Precision Manufacturing Research Articles

Influence of Machining Parameters on the Dimensional Accuracy of Drilled Holes in Engineering Plastics.

This paper explores the interaction between cutting parameters and the geometric accuracy of machined holes in a variety of engineering plastics, with the aim of improving manufacturing processes in the plastic processing industry. In the context of fast and precise manufacturing technology, the accuracy of drilled holes in polymers is of paramount importance, given their essential role in the assembly and functionality of finished parts. The objective of this research was to determine the influence of cutting speed and feed rate on the diameter and cylindricity of machined holes in six diverse types of plastics using a multilevel factorial design for analysis. The key message conveyed to the reader highlights that careful selection of cutting parameters is crucial to achieving high standards of accuracy and repeatability in plastic processing. The methodology involved structured experiments, looking at the effect of changing cutting parameters on a set of six polymer materials. A CNC machining center for drills and high-precision measuring machines were used to evaluate the diameter and cylindricity of the holes. The results of ANOVA statistical analysis showed a significant correlation between cutting parameters and hole sizes for some materials, while for others the relationship was less evident. The conclusions drawn highlight the importance of optimizing cutting speed and feed rate according to polymer type to maximize accuracy and minimize deviations from cylindricity. It was also observed that, under selected processing conditions, high- and medium-density polyurethane showed the best results in terms of accuracy and cylindricity, suggesting potential optimized directions for specific industrial applications.

Optimization of ultra-precision CBN turning of AISI D2 using hybrid GA-RSM and Taguchi-GRA statistic tools

Ultra-precision turning is a crucial process in the manufacturing industry as it helps to produce parts with high dimensional accuracy, surface finish, and tolerance. The process is similar to traditional turning but is carried out under special circumstances to achieve greater precision and surface finish. The process can be applied to conventional structural materials, but the demand for machining hardened steels is increasing. The optimization of ultra-precision turning of AISI D2 using cubic boron nitride (CBN) tools is a crucial aspect in the field of high-quality machining. This study aims to evaluate the performance of the process and identify the optimal parameters that result in the best quality components while using a CBN tool's ultra-precision turning of AISI D2. Ultra-precision turning process factors such as cutting speed, feed, and depth of cut were experimentally investigated to enhance the response output, such as surface roughness and cutting force components. The full factorial experimental design was used for determining the process characteristics under different conditions, and experimental results were applied to search for the optimum response of machining performance. The optimization process was done by combining the hybrid genetic algorithm-response surface methodology (GA-RSM) and the Taguchi-grey relational analysis (GRA) statistical tools. These methods are useful in situations where the relationship between the input variables and the output responses is complex and non-linear. The results showed that a hybrid GA-RSM approach, combined with Taguchi-GRA statistical analysis, can effectively find optimal process parameters, leading to the best combination of surface roughness and cutting force. In hybrid Taguchi - GRA, the optimal cutting conditions were found to be a cutting speed of 175 m/min, a feed of 0.025 mm, and a depth of cut of 0.06 mm. The findings of this study provide valuable insights for the optimization of ultra-precision CBN turning operations, contribute to the development of precision manufacturing technology, and can be used as a reference for similar machining processes.

Exploring role of microbatteries in enhancing sustainability and functionality of implantable biosensors and bioelectronics

Microbatteries are emerging as a sustainable, miniaturized power source, crucial for implantable biomedical devices. Their significance lies in offering high energy density, longevity, and rechargeability, facilitating uninterrupted health monitoring and treatment within the body. The review delves into the development of microbatteries, emphasizing their miniaturization and biocompatibility, crucial for long-term, safe in-vivo use. It examines cutting-edge manufacturing techniques like physical and chemical vapor deposition, and atomic layer deposition, essential for the precision manufacture of the microbatteries. The paper contrasts primary and secondary batteries, highlighting the advantages of zinc-ion and magnesium-ion batteries for enhanced stability and reduced reactivity. It also explores biodegradable batteries, potentially obviating the need for surgical extraction post-use. The integration of microbatteries into diagnostic and therapeutic devices is also discussed, illustrating how they enhance the efficacy and sustainability of implantable biosensors and bioelectronics.

