Product Assembly Process Research Articles

防差错管理方法在航天产品装配过程中的应用

防差错管理方法在航天产品装配过程中的应用

Fault Detection and Classification for Slider Attachment Process using Convolution Neural Network

Hard Disk Drive (HDD) utilizes automation machines for the assembly processes used in the industry to achieve higher production rates and lower costs. The Head Gimbal Assembly (HGA) production process has two main parts: glue dispensing and slider attaching by an Auto Core Adhesion mounting Machine (ACAM). The slider attaching process produces a mounted head to the suspension utilizing vacuum pressure to hold and position a slider. The errors from a vacuum leak from any step trigger system alarms resulting in machine downtime and slider loss defective (SLD). This paper proposes a classification algorithm derived from 250x250 micron images of mounted heads are 4 different categories: Good, Fault I, Fault II and Fault III using Convolution Neural Networks (CNN). CNN is a performance model for predictive maintenance before failure. The method has achieved a 95 % accuracy for detection and classification

Impact of Electrode Thick Spot Irregularities on Polymer Electrolyte Membrane Fuel Cell Performance

Polymer electrolyte membrane fuel cells (PEMFC) have great potential for power generation in many applications, but to implement them on a larger scale, understanding of quality requirements, tolerances, and controls during manufacturing must improve. As part of this broad challenge, irregularities resulting from the membrane electrode assembly (MEA) production process must be studied to determine if they impact the performance of the cell.1,2 One potential irregularity is a locally increased thickness of the coated or deposited electrode. In order to understand and provide insight into the impact of such irregularities, we intentionally created thick spots in the center of cathode electrodes, either by liquid casting or ultrasonic spraying of the additional catalyst ink. The thick spots fabricated by these two different approaches exhibited different sizes, morphologies, and Pt loading distributions, which were carefully characterized by optical microscopy, X-ray fluorescence spectroscopy (XRF), and scanning electron microscopy (SEM). Edge-protected MEAs were fabricated using both pristine electrodes and electrodes with thick spot irregularities. The effect of these irregularities on MEA structure were investigated by cross-sectional SEM. Electrochemical performance, including electrochemically active surface area (ECSA), H2/O2 polarization curves, mass activity and H2/air polarization curves, was measured to study the impact of the electrode irregularities on catalyst utilization and PEMFC initial performance. NREL’s segmented cell was utilized to investigate the resulting spatial performance of a representative thick spot MEA.The results indicate that thick spot irregularities that are present in the center of the cathode electrode impact initial cell performance although the impact of the thick spots on ECSA and mass activity was minimal. The latter suggests that the number of active Pt sites and the kinetics were not significantly altered. However, the H2/air polarization curves indicated that liquid-cast thick spots and large sprayed thick spots decrease cell performance dramatically at current densities above 0.8 A/cm2. Based on cross-sectional SEM analysis, the likely causes of this performance drop may originate from (i) delamination between the GDL and CL, (ii) the presence of thin spots in the membrane due to deformation associated with the thick spot, (iii) additional compression of the GDL and/or (iv) thick catalyst layer sections inhibiting local mass transport. Spatial performance diagnostics confirmed that the performance loss of MEAs containing liquid-cast thick spots is more pronounced at high current density than at low current density. Moreover, the performance of the area surrounding the liquid-cast thick spot is impacted as well, likely due to the various morphological changes resulting from the irregularity. We expect that the morphological changes resulting from these irregularities could serve as seed points for premature cell failure in long-term PEMFC operation. Future work will focus on the impact of electrode thick spot irregularities on PEMFC performance-over-time and lifetime, for both reinforced and non-reinforced membranes.

Design and Research of Electric Handling Device for An Aerospace Product

In the assembly process of aerospace products, manual loading and unloading, handling, overturning and other operations are often repeated. These operations have the problems of low efficiency, high labor intensity and low safety. In order to solve this problems, this paper designs a kind of electric transport turnover device according to the modular idea. In addition, the flexible design of the design is considered, which can be applied to the handling of various products with different structures. The reliability test of the device is carried out, and the results show that the device can meet the reliability requirements of the cabin level aerospace product in the process of handling and overturning.

