Manufacturing Accuracy Research Articles

The rotation stability of the tapered rollers in a novel ring-type lapping process

This work introduces a novel ring-type lapping method for precision machining of tapered rollers. In contrast to the conventional centerless grinding, this method allows for the simultaneous machining of a group of tapered rollers. The stable rotation of the tapered rollers during the lapping process is a prerequisite for achieving a high manufacturing accuracy. Therefore, an investigation is conducted to examine the criteria for achieving a stable rotation of the tapered rollers. First, the equilibrium equation for the tapered rollers in the lapping process was established. The stable rotation region for the tapered rollers was determined according to the stable rotation criteria. The impacts of the included angle of straight groove and the contact force of lapping sleeve on the stable rotation region were examined. The results demonstrated that the tapered roller's stable rotation can only be realized when a specific parameter combination was satisfied. Subsequently, to expand the stable rotation region, the electromagnetic driving force was introduced to enhance the lapping process. An electromagnetic lapping sleeve structure was designed according to the critical electromagnetic force required for the tapered roller's lapping process. Furthermore, the structure of the electromagnetic lapping sleeve was optimized by electromagnetic simulation in order to improve the uniformity of the electromagnetic driving force exerted on each tapered roller. Finally, the rotation movement of the tapered rollers and the critical electromagnetic forces exerted on the tapered rollers were validated on a ring-type tapered roller lapping platform. The results demonstrated that the stable rotation of the bearing rollers in the lapping process can be achieved throughout a wide range of processing parameters. The roundness of the tapered rollers was significantly improved from 0.83 μm to 0.47 μm on the stable rotation condition. This study established a solid foundation for the precision machining of tapered rollers.

Results of round robin form measurements of optical aspheres and freeform surfaces

High-quality aspherical and freeform surfaces are in high demand, and the high-accuracy form measurement of such surfaces is a challenging task. To explore the current status of form measurement systems for complex surfaces such as aspheres and freeforms, interlaboratory comparison measurements are performed. This study presents the pseudonymized results obtained using three different surfaces (metal asphere, glass asphere, toroidal surface) in a total of six different round robins. These results were taken from a total of 13 different measurement instruments based on 9 different measurement principles and operated at 12 different laboratories. They were analyzed using a sophisticated procedure that was first developed in 2018 and then refined and tested on simulated data in 2022 to address the challenges of such a comparison at this level of accuracy. In the current study, we applied these refined methods to data acquired from tactile and optical point measurements as well as from optical areal measurements. As there are no absolutely measured and very well characterized reference standard aspherical and freeform surfaces available at the accuracy level of a few tens of nanometers root-mean-square, the approximated true forms of the surfaces were derived from the measurements and indicate the manufacturing accuracy of the surface forms. Then, the measurement’s differences to the approximated true forms were analyzed, which directly indicate the systematic measurement errors of the instruments. By also comparing the approximated true forms from the two different round robins for each surface, additional insights into the reliability and stability of these so-called virtual reference topographies were gained.

Fast and accurate Zero-defect manufacturing using collaborative real-time photogrammetry

Abstract. For the machining of industrial components, their accurate alignment on operative machines is a crucial step with significant impacts on the whole process, especially when dealing with large-scale elements. To achieve this alignment, a trained operator is needed along with expensive equipment, such as laser trackers, whose correct use requires the measurements of many significant points and is time-consuming. The lack of a precise alignment comes with possible incorrect parts machining, resulting in quality concerns and potentially expensive rework. To face this problem, collaborative real-time photogrammetry is an effective solution for guiding untrained users in correctly positioning various measured and codified components to generate the best solution for machining high-volume parts. The solution proposed in this contribution is part of the TACCO project, co-financed by EIT Manufacturing (co-funded by the EU). It takes advantage of the TACCO system, where auxiliary components (scale bars, dome-shaped components, coded targets and a cross-reference system) are placed on the object to be measured for their correct positioning in order to obtain an optimal photogrammetric reconstruction. This allows the reduction of the error ellipsoids on several uncoded targets, which are calculated through an iterative simulation carried out in a MATLAB environment. Unskilled operators are then guided through an Augmented Reality headset for their correct placement on the real-world object and for defining the positions and orientations from which to acquire images. This methodology will lead to an accurate measurement of the target points to be machined and, thus, a precise alignment process for the subsequent machining operations.

