Precise Manufacturing Processes Research Articles

Bond strength of CAD-CAM and conventional veneering materials to different frameworks

Statement of problemNew materials and precise manufacturing processes allow for new processes in the veneering and production of fixed dental prostheses. However, data on the bond strength of computer-aided design and computer-aided manufacturing (CAD-CAM) and conventional veneering materials to substrates bonded with different composite resins are lacking. PurposeThe purpose of this in vitro study was to investigate the shear bond strength (SBS) of 2 CAD-CAM, Lava Ultimate (LVU) and VITABLOCS Mark II (VMII), and 3 conventional veneering materials (VM9, VM13, VTI) to 3 different substrates: zirconia (ZIR), cobalt-chromium (CC), and titanium (TIT). Material and methodsSubstrates and veneering cylinders were manufactured and bonded by using 3 different composite resins, RelyX Unicem (RUL), RelyX Ultimate (RXU), and Sinfony (SIN), after various pretreatments (n=18). Half the specimens underwent artificial aging before SBS testing, and failure types were analyzed. Univariate 1-way ANOVA, Kruskal-Wallis, and Mann-Whitney U were computed (α=.05). ResultsCC substrates bonded with RUL showed the highest SBS (P=.007). ZIR substrates bonded with RXU presented higher SBS than TIT substrates (P=.007). ZIR substrates bonded with SIN showed higher SBS than CC substrates (P<.001). SIN veneered groups showed lower SBS than that observed for VM9/13/VTI (P<.001). SIN veneered LVU and VMII substrates presented lower SBS (P<.001). Thermocycling led to a reduction in SBS for most groups (P=.001-.022). SIN veneered substrates and RXU veneered VMII substrates resulted in lower SBS than that seen for VM9/13/VTI and veneered ZIR substrates bonded with SIN or RXU (P<.001). Adhesive failures were most common. ConclusionsWhile RUL is capable of forming a stable bond to CC without pretreatment, ZIR substrates achieve higher SBS after conditioning with an MDP-containing primer when using RXU or SIN than that seen for RUL. Pretreated CAD-CAM–veneered ZIR substrates bonded with SIN or RXU led to similar SBS results to those observed for conventional veneers, while veneering with SIN resulted in lower SBS.

Vat photopolymerization of liquid, biodegradable PLGA-based oligomers as tissue scaffolds

Additive manufacturing (AM) of tissue scaffolds provides medical professionals and patients with personalized treatment options, which align with patients’ specific physiology and provide a more efficient and precise manufacturing process. Vat photopolymerization (VP) AM affords biocompatible, degradable, and high-resolution scaffolds capable of achieving specific pore sizes necessary for tissue regeneration. Earlier biodegradable, photoactive polymers for the VP platform usually require dissolution in a solvent or water, which often results in anisotropic shrinkage upon drying and inconsistencies in the final part geometry. This work describes a photoactive oligomeric precursor that eliminates the requirement for water or solvent during VP. Poly(lactide-co-glycolide) (PLGA) diacrylates with low number-average molecular weights (< 1400 g mol−1) provided liquid, viscous precursors. Upon crosslinking, the networks exhibited mechanical strength and low cytotoxicity, which are prerequisites for soft tissue scaffolds. Systematically varying the ratios of lactide to glycolide provided a range of degradation rates from 4 to 12 wks. Tailored degradation rates will enable use in different anatomical environments. Cytotoxicity and cell attachment studies revealed crosslinked films that promoted cell growth and proliferation. This manuscript describes an expanded polymer toolbox for AM of tissue scaffolds with precise resolution in the absence of solvents.

New Global Referencing Approach in a Camera-LCD Micro Positioning System.

In any precision manufacturing process, positioning systems play a very important role in achieving a quality product. As a new approach to current systems, camera-LCD positioning systems are a new technology that can provide substantial improvements enabling better accuracy and repeatability. However, in order to provide stability to the system a global positioning system is required. This paper presents an improvement of a positioning system based on the treatment of images on an LCD in which a new algorithm with absolute reference has been implemented. The method is based on basic geometry and linear algebra applied to computer vision. The algorithm determines the spiral center using an image taken at any point. Consequently, the system constantly knows its position and does not lose its reference. Several modifications of the algorithm are proposed and compared. The simulation and test of the algorithm provide an important improvement in the reliability and stability of the positioning system providing errors of microns for the calculation of the global position used by the algorithm.

