Ceramic microfabrication by rapid prototyping process chains

Fabrication of micropatterned ceramics or ceramic microparts make high demands on the precision and resolution of the moulding process. As finishing of miniaturised or micropatterned ceramic components is nearly impossible, shaping has to be done by a replication step in the green, unfired state. To avoid high tooling costs in product development, a rapid prototyping process chain has been established that enables rapid manufacturing of ceramic microcomponents from functional models to small lot series within a short time. This process chain combines the fast and inexpensive supply of master models by rapid prototyping with accurate and flexible ceramic manufacturing by low-pressure injection moulding. Besides proper feedstock preparation and sufficient small grain size, the quality of the final components is mainly influenced by the quality of the master model. Hence, the rapid prototyping method must be carefully selected to meet the requirements of the component to be fabricated.     

胶态无模快速成形陶瓷制件的应用及发展趋势

胶态无模快速成形陶瓷制件由于具有成形精度高、可机械加工能力好、能够制备大尺寸,复杂形状陶瓷制件等特点而备受关注。本文综述了近年来发展迅速的几种陶瓷胶态无模快速成型技术。着重介绍了各种技术的成形原理和方法、工艺过程及研究现状等,通过比较分析了不同快速成型制造技术在陶瓷零件制造中的特点及其存在的问题,对于陶瓷零件成形时不同成形技术的选择提出了一些参考意见,并结合课题组研究成果展望了胶态成形的发展趋势。     

新型陶瓷快速成型装置数控系统的研究

基于GT400运动控制器的开放式体系结构的数控系统软硬件平台及其关键技术,研究陶瓷零件快速成型设备数控系统对于缩短陶瓷零件的制造周期以及提高企业的生产效率所具有的重要意义.阐述了陶瓷零件快速成型机的新工艺方法和特点,对新型陶瓷零件快速成型机机械系统及其控制要求作了详细分析,着重介绍了陶瓷零件快速成型机控制系统的硬件设计及自顶向下的软件设计.利用Visual C++6.0开发工具和GT系列运动控制器自带的DLL动态链接库开发了操作方便、运行稳定、加工精度高的开放式陶瓷快速成型装置数控系统.控制系统能够很好地满足系统开放性的要求及产品自动化生产的要求,提高了经济效益.     

组织工程载体支架的无加热沉积制造

提出采用无加热液化过程的分层沉积制造工艺制造人体组织工程载体支架。开发了采用此工艺制造组织工程载体支架的专用快速成形设备，分析了此设备的单喷头、双喷头和三喷头沉积制造在过程在骨组织工程载体支架成形制造过程中的应用。     

陶瓷零件快速成型机铺料机构控制系统的研究

  加快陶瓷零件快速成型设备的研究对于缩短陶瓷制件的制造周期以及提高企业的生产效率具有重要的意义.简述了目前陶瓷零件快速成型设备的发展状况,着重介绍了基于陶瓷零件层合速凝技术所设计的一种陶瓷零件快速成型设备铺料机构的基本结构、工艺流程和工作原理,设计了该设备铺料机构PLC控制系统.该系统运行良好,满足了产品自动化生产的要求,提高了工作效率.     

From micro to nano: properties and potential applications of micro- and nano-filled polymer ceramic composites in microsystem technology

In microsystem technology, four important material classes are established either for the generation or the replication of microstructured surfaces: silicon, polymers, metals and ceramics. Composite materials consisting of a polymer matrix and ceramic fillers show improved thermomechanical properties in comparison to polymers and can be introduced as a new additional material class. The substitution of micro-sized ceramic fillers by nano-sized ceramics in composites has a strong influence on the composite's physical properties: the reduction of ceramic particle size down to the nanometre scale results in an improved sinter activity owing to the large surface area. The fabrication of dense ceramics is simplified and can be used for a rapid prototyping of microstructured ceramic parts. The addition of nano-sized ceramics with particle sizes of <40 nm to polymers allows the manufacturing of transparent polymer based composites with modified refractive indices for use in polymer waveguides. The influence of the ceramic particle size, the ceramic content and different dispersion methods on the composite's physical properties are discussed.     

Composites by rapid prototyping technology

The use of rapid prototyping (RP) technology for rapid tooling and rapid manufacturing has given rise to the development of application-oriented composites. The present paper furnishes succinct notes of the composites formed using main rapid prototyping processes such as Selective Laser Sintering/Melting, Laser Engineered Net Shaping, Laminated Object Manufacturing, Stereolithography, Fused Deposition Modeling, Three Dimensional Printing and Ultrasonic Consolidation. The emphasis of the present work is on the methodology of composite formation and the reporting of various materials used.     