Imperfections for the calculation of steel structures by the finite element method. Part 1

It is well known that imperfections are always present in structural elements. Imperfections can significantly affect the behavior and bearing capacity of steel structures, especially in the case of stability-related tasks. Therefore, inconsistencies must be taken into account in the loadbearing capacity model and their correct application (setting the shape and value) is a key point in the numerical analysis process. In recent decades, much attention has been paid in the domestic scientific space to updating imperfection models for use in numerical models, including taking into account modern more accurate manufacturing and installation technologies for steel structures. The purpose of this study is an analytical review and analysis of scientific research and technical literature, followed by synthesis and elaboration of recommendations on imperfections in relation to the calculation of steel structures using computer modeling technology, including the finite element method. The results of the study contain instructions on how to set the shapes and values of imperfections for different groups of imperfections. The article consists of two parts. The first part is devoted to the study of geometric imperfections, residual stresses and rules for the combination of imperfections, the second part of the article is devoted to equivalent imperfections.

Influence of base designs on the manufacturing accuracy of vat-polymerized diagnostic casts using two different technologies

Statement of problemDiagnostic casts can incorporate different base designs and be manufactured using different vat-polymerization technologies. However, the influence of the interrelation between the base design and the 3D printing technology on the casts' final accuracy remains unclear. PurposeThe purpose of this in vitro study was to assess the influence of different base designs of 3D printed casts on the accuracy of 2 vat-polymerization technologies. Material and methodsA digital maxillary cast was obtained and used to generate 3 different base designs: solid (S group), honeycombed (HC group), and hollow (H group). The HC and H groups were subdivided based on the wall thickness of the cast design, resulting in 2 subgroups with thicknesses of 1 mm (HC1 and H1) and 2 mm (HC2 and H2) (N=100, n=10). Eleven reference cubes were added to each specimen for subsequent measurements. Specimens were manufactured by using 2 vat-polymerization 3D printers: Nextdent 5100 (ND group) and Sonic Mini 4K (SM4K group) and a resin material suitable for both 3D printers (Nextdent Model 2.0). A coordinate measuring machine quantified the linear and 3-dimensional discrepancies between the digital cast and each reference specimen. Trueness was defined as the average absolute dimensional discrepancy between the virtual cast and the specimens produced through additive manufacturing (AM), while precision was delineated as the standard deviation in dimensional discrepancies between the digital cast and the AM specimens. The data were analyzed using the Kruskal-Wallis and Mann-Whitney U pairwise comparison tests (α=.05). ResultsFor the NextDent group the trueness ranged from 21.83 µm to 28.35 µm, and the precision ranged from 17.82 µm to 37.70 µm. For the Phrozen group, the trueness ranged from 45.15 µm to 64.51 µm, and the precision ranged from 33.51 µm to 48.92 µm. The Kruskal-Wallis test showed significant differences on the x-, y-, and z-axes and in the 3D discrepancy (all P<.001). On the x-axis, the Mann-Whitney U test showed significant differences for the Phrozen group between the H-2 and H-1 groups (P=.001), H-2 and S groups (P<.001), and HC-2 and S groups (P=.012). On the y-axis, significant differences were found in the Phrozen group between the H-2 and H-1 groups (P=.001), the H-2 and S, H-1 and HC-1, and HC-1 and S groups (P<.001), the H-1 and HC-2 groups (P=.007), and the HC-2 and S groups (P=.009). The NextDent group exhibited significant differences, particularly among the HC-1 and H-2 groups (P=.004), H-1 (P=.020), and HC-2 (P=.001) groups; and on the z-axis significant differences were found in the Phrozen group between the H-2 and H-1 and S groups and the HC-2 group and H-1 and S groups (both P<.001). In the NextDent group, significant differences were found between the H-2 and HC-2 (P=.047) and HC-1 (P=.028) groups. For the 3D discrepancy analysis, significant differences were found in the Phrozen group between the H-2 and H-1 and S groups (P<.001), the H-1 and HC-2 groups (P=.001), the S and HC-1 and HC-2 groups (P<.001), and the H-1 and HC-1 groups (P=.002). In the NextDent group, significant differences were observed between the H-2 and HC-1 groups (P=.012). ConclusionsThe accuracy of digital casts depends on the manufacturing trinomial and base design of the casts. The honeycomb and hollow based designs provided the highest accuracy in the NextDent and Phrozen groups respectively for the material polymer tested. All specimens fell in the clinically acceptable range.

