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…
Abstract
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.
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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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Research limitations/implications
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.
Originality/value
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.
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J.O. Obielodan, A. Ceylan, L.E. Murr and B.E. Stucker
The increasing interest in engineering structures made from multiple materials has led to corresponding interest in technologies, which can fabricate multi‐material parts. The…
Abstract
Purpose
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).
Design/methodology/approach
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.
Findings
Results show evidence of good bonding between many combinations of materials, thus illustrating increasing potential for multi‐material fabrication using UC.
Originality/value
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.
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Brent E. Stucker and Walter L. Bradley
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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Practical implications
This study illustrated that boron must be added to copper to achieve infiltration when surface oxides are present.
Originality/value
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.
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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…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
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.
Research limitations/implications
The developed method requires that at least one simple closed loop exist for each potential hole.
Originality/value
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.
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Joel Quincieu, Chris Robinson, Brent Stucker and Todd Mosher
This paper illustrates an effective application of rapid prototyping (RP) to produce a high definition polymer model of a satellite structure prior to final machining of the…
Abstract
Purpose
This paper illustrates an effective application of rapid prototyping (RP) to produce a high definition polymer model of a satellite structure prior to final machining of the aluminum panels. The benefits when using this type of model in the design and assembly stages of satellite fabrication make clear that RP can and should play an important role in the design and fabrication of small satellite structures.
Design/methodology/approach
Selective laser sintering was utilized to produce a full‐scale model of a novel modular small satellite structure. This model was then used as a tool for quality control, fit check, assembly process verification, mock‐up, and as a model for manufacturing tooling design.
Findings
This case study illustrates that the use of RP to create a model early in the design cycle is beneficial from a cost and time perspective even when applied to a product which will be produced in a quantity of one. In addition, the merits of RP mesh well with modular designs and for applications where assembly and test tooling is required to validate the quality of a product.
Practical implications
This paper illustrates an effective use of RP in the satellite fabrication industry. The benefits described are generally applicable to other complex systems which need design validation early in the design cycle.
Originality/value
There are few examples of the effective application of RP to produce models, but not the final product, of a complex structure in the satellite and other industries where small lot production occurs.
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This paper aims to comprehensively review ultrasonic additive manufacturing (UAM) process history, technology advancements, application areas and research areas. UAM, a hybrid 3D…
Abstract
Purpose
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.
Design/methodology/approach
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.
Findings
This paper summarizes key physics of the process, characterization methods, mechanical properties, past and active research areas, process limitations and application areas.
Originality/value
This paper reviews the UAM process for the first time.
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This paper presents a new 3D offset method for modifying CAD model data in the STL format. In this method, vertices, instead of facets, are offset. The magnitude and direction of…
Abstract
This paper presents a new 3D offset method for modifying CAD model data in the STL format. In this method, vertices, instead of facets, are offset. The magnitude and direction of each vertex offset is calculated using the weighted sum of the normals of the facets that are connected to each vertex. To facilitate the vertex offset calculation, topological information is generated from the collection of unordered triangular facets making up the STL file. A straightforward algorithm is used to calculate the vertex offset using the adjoining facet normals, as identified from the topological information. This newly developed technique can successfully generate inward or outward offsets for STL models. As with any offset methodology, this technique has benefits and drawbacks, which will be discussed in this paper. Finally, conclusions will be made regarding the applicability of the developed methodology.