Subtractive Technologies Research Articles

High-Value SLM Aerospace Components: From Design to Manufacture

Today additive manufacturing is shaping the future of global manufacturing and is influencing the design and manufacturability of tomorrows products. With selective laser melting (SLM), parts can be built directly from computer models or from measurements of existing components to be re-engineered, and therefore bypass traditional manufacturing processes such as cutting, milling and grinding. Benefits include: 1) new designs not possible using conventional subtractive technology, 2) dramatic savings in time, materials, wastage, energy and other costs in producing new components, 3) significant reductions in environmental impact, and 4) faster time to market. SLM builds up finished components from raw material powders layer by layer through laser melting. SLM removes many of the shape restrictions that limit design with traditional manufacturing methods, thereby allowing computationally optimised, high performance structures to be utilised. Functional engineering prototypes and actual components can then be built in their final shape with minimal material wastage. Samples and small product runs can be produced quickly at comparatively low cost to test and build market acceptance without major investment. In this chapter we present and discuss some of the concepts and findings involved in the design, manufacture and examination of high-value aerospace components from Ti-6Al-4V alloy produced at the RMITs Advanced Manufacturing Precinct.

Mobile Additive Remanufacturing

New requirement of remanufacturing industry development to digital and intelligence direction promote the development of mobile additive remanufacturing technology which is a core technology of remanufacturing engineering. The connotation and character of mobile additive remanufacturing technology are expatiated and relative research works at the mobile additive remanufacturing technology are introduced briefly. The research results indicate that the exploited mobile additive remanufacturing system possess the advantages such as good flexibility, high forming efficiency, wide application scope. Independent innovated reversing and modeling technology ensure the scanning and data processing precision and efficiency. Shape exact controlling can come true by the hybrid process combining additive technology with subtractive technology in mobile additive remanufacturing course.The prepared intensivism material may effectively reduce remanufacturing material kinds. The exploited magnetism controlling additive remanufacturing technology which can also make crystal grain thin and decrease structure defect may apply in aluminium alloy part remanufacturing.

Precision Patterned Thin Films without Photolithography: Additive Manufacturing of Printed Electronics

Additive manufacturing is the application of layer manufacturing techniques to fabricate microelectronic products. These techniques differentiate themselves from incumbent technologies in that they only add material to build the device and are an alternative to subtractive technologies such as lithography that globally coat layers and then etch-away unrequired materials. In this paper we discuss an additive technology that performs material evaporation through shadow masks. This process has shown significant potential for the fabrication of chip packaging, microelectronic devices and circuitry; specifically, high density interposers, fine conductor lines and embedded components such as capacitors, resistors, and transistors. The process is compatible with a number of both rigid and flexible substrates and deposition materials. Examples of devices and lines that have been manufactured by this technique are shown and discussed. Preliminary test data shows line / space resolution that has reached 5 / 20 microns and better.

Additive Manufacturing of Fine Lines and Embedded Electronics for use in Chip Carriers and Microelectronic Systems

Additive manufacturing is the application of layer manufacturing techniques to fabricate microelectronic products. These techniques differentiate themselves from incumbent technologies in that they only add material to build the device and are an alternative to subtractive technologies such as lithography that globally coat layers and then etch-away unrequired materials. In this paper we discuss an additive technology that performs material evaporation through shadow masks. This process has shown significant potential for the fabrication of chip packaging, microelectronic devices and circuitry; specifically, high density interposers, fine conductor lines and embedded components such as capacitors, resistors, and transistors. The process is compatible with a number of both rigid and flexible substrates and deposition materials. Examples of devices and lines that have been manufactured by this technique are shown and discussed. Preliminary test data shows line / space resolution that has reached 15 / 30 microns and better.