Efficient Method for Identifying Key Errors Based on 21-Geometric-Error Measurement of Three Linear Axes of Machine Tools

Key errors of machine tools have a significant impact on their accuracy, however accurately and quickly measuring the geometric errors of machine tools is essential for key error identification. Fortunately, a quick and direct laser measurement method and system for 21 geometric errors of three linear axes of machine tools were proposed previously, which enables the measurement of all 21 geometric errors via a one-step installation and a three-step automated measurement process. Based on this, to efficiently identify the key error factors, this paper first utilizes the 21 geometric errors obtained from the proposed measurement system to evaluate the contribution of each error to the volumetric errors of machine tools, leading to the building of a 21-geometric-error sensitivity analysis model. Then, experiments are carried out on the vertical machining tool TH5656, and all 21 geometric errors are obtained in 5 min. After this, the volumetric error distribution in the machining workspace is mapped according to the relationship between the geometric errors and the machining errors, and the key error factors affecting the manufacturing and machining accuracy of the TH5656 are ultimately determined. Thus, this new method provides a way to quickly identify key errors of the three linear axes of machine tools, and offers guidance for the machine tool configuration design, machining technology determination, and geometric error compensation.

Enhancing the geometry accuracy and mechanical properties of wire arc additive manufacturing of an Al-5%Mg alloy through longitudinal magnetic field influence

To address the issues of low deposition efficiency, poor geometric accuracy, and high porosity in wire arc additive manufacturing (WAAM) specimens, a longitudinal alternating current (AC) magnetic field-assisted WAAM method was employed. The results showed that the introduction of the longitudinal AC magnetic field significantly enhanced the geometric accuracy of the specimens. After magnetic field assistance, the porosity of the WAAM Al-5%Mg alloy specimens decreased from 0.372 % to 0.016 %. The grain size decreases from 71.95 μm to 56.3 μm, with a notable increase in the proportion of small grains (D < 30 μm) from 27.06 % to 44.57 %. The longitudinal tensile strength increased from 243 MPa to 260 MPa, while the transverse tensile strength increased from 232 MPa to 257.7 MPa. Moreover, the longitudinal and transverse tensile strengths tended to be isotropic. Therefore, the longitudinal AC magnetic field has a significant impact on the performance of AlMg alloy WAAM specimens. This study presents novel strategies and theoretical guidance for enhancing the efficiency and component performance of aluminum alloy WAAM technology.

Verifying the seating of a 3D-printed removable die using elastomeric matrices: A dental technique.

Computer-aided design and computer-aided manufacturing systems enable digital designing and 3-dimensional (3D) printing of definitive casts with removable dies. However, the fit of the removable dies should be without interferences for their accurate positioning in the cast. Given that the accuracy of additive manufacturing depends on design- and manufacturing-related factors, verifying the accuracy of the position of 3D-printed removable dies in their cast is essential to fabricate positionally accurate definitive prostheses, which would enable minimal or no laboratory and clinical adjustments. This dental technique article presents a straightforward approach to verify the seating of a 3D-printed removable die by using verification matrices made of a polyvinylsiloxane interocclusal registration material.