Techno-economic needs assessment for a sustainable novel solar panel production system

Techno-economic needs assessment for an automated solar panel production system is presented. Solar energy, a rapidly growing renewable energy source, has the potential to meet a significant portion of the world's energy needs. Solar panels, the key component of solar energy systems, there are produced in a major industry. Automated solar panel production systems offer the potential to increase production efficiency and reduce costs. The study outlines key factors necessary for successful establishment and operation of an automated solar panel production factory, including market analysis, financial projections, operational strategies, and sustainability initiatives. The market analysis through examination global trends in the solar energy market, identifying growth trends, potential competitors, and target customer segments. The study used a five-step methodology to assess needs, identifying major requirement such as the application of high-speed and precision manufacturing equipment, investment in reliable and efficient manufacturing processes, and development of cost-effective manufacturing methods. The study’s results highlight several key economic benefits of automated solar panel production, including increased production efficiency, reduced labor costs, and improved product quality. The findings are valuable to various stakeholders, including government officials, business leaders, and community members, informing decisions regarding solar industry development and new manufacturing facilities in specific regions. The paper recommends the use of eco-friendly manufacturing processes, utilization of recyclable materials, and adoption of energy-efficient automated technologies to minimize the carbon footprint of solar panel production.

Micropatternable Ink Composed of MAX Phase ZIF-8 for Gas Sensing Applications

This work provides a detailed introduction to the preparation methods, structural characteristics, and various performance tests of the Ti3C2/ZIF-8 composite material. Initially, the composite material is obtained through the synthesis, mixing, and subsequent processing of MXene solution and ZIF-8 nanoparticles. The coating structure and properties were comprehensively characterized using SEM, TEM, and XRD. These analyses revealed the material's layered structure, high crystallinity, and surface activity. BET analysis of Ti3C2/ZIF-8 also shows excellent gas adsorption-desorption performance, having an especially high-efficiency adsorption capacity for VOCs. TGA further demonstrates the thermal stability and chemical stability of Ti3C2/ZIF-8 and its printability was tested indicating widespread application potential in coating preparation through ultrasonic spray technology. Finally, we show methods to regulate and control coating thickness and roughness for precision manufacturing. These analyses together emphasize the application value of Ti3C2/ZIF-8 in fields such as gas-storage, gas-separation, and environmental monitoring.

Preparation and In Vitro Characterization of Lactococcus lactis-Loaded Alginate Particles as a Promising Delivery Tool for Periodontal Probiotic Therapy.

Probiotic microorganisms are used in a variety of food supplements and medical formulations to promote human health. In periodontal therapy, probiotics are mainly used in the form of gels, tablets or rinses that often tend to leak from the periodontal pocket, resulting in a strongly reduced therapeutic effect. In this pilot in vitro study, we present biodegradable alginate-based particles as an alternative, highly efficient system for a periodontal delivery of probiotic bacteria to the inflammation site. For this purpose, Lactococcus (L.) lactis was encapsulated using a standardized pump-controlled extrusion-dripping method. Time-dependent bacterial release in artificial saliva was investigated over 9 days. The effect of freeze drying was explored to ensure long-term storage of L. lactis-loaded particles. Additionally, the particles were bound to dentin surface using approved bioadhesives and subjected to shear stress in a hydrodynamic flow chamber that mimics the oral cavity in vitro. Thus, round particles within the range of 0.80-1.75 mm in radius could be produced, whereby the diameter of the dripping tip had the most significant impact on the size. Although both small and large particles demonstrated a similar release trend of L. lactis, the release rate was significantly higher in the former. Following lyophilization, particles could restore their original shape within 4 h in artificial saliva; thereby, the bacterial viability was not affected. The attachment strength to dentin intensified by an adhesive could resist forces between 10 and 25 N/m2. Full degradation of the particles was observed after 20 days in artificial saliva. Therefore, alginate particles display a valuable probiotic carrier for periodontal applications that have several crucial advantages over existing preparations: a highly stable form, prolonged continuous release of therapeutic bacteria, precise manufacturing according to required dimensions at the application site, strong attachment to the tooth with low risk of dislocation, high biocompatibility and biodegradability.

