选择性激光烧结方法加工仿生支架的工艺研究

在利用选择性激光烧结技术加工仿生支架过程中，加工参数（包括激光功率、扫描速度、扫描间距）是影响成形质量的重要因素，通过调整加工参数可以使成形零件内部保持一定的孔隙，从而产生支架内部微孔结构。正交试验方法可以科学地安排和分析多种因素的影响，从而优化加工参数，最终获得具有较高孔隙率的仿生支架。     

选择性激光烧结试验研究

在自行研制的实验型选择性激光烧结设备的基础上,进行了各种形状零件烧结实验研究。对比线扫描和分形扫描烧结成型零件的性能,以及激光功率神经网络控制与恒定功率控制两种功率控制方法,发现采用激光功率神经网络控制的分形扫描烧结而成的试件效果最好。     

陶瓷粉末选择性激光烧结的后处理工艺分析

陶瓷粉末经选择性激光烧结后形成零件的坯体，这种坯体还须进行后处理，以进一步提高其机械性能和热学性能。本文介绍了这种陶瓷坯体的后处理方法，分析了后处理工艺对最后陶瓷零件性能的影响，为正确选择和使用后处理工艺提供了依据。     

选择性激光烧结方法加工仿生支架的工艺研究

在利用选择性激光烧结技术加工仿生支架过程中,加工参数(包括激光功率、扫描速度、扫描间距)是影响成形质量的重要因素,通过调整加工参数可以使成形零件内部保持一定的孔隙,从而产生支架内部微孔结构。正交试验方法可以科学地安排和分析多种因素的影响,从而优化加工参数,最终获得具有较高孔隙率的仿生支架。     

ZrO2对激光烧结Al2O3/SiO2/ZrO2显微组织和显微硬度的影响

在Nd:YAG激光器低功率烧结的条件下,基于选择性激光烧结工艺（SLS）成形复相陶瓷Al2O3/SiO2/ZrO2材料,利用扫描电子显微镜（SEM）、X射线衍射分析仪（XRD）和显微硬度计分别对激光烧结层加入ZrO2前后的表面形貌和断口形貌、表面物相、表面显微硬度进行了分析。结果表明,部分四方相ZrO2(t-ZrO2)相变成单斜相ZrO2(m-ZrO2),应力诱导微裂纹增韧作用和Al2O3弥散强化共同作用在某种程度上提高了烧结试样的断裂韧性,对于改善零件整体寿命和可靠性有着重要的意义。     

镍基合金粉末的选择性激光烧结试验研究

分析了金属粉末选择性激光烧结的工艺特点，通过镍基合金粉末F105的系列选择性激光烧结试验及其产物的微观结构分析，研究了金属粉末在激光作用下的熔凝过程以及各烧结参数对其熔凝过程的影响；对镍基F105合金粉末的激光烧结工艺进行了初步优化，通过多层烧结试验对获得的烧结工艺进行了试验验证。研究结果表明，采用优化工艺制备的烧结制件内部组织主要由大量微米量级的等轴晶与少量枝晶组成，结构致密。     

选择性激光烧结陶瓷粉末机理初探

综述了烧结过程、烧结原动力,研究了选区激光烧结复合陶瓷粉末的烧结性能。结果表明,通过合理控制激光工艺参数（特别是激光功率和扫描速度）,能顺利实现粉末烧结成形,且无明显的“球化”效应和翘曲变形。扫描电镜分析证实,此复合粉末体系的激光烧结是基于液相烧结机制,表面自由能的改变是其烧结的原动力。     

基于微波烧结工艺的氧化铝基陶瓷刀具的研究

采用微波烧结的方法制备了Al_2O_3/TiC陶瓷刀具材料,研究了TiC含量和烧结温度对氧化铝基陶瓷刀具材料力学性能和微观组织的影响。结果表明,在烧结温度为1 700℃,TiC的含量为30%时,刀具材料具有最好的综合力学性能,其维氏硬度和断裂韧度分别为20.46GPa和4.90 MPa·m~(1/2)。微观组织分析可知,TiC可钉扎于材料晶界处,适量的TiC颗粒可改善材料的组织均匀性,提高刀具的力学性能。     

