Multiple platforms design and product family process planning for combined additive and subtractive manufacturing

Industry 4.0 promotes the utilization of new exponential technologies such as additive manufacturing in responding to different manufacturing challenges. Among these, the integration of additive and subtractive manufacturing technologies can play an important role and be a game changer in manufacturing products. In addition, using product platforms improves the efficiency and responsiveness of manufacturing systems and is considered an enabler of mass customization. In this paper, a model to design multiple platforms that can be customized using additive and subtractive manufacturing to manufacture a product family cost-effectively is proposed. The developed model is used to determine the optimal number of product platforms, each platform design (i.e. its features set), the assignment of each platform to various product variants, and the macro process plans for customizing the platforms while minimizing the overall product family manufacturing cost.The multiple additive/subtractive platforms and their process plans are determined by considering not only the commonality between the product variants but also their various manufacturing cost elements and the customer demand of each variant. The design of multiple product family platforms and their process plans is NP-hard problem. A genetic algorithm-based model is developed to reduce the computational complexity and find optimal or near optimal solution. Two case studies are used to illustrate the developed multiple platform model. The model results were compared with a single platform model in literature and the results demonstrate the multiple platform model superiority in manufacturing product families in lower cost. The use of the developed model enables manufacturing product families cost efficiently and allows manufacturers to manage diversity in products and market demands.     

Product platform configuration for product families: Module clustering based on product architecture and manufacturing process

Product family design utilizes platform-based modularity to enable product variety and efficient mass-production. While product platform issues have attracted much attention from both academia and industry, traditional product platform design for product families emphasized the platform-based modularity that focuses on product structure dimension (functional or non-functional) to realize cost reductions during the design stage. Both the design architecture and manufacturing process are objectives that define product family modularity (PFM). They should be closely coupled with each other for the planning and configuration of platforms. This paper focuses on the product platform configuration by recognizing and utilizing shared product modules for product families. Instead of clustering product modules only based on their design structure, this approach differentiates each product variant, and considers the inherent relationship between product architecture and processing activities. The advantage is that similar components can be grouped and produced on a shared platform, thus benefitting from lower cost and shorter production time. First, both the architecture and manufacturing information of the product variety are captured in matrix format. Then, hierarchical clustering is applied over the components to generate PFM. Finally, a set of platforms are constructed to efficiently process most components of variants.     

Feature-based assembly modeling and sequence generation

A feature-based model is proposed for assembly sequence planning automation. The fundamental assembly modeling strategy for a product is based on the mating features of its components. The objectives of this study are to integrate assembly planning of a product with its CAD model, generate a correct and practical assembly sequence and establish a software system to carry out the planning process. A disassembly approach in assembly planning is used in this study. The degree of freedom information between two mating features is used to characterize their kinematic conditions. Boolean operations of the degrees of freedom on all features of a component provides its local degree of freedom, which is used to set up the functional precedence relation. In some cases, where the functional precedence relation cannot be detected by geometric reasoning, clipping of the known `common sense' relation is applied by a user. A bounding box checking approach is used to ensure no global collision during assembly. Furthermore, a set of criteria based on assembly feasibility, manipulability, assembly direction, cost and stability is used to choose a good assembly sequence.     

Modelling and control of an assembly/disassembly mechatronics line served by mobile robot with manipulator

The aim of this paper is to reverse an assembly line using a mobile platform equipped with a manipulator. By reversibility we mean that the line is able to perform disassembly. For this purpose, an assembly/disassembly line balancing (A/DLB) and a synchronised hybrid Petri nets (SHPN) model will be used to model and control an assembly/disassembly mechatronics line (A/DML), with a fixed number of workstations, served by a wheeled mobile robot (WMR) equipped with a robotic manipulator (RM). The SHPN model is a hybrid type, where A/DML is the discrete part, and WMR with RM is the continuous part. Moreover, the model operates in synchronised mode with signals from sensors. Disassembly starts after the assembly process and after the assembled piece fails the quality test, in order to recover the parts. The WMR with RM is used only during disassembly, to transport the parts from the disassembling locations to the storage locations. Using these models and a LabView platform, a real-time control structure has been designed and implemented, allowing automated assembly and disassembly, where the latter is assisted by a mobile platform equipped with a manipulator.     