Laser-assisted screen-printing of graphene folded reflectarray antenna for millimeter-wave applications

Antennas operating at high frequency bands are sought after for applications in 5G, satellite, radar, and other communication systems. Graphene, a two-dimensional material known for its exceptional conductivity, mechanical strength, and chemical stability, is anticipated to serve as a viable substitute for copper in antenna applications. However, researches on graphene antennas at millimeter-wave and higher frequencies are mainly limited to theory and simulation, due to the fabrication challenges of achieving high-precision graphene patterns. Herein, we present the design and fabrication of a graphene folded reflectarray antenna (FRA) operating at millimeter-wave. The FRA is fabricated using screen-printing of graphene ink on an RT5880 substrate, followed by laser engraving for precise patterning. The main reflector has 918 patch units, and the polarizing grids have line widths and spacings of 100 μm. Measurements demonstrate that the antenna has a realized peak gain of 21.37 dBi at 37.5 GHz. The radiation patterns show a 3 dB beamwidth of 6° and 4° in the E-plane and H-plane respectively, with cross-polarization more than −18 dB. The laser-assisted screen-printing method provides a feasible strategy for the precision manufacture of graphene communication devices.

The design and research of two-stage series-connected helium turbine expanders for hydrogen liquefaction system

The helium turbine expander, is a crucial part of hydrogen liquefaction systems, that determines the overall efficiency of the system. In this paper, a two-stage series-connected helium turbine expanders is designed to achieve a hydrogen liquefaction capacity of 1.7 tonnes per day (TPD). The proposed expander is based on the reverse Brayton cycle and realizes a high pressure ratio of 8.32 to meet the design objective. A dynamic design process in the expansion end is developed and numerically simulated based on the turbine expander design methodology. The off-rated condition performance of the turbine expander is predicted by adjusting the rotational speed and flow rate. The results show that the reasonable rotational speed range of the turbine expander is 46000–54000 RPM, and the reasonable flow coefficient range is 0.6–1.2, which can maintain a high level of efficiency. The internal flow characteristics of the turbine expander are analysed through numerical simulation. The results show that the outlet temperature is suitable for hydrogen liquefaction, and flow loss mainly occurs in the upper-middle part of the impeller and near the tip clearance, followed by the throat of the nozzle. In the prototype tests to verify the rationality of the design of the turbine expanders, the experimental results show that the two turbine expanders can achieve a temperature drop of 31 K, and isentropic efficiencies of 76.8 % and 80.5 %, respectively, which are higher than the design requirements of 75 %. The actual outlet temperature and isentropic efficiency are compared with the numerical simulation results. The errors are less than 4 % and 10 %, respectively, which means that the prototype manufacturing precision meets the system requirements perfectly. Thus, the design of the two-stage series-connected turbine expanders can satisfy the performance design requirements.

Multi-view fringe projection profilometry for surfaces with intricate structures and high dynamic range

Fringe projection profilometry plays an important role for quality control in production line. However, it is facing challenges in the measurement of objects with intricate structures and high dynamic range that involved in precision manufacturing and semiconductor packaging. In this paper, a multi-view fringe projection profilometry system, which deploys a vertical telecentric projector and four oblique tilt-shift cameras, is presented to address the “blind spots” caused by shadowing, occlusion and local specular reflection. A flexible and accurate system calibration method is proposed, in which the corrected pinhole imaging model is used to calibrate the telecentric projection, and the unified calibration is performed by bundle adjustment. Experimental results show that the 3D repeated measurement error and standard deviation are no more than 10 μm within a measurable volume of 70 × 40 × 20 mm3. Furthermore, a group of experiments prove that the developed system can achieve complete and accurate 3D measurement for high dynamic range surfaces with complex structures.