Research on Sculpture Art Based on 3D Printing TechnologyTingzhou Tian, Lei Hua

With the development of society and economy, modern buildings around the world have spread rapidly, but these buildings are the same and lack artistic appeal. With the development of 3D printing technology, the combination of the traditional craftsmanship and 3D printing technology has made the building’s artistic sculptures more realistic and customizable. This article introduces the precise manufacturing process of art sculpture components based on 3D printing technology from the aspects of art sculpture component production, 3D modeling, 3D printing output, and post-processing.

Optimization of Pull-Type Production Process with Computer Aided Process Planning

Pull type is production that is based on actual demand and requires a fast and precise manufacturing process in the system. The conventional method caused consumers‘ frequent dissatisfaction with the results and took long production times and high cost. The purpose of this study was to compare between the application for conventional methods and Computer Aided Process Planning (CAPP) method in pull-type production system. Starting with identifying the problems that exist in the results of observations in the field study, then setting the goal of improving the initial production method. Furthermore, the process was conducted by comparing production time using time study method and breaking even calculation. The results show that CAPP method obtained the reduction in the cost and time production than conventional methods.

An adaptive-group-based differential evolution algorithm for inspecting machined workpiece path planning

In the precision manufacturing process, accuracy and precision are crucial when designing a workpiece inspection system. An efficient system minimizes inefficiencies caused by workpieces failing to meet customer needs and delays caused by slow workpiece inspection. In this study, a workpiece inspection system for measuring path planning is proposed that uses the given coordinate of inspection points discerned from 3D images. Then, an adaptive-group-based differential evolution (AGDE) algorithm is used to optimize the measuring path. The AGDE algorithm incorporates the grouping concept into conventional differential evolution, and this improves local search ability through referencing the direction of the best solution in each group. By using the proposed method, the shortest non-colliding measuring path is obtained. Moreover, the proposed workpiece inspection system shortens the workpiece inspection time and achieves faster performance than manual measuring path planning under multiple workpiece inspection points.

Fabrication of a Conjugated Fluoropolymer Film Using One-Step iCVD Process and its Mechanical Durability

Most superhydrophobic surface fabrication techniques involve precise manufacturing process. We suggest initiated chemical vapor deposition (iCVD) as a novel CVD method to fabricate sufficiently durable superhydrophobic coating layers. The proposed method proceeds with the coating process at mild temperature (40 °C) with no need of pretreatment of the substrate surface; the pressure and temperature are optimized as process parameters. To obtain a durable superhydrophobic film, two polymeric layers are conjugated in a sequential deposition process. Specifically, 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane (V4D4) monomer is introduced to form an organosilicon layer (pV4D4) followed by fluoropolymer formation by introducing 1H, 1H, 2H, 2H-Perfluorodecyl methacrylate (PFDMA). There is a high probability of covalent bond formation at the interface between the two layers. Accordingly, the mechanical durability of the conjugated fluoropolymer film (pV4D4-PFDMA) is reinforced because of cross-linking. The superhydrophobic coating on soft substrates, such as tissue paper and cotton fabric, was successfully demonstrated, and its durability was assessed against the mechanical stress such as tensile loading and abrasion. The results from both tests confirm the improvement of mechanical durability of the obtained film.

Coating of Ultra-Small Micro End Mills: Analysis of Performance and Suitability of Eight Different Hard-Coatings

Due to the constant need for better functionalized surfaces or smaller, function integrated components, precise and efficient manufacturing processes have to be established. Micro milling with micro end mills is one of the most promising processes for this task as it combines a high geometric flexibility in a wide range of machinable materials with low set-up costs. A downside of this process is the wear of the micro end mills. Due to size effects and the relatively low cutting speed, the cutting edge is especially subjected to massive abrasive wear. One possibility to minimize this wear is coating of micro end mills. This research paper describes the performance of eight different hard coatings for micro end mills with a diameter &lt;40 µm and discusses some properties for the best performing coating type. With this research, it is therefore possible to boost the possibilities of micro milling for the manufacture of next generation products.