Modeling automatic assembly and disassembly operations for virtualmanufacturing

A system for evaluating products in their design phase has been developed for virtual manufacturing. It is integrated into a CAD/CAM environment to calculate the cost for assembling and disassembling parts. In our earlier work, a generic assembly and disassembly model was developed to represent operations required for product manufacturing and de-manufacturing. To be useful, the model requires a method for translating high-level instructions from product designers into low-level assembly and disassembly instructions. This paper presents a set of rules for accomplishing this task. The developed rules are used for manipulating strings representing parts and handlers in binary assembly and disassembly operations. A telephone assembly and disassembly simulation is used to illustrate the developed system     

Co-development of product and supplier platform

The platform strategy has been implemented to efficiently manage the increased variety in products and manufacturing systems domains by achieving their effective and rapid re-configuration. Despite the increased development of platforms research, their back-end issues such as the supply chain and supplier selection have received little attention. In this research, a methodology that integrates the product platform synthesis with the selection of suppliers to form a supplier platform is introduced. The formed supplier platform is a collection of suppliers capable of supplying the components/modules of the product platform. The supplier platform remains unchanged for product generations, and non-platform suppliers are added or removed as needed for producing different product variants in different production periods. The presented co-development methodology consists of three phases. First, co-platforming is used to map the product requirements to the supplier’s domain; then an intuitionistic fuzzy TOPSIS method is employed to assign weights to the suppliers according to selected criteria. The suppliers are chosen next and their platform is synthesized. A laptop product family is used to illustrate the developed methodology. The significance of this research is the synthesis of a supplier platform which can be used without change for many product variants and many product generations. Its implementation enables the planning and creation of strategic alliances with the product platform suppliers.     

A case-based reasoning approach for automating disassembly process planning

One of the first processes for preparing a product for reuse, remanufacture or recycle is disassembly. Disassembly is the process of systematic removal of desirable constituents from the original assembly so that there is no impairment to any useful component. As the number of components in a product increases, the time required for disassembly, as well as the complexity of planning for disassembly rises. Thus, it is important to have the capability to generate disassembly process plans quickly in order to prevent interruptions in processing especially when multiple products are involved. Case-based reasoning (CBR) approach can provide such a capability. CBR allows a process planner to rapidly retrieve, reuse, revise, and retain solutions to past disassembly problems. Once a planning problem has been solved and stored in the case memory, a planner can retrieve and reuse the product's disassembly process plan at any time. The planner can also adapt an original plan for a new product, which does not have an existing plan in case memory. Following adaptation and application, a successful plan is retained in the case memory for future use. This paper presents the procedures to initialize a case memory for different product platforms, and to operate a CBR system, which can be used to plan disassembly processes. The procedures are illustrated using examples.     

基于DELMIA的发动机装配过程可视化仿真

为实现发动机的虚拟装配,用反装思路,通过DELMIA创建某汽油机拆卸路径来仿真装配过程.将产品开发过程中的产品设计和工艺设计2大重要环节在统一的软件平台上进行并行设计;在三维设计条件下,能利用DELMIA的数字化制造工艺（Digital Process of Manufacturing,DPM）与DELMIA工艺工程师（DELMIA Process Engineer,DPE）的数据交换提前安排制造计划.该方法可以实现生产、工艺与制造资源的虚拟协同设计,缩短设计周期,降低设计成本.     