Compact auto-aligning interferometers with picometer precision

This research introduces a compact, auto-aligning interferometer engineered for measuring translations with a wide angular working range and picometer precision above 1Hz. It presents a design ensuring automatic beam alignment during movement through secondary reflection from a corner reflector. The sensor head, a 20×10×10mm3 all-glass quasi-monolithic structure, exhibits a displacement sensitivity below 1pm/Hz1/2 above 1Hz and a wide angular working range of ±200mrad. This versatile optical design holds promise to improve the sensitivity in applications such as laser ranging, optical seismometers, precision manufacturing, and metrology.

Photoreaction Drives Efficient, Precise, and Sustainable Additive Manufacturing

Photoreaction Drives Efficient, Precise, and Sustainable Additive Manufacturing

Parameter impact on 3D concrete printing from single to multi-layer stacking

Previous studies have revealed that the design of printing parameters influences the filament shape, while the similarity degree between filament shape and modeled slice directly determines the precision of multi-layer stacking structures. This paper experimentally investigates the influence of printing parameters on filament shape and pressure along the printing path. Computational Fluid Dynamic simulation is employed to verify the experimental findings from the aspect of internal stress distribution. The results highlight the crucial role of printing pressure in connecting these parameters with filament shape. A settlement theory of the multi-layer structure is proposed and tested based the filament shape analysis. In practice, guaranteeing filament shape and adjusting printing progress can be achieved through proportional changes in nozzle travel speed and screw rotation speed. Controlling structure settlement is possible by adjusting nozzle height and time interval. These findings provide a solid foundation for the precise manufacturing of 3D printed structures.

Full-Scale Fire Experiments on Cross-Laminated Timber Residential Enclosures Featuring Different Lining Protection Configurations

AbstractThe adoption of timber, specifically cross-laminated timber (CLT), as a primary construction material is gaining traction due to its carbon sequestration capabilities, environmental advantages, and potential for precision manufacturing. However, the combustibility of wood raises legitimate concerns about fire safety in timber-based residential buildings. This paper investigates the fire performance of timber in a residential context, attempting to fill knowledge gaps and outline strategies for improving fire robustness in timber-built dwellings. Through comprehensive experimental studies on residential-type enclosures constructed with CLT panels, this research explores different configurations and the effects of varying degrees of non-combustible protective lining. The findings underscore the significance of considering timber surface exposure and adopting effective encapsulation strategies in CLT buildings. It has been estimated that the exposure of timber walls leads to a proportional increase in heat release rate, corresponding to the area of exposed timber surfaces and their charring rates. Consequently, the external flame has a larger projection, resulting in a much greater heat flux to the façade. Furthermore, threshold conditions for initial flaming self-extinguishment of timber defined in literature of 44.5 ± 1.2 kW/m2 have been found to be applicable to the experiments conducted in this research. Finally, it has been observed that partial encapsulation, where the protective lining will likely fall off during a fire, may hinder rather than increase the likelihood of self-extinguishment. This work contributes towards a nuanced understanding of fire dynamics in timber structures, offering insights for safer and more effective design strategies for CLT-based construction.

Optimal cut-off frequency and controller gain of an integrated skyhook active isolation

Vibration isolation is a crucial technology in precision manufacturing. With the rapid development of smart sensors, smart actuators, and microprocessors, active vibration isolation has emerged as a viable approach to improve the performance of manufacturing equipment. In integrated skyhook active vibration isolation, the cut-off frequency limits the controller gain. Base on the repeated poles technique, this paper reveals the simple analytical forms of the optimal cut-off frequency and controller gain of the integrated skyhook active isolation. The analytical formula is useful in the design of active isolation. Numerical calculations are performed to show the good performance of the optimal design. An experiment is carried out to show the existence of the optimal controller gain.