Manufacturability Assessment of the Product Assembly Processes Design in the Automotive Industry

The paper presents a methodology for the design of the production process of a new product from the point of view of manufacturability criterion assembly operations (Design for Assembly - DFA) in the automotive industry. Methods and techniques, used in implementation of the DFA method to produce a new product, are mentioned. Impact of those methods on improving the assembly technology of a complex product is described. Suggestions for improving the abovementioned methods are presented, as ell. The examples given illustrate the proposed procedures.

Mitigation of the Microsoft HoloLens’ hardware limitations for a controlled product assembly process

Studies have shown that using augmented reality (AR) reduces time and errors by as much as 50% for manufacturing and assembly operations. The use of head-mounted displays (HMDs) is very interesting for these situations as they free up a user’s hands. However, with the technology behind these HMDs still under development, limitations in input, field of view, tracking, and occlusion exist. For AR assembly instructions to be effective, these limitations must be mitigated so that a user receives accurate instructions. To investigate this, an application was developed that guides a user through the assembly of a mock aircraft wing using AR on a Microsoft HoloLens 1. The application displays 3D work instructions, user interfaces, and spatially registered content. To ensure accurate instructions were displayed, techniques were developed to mitigate the HoloLens’ tracking and display limitations. Image tracking was implemented to augment the HoloLens’ limited position determination, stabilize spatially registered virtual content, and account for spatial drift. Also, 3D augmented content was optimized for clarity through the display using specialized computer graphics methods. Lastly, the system provides raw data regarding head position, orientation, and assembly step times. A visualization application was developed that combines this information with wearable sensor data, to examine trends exhibited by a user during the assembly tasks and validate the delivered instructions. The outcomes of this research provided solutions to address limitations of the HoloLens for broad use.

Digital twin-based assembly data management and process traceability for complex products

Complex products such as satellites, missiles, and aircraft typically have demanding requirements for dynamic data management and process traceability. The assembly process for these complex products involves high complexity, strong dynamics, many uncertainties, and frequent rework and repair, especially in the model development stage. Achieving assembly data management and process traceability for complex products has always been a challenge. A recently proposed solution involves one-to-one mapping of the corresponding physical entity, also known as the digital twin method. This paper proposes a digital twin-based assembly data management and process traceability approach for complex products. First, the dynamic evolutionary process of complex product assembly data was analyzed from three dimensions: granularity, period and version. Then, a framework of digital twin-based assembly data management and process traceability for complex products was constructed. Some core techniques are: 1) workflow-based product assembly data organization and version management; 2) synchronous modeling of the product assembly process based on digital twin; and 3) hierarchical management and traceability of product assembly data based on digital twin. On this basis, an algorithm flowchart for generating a product assembly data package was created, which includes product assembly data management, assembly process traceability, and generation of a product assembly data package. Furthermore, the Digital Twin-based Assembly Process Management and Control System (DT-APMCS) was designed to verify the efficiency of the proposed approach. Some aerospace-related assembly enterprises are currently using DT-APMCS and achieving satisfactory results. Finally, a summary of our work is given, and the future research work is also discussed.

Impact of electrode thick spot irregularities on polymer electrolyte membrane fuel cell initial performance

Polymer electrolyte membrane fuel cells have great potential for power generation in many applications, but to implement them on a larger scale, understanding of quality requirements, tolerances, and controls during manufacturing must improve. As part of this broad challenge, irregularities resulting from the membrane electrode assembly production process must be studied to determine if they impact the performance of the cell. One potential irregularity is a locally increased thickness of the coated or deposited electrode. In order to understand and provide insight into the impact of such irregularities, we intentionally created thick spots in the center of cathode electrodes. The thick spots fabricated by two different approaches were carefully characterized by optical microscopy, X-ray fluorescence spectroscopy and scanning electron microscopy (SEM). The impact of the thick spots on the electrochemically active catalyst area and mass activity was minimal. However, specific electrode thick spot irregularities significantly impacted the mass transport properties of the cells. Based on SEM analysis, the likely cause of the performance drop is morphological changes associated with the creation of the thick spot irregularity. Spatial performance results obtained with a segmented cell system further indicated that the area of the performance impact exceeded that of the intentionally created thick spot.