Development, Prospect and Challenge for Additive Manufacturing of Polymer Materials

As a manufacturing technology that fabricates three-dimensional objects by stacking materials layer by layer, additive manufacturing can be divided into laser fused deposition, electron beam fused deposition, inkjet printing and so on based on different additive manufacturing processes. In recent years, remarkable progress has been made in the additive manufacture of polymer materials. Firstly, the additive manufacturing equipment and process parameters suitable for polymer materials have been successfully developed, which realized the accurate manufacturing of complex structures. Secondly, by optimizing the formula and post-treatment of polymer materials, the performance and durability of additive products are improved. In addition, the researchers also explored the application potential of additive manufacturing of polymer materials in medical, aerospace and other fields. However, the additive manufacturing of polymer materials still faces some challenges. One of them is that the rheological properties of polymer materials have a great impact on the progress of additive manufacturing, which needs further research and improvement. Meanwhile, the heat and stress generated in additive manufacturing may lead to the deformation and degradation of polymer materials, which requires effective thermal management. Finally, compared with the traditional cutting process, the additive manufacturing cost of polymer materials is still high, so it is necessary to reduce the cost and promote production efficiency. In a word, additive manufacturing of polymer materials has broad prospects and application potential, but further research and improvement are still needed to overcome related challenges.

Digital light processing-based bioprinting of microtissue hydrogel arrays using dextran-induced aqueous emulsion ink

As a microscale three-dimensional bionic model, a microtissue array is a promising method for disease modeling and drug screening. Digital light processing (DLP) 3D bio-printing technology with the capabilities of excellent printing speed and resolution shows great potential for fabricating microtissue arrays. However, the outcomes of the microtissue arrays using DLP are limited by the shortage of biomaterials. In this work, we prepare hydrogel microtissues by combining DLP printing technology with biphasic bio-ink consisting of gelatin methacrylate (GelMA) and dextran. GelMA/ dextran is mixed to form bio-inks with different volume ratios, which can achieve high-precision printing of various patterns. Due to the presence of dextran, the bio-inks form the internal porous structure of the hydrogel in the printed patterns. The pore size is related to the proportion of dextran in bio-inks, and the pore size of hydrogel becomes smaller with the increase of dextran ratio. In addition, the adipose-derived stem cells (ADSCs) cells encapsulated in the porous hydrogels can maintain a high survival rate of 98.01% after 3 days of culture, and the larger pore size in the hydrogels promotes cell migration. Combining the DLP printing system with the porous hydrogel allows multiple micro-size geometric pattern hydrogels to be printed simultaneously to form microtissue arrays. In this study, a new bio-ink suitable for microtissue arrays is proposed, and a simple, accurate, and high-throughput biological manufacturing method for microtissue arrays is developed, thus providing a valuable tool for drug screening and tissue engineering.

THE ROLE OF PRECISION METROLOGY IN ENHANCING MANUFACTURING QUALITY: A COMPREHENSIVE REVIEW

Precision metrology plays a pivotal role in modern manufacturing processes by ensuring the attainment of high-quality standards and the optimization of production efficiency. This comprehensive review delves into the significance of precision metrology in enhancing manufacturing quality across diverse industries. The review encompasses an examination of advanced metrological techniques, their applications, challenges, and future prospects. The review begins by elucidating the fundamental principles of precision metrology, emphasizing its critical role in quantifying dimensional accuracy, surface finish, and other crucial parameters in manufacturing. It explores the evolution of metrology from conventional methods to state-of-the-art technologies such as coordinate measuring machines (CMMs), optical metrology, and 3D scanning systems. The integration of these techniques into modern manufacturing environments has revolutionized quality control processes, enabling real-time monitoring and rapid feedback mechanisms. Furthermore, the review highlights the multifaceted applications of precision metrology across various industries, including automotive, aerospace, electronics, and medical devices. It elucidates how metrological advancements have facilitated the production of intricate components with tight tolerances, thereby enhancing product performance, reliability, and safety. Additionally, the review examines the role of metrology in ensuring compliance with regulatory standards and certifications, crucial for industries with stringent quality requirements. Despite its numerous benefits, precision metrology also poses challenges, such as measurement uncertainties, calibration complexities, and data interpretation issues. The review discusses these challenges in detail and explores emerging strategies and technologies aimed at mitigating them. Furthermore, it addresses the need for standardized metrological practices and international collaboration to foster interoperability and harmonization in global manufacturing ecosystems. Looking ahead, the review outlines future directions and opportunities in precision metrology, including advancements in artificial intelligence, machine learning, and Internet of Things (IoT) integration for predictive maintenance and autonomous quality control systems. It underscores the importance of continued research and innovation in metrology to address evolving manufacturing demands and ensure sustained improvements in product quality and competitiveness. In conclusion, this comprehensive review underscores the indispensable role of precision metrology in enhancing manufacturing quality, driving innovation, and shaping the future of modern industry.&#x0D; Keywords: Precision, Metrology, Manufacturing, Quality, Review.

