LASERS, SINTERING, RAPID prototyping, STEREOLITHOGRAPHY, and POLYMERS
Purpose – The purpose of this paper is to report experimental investigations performed to analyze the effect of process parameters on the shape accuracy of selective laser sintered (SLS) parts. Design/methodology/approach – The effect of process parameters, namely build orientation, laser power, scan speed, cylinder diameter and build chamber temperature has been studied on shape accuracy by using geometric tolerances such as cylindricity and flatness. Central composite design (CCD) is used to plan the experiments and a second order regression model has been developed to predict flatness and cylindricity. The significance of process variables on flatness and cylindricity has been evaluated using analysis of variance technique. Findings – It is observed that interaction effects are more dominant than individual effects. In case of cylindricity, it is found that the interaction between the scan speed and orientation is the dominant factor next to the orientation and quadratic effect of the geometry. In case of flatness, the interaction between build chamber temperature and scan speed is the dominant factor. Research limitations/implications – The empirical models presented in this paper work within the range of values used for the experiments and most of these models need to be redeveloped for use with other materials. Practical implications – The empirical models developed in this work would be useful in deciding the process parameters for parts with improved geometrical tolerances. The optimum parameters identified from the empirical model are found to yield accurate parts with minimum shape error. Originality/value – The paper establishes the interactions between this build orientation, geometry and process parameters on the shape accuracy of SLS process. [ABSTRACT FROM AUTHOR]
POLYMERIC composites, RAPID prototyping, RAPID tooling, SINTERING, LASERS, and HUAZHONG University of Science & Technology (Beijing, China)
Rapid prototyping (RP) and tooling (RT) are the technologies for quickly fabricating functional components and tooling inserts directly from CAD data by selectively adding material layer by layer. In this paper, multiphase polymeric materials for RP and RT technologies and their applications, which are developed by the Rapid Manufacturing (RM) Center of Huazhong University of Science and Technology (HUST) in China, were introduced. Selective laser sintering (SLS) is a powder-based RP process. Multi-types of multiphase polymer materials for SLS process were successfully developed in the RM center, and the SLS components were formed from these materials by using the commercial SLS machines HRPS series for various applications. High impact polystyrene (HIPS)/wax blend SLS parts were used as lost patterns for the investment casting process to make complex metal parts rapidly; nylon-12/organically modified rectorite and nylon-12/nanosilica composite powders were used to fabricate functional parts, which showed higher thermal and mechanical properties than neat nylon-12 SLS parts. As a RT application, Fe/epoxy composite tooling inserts were rapidly fabricated by SLS and post-processing. Stereolithography (SLA) uses photocurable resins to rapidly manufacture components with high accuracy and mechanical properties. A freeradical and cationic mixed-type radiation curable composite resin was also successfully developed, and SLA parts without obvious distortion were built on the SLA machines HRPL series from this hybrid resin, successfully and efficiently. [ABSTRACT FROM AUTHOR]
Dong Guo, Long-tu Li, Kenji, Kai Cai, Kenji, Zhi-lun Gui, Kenji, and Ce-wen Nan, Kenji
Journal of the American Ceramic Society; Jan2004, Vol. 87 Issue 1, p17-22, 6p
PIEZOELECTRIC ceramics, LASERS, SINTERING, PIEZOELECTRICITY, CERAMICS, and RAPID prototyping
This article presents a new lost mold rapid prototyping method which combines selective laser sintering (SLS) and gelcasting techniques for fabricating piezoelectric ceramics. SLS was used to fabricate sacrificial molds of the desired structure of the ceramic part. Then aqueous PZT (lead zirconate titanate) suspension was cast in the mold and solidified in situ through formation of a three-dimensional network gel. Because the polymer mold can be easily removed at the initial stage of sintering and the gelcast PZT body has a high green strength, the desired geometry of the PZT part can be completely retained after sintering of the ceramics. Complex-shaped PZT parts were successfully fabricated after using concentrated PZT suspension with low viscosity. Densities and electrical properties, such as the d[sub 33], the relative permittivity ε, the dielectric loss tgδ and the electromechanical coupling factor K[sub p] of the gelcast PZT parts were also compared with those of the die-pressed PZT samples. The results indicated that the gelforming process did not deteriorate the electrical properties of the samples, if proper dispersant was selected in developing concentrated ceramic slurry. [ABSTRACT FROM AUTHOR]
RAPID prototyping, PROTOTYPES, MANUFACTURING processes, TIME to market (New products), NEW product development, SINTERING, and LASERS
