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Recently, a number of research projects have been focused on an emerging additive manufacturing process, termed ultrasonic consolidation (UC). The purpose of this paper is to present an analytical energy model aimed at investigating the effects of process parameters on bond formation in UC.

In the model, two factors are defined, energy input to the workpiece within a single cycle of ultrasonic vibration (E₀) and total energy input to the workpiece (E_t), to evaluate to the magnitude of transmitted energy into the workpiece during UC.

It is found that linear weld density, E₀ and E_t are affected by process parameters in similar manners.

The current model is developed based on several simplifying assumptions, and energy dissipation and bond degradation during UC are not considered in the model.

The current model gives a useful understanding of the effects of process parameter on the bond formation in UC from an energy point of view.

This paper investigates wetting and infiltration of zirconium diboride by copper and copper/boron alloys in order to more effectively create electrodes for electrical discharge machining.

A high temperature furnace outfitted with a video recording system was utilized to observe wetting angles between molten copper alloys and zirconium diboride at various temperatures. A parallel, investigation of the thermodynamics involved with oxidation in the system was also undertaken.

This study showed that zirconium diboride can be wet by pure copper under carefully controlled conditions where oxygen contamination is minimized, and that the wetting angle increases with increasing temperature. Thermodynamic calculations reinforce the contention that oxygen contamination is the key barrier to wetting and infiltration. The addition of boron to copper significantly improves the wetting characteristics, and enables wetting and infiltration under higher oxygen contamination conditions.

This study illustrated that boron must be added to copper to achieve infiltration when surface oxides are present.

Infiltration of porous 3D green shapes of ceramics and metals is a common method for producing metal and ceramic components using rapid prototyping. Good wetting of the porous material by the infiltrant material is necessary for successful infiltration using capillary forces. This paper illustrates the alloys and conditions under which it is possible to produce electrodes of zirconium diboride/copper using rapid prototyping.

Subtractive rapid prototyping (SRP) uses layer‐based removal from a plurality of orientations in order to create geometry in a highly automated manner. However, unlike additive means, the method can be inefficient due to redundant cutting operations on previously machined regions. The purpose of this paper is to present process planning methods for SRP, specifically dealing with stock material management in multiple setup operations.

Analysis of remaining stock material was performed by considering slices of respective stereolithography (STL) models. Further, an initial approximation was made of accessibility to enable iterative visibility analysis. The combination of these approaches led to efficient and fast algorithms. After analysis, the slices could be converted back to useful STL models through polyhedral reconstruction.

This method of approximation yields results similar to exact geometry. Using remaining stock data from this approach leads to a significant reduction in tool path length and processing time in SRP.

This paper presents novel methods of geometric representation and inaccessible volume calculation for four‐axis layer‐based machining and shows a successful implementation in an SRP system.

The increasing interest in engineering structures made from multiple materials has led to corresponding interest in technologies, which can fabricate multi‐material parts. The purpose of this paper is to further explore of the multi‐material fabrication capabilities of ultrasonic consolidation (UC).

Various combinations of materials including titanium, silver, tantalum, aluminum, molybdenum, stainless steel, nickel, copper, and MetPreg^® were ultrasonically consolidated. Some of the materials were found to be effective as an intermediate layer between difficult to join materials. Elemental boron particles were added in situ between selected materials to modify the bonding characteristics. Microstructures of deposits were studied to evaluate bond quality.

Results show evidence of good bonding between many combinations of materials, thus illustrating increasing potential for multi‐material fabrication using UC.

Multi‐material fabrication capabilities using UC and other additive manufacturing processes is a critical step towards the realization of engineering designs which make use of functional material combinations and optimization.

This paper presents an offset‐based tool path generation method for STL format three‐dimensional (3D) models. The created tool‐paths can be effectively used to near‐net‐shaped parts, in particular those created using rapid prototyping.

The STL model is first offset by the distance of the selected cutter radius using a unique 3D offset method. The intersections between the top facing triangles of the offset model and tool‐path drive planes are calculated. The intersection line segments are sorted, trimmed and linked to generate continuous top envelope curves, which represent interference‐free tool paths.

The developed offset‐based algorithm can rapidly and successfully generate interference‐free tool paths as continuous lines, instead of a collection of discrete tool location points. The strategy of using adaptive step‐over distances based on local geometrical information can significantly increase machining efficiency.

