis transform and build appropriate pathing around this representation. In this chapter, a specific implementation consisting of three major steps will be discussed. These steps are Voronoi diagram generation, skeleton pruning, and path consolidation. With the major components of the implementation covered, two additional optimizations will also be described. These two optimizations, chamfering and smoothing, will be highlighted as ways to improve overall pathing quality.

Borish, Michael↗