Structure representation for concurrent analysis of product assembly and disassembly

This paper presents a simple and novel structure representation supporting the assembly and disassembly planning of electromechanical products. The proposed Relationship Matrix derived from a directed graph represents both the information of the component connectivity and the layout precedence of functional elements. The feasible assembly and disassembly sequences and the minimum service steps for the malfunction component can be easily derived with the corresponding inference rules. The structure representation and the inference kernel can be readily applied to future concurrent design review for assemblability, serviceability, and recyclability. A prototype software tool is introduced to demonstrate the application of the proposed scheme.     

Structure representation for concurrent analysis of product assembly and disassembly

This paper presents a simple and novel structure representation supporting the assembly and disassembly planning of electromechanical products. The proposed Relationship Matrix derived from a directed graph represents both the information of the component connectivity and the layout precedence of functional elements. The feasible assembly and disassembly sequences and the minimum service steps for the malfunction component can be easily derived with the corresponding inference rules. The structure representation and the inference kernel can be readily applied to future concurrent design review for assemblability, serviceability, and recyclability. A prototype software tool is introduced to demonstrate the application of the proposed scheme.     

Dynamic material flow control in mixed model assembly lines

This study investigates the control of material flow in mixed model assembly lines. It focuses on the use of tugger trains to feed stations in assembly lines by materials and parts from a warehouse or a supermarket. The movement of tugger trains is based on the principle of in-plant milk run. The study considers a strategy to deal with disturbances such as machine breakdown, line stoppage, defective parts, and resequencing of product models. These disturbances lead to unexpected fluctuations in stations demand for parts. The strategy is applied using a mix between the demand-oriented and e-kanban systems to facilitate the planning of three problems, namely, train routing, scheduling, and loading. The information obtained using e-kanban is combined with the information about the expected stations demand based on previously known sequence of product models and the materials needed for each model. Routing was investigated analytically while scheduling and loading problems were investigated using integer programming. Results showed that the method proposed outperforms the traditional methods of material flow planning.     

Dynamic analysis of an automobile assembly line considering starving and blocking

Dynamic analysis considering starving and blocking of machines in networks of closed loops has a great importance in most automobile assembly lines. In this work, an actual automobile assembly line is modelled as a network of closed loops of machines and intermediate buffers formed by conveyors. As a consequence of it, machines can work in both, stationary or transitory regimes. The influence of the working regimes of the machines or the proportion of four-door cars between the doors’ disassembly and assembly stations on the starving and blocking transmission from the main assembly line has been analyzed. These factors have not been considered yet by the existing literature and they have a great significance in the performance of this kind of manufacturing systems.     

Nested partitions method for assembly sequences merging

The severe competition in the market has driven enterprises to produce a wider variety of products to meet consumer’s need. However, frequent variation of product specification and more complexity of product cause the assembly sequence planning of product become more and more complicated. As a result, the issue of assembly sequence planning of complex product becomes a problem which is worthy of concern. In this study, a methodology for assembly sequence planning of complex components is presented, which consists of three phases: assembly-based modular design, assembly subsequences generation for each module and assembly sequences merging. Nested partitions (NP) method is used to merge assembly subsequences. Assembly sequences merging can make full use of subsequences information of modules and simplify assembly sequence planning of the complex products. A desk lamp is used as an example for implementation to validate the feasibility of this research.     

Intelligent decision making in disassembly process based on fuzzy reasoning Petri nets

Practical disassembly process planning is extremely important for efficient material recycling and components reuse. The research work for the process planning in literature focuses on the generation of optimal sequences based on the predictive information of products. The used products, unfortunately, exhibit high uncertainty since products may experience very different conditions during their use stage. The indeterminate characteristics associated to used products often makes the predetermined plan unrealistic. Their disassembly process has to be decided dynamically adaptive to the products' specific status. To be able to deal with uncertainty in a dynamic decision making process, this paper presents a fuzzy reasoning Petri net (FRPN) model to represent related decision making rules in disassembly process. Using the proposed fuzzy reasoning algorithm based on the FRPN model, the multicriterion disassembly rules can be considered in the parallel way to make the decision automatically and quickly. Instead of producing the disassembly sequences before disassembling a whole product, the proposed method makes intelligent decisions based on dynamically updated status of components in the product at each disassembly step. Therefore, it is adaptive to the changes that arise during the process. Finally, an example is used to illustrate the application of the proposed methodology.     