Direct Printing of Circuit Boards Using Aerosol Jet<sup>®</sup>

Printed Circuit boards (PCBs) are traditionally fabricated using subtractive technologies such as lithography and etching. Discrete passive and active components are typically attached by pick and place and then connected using wire bonding and soldering. In this paper we show that direct printing can replace many of the traditional steps and consequently allow circuits to be fabricated on novel substrates and 3D geometries. Specifically, we report on the integration of Aerosol Jet® with the printing of interconnects, passives and COTS attachment. The automated generation of the printed patterns (tool paths) is based on standard Eagle CAD PCB layout software. Multilayer circuits are fabricated by alternately printing metallic wires and a polymeric insulator. Passive components such as resistors and capacitors are printed from a library. The carbon-based resistors have a range of 50 Ω to 1 MΩ and the parallel plate capacitors range from 1 pF to 1 nF. Active devices can be incorporated into the circuit by attaching discrete IC chips with metallic and adhesive inks. The processing temperature is below 150°C for all the printing and curing steps. Overall, Aerosol Jet® is a cost effective method for directly printing circuits onto non-traditional substrates and is also desirable for prototyping and short-run manufacturing

The Change of the 3D Printing Product Mechanical Properties in the Function of Different Post-Treatment

Rapid prototyping (RP) has changed the method of product design and manufacturing. With the help of RP technologies a physical model can be created within couple of hours from any complex CAD model. RP technologies in contrast with conventional subtractive manufacturing technologies produce the end product by adding material layer-by-layer. 3D printing is one of the most widespread technologies in the industry. Because of the porous structure and bad mechanical properties of the models further post treatment is needed. Post treatment always means infiltration of the models, in case of gypsum and cellulose epoxy resin is mostly used. In our work the effect of post treatment method was examined on the mechanical properties of the pieces. The investigated pieces were prepared with four different setting of a printer.

Sugarcane genetic engineering research in South Africa: From gene discovery to transgene expression

Over the past 15 years, recombinant DNA and in vitro culture technologies have been used in concert at the South African Sugarcane Research Institute (SASRI) to genetically engineer sugarcane. The purpose of such research has been two-fold, viz. to establish proof-of-principle regarding the delivery of novel input and resistance traits to sugarcane and to investigate the genetic basis of sucrose accumulation. Underpinning these goals has been the in-house development of essential genetic resources, including the isolation of appropriate transgenes and gene promoter elements, and the optimisation of transformation and tissue culture technologies. With regard to the latter, emphasis has been placed on the development of tissue culture strategies that minimise the potential for somaclonal variation, while maximising the efficiency of germplasm transformation, selection, regeneration and acclimation. The isolation of promoters to drive high-level and targeted transgene expression, as well as the identification of DNA sequences with the potential to deliver the desired phenotype, have been strongly driven by advances in gene discovery and expression technologies. Early approaches relied on the analysis of Expressed Sequence Tag libraries constructed from sugarcane tissues at different developmental stages or challenged with selected abiotic and biotic stress agents. Subsequent improvements in DNA subtractive hybridisation technologies (e.g. suppression subtractive hybridisation) and gene expression analysis (e.g. Affymetrix® Sugarcane Genome GeneChip) provided new and powerful means for gene and promoter discovery. Reviewed here are the advances in in vitro culture, gene discovery and transgene expression research, which have formed the foundation of the genetic engineering program at SASRI. Also discussed are the opportunities and challenges in these areas of research that are presented by the availability of ultra-high throughput DNA sequencing (e.g. the 454 Sequencing System) for transcriptome analysis and technologies for rapid and accurate profiling of the sugarcane metabolomes.

Modelangelo: a subtractive 5-axis robotic arm for rapid prototyping

A PC-based, CAD-driven, 5-axis rapid prototyping (RP) robotic system that uses subtractive technology is presented. ModelAngelo, as it is called, consists of six integrated hardware and software subsystems. The system utilizes a virtual 3D CAD model to produce a set of commands used to control a 5-axis robotic setup to move the cutting tool, the tip of which is a heated wire, into a workpiece block (polystyrene foam or wax) to form complex-shaped objects. The user provides a 3D CAD model of the object to be sculpted. ModelAngelo Software generates layered contoured slices at predetermined incremental steps. It builds up a data file that contains the corresponding cutting tool radial, angular, elevation and rotational positions of the modeled work. Then ModelAngelo PortMessenger feeds the computer parallel port with consecutive commands that are read by ModelAngelo Controller. Consequently, ModelAngelo ReadNFeed performs the commands and sends feedback signals to the processor. The actuators then place the tool tip and the workpiece in their respective cutting positions via ModelAngelo Mechanisms, which puts the model and the tip tool in the cutting position, where ModelAngelo TipTool cutting-by-heat role starts.

