Clean color: Improving multi‐filament 3D prints

Fused Filament Fabrication is an additive manufacturing process by which a 3D object is created from plastic filament. The filament is pushed through a hot nozzle where it melts. The nozzle deposits plastic layer after layer to create the final object. This process has been popularized by the RepRap community. Several printers feature multiple extruders, allowing objects to be formed from multiple materials or colors. The extruders are mounted side by side on the printer carriage. However, the print quality suffers when objects with color patterns are printed – a disappointment for designers interested in 3D printing their colored digital models. The most severe issue is the oozing of plastic from the idle extruders: Plastics of different colors bleed onto each other giving the surface a smudged aspect, excess strings oozing from the extruder deposit on the surface, and holes appear due to this missing plastic. Fixing this issue is difficult: increasing the printing speed reduces oozing but also degrades surface quality – on large prints the required speed level become impractical. Adding a physical mechanism increases cost and print time as extruders travel to a cleaning station. Instead, we rely on software and exploit degrees of freedom of the printing process. We introduce three techniques that complement each other in improving the print quality significantly. We first reduce the impact of oozing plastic by choosing a better azimuth angle for the printed part. We build a disposable rampart in close proximity of the part, giving the extruders the opportunity to wipe oozing strings and refill with hot plastic. We finally introduce a toolpath planner avoiding and hiding most of the defects due to oozing, and seamlessly integrating the rampart. We demonstrate our technique on several challenging multiple color prints, and show that our tool path planner improves the surface finish of single color prints as well.     

ZomeFab: Cost-Effective Hybrid Fabrication with Zometools

In recent years, personalized fabrication has received considerable attention because of the widespread use of consumer-level three-dimensional (3D) printers. However, such 3D printers have drawbacks, such as long production time and limited output size, which hinder large-scale rapid-prototyping. In this paper, for the time- and cost-effective fabrication of large-scale objects, we propose a hybrid 3D fabrication method that combines 3D printing and the Zometool construction set, which is a compact, sturdy and reusable structure for infill fabrication. The proposed method significantly reduces fabrication cost and time by printing only thin 3D outer shells. In addition, we design an optimization framework to generate both a Zometol structure and printed surface partitions by optimizing several criteria, including printability, material cost and Zometool structure complexity. Moreover, we demonstrate the effectiveness of the proposed method by fabricating various large-scale 3D models.     

熔丝制造的三维连续编织填充图案

为提高熔丝制造(FFF)工件的机械强度,降低各向异性,提出一种3D连续编织路径规划方法.采用连续纤维增强丝材作为打印材料,设计了1个8层循环结构,利用3D打印机喷嘴挤出丝材生成经纬纱线,控制FFF平台在z方向的运动,生成类似3D编织的连续沉积路径,不同层的纤维相互交错和嵌入以实现相邻切片平面之间的互锁,以提高层内与层间...     

3D printing: an emerging tool for novel microfluidics and lab-on-a-chip applications

In the past few years, 3D printing technology has witnessed an explosive growth, penetrating various aspects of our lives. Current best-in-class 3D printers can fabricate micrometer scale objects, which has made fabrication of microfluidic devices possible. The highest achievable resolution is already at nanometer scale, which is continuing to drop. Since geometric complexity is not a concern for 3D printing, novel 3D microfluidics and lab-on-a-chip systems that are otherwise impossible to produce with traditional 2D microfabrication technology have started to emerge in recent years. In this review, we first introduce the basics of 3D printing technology for the microfluidic community and then summarize its emerging applications in creating novel microfluidic devices. We foresee widespread utilization of 3D printing for future developments in microfluidic engineering and lab-on-a-chip technology.     