Identification of critical part in ripple mill repair design using quality function deployment method

At the company found problems related to the length of the product assembly process. The assembly system can be optimized by eliminating, combining, or simplifying the way the product is assembled so that the time needed in the assembly process becomes more minimum. If this design improvement is also carried out on other products produced by Jayatech Palmindo company, it will have a significant impact on reducing assembly time and unit costs in the production process. The integration of the Quality Function Deployment, Design for Manufacture and Assembly methods is expected to provide the right solution to improve the design of the ripple mill product and other products at Jayatech Palmindo company so that assembly time can be further shortened, and minimal unit costs without changing the value from the company’s products.

Data-driven and AR assisted intelligent collaborative assembly system for large-scale complex products

With the continuous improvement of function diversity, quality and reliability, the complexity and scale of significant products such as aerospace equipment are increasing. This trend poses severe challenges to the assembly process. The large scale of products requires the fixed-position assembly with multiple roles of workers in parallel, and it increases the difficulty of multi-person assembly. The high complexity of products makes the assembly process tedious. It is time-consuming and laborious for workers to understand the 2D documents, and it easily leads to mis-operation. The assembly process of complex products can produce huge amounts of data, which have the potential for improving efficiency and quality but remain underutilized. The high reliability of products puts forward high requirements for real-time detection of the assembly process. With the development of information technology, data driven approach and Augmented Reality (AR) provide an efficient way to change the above situation. Therefore, this paper proposes an intelligent collaboration assembly system (ICAS) combining real-time data driven method with AR technology. In the ICAS, real-time data driven method is used to realize the human-to-human and human-to-machine collaboration under the fixed-position assembly, and AR is introduced to the system to assist the assembly of large-scale complex products. The intelligent detection method in the ICAS combines 3D reconstruction with sensors measurement data, and the detection result is displayed in an intuitive way by AR. The proposed system is verified in the assembly process of a large-scale space deployable mechanism, and it paves the way for the further development of intelligent assembly in the future.

Automatically generating assembly sequences with an ontology-based approach

PurposeThe purpose of this paper is to present and develop an ontology-based approach for automatic generation of assembly sequences.Design/methodology/approachIn this approach, an assembly sequence planning ontology is constructed to represent the structure and interrelationship of product geometry information and assembly process information. In the constructed ontology, certain reasoning rules are defined to describe the knowledge and experience. Based on the ontology with reasoning rules, the algorithm for automatically generating assembly sequences is designed and implemented.FindingsThe effectiveness of this approach is verified via applying it to generate the assembly sequences of a gear reducer.Originality/valueThe main contribution of the paper is presenting and developing an ontology-based approach for automatically generating assembly sequences. This approach can provide a feasible solution for the issue that mathematics-based assembly sequence generation approaches have great difficulty in explicitly representing assembly experience and knowledge.

Smart work packaging-enabled constraint-free path re-planning for tower crane in prefabricated products assembly process

Lack of constraint-free crane path planning is one of the critical concerns in the dynamic on-site assembly process of prefabrication housing production (PHP). For decades, researchers and practitioners have endeavored to improve both the efficiency and safety of crane path planning from either static environment or re-planning the path when colliding with constraints or periodically updating the path in the dynamic environment. However, there is a lack of approach related to the in-depth exploration of the nature of dynamic constraints so as to assist the crane operators in making adaptive path re-planning decisions by categorizing and prioritizing constraints. To address this issue, this study develops the smart work packaging (SWP)-enabled constraints optimization service. This service embraces the core characteristics of SWP, including adaptivity, sociability, and autonomy to achieve autonomous initial path planning, networked constraints classification, and adaptive decisions on path re-planning. This service is simulated and verified in the BIM environment, and it is found that SWP-enabled constraints optimization service can generate the constraint-free path when it is necessary.