Regulated expression and subcellular localization of HMGB1, a chromatin protein with a cytokine function.

High mobility group box protein 1 (HMGB1) has been considered as a ubiquitous nuclear protein with an architectural function, but even early reports have described its presence outside of the nucleus. Today, we have only started to understand the extranuclear and extracellular functions of HMGB1: we know that it participates in developmental and differentiation processes, triggers and modulates many of the inflammatory cascades in the body, and may even be involved in the metastatic invasion programme of cancer cells. Given such diverse roles, it is important to know which cells express HMGB1, where, and how much. The present review deals with the expression pattern of HMGB1 and provides evidence that, far from being housekeeping, the HMGB1 gene is tightly regulated. This can have implications for therapeutic intervention on inflammatory diseases as well as cancer.

Recent developments in metal laminated tooling by multiple laser processing

Time reduction and quick geometrical changes of complex components and tools are currently the most important demands in product development. The manufacturing process presented in this paper is based on multiple additive and subtractive technologies such as laser cutting, laser welding, direct laser metal deposition and CNC milling. The process chain is similar to layer‐based Rapid Prototyping Techniques. In the first step, the 3D CAD geometry is sliced into layers by a specially developed software. These slices are cut by high speed laser cutting and then joined together. In this way laminated tools or parts are built. To improve surface quality and to increase wear resistance a CNC machining center is used. The system consists of a CNC milling machine, in which a 3 kW Nd:YAG laser, a coaxial powder nozzle and a digitizing system are integrated.

Laser drilling of microvias in epoxy-glass printed circuit boards

The results of an investigation exploring the feasibility of laser-drilled microvias are reported. The process relies on the use of a single pulses from a CO/sub 2/ laser to drill small holes in panels of epoxy-glass. It is suitable for the generation of both buried and blind vias. Stop-and-go and on-the-fly drilling methods were examined. To test the quality of laser-drilled holes, daisy-chain patterns including these holes were fabricated using conventional subtractive technology. These patterns were subjected to successive thermal shocks to detect connection failure via resistance changes. The specimens tested showed no degradation when certain metallization procedures were followed. Other samples were subjected to reliability testing and compared to mechanically drilled vias. No statistical difference between the two groups could be established. Based upon these results, a production-type laser system was constructed capable of drilling sub-0.004-in-diameter holes over 18 in*24 in panels at rates of up to several hundred holes per second. High resolution and a high absolute accuracy were achieved. A description of the system is provided. >

Concluding remarks

The past two days have been hectic, heavy with compressed information. I have no intention of burdening you with more technicalities, nor of attempting to summarize the crucial points, for there are too many. Instead, we should stand back from the detail, and try to assess what has been achieved in our field. We must first accept that the word ‘applications’ in the title of our meeting really means ‘display devices’, for today we have few other practical uses of liquid crystals. Nevertheless, liquid crystal displays have an annual world market of £150 million, and this is predicted to grow by 50% per year for the next 5 years. Three years ago rival subtractive technologies, electrophoresis, electrochromism and electroplating were potential competitors, with much activity in research laboratories. Now their limitations have been exposed, and few discuss them. This domination of the field has been accompanied by an extension of our interest to all three types of liquid crystal. The nematic display is well established, and the newer uses of cholesterics and smectics have been discussed by a number of speakers. The wealth of possibilities is enormous, and this presents a danger, because our efforts may become too diffuse. We should be comforted by the size of the display market, but more impressed with the growth. Most of this audience will realize that the differential has great significance for them. A static industry, though large, calls for little research. A dynamic industry needs new developments, new effects, new materials. Dr Scheffer was concerned about the ability - and willingness — of manufacturers to adopt new developments, such as the dyed phase-change display. Such caution is understandable. A manufacturer who has mastered a device technology with one material will be reluctant to try another. He will be even more resistant to a completely new device structure, unless this can readily lead to an expansion in his market. His profits are not raised if he simply substitutes one device he makes for another. But if the timing is right, new devices will find a place. The history of liquid crystals shows this, because they were ready when the market called for them.