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In the process of selective assembly for precision and complex mechanical products, it is necessary to perform the selective material kitting one by one and conduct check repeatedly according to the optimal matching result to ensure quality. The traditional manual picking and checking method by Bill of Material is inefficient and laborious. Currently, there is still no consensus reached on how to better transmit information and implement the material kitting in the course of selective assembly. In this paper, we pioneer in testing the performance between mainstream methods (Pick-by-Voice, Pick-by-Light, Pick-by-AR) and traditional methods (Pick-by-Paper) in terms of task time, errors, workload, and information perception for the selective material kitting. We developed an AR (augmented reality) on the level of material individual information level and verified its applicability. Meanwhile, we enhanced the effect of material individual information expression from different visual perspectives. We found that Pick-by-AR can outperform others in terms of selective assembly, which means expanding the dimension of information expression and enhancing users' perception of information can help users quickly and accurately select parts with the same appearance but different quality characteristics fast and accurately, thus providing a viable option for material kitting in the selective assembly process. [ABSTRACT FROM AUTHOR]

Non-productive auxiliary processes affect the single part and small badge production of milling tools. The key production process grinding is inevitably linked to the auxiliary conditioning process. The time demand of those process steps decreases the overall productivity of the manufacturing process. However, today the machine operator decides on conditioning cycles individually by the use of experience. Until today, there is no objective data based approach available that supports the initiation of these conditioning processes or the adaption of the grinding process itself in order to improve its process efficiency. For this purpose, a process-related topography evaluation method of the grinding wheel surface is developed within this study. For the measurement, an optical method based on laser triangulation is used. The measurement system is implemented into a common tool grinding machine tool. In addition, characteristic topography values are defined that show the wear conditions of the grinding tool. Moreover, the data is summarized in a database of wear conditions. The developed measurement method can save grinding and dressing tool resources, process times and minimizes scrap parts. In addition, an adaptation of the process and a targeted launch of auxiliary processes can be enabled. The novel characteristic-based topography measurement creates the opportunity to enhance the tool life of the grinding wheels up to 30% without losing productivity. [ABSTRACT FROM AUTHOR]

Surface finish quality is becoming even more critical in modern manufacturing industry. In machining processes, surface roughness is directly linked to the cutting tool condition; a worn tool generally produces low-quality surfaces, incurring additional costs in material and time. Therefore, tool wear monitoring is critical for a cost-effective production line. In this paper, the feasibility of a vibration-based approach for tool wear monitoring has been checked for turning process. AISI 1045 unalloyed carbon steel has been machined with TNMG carbide insert twenty-one times for a total of 27 min of machining, which was a necessary amount of time to exceed (300 μm) as a flank wear threshold. Vibration signals have been acquired during the operation and then processed in order to extract a correlation between the surface roughness, tool wear level, and vibration comportment. First, spectral kurtosis has been calculated for the twenty-one performed runs signals; this step has allowed the locating of the optimal frequency band that contains the machining vibration signature, yet it did not give significant information about wear evolution. The signals have then been decomposed with ICEEMDAN and the energy of the high-frequency modes has been calculated. It has been found that the energy of the optimal frequency ICEEMDAN modes has increased in proportion to the increase of surface roughness degradation and thus, to tool wear increase. Therefore, IMF's energy can be used for tool wear condition monitoring. [ABSTRACT FROM AUTHOR]

In additive manufacturing (AM), it is necessary to know the influence of processing parameters in order to have better control over the microstructure and mechanical performance of the part. Laser powder bed fusion (LPBF) AM is beneficial for many reasons; however, it is limited by the thermal solidification conditions achievable in the available processing parameter ranges for single-beam processing methods. Therefore, this work investigates the effect of multiple, coordinated heat sources, which are used to strategically modify the melting and solidifying in the AM process. To model this, existing thermal models of the LPBF process have been modified to include the effects of multiple, coordinated laser beams. These computational models are used to calculate melt pool dimensions and thermal conditions (thermal gradient and cooling rate). Furthermore, the results of the simulations are used to determine the influence of the distance between the coordinated laser beams in different configurations. The multi-beam scanning strategies modeled in the present study are shown to alter both melt pool shape and size, and the thermal conditions at the onset of solidification. However, these variations are not shown to result in alterations in the grain morphology of Ti-6Al-4V components. This predictive method used in this research provides insight into the effects of using multiple coordinated beams in LPBF, which is a necessary step in increasing the capabilities of the AM process. [ABSTRACT FROM AUTHOR]