Surface wettability and tribological performance of Ni-based nanocomposite moulds against polymer materials

In the mass-production of microfluidic devices through micro hot embossing/injection moulding, the longevity of mould inserts is influenced by elevated adhesion and friction between the polymer and the mould. Thus, accurate prediction of mould lifespan requires a comprehensive understanding of surface wettability and tribological performance during polymer contact. The current study addresses this gap by characterizing fabricated micro-structured Ni, Ni-WS2, and Ni-PTFE nanocomposite moulds (surface morphologies, crystal structures and microhardness) to investigate inherent lubrication mechanisms. Surface wettability of mould material was systematically studied by measuring the contact angles with eight different polymer melts. Pin-on-disk tests with polymer pins made of cyclic olefin copolymer (COC 8007), polypropylene (PP), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were conducted to elucidate the wear resistance of the nanocomposite moulds. Pressure-dependent friction coefficient and wear resistance were further explored under increasing external loads, simulating the actual moulding processes where contact pressure may vary considerably depending on the part shape. Results indicate that Ni-WS2 exhibits the highest microhardness (532 Hv), followed by Ni-PTFE (465 Hv) and Ni (198 Hv). Notably, Ni-PTFE demonstrates exceptional hydrophobicity against all polymer melts, signifying low surface energy during polymer contact. Moreover, both nanocomposite moulds exhibit reduced friction coefficients and enhanced wear resistance across various polymers. Counterintuitively, despite its lower hardness, the Ni-PTFE mould displays superior wear resistance against the COC pin under higher loads, while the Ni-WS2 mould experiences severe adhesive wear, as observed from wear morphology and profile analysis. This finding establishes the Ni-PTFE as a promising alternative as a mould insert material for precision manufacturing.

Direct laser patterning of glass mask for micro display using GHz bursts

AbstractDevelopment of high‐precision RGB patterning process is needed to implement high‐resolution micro display (OLEDoS) for next‐generation VR/AR products. In general, specially designed and manufactured masks are required to realize above 3000‐ppi high‐resolution display in structured OLED material deposition. In this study, we developed direct laser patterning IR‐fs optical system operating in MHz and GHz burst modes and evaluated its capability for precise micro‐drilling of aluminoborosilicate glass materials. The fine hole‐shaped pattern is produced at a minimum of 5 μm pitch level for about 0.6 in. area without sacrificing the glass strength. It is expected to contribute to the high precise manufacture of ultra fine mask (UFM) using thin glass platform corresponding to micro displays in the future.

Distance‐Driven Terahertz Metallic Metasurface Supporting QGM in the Continuum

AbstractThe metasurfaces that support high‐Q resonances can provide ultra‐sharp resonance and achieve strong light‐matter interaction, which promotes their application in various fields such as sensing, lasing, and imaging. Bound modes, unable to radiate into free space, can be transformed into quasi‐bound modes and coupled with external radiation, achieving high‐Q resonances. For periodic structures, by introducing appropriate periodic perturbations, the guided modes (GMs) below the light line can be exposed above the light line, forming the high‐Q quasi‐guide modes (QGMs). Herein, a metallic metasurface is designed that supports the QGM in the continuum by introducing the Brillouin zone folding strategy. The simulation and experiment demonstrate that the GM below the light line can be transformed into the QGM in the continuum by tuning the distance parameter, and a typical “electromagnetic‐induced transparency‐like (EIT‐like)” spectrum is observed. The design unlocks additional degrees of freedom for generating high‐Q metallic metasurface. The advantage of avoiding the production of asymmetric defects contributes to releasing the strict requirement on manufacturing precision. The combination of the metallic metasurface supporting QGM resonance with high‐Q factors and the flexible substrate can improve the performance of the flexible devices and broaden its application in terahertz optoelectronic devices.

