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Therefore, the purpose of this study is to understand the relationships between the processing parameters and the geometric form of the produced single tracks, in order to control dimensional quality in future experimentations. The quality of the deposited single track and layer is of prime importance in the selective laser melting (SLM) process, as it affects the product quality in terms of dimensional precision and product performance.

In this paper, a vertical milling machining center equipped with an Ytterbium-fiber laser was used in the SLM experimentation to form single cobalt-chromium-molybdenum (CoCrMo) tracks. The different geometric features and the influence of the scanning parameters on these morphologic characteristics were studied statistically by means of ANOVA.

Evidently, track height (h1) inaccuracy reduced in layer thicknesses between 100 and 200 μm. The re-melt depth (h2) was determined by the energy parameters, with laser power of 325-350 W and scanning speed (SS) of 66.6-83.3 mm/s being the most favorable parameters to obtain the required anchoring. Moreover, a contact angle of 117° was proposed as optimal, as it permitted an adequate overlapping region and a full densification, and, finally, an SS of 50 mm/s and a layer thickness of 250 were suggested for its development.

The comprehension of the phenomena inherent to the process is related to the single track geometrical characteristics, which allow the definition of an optimal value for each factor for a further proposal of processing conditions that can finally derive a higher precision, wetting, density and mechanical properties.

The purpose of this paper is to describe, review, classify and analyze the current challenges in three-dimensional printing processes for combined electrochemical and microfluidic fabrication areas, which include printing devices and sensors in specified areas.

A systematic review of the literature focusing on existing challenges is carried out. Focused toward sensors and devices in electrochemical and microfluidic areas, the challenges are oriented for a discussion exploring the suitability of printing varied geometries in an accurate manner. Classifications on challenges are based on four key categories such as process, material, size and application as the printer designs are mostly based on these parameters.

A key three-dimensional printing process methodologies have their unique advantages compared to conventional printing methods, still having the challenges to be addressed, in terms of parameters such as cost, performance, speed, quality, accuracy and resolution. Three-dimensional printing is yet to be applied for consumer usable products, which will boost the manufacturing sector. To be specific, the resolution of printing in desktop printers needs improvement. Printing scientific products are halted with prototyping stages. Challenges in three-dimensional printing sensors and devices have to be addressed by forming integrated processes.

The research is underway to define an integrated process-based on three-dimensional Printing. The detailed technical details are not shared for scientific output. The literature is focused to define the challenges.

The research can provide ideas to business on innovative designs. Research studies have scope for improvement ideas.

Review is focused on to have an integrated three-dimensional printer combining processes. This is a cost-oriented approach saving much of space reducing complexity.

To date, no other publication reviews the varied three-dimensional printing challenges by classifying according to process, material, size and application aspects. Study on resolution based data is performed and analyzed for improvements. Addressing the challenges will be the solution to identify an integrated process methodology with a cost-effective approach for printing macro/micro/nano objects and devices.

The conventional statistical method of three-dimensional tolerance analysis requires numerous pseudo-random numbers and consumes enormous computations to increase the calculation accuracy, such as the Monte Carlo simulation. The purpose of this paper is to propose a novel method to overcome the problems.

With the combination of the quasi-Monte Carlo method and the unified Jacobian-torsor model, this paper proposes a three-dimensional tolerance analysis method based on edge sampling. By setting reasonable evaluation criteria, the sequence numbers representing relatively smaller deviations are excluded and the remaining numbers are selected and kept which represent deviations approximate to and still comply with the tolerance requirements.

The case study illustrates the effectiveness and superiority of the proposed method in that it can reduce the sample size, diminish the computations, predict wider tolerance ranges and improve the accuracy of three-dimensional tolerance of precision assembly simultaneously.

The proposed method may be applied only when the dimensional and geometric tolerances are interpreted in the three-dimensional tolerance representation model.