A dynamic and static data based matching method for cloud 3D printing

3D printing is widely used in such sectors as industry, medical, sports and education with the rapid development 3D printing technology and continual breakthrough of new material technology. Faced with the continual expansion of 3D printing market and the diversity and rapid growth of the scale of 3D printing devices, efficiently manage 3D print resources in the environment of distributed network manufacturing is a critical problem urgently to resolve. As a novel business paradigm, Cloud manufacturing can effectively integrate and manage manufacturing resources. Therefore, based on the cloud manufacturing paradigm, this study focuses on dynamic and static data based matching method for cloud 3D printing. In this paper, we propose a modeling framework to describe two models of the print task and print resource by model-based systems engineering. This modeling framework can support the efficient matching of the two types of models. Finally, the dynamic and static data based matching method can realistically simulate the supply-demand matching process of cloud 3D printing platform and provide a technical solution for quick supply-demand matching of large-scale resources in the environment of cloud manufacturing. During in the modeling process, we not only consider the static characteristics of 3D printers and analyze quantitatively all the parameter indicators of static characteristics, but also consider the dynamic characteristics of 3D printers to establish a universal dynamic data acquisition system, which can be used for real-time monitoring and automatic diagnosis of the health status of 3D printers. Therefore, this matching method has important theoretical significance and engineering value.     

Recursive symmetries for geometrically complex and materially heterogeneous additive manufacturing

We present a generative method for the creation of geometrically complex and materially heterogeneous objects. By combining generative design and additive manufacturing, we demonstrate a unique form-finding approach and method for multi-material 3D printing. The method offers a fast, automated and controllable way to explore an expressive set of symmetrical, complex and colored objects, which makes it a useful tool for design exploration and prototyping. We describe a recursive grammar for the generation of solid boundary surface models suitable for a variety of design domains. We demonstrate the generation and digital fabrication of watertight 2-manifold polygonal meshes, with feature-aligned topology that can be produced on a wide variety of 3D printers, as well as post-processed with traditional 3D modeling tools. To date, objects with intricate spatial patterns and complex heterogeneous material compositions generated by this method can only be produced through 3D printing.     

熔融沉积快速成型技术与三维扫描技术的结合应用

随着逆向、创意行业的迅速发展,熔融沉积快速成型技术在3D打印领域作用日趋重要,本文结合熔融沉积快速成型3D打印机与白光扫描仪的特点,介绍目前熔融沉积快速成型技术的研究应用状况及其在3D打印领域的重要作用,并阐述3D打印与白光扫描的结合应用。     

Time and freestyle piling: a subjective approach to 3D printing

This paper considers the influence of 3D printers on the temporality and subjectivity of making by looking at current 3D printing processes through the concept of ‘duration’ that was theorized by the philosopher Henri Bergson. The discussion is contextualized within technological developments at the turn of the twentieth century—specifically, European railways—that changed our perception of time. The foundational ideas of duration are introduced as a response to these developments. The contemporary technological concept of ‘real-time computing’ is presented to contrast with duration and set up an in-depth explanation of the delays inherent to the 3D printing process. These delays are discussed within the discourse of 3D printing and technological innovation, in general. Current maker-3D printer interactions are then critiqued. Finally, an alternative method of 3D printing concrete that is founded on working with its inherent delays is introduced, along with its implications for digital making and the act of making time.     

Koala 3D: A continuous climbing 3D printer

The size of manufactured parts is naturally bound by the size of their production machines. In this paper, we explore the alternative of making a machine that can continuously navigate along an object being fabricated, producing objects larger than itself. The machine combines a climbing robot and a 3D printer. It uses an infinite fabrication loop which includes printing, reanchoring to a new station, and printing again. We present the design, construction, and characterization of the machine along with experiments on the fabrication of vertical columns. We also demonstrate the freeform fabrication capabilities of the machine by printing a moai statue. The results obtained have a wide range of applications for construction, product fabrication and promisingly broaden the current applications of 3D printing.     

Dual‐color mixing for fused deposition modeling printers

In this work we detail a method that leverages the two color heads of recent low‐end fused deposition modeling (FDM) 3D printers to produce continuous tone imagery. The challenge behind producing such two‐tone imagery is how to finely interleave the two colors while minimizing the switching between print heads, making each color printed span as long and continuous as possible to avoid artifacts associated with printing short segments. The key insight behind our work is that by applying small geometric offsets, tone can be varied without the need to switch color print heads within a single layer. We can now effectively print (two‐tone) texture mapped models capturing both geometric and color information in our output 3D prints.     

