Comparison of different additive manufacturing patterns on the performance of rapid vacuum casting for mating parts via the Taguchi method

Rapid vacuum casting has been proven to be a successful method in producing high-quality parts in small series. However, a challenge lies in the selection of proper Additive Manufacturing (AM) technologies for the development of a master pattern for the vacuum casting process. Each AM technologies differ from one another in terms of dimensional accuracy, surface finish, cost and lead times. The aim of this study is to investigate the performance of casting mating parts based on different additive manufacturing patterns for small batch. Three types of AM-based patterns: Fused Deposition Modeling (FDM), Stereolithography (SLA) and Multi-Jet Fusion (MJF) were compared. The Taguchi method, Signal to Noise ratio (S/N), Analysis of Variance (ANOVA) and T-test were conducted in determining the optimized parameters. From the findings, curing time is shown to be a significant parameter for dimensional accuracy and surface finish. Dimensional deviation varies in different directions of parts. For surface finish, there was only a slight change from the master pattern whereas the surface roughness of casting parts decreased within the range 0.23% to 2.85%. Tolerance grades for the selected dimensions of the parts were in the permissible range, based on ISO286-1:2010. When using distinct kinds of AM patterns to create replacement components, design tolerance is needed. It was suggested to select AM technology similar to that had been used for the original components. Battery cover was selected as a case study to represent the mating application parts.

3D Printing Technology with Plastic Materials for Hip Implant Master Patterns Manufacturing

This paper describes a hip implant model designed to assess the Fused Deposition Modeling (FDM) process for manufacturing investment casting master patterns. In addition, an indirect approach toward manufacturing master pattern via silicone rubber moulding in conjunction with 3D Printing process manufactured hip implant master pattern has been investigated. The dimensional accuracies of the manufactured AM master patterns and the wax pattern are presented. Finally, cost and lead time comparisons carried out between FDM ABS pattern manufacturing, indirect pattern manufacturing via silicone rubber moulding and conventional pattern manufacturing by metal mould are also presented.

The excavation of water well J3 at the Ancient City Site of the Zhu State in Zoucheng City, Shandong Province in 2017

In March through July 2017, School of History and Culture of Shandong University and other institutions conducted the second term of excavation in the Ancient City Site of the Zhu State, which recovered over 350 features of various types belonging to the Spring-and-Autumn and Warring-States Periods and the Han and Tang Dynasties. Among them, the water well J3 was in a cylindrical vertical pit shape and lined with rectangular bricks and pottery well curbs; the artifacts unearthed from it included pottery wares, iron implements and bronze weighing instruments of the Xin Dynasty (Wang Mang Interregnum, 8–23 CE). The main period of using of J3 was the late Western Han Dynasty, and it was abandoned at the end of the Western Han Dynasty to the Xin Dynasty. The unearthing of the bronze weighing instruments from J3 provided important materials for further exploration to the issues about the measurement system of the Xin Dynasty; the unearthing of the bronze coin master pattern provided important materials for the exploration to the monetary reform in Wang Mang Interregnum. The excavation of this year provided rich data for the establishment of the chronology and cultural genealogy of the site, clarification of the functions and properties of the excavated area and exploration of the evolution of the settlement pattern of the site.

Direct Metal Forming of a Microdome Structure with a Glassy Carbon Mold for Enhanced Boiling Heat Transfer

The application of microtechnology to traditional mechanical industries is limited owing to the lack of suitable micropatterning technology for durable materials including metal. In this research, a glassy carbon (GC) micromold was applied for the direct metal forming (DMF) of a microstructure on an aluminum (Al) substrate. The GC mold with microdome cavities was prepared by carbonization of a furan precursor, which was replicated from the thermal reflow photoresist master pattern. A microdome array with a diameter of 8.4 μm, a height of ~0.74 μm, and a pitch of 9.9 μm was successfully fabricated on an Al substrate by using DMF at a forming temperature of 645 °C and an applied pressure of 2 MPa. As a practical application of the proposed DMF process, the enhanced boiling heat transfer characteristics of the DMF microdome Al substrate were analyzed. The DMF microdome Al substrate showed 20.4 ± 2.6% higher critical heat flux and 34.1 ± 5.3% higher heat transfer coefficient than those of a bare Al substrate.