Resonant vibration generators, such as vibratory feeders or ultrasonic sonotrodes, are often employed in manufacturing to generate harmonic vibrations with suitable amplitude, spatial shape, and frequency, in order to meet the process requirements. These underactuated systems are usually excited in open loop by few actuators, and therefore, it is not ensured that the desired response is correctly achieved, since the feasible motions should belong to the subset of the allowable motions. To achieve the closest approximation of the desired vibrations, some new solutions are here proposed. The first strategy is the optimal shaping of the harmonic forces exerted by the actuators, by solving an inverse dynamic problem through a coordinate transformation and the projection of the desired response onto the subspace of the allowable motion. By exploiting the formulation of such a subspace, a second approach that involves concurrently both the force shaping and the modification of the inertial and elastic system parameters is proposed. The idea of this approach is to exploit the modification of the elastic and inertial parameters to properly shape the allowable subspace in such a way that it spans the desired response. A solution method is developed, and analytical sensitivity analysis is proposed to choose the design variables. Validation is proposed through a linear vibratory feeder with a long flexible tray, taken from the literature. The results show the effectiveness of the proposed strategies that lead to a very precise approximation of the desired response. [ABSTRACT FROM AUTHOR]

In manual order picking systems, a paper list specifying the name, location, and amount of each item is often given, and this would exert mental pressure on pickers while finding target shelf bins in high-density picking environments. Augmented reality (AR) can provide a friendly alternative to improve the manual order picking performance by conveying picking information into visual instruction. Nevertheless, there is still no systematic consensus to deploy the pick-by-AR associated with actual warehouse workplaces. To establish a spatial correspondence between the visual guidance with the actual workplace, the multi-marker-based global map about the warehouse floor is established in advance. Instead of traditional single marker-based pick-by-AR methods, the warehouse floor-related map can provide an accurate and continuous navigation performance for intuitive AR guidance, allowing the picker to move freely on the warehouse floor without limiting to some certain locations. Besides, a systematic pick-by-AR solution is available by integrating the proposed method to a lightweight wearable AR device, and this easy-to-deploy pick-by-AR solution can alleviate the worker's mental effort while doing picking action. Finally, the pick-by-AR system described in the paper is deployed in the automobile assembly line, and experimental results illustrate that the proposed method can improve the picking efficiency while reducing the picking errors compared with the current paper-based order picking. [ABSTRACT FROM AUTHOR]

Micromilling allows for the high precision machining of different types of materials and thus promotes the manufacturing of micro-components for various technological applications. Evaluating tool wear in micromilling poses challenges not yet fully researched, more specifically the widely known size effect of micromilling processes contributes to an intricate cause-and-effect mechanism, and its research requires an understanding of the relationship of machining parameters in order to improve the process control. Thus, this paper researches the relationship between flank wear, feed, and specific cutting forces and roughness for the tool steel H13. Experiments with different levels of feed per tooth and spindle speed were carried out to measure and analyze tool flank wear, cutting forces, and the roughness of the workpiece. The lowest roughness value (Rz < 200 nm) was obtained for the feed per tooth of 2 μm at the beginning of the cut. However, this parameter also presented the highest flank wear, which led to the highest roughness value (Rz = 423 nm) at the final cutting length. Moreover, the interaction between the parameters feed per tooth and spindle speed occurs only at the maximum feed per tooth level. Increasing the feed per tooth to 5 μm and the spindle speed to 46,000 rpm significantly reduces flank wear. This behavior shows that not only increased feed rate but also increased spindle speed provided a combined reduction in plowing and improved shear mechanism. [ABSTRACT FROM AUTHOR]