An In-Depth Review on Direct Additive Manufacturing of Metals

Additive manufacturing (AM), also known as 3D Printing, is a revolutionary manufacturing technique which has been developing rapidly in the last 30 years. The evolution of this precision manufacturing process from rapid prototyping to ready-to-use parts has significantly alleviated manufacturing constraints and design freedom has been outstandingly widened. AM is a non-conventional manufacturing technique which utilizes a 3D CAD model data to build parts by adding one material layer at a time, rather than removing it and fulfills the demand for manufacturing parts with complex geometric shapes, great dimensional accuracy, and easy to assemble parts. Additive manufacturing of metals has become the area of extensive research, progressing towards the production of final products and replacing conventional manufacturing methods. This paper provides an insight to the available metal additive manufacturing technologies that can be used to produce end user products without using conventional manufacturing methods. The paper also includes the comparison of mechanical and physical properties of parts produced by AM with the parts manufactured using conventional processes.

Microstructure and tensile properties of Ti-6Al-4V alloys manufactured by selective laser melting with optimized processing parameters

Selective laser melting (SLM) is a precise additive manufacturing process that the metallic powders without binder are melted layer by layer to complex components using a high bright fiber laser. In the paper, Ti-6Al-4V alloy was fabricated by SLM and its microstructure and mechanical properties were investigated in order to evaluate the SLM process. The results show that the microstructure exists anisotropy between the horizontal and vertical section due to the occurrence of epitaxial growth, and the former microstructure seems equal-axis and the latter is column. Moreover, there is little difference in tensile test between the horizontal and vertical sections. Furthermore, the tensile properties of fabricated Ti-6Al-4V alloy by SLM are higher than the forged standard ones. However, the fatigue results show that there are some scatters, which need further investigation to define the fatigue initiation.

Arc evaporated W-alloyed Ti-Al-N coatings for improved thermal stability, mechanical, and tribological properties

The protection of various tools and components through wear resistant coatings is imperative in highly efficient and precise industrial manufacturing processes. Especially, physical vapor deposited Ti1−xAlxN and Cr1−xAlxN coatings have been commonly used as hard protective coatings due to their outstanding thermal stability and mechanical strength. However, to increase the applicable working temperatures by simultaneously enhancing the wear performance (e.g., to allow for higher cutting speeds) further improvements are required.Therefore, we studied in detail the impact of tungsten (W)—in combination with the substrate bias potential (Ubias)—on the thermo-mechanical properties and wear performance of arc evaporated Ti1–x−yAlxWyN thin films. With increasing W content, the quality of our coatings significantly increases due to pronounced reduction of growth defects (quantity of macro particles). All coatings studied crystallize in a supersaturated, single-phased face-centered cubic Ti1−x−yAlxWyN structure and their hardness (H) increases whereas the indentation modulus (E) decreases with increasing W content. This results in increased H3/E2 values, with a maximum of 0.19GPa for Ti0.50Al0.41W0.09N prepared with Ubias=−120V (H≈35GPa, E≈483GPa). All W-alloyed coatings exhibit wear rates below 4∙10−5mm3/Nm during our dry sliding pin-on-disk tests against alumina balls at room temperature, with a tendency for reduced values if more droplets are present. The highest thermal stability, with respect to the decomposition of the supersaturated Ti1–x−yAlxWyN phase towards the stable constituents (at high temperature) TiN, AlN, and W, is obtained for Ti0.53Al0.42W0.05N prepared with Ubias=−80V. Here, the formation of the wurtzite-structured AlN can be delayed to 1000°C after 60min lasting isothermal annealings in vacuum.