制备陶瓷件的快速成型技术

对制备复杂陶瓷件的快速成型技术,如分层实体制造、熔化沉积造型、形状沉积成型、立体光刻、选区激光烧结、喷墨打印等的原理,工艺和特点进行了评述。结果表明,快速成型技术有潜力制造复杂的结构陶瓷件、功能陶瓷件、生物陶瓷件和压电陶瓷件。这些技术制备的陶瓷件的性能可与传统方法制备的陶瓷件相媲美。展望了这些技术和前景。     

High density net shape components by direct laser re-melting of single-phase powders

Direct Metal Laser Re-Melting is a variant of the Selective Laser Sintering process, a Rapid Prototyping (RP) technology. This tool-less manufacturing technology has the potential of producing complex, high quality components from single-phase metal powders in short time scales. This is made possible by the production of consecutive two-dimensional layers. Unfortunately, finished components manufactured by this technique have their integrity and material properties dictated by the porosity within the laser re-melted structure. In order to maintain structural integrity comparable to conventionally produced components, metal components produced by the rapid prototyping method should exhibit a porosity of the order of maximum of 2% with corresponding bulk material properties. To achieve these objectives, process and laser parameters require optimisation for maximum densities to be attained. This paper reports on the development of a scanning strategy that produces stainless steel (316L) laser re-melted components which exhibit porosities of <1%, while maintaining the concept of rapid prototyping.     

The effect of chromium coating in RP technology for airfoil manufacturing

Most wind tunnel models are fabricated of all metal components using computerized numerical control (CNC) milling machines. Fabrication of metal wind tunnel models is very expensive and time consuming. The models can require months to manufacture and are often made by small high technology companies that specialize in wind tunnel model manufacture. Using rapid prototype manufacturing techniques and materials in this way significantly reduces time and cost of production of wind tunnel models. This study was done by fused deposition modelling and their ability to make components for wind tunnel models in a timely and cost effective manner. This paper discusses the application of wind tunnel model configuration constructed using FDM and FDM with chromium coating for subsonic wind tunnel testing. A study was undertaken comparing a rapid prototyping model constructed of FDM technologies using polycarbonate to that of a standard machined steel model. Results from this study show relatively good agreement among the three models and rapid prototyping method with chromium coating does have an effect on the aerodynamic characteristics which produced satisfactory results.     

EDM electrode manufacture using rapid tooling: a review

Electrical discharge machining (EDM) is a non-conventional process for the manufacture of complex or hard material parts that are difficult to machine by conventional machining processes. During EDM, the electrode shape is mirrored in the workpiece. As a result, problems are transferred on the electrode manufacturing process. Rapid tooling (RT) is a new technology which uses rapid prototyping (RP) models to reduce the time and cost of tool manufacture. The various methods of manufacturing RT electrodes, with respect to different materials and the incorporated supplementary processes, are classified in the present work. Recent international research work on RT electrodes is reviewed and the results on the performance of RT electrodes are tabulated.     

Additive manufacturing of AlSi10Mg samples using the selective laser melting technique: correlation between tensile and torsion behaviour

Additive manufacturing offers unique possibilities to produce complex components, which would not be possible or only very difficult to be realizable with conventional manufacturing processes. The potential of additive manufacturing of aluminum alloys has already been realized in prototyping, but still offers potential in the establishment of series applications. For enabling the establishment of additive manufacturing in series applications, comprehensive knowledge about the material behavior is necessary. This study examines the torsional behavior of additive manufactured AlSi10Mg samples and shows the correlation between tensile and torsional strength. Comprehensive torsion tests with strain gauges were performed and significant directional dependencies were shown. The correlation factor in the area of torsional yield strength/tensile yield strength and torsional strength/tensile strength was determined and was compared with the yield/failure conditions according to Tresca and von Mises.     

Stereolitography of ceramic suspensions

The need of fast production of prototypes of complex shapes in very short time lead to the development in the last years of many additive rapid prototyping (RP) technologies for the production of single objects or of very limited series. The new fabrication concept allowed the construction of complex parts, starting from a 3D-CAD model, without using a mould. However, most of these additive processes produce polymeric objects and only recently the laser sintering of metal powders has been commercially introduced. In this work the production of ceramic objects by stereolithography is presented starting from the development of UV curable pre-ceramic suspensions for free form fabrication of alumino-silicate parts. The suspensions are characterized by 40%–50% by volume of powder content and by a reactivity and a viscosity compatible with their application in stereolithography. The ceramic green is built in a stereolithographic system operating with a He-Cd laser (325 nm). Then, the ceramic objects are obtained by pyrolisis of the organic binder and subsequent sintering of the green at 1600 °C. Finally, a characterisation of the mechanical properties and of the microstructure of the samples is presented.     