Extension of the target cascading formulation to the design of product families

The target cascading methodology for optimal product development is extended to product families with predefined platforms. The single-product formulation is modified to accommodate the presence of shared systems, subsystems, and/or components and locally introduced targets. Hierarchical optimization problems associated with each product variant are combined to formulate the product family multicriteria design problem, and common subproblems are identified based on the shared elements (i.e. the platform). The solution of the overall design problem is coordinated so that the shared elements are consistent with the performance and behaviour of the product variants. A simple automotive design example is used to demonstrate the proposed methodology.     

Utilizing variant differentiation to mitigate manufacturing complexity in mixed-model assembly systems

A measure of product variety induced complexity has been proposed for mixed-model assembly systems with serial, parallel and hybrid configurations. The complexity model was built based on the assumption of identical parallel stations, i.e., same product variants are produced at all parallel stations in the same volume and with the same mix ratio. In this paper, the existing complexity model is extended to general mixed-model assembly systems with non-identical parallel stations in the presence of product variety. Then it is discussed that how to reduce the system complexity using the variant differentiation, based on which a mathematical formulation is developed to minimize the complexity of a mixed-model assembly system. The formulated problem is a non-linear programming problem and then solved by genetic algorithm. Last the developed complexity mitigation model is applied to the configuration selection of assembly systems, i.e., to identify the system configuration with the minimum complexity.     

Designing an assembly line for modular products

To respond to the challenge of agile manufacturing, companies are striving to provide a large variety of products at low cost. Product modularity has become an important issue. It allows to produce different products through combination of standard components. One of the characteristics of modular products is that they share the same assembly structure for many assembly operations. The special structure of modular products provides challenges and opportunities for operational design of assembly lines. In this paper, an approach for design of assembly lines for modular products is proposed. This approach divides the assembly line into two subassembly lines: a subassembly line for basic assembly operations and a subassembly line for variant assembly operations. The design of the subassembly line for basic operations can be viewed as a single product assembly line balancing problem and be solved by existing line balancing methods. The subassembly line for the variant operations is designed as a two-station flowshop line and is balanced by a two-machine flowshop scheduling method. A three-station flowshop line for a special structure of modular products is proposed and illustrated with an example.     

A heuristic approach for U-shaped assembly line balancing to improve labor productivity

The assembly line balancing problem is a non deterministic polynomial type planning problem for mass production. Layout design changes constitute a major decision that yields investment for assembly operations and numerous heuristics have been reported in the literature for solving the line balancing problems. U-shaped assembly layout offers several benefits over traditional straight-line layout in implementation of lean manufacturing and Just-In-Time technology. In the paper an attempt has been made to evaluate labor productivity in U-shaped line system and straight line system. A Critical Path Method (CPM) based approach for U-shaped assembly line has been applied for assigning the task to the work stations for assembly line layout. Results show that the CPM based U-shaped approach performs better and improve the labor productivity of assembly line layout.     

Mechanical assembly planning using ant colony optimization

In mechanical assembly planning research, many intelligent methods have already been reported over the past two decades. However, those methods mainly focus on the optimal assembly solution search while another important problem, the generation of solution space, has received little attention. This paper proposes a new methodology for the assembly planning problem. On the basis of a disassembly information model which has been developed to represent all theoretical assembly/disassembly sequences, two decoupled problems, generating the solution space and searching for the best result, are integrated into one computation framework. In this framework, using an ant colony optimization algorithm, the solution space of disassembly plans can be generated synchronously during the search process for best solutions. Finally, the new method’s validity is verified by a case study.