Modeling of normal force and finishing torque considering shearing and ploughing effects in ultrasonic assisted magnetic abrasive finishing process with sintered magnetic abrasive powder

Ultrasonic assisted magnetic abrasive finishing process (UAMAF) is a precision manufacturing process that results nano-scale level finish in a part. Normal force on a particle helps indenting the particle in the work surface whereas horizontal force provides finishing torque that in-turn helps the particle to perform micro-machining. Better understanding of the effect of these forces on material removal and wear pattern of the work-piece necessitates mathematical modeling of normal force and finishing torque and subsequently its validation with experimental results. In the present study, single particle interaction concept is considered to develop a model which is subsequently applied for all active particles of magnetic abrasive powder (MAP). Separation point theory is applied to consider the effect of ploughing below a critical depth and shearing above that depth. Normal components of shearing and ploughing forces are considered for calculating normal force and horizontal components of shearing and ploughing forces are taken to calculate finishing torque. Johnson-Cook model is applied to calculate shearing strength of the work material during UAMAF. The impact of ultrasonic vibrations is considered while calculating strain rate. Images are taken with the help of scanned electron microscope and atomic force microscope to study the material removal and wear mechanism during UAMAF process. Predicted values of force and torque model are validated with the experimental values.

Characterization of an Electrochemical Machining Process for Precise Internal Geometries by Multiphysics Simulation

In several fields of mechanical engineering internal precision geometries are applied. For this, application requirements like high shape accuracy, sufficient stability, high wear resistance or an increase of life time have to be fulfilled. However, there is also a demand on quick and precise manufacturing processes that are flexible in machining various internal geometries. Electrochemical machining (ECM) is a process which meets these requirements. This process allows surface structuring and shaping of metal components with high shape accuracy independently of the materials strength and hardness [1].This study presents investigations on a developed process design for manufacturing internal precision geometries by pulsed electrochemical machining (PECM) with help of multiphysics simulations. The peculiarity of this process is the shaping of the workpiece by the lateral working gap. Multiphysics simulations were carried out to understand the respective interactions between several physical phenomena. Especially, fluid dynamical effects are described in detail within the developed model. Furthermore, Joule heating and cathodic hydrogen formation are included. The fluid flow ensures the removal of heat and hydrogen and a continual supply with fresh electrolyte, respectively. The electrical conductivity of the electrolyte is modeled as a function of hydrogen volume concentration and temperature. Hence, both effects, Joule heating and hydrogen formation, influence the current density distribution which in turn determines the material removal.

Design of sound phase diffusers by means of multiobjective optimization approach using ev-MOGA evolutionary algorithm

In this paper a new approach to design sound phase diffusers is presented. The acoustic properties of such diffusers are usually increased by using single objective optimization methods. Here we propose the use of a multiobjective (MO) approach to design them in order to take into account several conflicting characteristic simultaneously. Three different MO problems are posed to consider various scenarios where fundamentally the objective is to maximize the normalized diffusion coefficient (following the corresponding Audio Engineering Society standard) for the so-called medium frequencies. This single objective could be divided into other several objectives to adjust performances to designer preferences. A multi-objective evolutionary algorithm (called ev-MOGA) is used to characterize the Pareto front in a smart way. ev-MOGA is modified, by using integer codification and tuning some of its genetic operators, to adapt it to the new requirements. Special interest is posed in selecting the diffusers codification properly to eliminate duplicities that would produce a multimodal problem. Precision in the manufacturing process is taking into account in the diffuser codification causing, that the number of different diffusers are quantified. Robust considerations related with the precision manufacturing process are considered in the decision making process. Finally, an optimal diffuser is selected considering designer preferences.

Plastic straw: future of high-speed signaling.

The ever-increasing demand for bandwidth triggered by mobile and video Internet traffic requires advanced interconnect solutions satisfying functional and economic constraints. A new interconnect called E-TUBE is proposed as a cost-and-power-effective all-electrical-domain wideband waveguide solution for high-speed high-volume short-reach communication links. The E-TUBE achieves an unprecedented level of performance in terms of bandwidth-per-carrier frequency, power, and density without requiring a precision manufacturing process unlike conventional optical/waveguide solutions. The E-TUBE exhibits a frequency-independent loss-profile of 4 dB/m and has nearly 20-GHz bandwidth over the V band. A single-sideband signal transmission enabled by the inherent frequency response of the E-TUBE renders two-times data throughput without any physical overhead compared to conventional radio frequency communication technologies. This new interconnect scheme would be attractive to parties interested in high throughput links, including but not limited to, 100/400 Gbps chip-to-chip communications.