Traditional methods of creating new products are being challenged by the rise of 'rapid' techniques and technologies. A company wanting to engage in 'rapid manufacturing' now has a wide choice of machines, processes and technologies for getting its product ideas quickly into production. What many of these processes are essentially about is 'growing' parts out of minuscule pieces, as opposed to traditional manufacturing methods of machining, shaping or injection-moulding materials. Commonly, rapid manufacturing (also known as rapid prototyping) involves using laser technology to solidify or shape liquids or materials very precisely. [ABSTRACT FROM AUTHOR]
Rapid prototyping (RP) technologies, which are based on computer-aided design and computer-aided manufacturing, are widely employed in traditional industries. They are capable of achieving extensive and detailed control over the architecture of objects to be formed and therefore are increasingly used in the biomedical engineering field. Selective laser sintering (SLS), a versatile RP technique, uses a laser beam to selectively sinter powdered materials to form three-dimensional objects according to designs that can be based on data obtained from computer-based medical imaging technologies. In this article relating to biomedical applications, the principle, materials, machine modification, and parameter optimization for SLS are reviewed. Biomedical applications of SLS, especially in the fabrication of tissue engineering scaffolds and drug/biomolecule delivery vehicles, are presented and discussed. SLS exhibits great potential for many applications in biomedical engineering. [ABSTRACT FROM AUTHOR]
RAPID prototyping, PROTOTYPES, SINTERING, LASERS, and INDUSTRIAL design
The article focuses on the technologies and processes used in the rapid prototyping (RP) system and offers steps involved in selecting the right RP. It discusses the scanning laser autotype (SLA) systems and the Selective Laser Sintering process which are part of the RP systems. It is stated that while choosing the right RP system, it is important to select a reputable service provider which offers a breadth of RP solutions.
SINTERING, RAPID prototyping, PROTOTYPES, LASERS, and POLYMERS
Selective laser sintering (SLS) is one of the most rapidly growing rapid prototyping techniques (RPT). This is mainly due to its suitability to process almost any material: polymers, metals, ceramics (including foundry sand) and many types of composites. The material should be supplied as powder that may occasionally contain a sacrificial polymer binder that has to be removed (debinded) afterwards. The interaction between the laser beam and the powder material used in SLS is one of the dominant phenomena that defines the feasibility and quality of any SLS process. This paper surveys the current state of SLS in terms of materials and lasers. It describes investigations carried out experimentally and by numerical simulation in order to get insight into laser-material interaction and to control this interaction properly. [ABSTRACT FROM AUTHOR]
LASERS, SINTERING, RAPID tooling, MANUFACTURING processes, and RAPID prototyping
Selective laser sintering can be used to manufacture injection mould inserts using an indirect metal laser sintering process, such as the RapidTool[tm] process commercialised by 3D Systems. The volume of material to be laser processed for insert manufacturing is very high when compared to that for plastic prototype manufacturing. Consequently, the time involved in the laser processing is also very long. This paper describes the development and assessment of shelling strategies to be applied in an indirect rapid tooling process aimed at reducing time in the process. The feasibility of the shelling idea has been confirmed and although the scanning system offers some limitations to the idea two strategies are presented as successful, open shell and closed shell, with a great potential to save time. [ABSTRACT FROM AUTHOR]
RAPID prototyping, PHOTOPOLYMERS, SINTERING, LASERS, and ELECTRON beam furnaces
The article discusses tools and methods to enhance rapid prototyping. A description on how to accurately cure layers of liquid ultraviolet (UV)-curable photo-polymer resin using stereolithography is provided. A discussion of the selective laser sintering (SLS) process is given. Other competing technologies for fast and easy model building are discussed, including fused deposition modeling, electron beam melting, three-dimensional (3D) printing and laminated object manufacturing.
Presents a list of facts relating to the prototyping technique known as stereolithography. Increase in use of selective laser sintering; View of stereolithography enthusiasts who say that homeowners may someday construct their own kitchenware; Comments on stereolithography from Ron Barranco of stereolithography.com.
DRONE aircraft, SINTERING, LASERS, AEROSPACE industries, RAPID prototyping, and VEHICLE design & construction
The article discusses the increased use of selective laser sintering (SLS) in unmanned aerial vehicles (UAVs). Topics include an overview of SLS, which is a additive manufacturing process related to stereo lithography, SLS's versatility, such as its use in dentistry, the automotive industry, and architecture, and how rapid prototyping has helped several Aerospace & Defense (A&D) companies incorporate SLS.