Digital Fabrication Techniques for Cultural Heritage: A Survey

Digital fabrication devices exploit basic technologies in order to create tangible reproductions of 3D digital models. Although current 3D printing pipelines still suffer from several restrictions, accuracy in reproduction has reached an excellent level. The manufacturing industry has been the main domain of 3D printing applications over the last decade. Digital fabrication techniques have also been demonstrated to be effective in many other contexts, including the consumer domain. The Cultural Heritage is one of the new application contexts and is an ideal domain to test the flexibility and quality of this new technology. This survey overviews the various fabrication technologies, discussing their strengths, limitations and costs. Various successful uses of 3D printing in the Cultural Heritage are analysed, which should also be useful for other application contexts. We review works that have attempted to extend fabrication technologies in order to deal with the specific issues in the use of digital fabrication in the Cultural Heritage. Finally, we also propose areas for future research.     

Automatic balancing of 3D models

3D printing technologies allow for more diverse shapes than are possible with molds and the cost of making just one single object is negligible compared to traditional production methods. However, not all shapes are suitable for 3D print. One of the remaining costs is therefore human time spent on analyzing and editing a shape in order to ensure that it is fit for production. In this paper, we seek to automate one of these analysis and editing tasks, namely improving the balance of a model to ensure that it stands. The presented method is based on solving an optimization problem. This problem is solved by creating cavities of air and distributing dense materials inside the model. Consequently, the surface is not deformed. However, printing materials with significantly different densities is often not possible and adding cavities of air is often not enough to make the model balance. Consequently, in these cases, we will apply a rotation of the object which only deforms the shape a little near the base. No user input is required but it is possible to specify manufacturing constraints related to specific 3D print technologies. Several models have successfully been balanced and printed using both polyjet and fused deposition modeling printers.     

熔丝沉积制造中稳固低耗支撑结构生成

熔丝沉积制造(Fused deposition modeling, FDM)是利用熔融塑料丝的一种3D打印技术,热塑料由喷嘴喷出逐层堆积完成打印.由于熔丝只能沉积在已存在物体的上层,因此需要构造支撑结构以支撑悬空部分.针对现有支撑结构生成算法中存在的或结构不稳固或耗材多的缺陷,提出一种以熔丝为支撑单位的树形稀疏支撑结构.与传统算法计算模型表面支撑区域不同,本算法计算每段熔丝需要支撑的区域,使支撑结构更契合熔丝沉积特点.算法还将支撑结构分为三类,将多约束优化问题分解,降低算法复杂度.实验结果表明,本文算法生成的支撑结构算法耗材少、支撑稳定.     

熔融沉积制造表面粗糙度参数显著性及预测模型研究

为了确定影响熔融沉积制造(FDM)打印件表面粗糙度的显著性因素,设计了基于 温度、打印速度和层厚的9 组正交实验。通过探针式粗糙度仪测量打印件表面粗糙度,并进行 了信噪比计算和波动分析,确定了影响表面粗糙度的显著性因素。利用田口法、多元回归方程 和指数方程对表面粗糙度进行预测,确定FDM 打印件最小表面粗糙度的参数组合。分析结果 表明：层厚对于表面粗糙度的影响程度最大,温度次之,打印速度最小;为了验证其有效性和 适用性,针对不同打印模型和FDM 打印机进行了验证性实验。实验结果表明：在预测模型方 面,多元回归方程的预测结果优于指数方程和田口法。并且,上述结论对不同打印模型和FDM 打印机具有较为宽泛的适用性。     

Compound fabrication: A multi-functional robotic platform for digital design and fabrication

Supporting various applications of digital fabrication and manufacturing, the industrial robot is typically assigned repetitive tasks for specific pre-programmed and singular applications. We propose a novel approach for robotic fabrication and manufacturing entitled Compound Fabrication, supporting multi-functional and multi-material processes. This approach combines the major manufacturing technologies including additive, formative and subtractive fabrication, as well as their parallel integration. A 6-axis robotic arm, repurposed as an integrated 3D printing, milling and sculpting platform, enables shifting between fabrication modes and across scales using different end effectors. Promoting an integrated approach to robotic fabrication, novel combination processes are demonstrated including 3D printing and milling fabrication composites. In addition, novel robotic fabrication processes are developed and evaluated, such as multi-axis plastic 3D printing, direct recycling 3D printing, and embedded printing. The benefits and limitations of the Compound Fabrication approach and its experimental platform are reviewed and discussed. Finally, contemplation regarding the future of multi-functional robotic fabrication is offered, in the context of the experiments reviewed and demonstrated in this paper.     