Structure-function correlations analysis and functional semantic annotation of mechanical CAD assembly model

PurposeThree-dimensional computer-aided design (CAD) assembly model has become important resource for design reuse in enterprises, which implicates plenty of design intent, assembly intent, design experience knowledge and functional structures. To acquire quickly CAD assembly models associated with specific functions by using product function requirement information in the product conceptual design phase for model reuse, this paper aims to find an approach for structure-function correlations analysis and functional semantic annotation of mechanical CAD assembly model before functional semantic-based assembly retrieval.Design/methodology/approachAn approach for structure-function correlations analysis and functional semantic annotation of CAD assembly model is proposed. First, the product knowledge model is constructed based on ontology including design knowledge and function knowledge. Then, CAD assembly model is represented by part attributed adjacency graph and partitioned into multiple functional regions. Assembly region and flow-activity region are defined for structure-function correlations analysis of CAD assembly model. Meanwhile, the extraction process of assembly region and flow-activity region is given in detail. Furthermore, structure-function correlations analysis and functional semantic annotation are achieved by considering comprehensively assembly structure and assembled part shape structure in CAD assembly model. After that, a structure-function relation model is established based on polychromatic sets for expressing explicitly and formally relationships between functional structures, assembled parts and functional semantics.FindingsThe correlation between structure and function is analyzed effectively, and functional semantics corresponding to structures in CAD assembly model are labeled. Additionally, the relationships between functional structures, assembled parts and functional semantics can be described explicitly and formally.Practical implicationsThe approach can be used to help designers accomplish functional semantic annotation of CAD assembly models in model repository, which provides support for functional semantic-based CAD assembly retrieval in the product conceptual design phase. These assembly models can be reused for product structure design and assembly process design.Originality/valueThe paper proposes a novel approach for structure-function correlations analysis and functional semantic annotation of mechanical CAD assembly model. Functional structures in assembly model are extracted and analyzed from the point of view of assembly structure and function part structure. Furthermore, the correlation relation between structures, assembled parts and functional semantics is expressed explicitly and formally based on polychromatic sets.

Determination of rational parameters of the assembly process of one-piece products which are based on modeling

The article is devoted to the development of methods for determining the rational parameters of the assembly of one-piece products. Based on the simulation of the open-source process of cylindrical samples, mathematical models were obtained that allow accurate calculation of the assembly parameters and ensure high quality of one-piece products.

Intelligent configuring for agile joint jig based on smart composite jig model

Agile joint jig (AJJ) is a novel and promising reconfigurable assembly jig, which is put forward to deal with the disadvantages of traditional dedicated assembly jig in aerospace industry. For AJJ design, it is under the combined influence of aircraft product and assembly process requirements, especially the experience and knowledge of designers. Although case-based reasoning (CBR) gives the possibility to make fixture design more efficiently, this method has its weakness that the most similar case maybe is not the optimal selection and the designers still depend on their knowledge to determine what changes need to be made and how these changes can be achieved. In order to lower the requirement for designers’ skills and enhance the AJJ design efficiency, this paper presents an intelligent configuration method based on smart composite jig model (SCJM). Firstly, the concept and definition of SCJM are presented. It is not only a generic assembly jig architecture for a certain aircraft product family but also appends information and knowledge through MBD (model-based definition). Secondly, the requirement information model including product general information and assembly process information and so on is established with MBD for driving AJJ design automatically. Based on the above models, the intelligent configuration method for AJJ is proposed and realized by combing auto-selection reasoning with auto-assembly reasoning. The auto-selection reasoning is to achieve that the standardized components are selected actively by matching attributes between SCJM and product model. The auto-assembly reasoning is to automatically assemble the selected components in terms of the typical constraint relationships. By these ways, the SCJM can perceive the product assembly requirements by itself and then achieve appropriate design automatically. Finally, a computer-aided system for intelligent design of airplane assembly jig was developed. The results indicated that the proposed methods are able to significantly improve the design efficiency and quality of reconfigurable assembly jig.