Assessment of natural variations in letter formations incorporating master pattern of handwriting

Handwriting is made up of countless habitual patterns. An individual’s handwriting is made up of a complexity of habitual patterns that are repeated within a typical range of vari­ation around the model patterns. The muscle coordination of these and perceptions of how an individual sense form helps each one to develop one’s own Master Pattern of writing. A total number of 540 60 samples from each age group — 30 samples each from males & females, has been collected from 9 different age groups. Three handwriting samples — two in present handwriting with a gap of 5–10 minutes between the two handwritings and one old or past handwriting sample collected from each individual gap ranged from 2–33 years between present and old handwritings.With the due effect of the findings gathered from the present investigation the cases lacking in contemporary handwritings can be undertaken with ease by taking into account the letters — ‘f, y, r and i’ which have a major effect of natural variations on them which in turn makes them unreliable and should be avoided in the process of comparison as well as while forming an opinion.

Combining Optical Metrology and Additive Manufacturing for Efficient Manufacturing of Carbon Fiber Reinforced Plastic Orthopedics: A Case Study

Often, carbon fiber reinforced plastic (CFRP) manufacturing represents an expensive, time-consuming, small-scale production due to products and components characterized by complex geometric properties. In the field of orthopedic products individual molds, usually made of metal alloys or plaster, are necessary to shape the contour of the components. The presented case study focuses on individually manufactured masks for post-operative treatment of uncomplicated midfacial fractures that are frequent and typical injuries in popular contact sports like football or handball. To improve the costly process of CFRP production of individually manufactured masks, this paper describes the advantages of the combination of optical metrology (i.e. 3D-scanning) and additive manufacturing (i.e. 3D-printing). Therefore, the conventional process chain consisting of the main process steps molding (master pattern), casting (mold), CFRP laminating, curing, cutting and final assembly is replaced by 3D-scanning (instead of master pattern), followed by the revision of the CAD-model (to prevent cutting efforts), 3D-printing (mold), CFRP laminating, curing and final assembly. Summarizing, this case study on manufacturing of carbon fiber reinforced plastic orthopedics shows that the combination of innovative manufacturing technologies opens up new possibilities to increase efficiency in craft based manufacturing.

Dictionary Indexing of Electron Channeling Patterns

The dictionary-based approach to the indexing of diffraction patterns is applied to electron channeling patterns (ECPs). The main ingredients of the dictionary method are introduced, including the generalized forward projector (GFP), the relevant detector model, and a scheme to uniformly sample orientation space using the “cubochoric” representation. The GFP is used to compute an ECP “master” pattern. Derivative free optimization algorithms, including the Nelder–Mead simplex and the bound optimization by quadratic approximation are used to determine the correct detector parameters and to refine the orientation obtained from the dictionary approach. The indexing method is applied to poly-silicon and shows excellent agreement with the calibrated values. Finally, it is shown that the method results in a mean disorientation error of 1.0° with 0.5° SD for a range of detector parameters.

Surface roughness improvement of cast components in vacuum moulding by intermediate barrel finishing of fused deposition modelling patterns

In this work, investigations have been made for surface roughness (Ra) improvement of vacuum moulding (VM) components by introducing barrel finishing (BF) on fused deposition modelling patterns at preliminary stage (i.e. before being used as master patterns). The Ra improvement will help to avoid/reduce post machining/finishing operations for green manufacturing. The VM master patterns were prepared using P-430 grade acrylonitrile butadiene styrene material on commercial fused deposition modelling setup. Further, Ra of VM master pattern prepared was improved by using BF process (as intermediate process). The controllable parameters of BF and VM process (namely, media weight, cycle time, vacuum pressure and grain size of refractory sand) were studied at three levels by using Taguchi L9 orthogonal array to explore their affects on Ra of the final cast components. The results of study suggest that media weight of BF and sand grain size of VM process contribute significantly for improving Ra.

Industrial Machining Robot with Incorporated Robotic CAM System

This chapter first describes the robotic CAM system proposed from the viewpoint of robotic servo controller for an industrial robot RV1A. Then, a reverse post-processor is proposed for the robotic CAM system to online generate the original CL data from the NC data post-processed for a five-axis NC machine tool with a tilting head. Next, an application of the industrial robot with incorporated the robotic CAM system is introduced. The application is developed to efficiently machine foamed polystyrene patterns which are typically used for master pattern of sand mold or for lost-foam pattern for full mold casting (i.e., lost-foam casting). If the target material is limited to such foamed polystyrenes, it is expected that the developed machining robot is superior to conventional NC machine tools in terms of introduction cost, running cost, compactness, and easiness of use. Finally, promising machining results of foamed polystyrene materials are shown.