Magnetic focusing sensor and its characterizations of defect non-destructive testing for ferromagnetic steel plate

The fast development in precision manufacturing and product quality inspection of ferromagnetic material desperately demands that the defect determining the performance, service life and reliability of the mechanical part should be accurately sensed, detected and evaluated. However, conventional defect detection methods and related magnetic induction sensors are usually characterized with low accuracy in small defect detection, which makes the non-destructive testing (NDT) for ferromagnetic material full of challenges. Thus, a new magnetic focusing sensor is proposed and designed for the precision defect detection of ferromagnetic steel plate here. First, the theoretical principle analysis of the magnetic focusing sensor is introduced, and the preliminary finite element modeling (FEM) is conducted to demonstrate the feasibility of the magnetic focusing sensor in tiny defect inspection. Then, both the static and coupling dynamic characterizations of the magnetic focusing sensor are investigated using the FEM method. The optimal structural parameters of the magnetic focusing (MF) sensor in static conditions are summarized. Furthermore, the effects of the dynamic movement of the MF sensor on the multi-physical fields of the magnetization field, electric field, electromagnetic attraction force field and thermal field are all revealed. Finally, experiments regarding the performance evaluation and comparison between the MF sensor and other two magnetic flux leakage (MFL) sensors are conducted, and the prominent capabilities of accurate and precise defect detection for the MF sensor is demonstrated through the defect detection with different sizes. The effectiveness and feasibility of the MF sensor in detecting tiny defects on ferromagnetic object, as well as its great potential for practical application is therefore validated. Additionally, the main conclusions, advantages of the MF sensor are summarized and the future work is discussed.

Pulse current electroforming of Ni-PTFE nanocomposite mold insert with long-lifetime and anti-adhesive properties

Polymeric micro features tend to deform and break under the demolding force during injection molding process, which becomes a bottleneck problem limiting its precision manufacturing. To reduce the polymer-mold interfacial adhesion, nickel-polytetrafluoroethylene (Ni-PTFE) nanocomposite molds with low surface adhesion and high wear resistance were manufactured via pulse current electroforming. The electrodeposited Ni-PTFE nanocomposite showed a good hydrophobic property and low friction coefficient (between 0.1 and 0.3) than pure nickel (0.78). Compared with direct current, pulse current electrodeposition was beneficial to reduce the crystallite size and internal stress, thus improving the wear resistance and reducing the cracking defects. The hardness of pulse current electrodeposited Ni-PTFE reached 442.3 HV, which was 51.7 % higher than that of pure nickel. Compared to nickel mold, Ni-PTFE nanocomposite mold significantly improved the dimensional accuracy of molded microfluidic chips. This study systematically investigates the Ni-PTFE nanocomposite electroforming process under both direct and pulse currents, which provides a new approach for the manufacturing of high-performance precision injection mold insert.

Experimental analysis of augmented reality interfaces for robot programming by demonstration in manufacturing

Augmented Reality (AR) technology has been effectively utilized to support various manual operations in the manufacturing industry. An important application is serving as a user interface for human-robot collaboration. This paper presents an experimental study on the feasibility of robot programming by demonstration (PbD) through AR interfaces in the context of manufacturing. Our focus is on comparing the pointing and line tracing processes using three input methods provided by an AR headset: hand ray, head gaze, and eye gaze, based on both objective and subjective measures obtained from the experiment. The hand ray method performs the best in terms of accuracy, precision, and completion time in most experimental conditions. The SUS and NASA-TLX scores indicate acceptable usability for the hand ray method but low usability for the others. A prototyping AR tool using the hand ray as non-contact input in the real world is developed for motion planning of an industrial robotic arm. A test case of tire mold welding verifies the feasibility of the AR tool while also showing its limited capability in precision manufacturing. This work demonstrates a new approach for robot PbD on tangible objects enabled by AR.