Ribbed Support Vaults for 3D Printing of Hollowed Objects

Additive manufacturing techniques form an object by accumulating layers of material on top of one another. Each layer has to be supported by the one below for the fabrication process to succeed. To reduce print time and material usage, especially in the context of prototyping, it is often desirable to fabricate hollow objects. This exacerbates the requirement of support between consecutive layers: standard hollowing produces surfaces in overhang that cannot be directly fabricated anymore. Therefore, these surfaces require internal support structures. These are similar to external supports for overhangs, with the key difference that internal supports remain invisible within the object after fabrication. A fundamental challenge is to generate structures that provide a dense support while using little material. In this paper, we propose a novel type of support inspired by rib structures. Our approach guarantees that any point in a layer is supported by a point below, within a given threshold distance. Despite providing strong guarantees for printability, our supports remain lightweight and reliable to print. We propose a greedy support generation algorithm that creates compact hierarchies of rib-like walls. The walls are progressively eroded away and straightened, eventually merging with the interior object walls. We demonstrate our technique on a variety of models and provide performance figures in the context of fused filament fabrication 3D printing.     

Experimental-based feedforward control for a DoD inkjet printhead

Markets demand continuously for higher quality, higher speed, and more energy-efficient professional printers. Drop-on-Demand (DoD) inkjet printing is considered as one of the most promising printing technologies. It offers many advantages including high speed, quiet operation, and compatibility with a variety of printing media. Nowadays, it has been used as low-cost and efficient manufacturing technology in a wide variety of markets. Although the performance requirements, which are imposed by the current applications, are tight, the future performance requirements are expected to be even more challenging. These print requirements are related to the jetted drop properties, namely, drop velocity, drop volume, drop velocity consistency, productivity, and reliability. Meeting these performance requirements is restricted by several operational issues that are associated with the design and the operation of inkjet printheads. Major issues that are usually encountered are residual vibrations and crosstalk among ink channels. These result in a poor printing quality for high-speed printing. The main objective is to design a feedforward control strategy such that variations in the velocity and volume of the jetted drops are minimized. In this article, an experimental-based feedforward control scheme is proposed to improve the performance of a professional inkjet printer.     

基于FDM工艺结构的3D打印机高温喷头结构优化研究

打印机喷头结构不合理,会出现温度场分布不均现象,导致喷头堵塞,影响打印速度.为此,本文提出基于FDM工艺结构的3D打印机高温喷头结构优化研究.设计三维CAD模型,控制喷头移动,结合喷头结构,计算热传导遵循的傅里叶定律与稳定热传导规律;从模型"台阶效应"、挤出丝材两方面探究影响喷头打印效果的主要因素,在确保打印质量前提下...     

Deep learning-based optimal segmentation of 3D printed product for surface quality improvement and support structure reduction

Large-sized product cannot be printed as one piece by a 3D printer because of the volume limitation of most 3D printers. Some products with the complex structure and high surface quality should also not be printed into one piece to meet requirement of the printing quality. For increasing the surface quality and reducing support structure of 3D printed models, this paper proposes a 3D model segmentation method based on deep learning. Sub-graphs are generated by pre-segmenting 3D triangular mesh models to extract printing features. A data structure is proposed to design training data sets based on the sub-graphs with printing features of the original 3D model including surface quality, support structure and normal curvature. After training a Stacked Auto-encoder using the training set, a 3D model is pre-segmented to build an application set by the sub-graph data structure. The application set is applied by the trained deep-learning system to generate hidden features. An Affinity Propagation clustering method is introduced in combining hidden features and geometric information of the application set to segment a product model into several parts. In the case study, samples of 3D models are segmented by the proposed method, and then printed using a 3D printer for validating the performance.     

Impact printing becomes faster and quieter

The state of the printer market is examined. Greater speeds are being achieved in nonimpact printing and for line printers. Daisy wheel printers are being challenged by matrix printers for quality printing. Printers for personal computers are being produced, led by Japanese companies.