Thermo-Hydric Study of Wood-Based Materials under Thermal Comfort Conditions.

This paper tackles the issue of moisture variation in wood-based materials, explicitly focusing on melamine-coated particleboard (hereafter referred to as melamine) and medium-density fiberboard (MDF) used in the third phase of wood industry transformation. The approach involves a comprehensive strategy for predicting moisture content variation, incorporating numerical simulation, experimental testing, and the application of artificial neural network (ANN) technology to enhance accuracy in furniture manufacturing. The developed ANN models are tailored to predict moisture content changes under specific thermal comfort conditions. Remarkably, these models demonstrate high precision, with an average error margin of only 1.40% for 8% moisture content (MC) and 2.85% for 12% MC in melamine, as well as 1.42% for 8% MC and 2.25% for 12% MC in MDF. These levels of precision surpass traditional models, emphasizing this study's novelty and practical relevance to the industrial context. The findings indicate that ANN models adapt to diverse environmental conditions, presenting a robust tool for optimizing moisture management in wood-based materials. This research contributes valuable insights for improving the reliability and efficiency of moisture content predictions in the wood industry.

Manufacturing Accuracy, Intaglio Surface Adaptation, and Survival of Additively and Subtractively Manufactured Definitive Resin Crowns After Cyclic Loading: An In Vitro Study.

To assess the manufacturing accuracy, intaglio surface adaptation, and survival of resin-based CAD/CAM definitive crowns created via additive manufacturing (AM) or subtractive manufacturing (SM). A maxillary right first molar crown was digitally designed and manufactured using AM hybrid resin composite (VarseoSmile Crown Plus, Bego [AM-HRC]), AM glass filler-reinforced resin composite (Crowntec, Saremco Dental [AM-RC]), and SM polymer-infiltrated ceramic (Vita Enamic, VITA Zahnfabrik [SM-PICN]). Manufacturing accuracy (trueness and precision) was assessed by computing the root mean square (RMS) error (in μm; n = 15 per material). Intaglio surface adaptation was assessed by calculating the average gap distance (μm). Ten crowns from each group were cemented on fiberglass-reinforced epoxy resin dies and cyclically loaded to simulate 5 years of functional loading. One-way ANOVA, post hoc Bonferroni comparison tests, and Levene's test were used to analyze the data (α = .05). AM-RC had higher overall trueness than AM-HRC and SM-PICN (P ≤ .05), whereas the trueness of AM-RC on the external surface was similar to that of SM-PICN (P = .99) and higher than AM-HRC (P = .001). SM-PICN had lower precision than AM-RC and AM-HRC overall and at internal occlusal surfaces (P ≤ .05). Overall intaglio surface adaptation was similar between all groups (P = .531). However, for the axial intaglio surface, AM-RC and AM-HRC had higher adaptation than SM-PICN (P ≤ .05). All tested crowns survived the cyclic loading simulation of 5 years clinical use. AM-RC showed high manufacturing accuracy and adaptation. The tested resin-based CAD/CAM materials demonstrated clinically acceptable manufacturing accuracy and simulated medium-term durability, justifying the initiation of clinical investigations to determine their potential implementation in daily clinical practice.