Hybrid approach in prototyping functional medical safety devices: A case study

Utilisation of functional prototypes during the upstream design stage is able to shorten the product development cycle of a medical device and quicken the transfer process to mass manufacturing. Innovative synergy of conventional manufacturing techniques and rapid prototyping techniques is thus needed to fabricate functional prototypes successfully. This case study reports on the development of an automatically activated safety needle using different prototyping approaches for the fabrication of functional prototypes. The approaches include rapid prototyping, computer numerical control (CNC) machining and vacuum casting. The challenges of each technique are discussed and solutions are presented. A hybrid technique involving CNC machining and vacuum casting is adopted to fabricate the prototypes. This hybrid prototyping approach was able to expand the choices for materials to fabricate the prototypes and thus enabling the validation of the design mechanism in a shorter time.     

Hybrid approach in prototyping functional medical safety devices: A case study

Utilisation of functional prototypes during the upstream design stage is able to shorten the product development cycle of a medical device and quicken the transfer process to mass manufacturing. Innovative synergy of conventional manufacturing techniques and rapid prototyping techniques is thus needed to fabricate functional prototypes successfully. This case study reports on the development of an automatically activated safety needle using different prototyping approaches for the fabrication of functional prototypes. The approaches include rapid prototyping, computer numerical control (CNC) machining and vacuum casting. The challenges of each technique are discussed and solutions are presented. A hybrid technique involving CNC machining and vacuum casting is adopted to fabricate the prototypes. This hybrid prototyping approach was able to expand the choices for materials to fabricate the prototypes and thus enabling the validation of the design mechanism in a shorter time.     

光丝同轴激光增材制造研究进展

增材制造作为实现三维结构快速成形的技术,广泛用于航空航天、汽车交通等领域.当前,激光熔丝增材制造多依托于传统的激光焊接设备,采用旁轴送丝方式,在增材过程中,需调整激光头方向保证送丝和焊接头行进的相对方位,增大了复杂构件增材制造系统控制难度,损失了加工自由度.随着激光加工设备和技术的发展,近年来出现了一种可以解决上述问题...     

基于 RE / RP / RT 技术人工骨的快速成形

介绍人工骨的数字开发流程,阐述各种快速成形技术(RP)在医学上的应用。通过医学三维重构软件MIMICS对部分头骨进行三维实体重构,并利用FDM快速成形工艺进行快速成形,以RP成形件为母体进行快速硅橡胶模的开发。实践证明,应用数字制造技术为修复体等医学产品制作提供了一种有效提高临床治疗效果和修复美学效果的方法。     

Rapid hard tooling by plasma spraying for injection molding and sheet metal forming

Amidst the harsh competition over the development of new products around the world, rapid prototyping, especially rapid tooling methods have received widespread attention. Amongst the rapid hard tooling methods, thermal spraying can manufacture metal molds without limitation of pattern size. However, it has the disadvantage that only soft metals with low melting points such as zinc alloy can be sprayed to original mold, such as a rapid prototyping model or a natural material pattern, due to their lack of heat resistance and shrinkage of spray metals. So the wear resistance of spray tool is poor, it can be used only for trial or small-lot production. In this study, attempts were made to improve the heat resistance by using composite materials made of ceramic and metal powders as the sprayed original mold materials, and using stainless steel, tungsten carbide alloy, iron–nickel–chromium alloy with excellent wear resistance as spraying materials, respectively. The results show that injection molding spray mold and sheet metal forming spray die can be made by transferring from natural patterns and rapid prototyping models. As the durability and dimensional accuracy of the sprayed tools has sharply improved, the tools can be used for mass production.     

增材制造Ti-6Al-4V合金组织调控研究现状

增材制造技术可实现复杂钛合金零件的快速成形,制造的Ti-6Al-4V合金具有较高的强度以及优异的高温性能,被广泛应用于航空、医疗等各大领域。综述了金属增材制造的典型工艺,分析了Ti-6Al-4V合金的相变特征,总结了选区激光熔化制造Ti-6Al-4V的力学性能和组织调控方法,着重分析了热处理温度、冷却速率、变质处理以及超声冲击等对合金组织的影响;展望了增材制造Ti-6Al-4V合金的主要发展方向。