The proposed tolerance analysis method can evaluate the impact of manufacturing errors on the product structure quantitatively and provide a theoretical basis for structural design, process planning and manufacture inspection.

The paper is original in proposing edge sampling as a sampling strategy to generating deviation numbers in tolerance analysis.

Extreme temperature and humidity are major causes of errors in industrial precision and in dimensional measurement. In addition, hot and/or humid workplaces have adverse effects on humans which include reduced work time due to more frequent and longer breaks, reduced production rates, and increased error rates. Managers considering investments in air conditioning their manufacturing facilities must weigh many uncertain benefits against more certain costs. In this paper, we identify the benefits resulting from air conditioning manufacturing facilities and develop a Monte Carlo computer simulation model to evaluate investments in air conditioning. The model uses projected incremental cash flows to compute net present value and internal rate of return. Simulation is used to take into account the uncertainty associated with projecting the benefits of air conditioning, deal with possible correlation among some benefits of air conditioning, and sensitize decision makers to the range of possible outcomes. The proposed model is programmed into user‐friendly menu‐driven software which is tested on actual cases and is illustrated in this paper.

The purpose of this paper is to enhance the accuracy as well as efficiency of high-speed machining, avoid the speed fluctuation caused by acceleration/deceleration (ACC/DEC) and increase the smoothness of feedrate in continuous corners or curves machining. The Hbot kinematic system was analyzed and combined with fused deposition modeling-based (FDM) additive manufacturing (AM) technology. Then a real-time adaptive look-ahead speed control algorithm was proposed.

To validate the performance of Hbot kinematic system and the proposed speed control algorithm, the positioning accuracy of Hbot and cross structure was compared. Also, the experimental verification was conducted among FDM based 3-D printer with cross structure as well as open source speed control algorithm (FDM with cross-OS), cross structure and the proposed speed control algorithm (FDM with cross-PS) and Hbot structure, as well as the proposed speed control algorithm (FDM with Hbot-PS), respectively.

The results indicate that the Hbot kinematic system leads to the high stability of positioning accuracy due to the small motion inertia. Furthermore, the experimental verification shows that the efficiency, printing precision and surface finish of models for FDM with Hbot-PS are obviously higher than that for FDM with cross-PS as well as FDM with cross-OS, while FDM with cross-OS shows the worst performance. The contribution of Hbot kinematic system and the proposed speed control algorithm to FDM based AM technology was validated by this work.

The Hbot kinematic system and proposed speed control algorithm have the important implication of improving the accuracy of FDM machines, especially in the low-price range segment. Also, this work can help future system developers show a possible way of tackling the motion inertia problem.

The study of Hbot kinematic system and proposed algorithm are expected to advise the current research for improving the accuracy as well as the efficiency of FDM-based AM technology.

Fabrication settings such as printing speed and nozzle temperature in fused deposition modeling undeniably influence the quality and strength of fabricated parts. As available market filaments do not contain any exact information report for printing settings, manufacturers are incapable of achieving desirable predefined print accuracy and mechanical properties for the final parts. The purpose of this study is to determine the importance of selecting suitable print parameters by understanding the intrinsic behavior of the material to achieve high-performance parts.

Two common commercial polylactic acid filaments were selected as the investigated samples. To study the specimens’ printing quality, an appropriate scaffold geometry as a delicate printing sample was printed according to a variety of speeds and nozzle temperatures, selected in the filament manufacturer’s proposed temperature range. Dimensional accuracy and qualitative surface roughness of the specimens made by one of the filaments were evaluated and the best processing parameters were selected. The scaffolds were fabricated again by both filaments according to the selected proper processing parameters. Material characterization tests were accomplished to study the reason for different filament behaviors in the printing process. Moreover, the correlations between the polymer structure, thermo-rheological behavior and printing parameters were denoted.

Compression tests revealed that precise printing of the characterized filament results in more accurate structure and subsequent improvement of the final printed sample elastic modulus.