In order to reveal the process principle of three-roller setting round process and optimize the setting round strategy, the three-roller setting round process is simulated and experimented. The results show that there are three positive bending regions and three reverse bending regions in the cross section of pipe in the setting round process. The absolute value of equivalent stress and equivalent strain not only decreases from both ends to the geometric neutral layer along the thickness direction of pipe but also decreases from the center of each positive and negative bending region to both sides along the circumferential direction of pipe. The distribution of maximum stress and minimum stress conforms to the characteristics of pure bending deformation in the setting round process. The direction of tangential stress is the direction of main stress, and the direction of tangential strain is the direction of main strain. The geometrical dimensions of pipe do not change in axial and radial directions. The residual ovality of pipes with different initial ovality is basically the same, which proves that the uniform curvature theorem of reciprocating bending is correct. The residual ovality of pipes decreases with the increase of the reduction. With the increase of the relative thickness of pipes, the optimum reduction of pipes decreases gradually. Comparing experimental results with simulation results, the residual ovality of pipes can be less than 0.2%. [ABSTRACT FROM AUTHOR]

The logistics market has been impacted by increase of e-commerce, mass customization, omni-channel distribution, and just-in-time philosophy. In order to attend to this dynamic change, automation has been applied in warehouses. Although, some researches point out the lack of flexibility as a bottleneck. Therefore, a comprehensive literature review of recent papers is vital to draw a framework of the past and to shed light on future directions. This paper aims to review published papers in the last ten years related to flexible automation in warehouses and to construct a framework that could guide future researchers in the construction of an innovative conceptual model that may be applied at warehouses in the future. A total of 113 papers published between January 2008 and December 2018 have been selected, reviewed, and categorized to construct a useful foundation of past research. Results showed the key point to achieve a flexible automated warehouse is the combination of automated equipment, data collection technologies, and management solutions. Finally, based on the reviewed papers, an innovative framework of a flexible automated warehouse is proposed. [ABSTRACT FROM AUTHOR]

On-machine inspection (OMI) systems have been widely used for the automatic setting of workpieces and the determination of the kinematic errors of a machine tool. Touch-trigger probes are commonly used in OMI systems due to their high reliability and low cost. However, the associated pre-travel error, which is inherent by nature, often severely affects the measurement accuracy and must be compensated during the measuring process in order to ensure the required measurement precision. This paper proposes a compensation method for probe errors using a 3D error map. To construct the 3D error map of the probe, a weighted least squares (WLS) method based on the probe's mechanical model was first employed to accurately fit the reference sphere center; subsequently, the errors of the calibrated directions could be obtained. Finally, the bicubic Coons patch (BCP) interpolation method was used to calculate the errors of the uncalibrated directions. To validate the proposed method, calibration tests were conducted on an OMI system mounted with a strain gauge probe. The compensation results indicated an increase of 57.40% in the accuracy compared to that of the existing method. [ABSTRACT FROM AUTHOR]

This paper describes an Augmented Reality system for the improvement of the manufacturing process in the packaging sector. It presents a successful use case of how to integrate the Augmented Reality technology in a factory shop floor by providing a tool that helps operators in their daily work. Given a product reference, the proposed system digitizes the setting of the die cutter automatically from an image and stores it in a database to subsequently consult and analyze. Furthermore, the content display is not carried out as a conventional Augmented Reality system (wearable devices such as glasses or mobile), but projecting directly on the workspace to facilitate its interpretation. Compared to the current workflow, where the data is recorded on sheets of paper and stored physically in warehouses, the proposed system offers several advantages such as preventing data loss, reducing costs, or the possibility of increasing knowledge from the post-processing of digitized data. [ABSTRACT FROM AUTHOR]