Millipixel accuracy optical localization for point-like targets on pixelated image sensors

Localizing point-like targets, such as stars and single molecules on pixelated image sensors, are of great importance in optical measurement fields, including astronomy and microscopy. To date, a localization accuracy of 0.01 pixels has been considered high in practical applications. It is difficult to assess or achieve a higher accuracy (e.g., millipixel level) using experimental data due to noise from conventional setups or environment. Here, we propose a millipixel-scale localization accuracy assessment and realization method. The method combines organic light emitting diode subpixel precise motion control and large-ratio optical scaling to form spot array motion with ultrahigh accuracy in digital images for localization assessment and uses effective point spread function (PSF) modeling and maximum likelihood estimation fitting to realize millipixel localization performance. A localization accuracy better than 0.001 pixels has been demonstrated on two types of practical spots. The work not only provides an experimental assessment method for localization techniques with ultrahigh accuracy but also verifies the ability of optical localization as a powerful tool to measure 2D displacements at nano-scale accuracy in advanced manufacturing.

A Mobile Hybrid Robot and Its Accuracy Issue in Machining of Large-Scale Structures

Accurate and efficient manufacturing of large-scale structures is an important and challenging issue. To this end, a mobile hybrid robot named CraftsRobot is designed and developed for in-situ machining the local features of large-scale structures. The mobile hybrid robot comprises a mobile vehicle, a guide rail, a two degree-of-freedom (DoF) mechanical arm, and a five-DoF light-weight parallel module. The interaction mechanism between the parallel module and the mechanical arm is disclosed to build the error prediction model. On this basis, a model predictive compensation method is proposed. In each servo cycle, the command pose of the parallel module is modified and under the effect of the interaction-induced error superimposed on the modified command pose, the parallel module will reach the target pose. The results of simulation and experiment both verify the effectiveness of the compensation model. After compensation, the mobile hybrid robot is applied to machine the features on a typical large-scale structure and the machining errors are within 0.04 mm. The experimental results show that the designed robot can machine local features of large-scale structures in situ and meet the precision requirements. Together, this study provides a novel approach to achieve accurate and efficient manufacturing of large-scale structures.

Effect of surface modification of metal powders (by aluminum stearate) on the properties of metal injection molding feedstock

Metal injection molding (MIM) is a net-forming technology for manufacturing miniature metal parts, which can improve the manufacturing accuracy of complex-shaped parts. In this study, aluminum stearate was used to modify the 17-4PH stainless steel powder, the binder was composed of (PMMA) and (PEG) with the volume ratio of 7:3. The effects of aluminum stearate surfactant amount on the feedstock viscosity, water debinding rate and thermal debinding shape were studied. The results showed that the coating of aluminum stearate breaks the agglomeration between the powders and decreases the viscosity of the feedstock. When the addition of aluminum stearate was 0.6wt% of the powder mass, the melt index, density and flexural modulus of the feedstock were 81.5 g/10 min, 5.44 g/cm3, and 1643Mpa, respectively, and the thermal debinding shape retention was the best of all debinded parts. However, too much aluminum stearate makes the feedstocks thicker and the green part weaker.

Accurate additive manufacturing of lightweight and elastic carbons using plastic precursors

Despite groundbreaking advances in the additive manufacturing of polymers, metals, and ceramics, scaled and accurate production of structured carbons remains largely underdeveloped. This work reports a simple method to produce complex carbon materials with very low dimensional shrinkage from printed to carbonized state (less than 4%), using commercially available polypropylene precursors and a fused filament fabrication-based process. The control of macrostructural retention is enabled by the inclusion of fiber fillers regardless of the crosslinking degree of the polypropylene matrix, providing a significant advantage to directly control the density, porosity, and mechanical properties of 3D printed carbons. Using the same printed plastic precursors, different mechanical responses of derived carbons can be obtained, notably from stiff to highly compressible. This report harnesses the power of additive manufacturing for producing carbons with accurately controlled structure and properties, while enabling great opportunities for various applications.

