Rapid Manufacturing of Silicon Carbide Composites

From the earliest days of SFF technology development, a viable technique for the direct manufacture of fully-functional parts has been a major technology goal. While direct metal methods have been demonstrated for a variety of metals including aluminum, steel and titanium, they have not reached wide commercial application due to processing speed, final material properties and surface finish. In this paper the development of an SLS-based rapid manufacturing (RM) platform is reviewed. The core of this platform is a thermosetting binder system for preform parts in contrast to the thermoplastic materials currently available for SLS. The preforms may include metal and/or ceramic powders. A variety of fully functional parts can be prepared from different combinations of materials and post processing steps including binder pyrolysis, free-standing alloy infiltration, room temperature polymer infiltration and machining. The main issues of these steps are reviewed followed by a discussion about the support of RM. This paper is an intermediate report additional materials, applications, process models and product design strategies will be incorporated into the project in the next year.Mechanical Engineerin

SLS Materials Development Method for Rapid Manufacturing

As soon as SFF technology development began to make Rapid Prototyping possible the interest in Rapid Manufacturing (RM) began to grow. The advantages in terms of functional integration, elimination of tooling and fixtures and mass customization make a compelling case for RM, leading some in the field to call it the next industrial revolution. Yet without the materials properties necessary to provide the function and variety currently available from mass production methods, the application of RM will remain limited. Developing new materials for the SLS process, one immediate step toward a larger portfolio of RM materials, is very challenging. The formation of high quality SLS parts relies on appropriate powder characteristics, thermal cycles and sintering behavior. Based on a brief examination of the key factors in SLS processing and a research project to develop a new binder material for Silicon Carbide composites, a systematic materials development method is proposed in this paper. The method provides guidance for introducing new SLS materials, support for educating new SLS users and researchers and direction for several future research projects.Mechanical Engineerin

Innovative Selective Laser Sintering Rapid Manufacturing using Nanotechnology

The objective of this research is to develop an improved nylon 11 (polyamide 11) polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing (RM). A nanophase was introduced into nylon 11 via twin screw extrusion to provide improved material properties of the polymer blends. Atofina (now known as Arkema) RILSAN® nylon 11 injection molding polymer pellets was used with three types of nanoparticles: chemically modified montmorillonite (MMT) organoclays, nanosilica, and carbon nanofibers (CNF) to create nylon 11 nanocomposites. Wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) were used to determine the degree of dispersion. Fifteen nylon 11 nanocomposites and control nylon 11 were fabricated by injection molding. Flammability properties (using a cone calorimeter with a radiant flux of 50 kW/m2 ) and mechanical properties such as tensile strength and modulus, flexural modulus, elongation at break were determined for the nylon 11 nanocomposites and compared with the baseline nylon 11. Based on flammability and mechanical material performance, five polymers including four nylon 11 nanocomposites and a control nylon 11 were cryogenically ground into fine powders for SLS RM. SLS specimens were fabricated for flammability, mechanical, and thermal properties characterization. Nylon 11-CNF nanocomposites exhibited the best overall properties for this study.Mechanical Engineerin

Investigating Dielectric Properties of Sintered Polymers for Rapid Manufacturing

Selective Laser Sintering (SLS) of polymers is the leading technology in the growing field of Rapid Manufacturing. High Speed Sintering (HSS) is a process that offers the potential to reduce costs and processing times and thus open significant new markets for Rapid Manufactured parts. Much academic research has been performed with respect to mechanical properties of Rapid Manufactured parts, however the area of electrical properties has received little attention to date. Electrical properties are obviously important in applications that will involve embedding of circuits with Rapid Manufactured 3D objects. However electrical properties are also important for a wide variety of electrical products where Rapid Manufactured parts can be used as housings etc. This paper focuses on the dielectric properties of parts made by SLS and HSS and compares properties with those for conventionally processed polymers. Dielectric strength results show that SLS parts are comparable with injection moulded parts, while HSS parts are inferior to SLS parts. Dielectric constant and dissipation factor results show that HSS parts are comparable with injection moulded parts, whilst SLS parts have superior properties. The presence of porosity (SLS and HSS) and the presence of carbon (HSS) are suggested as reasons behind the variation in dielectric properties when compared with injection moulded parts.Mechanical Engineerin

Strategic, tactical decisions and information in Rapid Manufacturing supply chain

The efficiency and agility of its supply chain is vital to the commercial success of any product. Sharing strategic and tactical information effectively within the supply chain is often a key factor in achieving this goal. This paper proposes a framework to identify strategic, tactical decisions and information. The framework is used to conduct a sector based analysis of the Rapid Manufacturing (RM) industry. The decisions and information identified include amongst others various supply chain strategies and technical information

Development of a regenerative pump impeller using rapid manufacturing techniques

This paper presents a method of rapid manufacture used in the development of a regenerative pump impeller. Rapid manufacturing technology was used to create complex impeller blade profiles for testing as part of a regenerative pump optimisation process. Regenerative pumps are the subject of increased interest in industry. Ten modified impeller blade profiles, relative to the standard radial configuration, were evaluated with the use of computational fluid dynamics and experimental testing. Prototype impellers were needed for experimental validation of the CFD results. The manufacture of the complex blade profiles, using conventional milling techniques, is a considerable challenge for skilled machinists. The complexity of the modified blade profiles would normally necessitate the use of expensive CNC machining with 5 asis capability. With an impeller less than 75mm in diameter and a maximum blade thickness of 1.3mm, a rapid manufacturing technique enabled production of complex blade profiles that were dimensionally accurate and structurally robust enough for testing. As more advanced rapid prototyping machines become available in the study in the future, e.g. 3D photopolymer jetting machine, the quality of the parts, particularly in terms of surface finish, will improve and the amount of post processing operations will reduce. This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture. The ability to manufacture complex blade profiles that are robust enough for testing, in a rapid and cost effective manner is proving essential in the overall design optimisation process for the pump

Design of Embedded Resistance Heating Element Using Rapid Manufacturing Process

Mechanical Engineerin

Rapid manufacturing- state of the art, analysis and future perspectives

Layer based manufacturing system often referred to as Rapid Prototyping (RP) have been in existence for 22 years, in the past 5 years Rapid Manufacturing (RM) has emerged from these RP systems to produce functional and structural customer focused end use components and products. This keynote paper will review the current range of technologies for metallic systems, it will also evaluate the operating principles, features, potential and limitations of current commercially available systems. Rapid Manufacture is increasingly being used for high value difficult to manufacture components with a new set of design rules required to fully exploit the RM systems inherent characteristics. A case studies approach will be used to show the benefits and pitfalls this new design freedom can provide designers