基于选择性激光烧结技术的过渡法兰制造工艺研究

详细介绍了采用选择性激光烧结技术(SLS)制造过渡法兰实体零件的工艺过程,评论了直接成型零件过程中的质量控制及其解决方法,重点分析了翘曲变形的产生原因和影响因素。     

选择性激光烧结原理及实例应用

介绍了选择性激光烧结（SLS）技术的工艺原理及特点.用原理图直观地展示了SLS系统的工艺过程,并详细地阐述了选择性激光烧结技术在实际例子中的应用.通过SLS技术在烧结实体零件-过渡法兰的全部制作过程的介绍,使应用者熟悉实体零件的整个制作的工艺过程,从而对选择性烧结技术有进一步了解.同时随着SLS技术的发展和新工艺新材料的不断出现,势必会对未来的实际零件制造产生重大影响,对制造业产生巨大的推动作用.     

Optimizing process parameters for selective laser sintering based on neural network and genetic algorithm

Selective laser sintering (SLS) is an attractive rapid prototyping (RP) technology capable of manufacturing parts from a variety of materials. However, the wider application of SLS has been limited, due to their accuracy. This paper presents an optimal method to determine the best processing parameter for SLS by minimizing the shrinkage. According to the nonlinear and multitudinous processing parameter feature of SLS, the theory and the algorithms of the neural network are applied for studying SLS process parameters. The process is modeled and described by neural network based on experiment. Moreover, the optimum process parameters, such as layer thickness, hatch spacing, laser power, scanning speed, work surroundings temperature, interval time, and scanning mode are obtained by adopting the genetic algorithm based on the neural network model. The optimum process parameters will be benefit for RP users in creating RP parts with a higher level of accuracy.     

Development of composite porous scaffolds based on poly(lactide-co-glycolide)/nano-hydroxyapatite via selective laser sintering

Poly(lactide-co-glycolide) (PLGA)/nano-hydroxyapatite (nano-HAP) composite porous scaffolds with well-controlled pore architectures as well as high exposure of the bioactive ceramics to the scaffold surface were fabricated via selective laser sintering. Neat PLGA and the composite of PLGA/nano-HAP were used to obtain suitable process parameters. The effects of nano-HAP content on the microstructure and mechanical properties were investigated. The testing results showed that the compressive strength and modulus of the scaffolds were highly enhanced when the nano-HAP content reached from 0 to 20 wt%, while the mechanical properties experienced a sharp dropped with the nano-HAP content further increased. This might be due to the large reduction in polymer which decreased the interface bond strength between particles. It suggests that the introduction of nano-HAP as a reinforcing phase can improve the mechanical properties of the polymer porous scaffolds. The novel developed scaffolds may serve as a three-dimensional bone substrate in tissue engineering.     

Research on manufacturing Cu matrix Fe-Cu-Ni-C alloy composite parts by indirect selective laser sintering

The property of alloy parts can be adjusted conveniently if alloy element powders are used for manufacturing alloy parts by indirect selective laser sintering (SLS), but there have been no reports in this field. Fe, Cu, Ni, C composite powders of two compositions were obtained through a 3D blending way in this paper. Green parts of above composite powder were manufactured by indirect SLS. Then, Cu matrix Fe-Cu-Ni-C alloy composites were produced after green parts had been depolymerized, high temperature sintered and infiltrated by molten Cu. The post-processing of green parts, microstructure and mechanical properties of alloy composites were investigated. The results show: Ni, Cu and C diffuse into γ-Fe when green parts are being sintered at high temperature and the distributing non-uniformity of alloy elements is eliminated basically; at room temperature, alloy composite microstructures are composed of lower bainite, α-Cu precipitated out of γ-Fe and Fe-Ni after they have been solution treated at 930°C and held at 350°C for 1 h later; the yield strength of alloy composites is near to 400 MPa and the elongation is under 3%. It can be used for manufacturing injection mold or other functional parts by indirect SLS.     