The aim of this paper is to introduce a practice-ready systematic methodology for the management of storage assignments and allocation decisions as well as an assessment of the resulting performance in an order picking system (OPS). Built on extant and well-known metrics of performance this method implements a double cross-analysis through an original visual tool that is easy to understand by warehousing managers and practitioners. This tool is organized in two main steps. The first step is a cross-analysis that combines multiple performance indicators to help the decision-maker understand whether an OPS provides the scope for performance improvement. A comparison with potential storage configurations is then conducted in the second step through a tailored multi-scenario cross-analysis, which attempts to identify the best combination of allocation and assignment policies capable of minimizing the overall traveling performance. The proposed methodology is applied to a significant real-world OPS. The selected case study represents a reference framework for decision-makers and practitioners. [ABSTRACT FROM AUTHOR]

This paper considers the layout design problem of a single block order-picking rack-based warehouse that employs turnover-based storage assignment in both vertical and horizontal dimensions. An analytical expression for vertical travel distance is derived which is incorporated in the pick distance model. The effect of inventory staggering on storage space requirement is considered in arriving at warehouse dimensions. A model that incorporates area cost along with handling cost in optimizing warehouse design is developed and a solution algorithm is presented. The analytical model for vertical travel and the optimization model are applied to data from a real life case. It was found that the model would offer considerable operational cost savings, especially when space costs are high. Computational experiments show that the effect of inventory staggering is quite significant in the estimated storage space. Experiments also demonstrated the importance of segregating products based on turnover in the vertical dimension. [ABSTRACT FROM AUTHOR]

Even small improvements in storage operations can bring significant benefits in customer response time, increasing the level of service offered. However, a company cannot offer high level of service for all products. In this sense, one of the ways used to optimize the activities for order picking is the study of storage location assignment problem (SLAP). Thus, this paper proposed a multi-criteria decision model to perform the products classification and to solve the SLAP in a multi-layer warehouse. The ELECTRE TRI method is used to define the shelf level for each product, and the ELECTRE III method is used to establish a fixed location for each product on the shelf it belongs to. The great advantage of this model is that there is not trade-off among the criteria, and it is able to consider several criteria simultaneously. However, the main goal is not optimization, but the search for a storage operations performance balance, considering multiple criteria, allowing for a better inventory management when considering profitability criteria, for example, and improvement in the order picking operations, through the demand and space required criteria. In addition, it considers the preferences of the decision maker. [ABSTRACT FROM AUTHOR]

The warehouse operation planning in the scholar and office supplies industry encompasses the activities of receiving, storing, order picking, and shipping products. The order picking operation is a laborious and capital intensive procedure. Despite the extensive literature to solve practical problems of warehouse routing as a step of the order picking process, the application of general approaches to deal with the routing of the warehouse pickers is not straightforward given the specific conditions and configurations and the singular design and operational policies commonly found in practice. In this paper, we present an optimization approach to the stacker routing problem found in the order picking of a Brazilian scholar and office supplies company. The approach is based on a routing algorithm that solves different integer linear problems to define the optimal routes of the stacker inside the facility. The solutions of several numerical experiments show the potential and effectiveness of the approach, for instance, that only one fifth of the routes actually performed by the company are optimal and that the algorithm application to a real set of batches reduced by more than one fourth the total distance monthly traveled by the stacker. [ABSTRACT FROM AUTHOR]

This paper addresses an order picking problem in a multi-aisle automated warehouse, in which a single storage/retrieval (S/R) machine performs storage and retrieval operations. When retrieval requests consist of multiple items and the items are in multiple stock locations, the S/R machine must travel to several storage locations to complete a customer order. The objective is to minimize the total time traveled by the S/R machine to complete the retrieval process of customer orders at the shortest time. First, we formulate the problem as a nonlinear programming model. Then, we propose a heuristic to solve the problem. Finally, we provide numerical experiments to evaluate the performance of the proposed heuristic. The results show that as the number of items in customer order increases, the heuristic shows a better performance by obtaining solutions close to optimal but in very small amount of times. [ABSTRACT FROM AUTHOR]