The current tool path generation method only works for ball‐end mills. The entire surface of the STL model is treated as a single composite surface to be machined using raster milling. To improve machining efficiency, an automatic surface splitting algorithm could be developed to divide the model into several regions based on the characteristics of a group of triangular facets, and then machine these identified regions using different strategies and cutters.

The offset‐based tool‐path generation algorithm from STL models is a unique and novel development, which is useful in the rapid prototyping and computer‐aided machining areas.

Rapid prototyping (RP) techniques are being increasingly used to manufacture injection molding and die casting core and cavity sets, known as tools, and for other tooling‐related parts, such as EDM electrodes. This paper presents a STL‐based finish machining technique for tools and parts made using RP techniques in order to achieve the tight tolerance and surface finish requirements necessary for tooling applications. Rotate, scale, translate and offset algorithms are used to pre‐process the 3D model prior to its manufacture. A machining strategy of adaptive raster milling of the surface, plus hole drilling and sharp edge contour machining, is developed to finish the parts and tools after fabrication using RP. Finally, a benchmark part was designed and fabricated using the above‐mentioned strategies and the results show the effectiveness of the developed software.

This paper aims to comprehensively review ultrasonic additive manufacturing (UAM) process history, technology advancements, application areas and research areas. UAM, a hybrid 3D metal printing technology, uses ultrasonic energy to produce metallurgical bonds between layers of metal foils near room temperature. No melting occurs in the process – it is a solid-state 3D metal printing technology.

The paper is formatted chronologically to help readers better distinguish advancements and changes in the UAM process through the years. Contributions and advancements are summarized by academic or research institution following this chronological format.

This paper summarizes key physics of the process, characterization methods, mechanical properties, past and active research areas, process limitations and application areas.

This paper reviews the UAM process for the first time.

This paper presents a unique method to recognize circular holes from 3D models in the STL format. The topological information generated by this method enables identification of holes and tool path generation for holes which should be drilled rather than milled.

A method based on a set of developed algorithms is used to identify closed loops from a STL model, identify which closed loops correspond to cylindrical holes, find hole orientations, locations and diameters, and calculate the depth for the recognized holes. The developed procedure and algorithms have been implemented in Visual C++ to illustrate the efficacy of the method.

The implementation results showed that the developed algorithms can successfully recognize circular holes of differing sizes on both simple and complex surfaces, and in any orientation. Tool paths can thus be generated from STL models to more efficiently and accurately machine circular holes.

The developed method requires that at least one simple closed loop exist for each potential hole.

A new and unique hole recognition method for use with STL models was developed. This method is useful for accurately and efficiently machining parts with circular holes from STL models as well as finish machining near‐net shape parts with circular holes created using rapid prototyping.

The purpose of this paper is to familiarize the reader with the capabilities of EFAB technology, a unique additive manufacturing process which yields fully assembled, functional mechanisms from metal on the micro to millimeter scale, and applications in medical devices.

The process is based on multi‐layer electrodeposition and planarization of at least two metals: one structural and one sacrificial. After a period of initial commercial development, it was scaled up from a prototyping‐only to a production process, and biocompatible metals were developed for medical applications.

The process yields complex, functional metal micro‐components and mechanisms with tight tolerances from biocompatible metals, in low‐high production volume.

The process described has multiple commercial applications, including minimally invasive medical instruments and implants, probes for semiconductor testing, military fuzing and inertial sensing devices, millimeter wave components, and microfluidic devices.

The process described in this paper is unusual among additive fabrication processes in being able to manufacture in high volume, and in its ability to produce devices with microscale features. It is one of only a few additive manufacturing processes that can produce metal parts or multi‐component mechanisms.

The purpose of this paper is to establish a scientific understanding for electrochemical infiltration of laser sintered (LS) preforms.

Electrochemical deposition techniques were modified to induce infiltration of nickel ions inside porous LS structures with deposition on pore walls.

This novel process is feasible and has the potential to produce fully dense parts. Both conductive and non‐conductive preforms can be infiltrated by this method.

Removal of trapped fluids and gases inside the porous structure is one of the major challenges in the described electrochemical infiltration process.

This work enables low‐cost production of structural parts. It expands the application base for additive manufacturing, especially laser sintering technology.

The novel process carried out in this research is energy efficient when compared to state‐of‐the‐art vacuum‐melt infiltration.

The proposed process is a novel method for facilitating room‐temperature infiltration of porous LS preforms.