THE QUALITY OF THIN-WALLED STRUCTURES OF AlSi10Mg PRODUCED BY SELECTIVE LASER MELTING

The process of manufacturing thin walls using selective laser melting (SLM) from aluminum alloy powder AlSi10Mg was studied. The research aims at specifying a type of lattice structure based on skeletal-triple periodic minimal surface (TPMS) and sheet-TPMS shells. In this regard, the possibility of obtaining well-quality thin walls was studied. The accuracy of manufacturing, surface roughness and porosity of the samples were taken as quality criteria. The dependences of the influence of SLM parameters on the geometric characteristics, roughness, and porosity of thin walls were obtained. The preferential parameters for manufacturing thin-walled aluminum alloy samples have been determined. The microstructure and phase composition of the studied alloy after SLM were studied.

МЕТОДИКА ВОССТАНОВЛЕНИЯ РАЗМЕРНЫХ СВЯЗЕЙ ПРИ РЕГУЛИРОВКЕ КЛАПАННОГО ЗАЗОРА В МЕХАНИЗМЕ ГАЗОРАСПРЕДЕЛЕНИЯ АВТОМОБИЛЬНОГО ДВИГАТЕЛЯ ВНУТРЕННЕГО СГОРАНИЯ

The relevance of research is due to the problems of organizing auto repair production in modern conditions associated with the difficulty of logistics and the high cost of foreign spare parts, which is confirmed by the analysis of domestic and foreign literary sources. Of particular importance in this case are the methods of optimizing the balance of costs for performing repair and restoration actions and replacing defective parts. The purpose of the work is to improve the quality of repair of rolling stock of road transport based on the use of methods for restoring dimensional connections. This study is designed to fill the existing knowledge gap caused by the lack of methods for restoring specific repair links. The use of new parts in repair, along with restored or used ones, necessitates the wider use of methods for optimizing the limit values of wear and recovery processes of dimension chain elements. The materials and methods of research are presented as an example of the development of a technique for restoring the necessary parameters of dimensional connections when adjusting the valve gap value, since the thermal gap in the timing mechanism of an internal combustion engine is an important element affecting the efficiency of the car engine. The scientific novelty of the work lies in the study of two different methods potentially suitable for implementation in the repair industry for restoring dimensional ties while reducing the valve gap by machining the outer or inner contact surfaces of car engine pushers. Studies have been carried out in relation to the decrease in the gap in operating conditions, which is widespread in automobile engines with overhead camshafts, since a decrease in the valve gap to a greater extent than an increase in it affects the efficiency of the machines. The equation of the size chain of the valve group is given, in which the valve gap is the closing link. As a result of sequentially discretely removing the surface layers of the pusher metal at 0.05 mm intervals and measuring the hardness of the surface layers, it has been found that this approach to restoring repair bonds can be recommended for use in auto repair production, with a more preferred method being to adjust the valve clearance by grinding the outer surface of the pushers. The data obtained can serve as the basis for further research in the development of a set of technologies for restoring specific size chains using repair kits that include parts with different manufacturing accuracy or that have been in operation.

XMKR: Explainable manufacturing knowledge recommendation for collaborative design with graph embedding learning

Design for manufacturability is crucial to ensure high-quality products. It fully considers manufacturing-related factors in a collaborative design manner. However, since manufacturing knowledge is unstructured and hard to reuse, designers mainly depend on frequent design iterations to meet complex manufacturing constraints. Such insufficient design-manufacturing collaboration is not conducive to design efficiency improvement. To alleviate the problem, this paper proposes a novel graph embedding-based approach of Explainable Manufacturing Knowledge Recommendation (XMKR) for collaborative product design, which could achieve designer-oriented manufacturing knowledge reuse to avoid design errors proactively and minimize excessive iterations. Firstly, a graph embedding model based on the graph neural network (MKGE-GNN) is proposed to learn implicit semantic information of manufacturing knowledge. Secondly, with MKGE-GNN learning results, the potential manufacturing knowledge preferences of designers are identified in the design context graph by Personalized PageRank to achieve context-aware explainable manufacturing knowledge recommendation. Finally, a car body collaborative design case is conducted to validate the efficacy of the proposed approach, which not only provides accurate manufacturing knowledge in designers’ decision-making, but also enhances designers’ cognitions for manufacturability in the dynamic design context.