The objective of this study is to design a correlated storage assignment system by storing items with demand dependences together to minimize zone visits when picking materials/parts in production line. The demand dependences can be obtained from the products' bill of materials (BOMs) and production rates. Due to the large number of materials in a BOM, picking capacity constraint is explicitly considered. A mathematical model is formulated and heuristic algorithms are proposed, including two direct heuristics and two hybrid genetic algorithms with different crossover mechanisms. Numerical experimentation shows that the hybrid genetic algorithm with 2-point crossover outperforms others and can be practical in warehouse design. [ABSTRACT FROM AUTHOR]

The objective of this study is to design storage assignment and order picking system using a developed mathematical model and stochastic evolutionary optimization approach in the automotive industry. It is performed in two stages. At the first stage, storage location assignment problem is solved with a class-based storage policy with the aim of minimizing warehouse transmissions by using integer programming. At the second stage, batching and routing problems are considered together to minimize travel cost in warehouse operations. A warehouse in the automotive industry is analyzed, and an optimum solution is obtained from an integer programming model. Due to the computational time required for solving the integer programming problem, a faster genetic algorithm is also developed to form optimal batches and optimal routes for the order picker. The main advantage of the algorithm is the quick response to production orders in real-time applications. The solutions showed that the proposed approach based on genetic algorithms can be applied and integrated to any kind of warehouse layout in automotive industry. [ABSTRACT FROM AUTHOR]

In today's competitive scenario of increasingly faster deliveries and smaller order sizes, a solution that is being used more frequently is the pick-and-pass Order Picking System (OPS). The purpose of this study is to define a framework for the pick-and-pass system design, by expanding previous literature on this topic. The framework aims at minimising the overall picking costs while respecting the required service level (i.e. order throughput time), and can be easily applied to the selection stage of OPS design. The number of zones and the number of pickers per zone are among the main project data for the framework application. Analytical models are used to estimate the travel distance, and network queuing theory to analyse the mean order throughput. On the basis of the proposed framework, pick-and-pass system performance is examined as a function of two typical design conditions: order size and number of items. [ABSTRACT FROM AUTHOR]

Numerous design and cost parameters, combined with an endless variety of equipment types, make it difficult to choose the right order picking system (OPS). The purpose of this study is to develop a methodology to support warehouse designers in choosing the most suitable OPS. By developing a new OPS classification, we carried out an in-depth survey on over 68 distribution centres that have been recently built in Italy. The results of the critical analysis allowed developing a design methodology to choose the most suitable OPS. This methodology has been integrated in the structured procedure for OPS design, developed by Yoon and Sharp ( IIE Trans 28:379–389, ). Finally, a numerical case study is presented to illustrate the application of the proposed design methodology. [ABSTRACT FROM AUTHOR]

In recent years the increase in time-based competition and the growth of e-commerce have put pressure on managers to reduce the costs of warehouse design and management activities. This paper presents a new integrated approach to support the decision making process in optimising a picker to part, forward-reserve, less than unit load order picking system. An analytical model and a multi-parametric dynamic model to quickly estimate the travelled distance during a picking cycle are introduced. The factorial analysis of several what-if scenarios reveals which factors and combinations of factors are the most critical in affecting the picking system’s response. [ABSTRACT FROM AUTHOR]

From literature review and deep understanding on the practical industry, it is understood that the proper use of storage assignment policies can use minimum storage space to reach the purpose of minimum total traveling distance, and this has a direct impact on enhancing the order picking performance. At the same time, proper routing planning can minimize overall order picking cost, and finally reach the goal of picking performance enhancement in unit time. Therefore, this paper considers the effects on the order picking system performance for factors such as quantity and layout type of cross aisles in a warehouse system, storage assignment policy, picking route, average picking density inside an aisle, and order combination type, etc. A software, eM-plant, will be used as a simulation and analysis tool, a warehouse design database will be developed, which is based on the minimum overall traveling distance as the optimum performance index, the cross aisle quantity, warehouse layout, storage assignment, picking route planning, picking density and order combination type will be optimally integrated and planned in the warehouse system. Finally, we provide this database to the industry as a reference in the warehouse planning or warehouse design improvement in the future . [ABSTRACT FROM AUTHOR]