Towards selective laser sintering of objects with customized mechanical properties based on ANFIS predictions

Recently, the adaptive network-based fuzzy inference system (ANFIS) has been used extensively in modeling of manufacturing processes to save both optimization time and manufacturing costs. ANFIS is a powerful iterative tool for optimizing non-linear and multivariable manufacturing operations. In the present study, ANFIS is used to predict the optimum manufacturing parameters in selective laser sintering (SLS) of cement-filled polyamide 12 (PA12) composite. For this purpose, a set of cement-filled PA12 test specimens is manufactured by SLS technique with 8 different values of laser power (4.5–8 Watt) and 8 different weight fractions of white cement (5 %–40 %). Mechanical characterization of cement-filled PA12 is carried out to evaluate the ultimate tensile strength (UTS), compressive strength, and flexural properties. The experimental data are then divided into two groups; one group for training the ANFIS model and the other group for checking the validity of the identified model. The built ANFIS model was validated experimentally and comparison with experimental results revealed mean relative errors of 2.92 %, 3.84 %, 4.75 %, and 3.31 % in the predictions of UTS, compressive strength, flexural modulus, and flexural yield strength, respectively.

     

Development and application of new composite materials as EDM electrodes manufactured via selective laser sintering

The cost of a part manufactured by electrical dischargeEDM machining (EDM) is mainly determined by electrode cost. The production of electrodes by conventional machining processes is complex, time consuming, and can account for over 50 % of the total EDM process costs. The emerging additive manufacturing (AM) technologies provide the possibility of direct fabrication of EDM electrodes. Selective laser sintering (SLS) is an alternative AM technique because it has the possibility to directly produce functional components, reducing the tool-room lead time and total EDM costs. The main difficulty of manufacturing an EDM electrode using SLS is the selection of an appropriate material, once both processes require different material properties. The current work focused on the investigation of appropriate materials that fulfill EDM and SLS process demands. Three new metal-matrix materials composed of Mo–CuNi, TiB₂–CuNi, and ZrB₂–CuNi were developed and characterized. Electrodes under adequate SLS conditions were manufactured through a systematic methodology. EDM experiments using different discharge energies were carried out, and the performance evaluated in terms of material removal rate and volumetric relative wear. The results showed that the powder systems composed of Mo–CuNi, TiB₂–CuNi, and ZrB₂–CuNi revealed to be successfully processed by SLS, and the EDM experiments demonstrated that the new composite electrodes are promising materials. The work also suggests important topics for future research work on this field.     

SLS烧结实验的优化设计

激光功率、扫描速度、铺粉厚度、预热温度及扫描间距是影响SLS成型质量的主要因素.通过激光快速成型机AFS-450制作专门的样件,采用正交试验和方差分析,对SIS成型工艺参数进行优化设计.确定了ABS粉末最佳的烧结参数,即预热温度为100℃、扫描速度为2000mm/s、激光功率为24W、铺粉厚度为0.2mm.     

选择性激光烧结主要成型材料的研究进展

简要介绍了选择性激光烧结的原理以及特点,比较和分析了几种选择性激光烧结主要成型材料的特点和国内外的研究现状,展望了选择性激光烧结材料的展前景.     

基于正交实验的多孔金属激光烧结成型工艺的研究

文章介绍了正交实验设计法的特点及其对实验研究的科学指导作用。正交实验设计法可以用少数几个代表性的实验代表全面实验。采用正交试验设计和直观分析的方法,对影响激光烧结多孔金属的各因素进行研究,从而找出了最佳工艺参数。     

Effect of delay time on part strength in selective laser sintering

Selective laser sintering (SLS) is one of the most popular layered manufacturing processes used for making functional prototypes of polymers and metals. It is a powder-based process in which layers of powder are spread and laser is used to sinter selected areas of preheated powder. In the present work, experimental investigations have been made to understand effect of delay time on SLS prototypes. Delay time is the time difference for laser exposure between any two adjacent points on successive scanning lines on a layer. Tensile specimens of polyamide material as per the ASTM standard are fabricated on SLS machine keeping delay time range constant for the entire specimen. Specimens are fabricated for different ranges of delay time and tested on universal testing machine for tensile strength. An optimum value of delay time range is obtained experimentally. As delay time depends on part build orientation, an algorithm has been developed and implemented to find out optimum part build orientation for improving tensile strength. The obtained results from developed code are validated experimentally for tensile specimen. Case study for a typical 3D part is also presented to demonstrate the capabilities of developed algorithm.     

Surface microgeometry after selective laser sintering of metal powder

A multifactorial model is proposed for the surface microgeometry after selective laser sintering of metal powder. The dependence of the microgeometry on the following dominant factors is established: the laser power, the speed of the laser beam, and the scanning increment.