Vacuum systems for the TPS accelerator

The Taiwan Photon Source (TPS) is a 3 GeV third generation accelerator light source. The vacuum systems contain an electron storage ring (SR) of 518.4 m in circumference and a concentric booster (BR) of 496.8 m in circumference, linked with the transport lines one from the booster to storage ring (BTS) and the other from the linear accelerator to the booster (LTB). To ensure the highest stability of the electron beam in the storage ring, all the vacuum systems for the SR, BTS, and BR, have been baked to the ultrahigh vacuum (UHV). The aluminum vacuum chambers with the completely oil-free precise manufacturing process provide a lowest surface outgassing rate and lowest broadband impedance for accommodating the beam in stable. The combination of the triode ion pumps and the non-evaporable getter (NEG) pumps provides a superior pumping efficiency and the ultimate pressure < 5 nPa. The 24 arc-cell vacuum systems, each about 14 m in length, have been baked to the UHV and sealed in the laboratory prior to transport to the TPS tunnel for the installation. Other vacuum systems were installed and baked on site in parallel. After completing the installations, commissioning of TPS was started in August 2014.

The First Thin Film Electronic Package

The magnetic thin-film head, announced by IBM in 1979, marked the transformation of electrochemical technology from a shop art to a precision manufacturing process with far wider applications than the thin film head. An important application of electroplating was in the fabrication of the multichip module that provided the packaging for chips in advanced computers. These modules included copper strip lines for data transmission between chips. To minimize pulse distortion, these lines had to have precisely controlled propagation characteristics, and plating through a lithographic mask was the most effective way to insure the tight control on the geometry of the lines necessary to meet this requirement. This paper highlights the evolution of packaging for computers and tells how the scientists and engineers from the IBM T.J. Watson Research Center who had created the thin film head, worked with the development and manufacturing groups at IBM’s East Fishkill plant to bring electrochemistry into the manufacture of advanced packaging modules.

New Trends in Manufacturing: Converging to Service and Intelligent Systems

Manufacturing processes and models have been influenced by the linear approach, called Fordism, for almost a century, since the first automated devices and discrete control systems were introduced. At the same time, new ideas to organize manufacturing process have appeared that question the absolute dominance of gain in scale. More recently, new criteria invaded the scenario of manufacturing where quality led manufacturing process to a phase based on accurate supply chain and surrounded by ubiquitous computer and robotic devices. A very precise manufacturing processes can now be designed and implemented in almost all sectors of industry, where special sub-processes can be delivered by other players. In this new scenario, a new paradigm for manufacturing design emerged, based on a set of very specialized services that could be arranged to provide new creative and sustainable processes. In this paper we go into this new paradigm for manufacturing (process) design comparing it with the classic approach that relies on layers classified as production plant, control (software oriented) and supervisory.

Precision Manufacturing Process of Parts Realized by FDM Rapid Prototyping

Rapid Prototyping (RP) can be defined as a group of techniques used to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data. What is commonly considered to be the first RP technique, Stereolithography, was developed by 3D Systems of Valencia, CA, USA. In this contribution are presented basic characteristics and problems in area of technology of Rapid Prototyping with use of Fused Deposition Modelling. It belongs to methods of precision model creation based on geometry obtained from CAD environment. Chapters are focused on optimization of FDM technology preparation process with aim of maximal precision of the parts. There also is algorithm that leads to selection of suitable settings for these problems. There are outputs in form of graph and tables accumulating information directly affecting precision aspects of manufacturing.

Monitoring on GBT Series Small Flow Pump Shell Long Position of Computer-Aided Process

GBT Series Small flow Pump body long position complex shape, size, high precision manufacturing process complexity, the process is prone to waste, the use of computer-aided process control, by means of the signal characteristics of the collection, analysis and processing of information, the timely issue of warning signal or direct feedback to the error correction processing equipment to ensure product quality and processing operation of the system reliability.