The importance of material characterization to achieve desired properties for any purpose was emphasized. Obtained results from the rheological characterizations would help other users to benefit from the highest performance of their specific filament.

This paper aims to develop an additive manufacturing technique for complex zirconia ceramic dental bridges.

To carry out this study, a dental bridge model was obtained by three-dimensional reverse engineering, and a light-curable zirconia ceramic suspension was formulated. Zirconia bridges were manufactured by stereolithography and then treated by vacuum freeze drying, vacuum infiltration and sintering. The optimal scanning speed was determined according to the shape precision comparison. Then, characteristics of the sintered ceramic parts were tested as size shrinkage, relative density, surface Vickers hardness, surface roughness and microstructure.

The method for preparation of light-curable zirconia suspension (40 volume per cent solid loading) with a viscosity value of 127 mPa·s was proposed. The optimal laser scanning speed for zirconia bridge fabrication was 1200 mm/s. A relative density of 98.58 per cent was achieved; the obtained surface Vickers hardness and surface roughness were 1,398 HV and 2.06 µm, respectively.

This paper provides a potential technical method for manufacturing complex zirconia dental bridges and other small complex-shaped ceramic components which are difficult to be made by other manufacturing techniques.

A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting.

The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment.

20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns.

The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device.

This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.

The purpose of this paper is to study the functionality of additively manufactured (AM) parts, mainly depending on their dimensional accuracy and surface finish. However, the products manufactured using AM usually suffer from defects like roughness or uneven surfaces. This paper discusses the various surface quality improvement techniques, including how to reduce surface defects, surface roughness and dimensional accuracy of AM parts.

There are many different types of popular AM methods. Unfortunately, these AM methods are susceptible to different kinds of surface defects in the product. As a result, pre- and postprocessing efforts and control of various AM process parameters are needed to improve the surface quality and reduce surface roughness.

In this paper, the various surface quality improvement methods are categorized based on the type of materials, working principles of AM and types of finishing processes. They have been divided into chemical, thermal, mechanical and hybrid-based categories.

The review has evaluated the possibility of various surface finishing methods for enhancing the surface quality of AM parts. It has also discussed the research perspective of these methods for surface finishing of AM parts at micro- to nanolevel surface roughness and better dimensional accuracy.

This paper represents a comprehensive review of surface quality improvement methods for both metals and polymer-based AM parts.

There is an increasing demand for higher-accuracy dimensional measurements of nano- and micro-structures. Recently, the authors presented a fiber Bragg grating (FBG) sensor-based dynamic nano-coordinate-measuring machine (CMM) probe for true three-dimensional coordinate measurement, in which a specific mechanical structure with several FBG sensors was developed to provide the probe with sensitivity to loading in all directions.

The study presents a three-dimensional sensing and demodulation system based on an improved matched filter design and the time division multiplexing technique that helps solve the problem of multiplex FBG-signals conflicts. In addition, the application of the dynamic mode of the probe system effectively solves the problem presented by the surface interaction forces.

Consequently, this FBG-based vibrating probe system has increased sensitivity to strain, while maintaining smaller contact force. The experiments for testing probe performance show that the prototype yielded a measurement resolution of 13 nm, a repeatability of 50 nm and a vertical measurement force of less than1.5 mN.

The force tests in the horizontal directions are difficult to conduct because both the probe and the dynamometer are only adaptable to vertical use.

Development of the FBG-based dynamic nano-coordinate-measuring machine probe will achieve a new and inexpensive method for higher-accuracy dimensional measurements of nano- and micro-structures, such as micro-electromechanical systems, micro-fluidic chips, inkjet and diesel engine injector nozzles that are in overall dimensions within the micrometer scale.

The study presents a three-dimensional sensing and demodulation system for the vibrating nano-coordinate-measuring machine probe based on FBG sensors. The prototype yielded a measurement resolution of 13 nm, a repeatability of 50 nm and a vertical measurement force of less than1.5 mN.