THU-408-Screening for viral immunity prior to immunosuppressive or biologic therapy

With the continuous improvement of function diversity, quality and reliability, the complexity and scale of significant products such as aerospace equipment are increasing. This trend poses severe challenges to the assembly process. The large scale of products requires the fixed-position assembly with multiple roles of workers in parallel, and it increases the difficulty of multi-person assembly. The high complexity of products makes the assembly process tedious. It is time-consuming and laborious for workers to understand the 2D documents, and it easily leads to mis-operation. The assembly process of complex products can produce huge amounts of data, which have the potential for improving efficiency and quality but remain underutilized. The high reliability of products puts forward high requirements for real-time detection of the assembly process. With the development of information technology, data driven approach and Augmented Reality (AR) provide an efficient way to change the above situation. Therefore, this paper proposes an intelligent collaboration assembly system (ICAS) combining real-time data driven method with AR technology. In the ICAS, real-time data driven method is used to realize the human-to-human and human-to-machine collaboration under the fixed-position assembly, and AR is introduced to the system to assist the assembly of large-scale complex products. The intelligent detection method in the ICAS combines 3D reconstruction with sensors measurement data, and the detection result is displayed in an intuitive way by AR. The proposed system is verified in the assembly process of a large-scale space deployable mechanism, and it paves the way for the further development of intelligent assembly in the future.

Integrated Multi-Project Scheduling and Hierarchical Workforce Allocation in the ETO Assembly Process

The engineer-to-order (ETO) production strategy plays an important role in today’s manufacturing industry. This paper studies integrated multi-project scheduling and hierarchical workforce allocation in the assembly process of ETO products. The multi-project scheduling problem involves the scheduling of tasks of different projects under many constraints, and the workforce allocation problem involves assigning hierarchical workers to each task. These two problems are interrelated. The task duration depends on the number of hierarchical workers assigned to the task. We developed a mathematical model to represent the problem. In order to solve this issue with the minimization of the makespan as the objective, we propose a hybrid algorithm combining particle swarm optimization (PSO) and Tabu search (TS). The improved PSO is designed as the global search process and the Tabu search is introduced to improve the local searching ability. The proposed algorithm is tested on different scales of benchmark instances and a case that uses industrial data from a collaborating steam turbine company. The results show that the solution quality of the hybrid algorithm outperforms the other three algorithms proposed in the literature and the experienced project manager.

A hybrid algorithm of product-service framework for the multi-project scheduling in ETO assembly process

The engineer-to-order (ETO) production strategy plays an important role in today’s manufacturing industry. This paper studies the multi-project scheduling in assembly process of ETO products. The multi-project scheduling problem is to schedule tasks of different projects under many constraints and assign hierarchical workers to each task. We develop a mathematical model to represent the problem. In order to solve with the minimization of makespan as the objective, we propose a hybrid algorithm combining particle swarm optimization (PSO) and Tabu search (TS). The improved PSO is designed as the global search process and the Tabu search is introduced to improve the local searching ability. The proposed algorithm is tested on different scale benchmark instances and the case that uses industrial data from a collaborating steam turbine company. The results show that the solution quality of the hybrid algorithm outperforms the other three algorithms proposed in the literature and the experienced project manager.

From 3D product data to hybrid assembly workplace generation using the AutomationML exchange file format

The derivation of product features and assembly process characteristics from CAD data is typically manually performed by experienced design engineers. This paper presents an approach for systematic feature detection from CAD data with identification of a product liaison matrix and the corresponding assembly sequence. The results are stored in AutomationML exchange file format to be used in the subsequent step of automatic workplace design based on the idea of optimized resource to process allocation by heuristic search. The approach is demonstrated and validated using an application example of three different lot size scenarios.

A Design Framework for Integrating Product Architecture and Assembly Process

A Design Framework for Integrating Product Architecture and Assembly Process