Modeling of the Thermomechanical Process Effects on Machine Tool Structures

AbstractThermally induced deviations are a key issue in the development of machine tools, especially when considering the actual trends of high performance and dry cutting. The interactions between the cutting process and the machine tool structure are significant boundary conditions for the numerical prediction of the thermomechanical machine behavior. Within this paper an approach for the holistic modeling of process effects is presented, including process heat, cutting forces and increased load on feed and main drives. The modeling approach is supported by experimental investigations on a lathe to provide empiric data for the link between cutting forces and active drive power

A Concept For Data-Driven Decision-Making During The Production Ramp-Up To Increase Resilience In Value Networks

Manufacturing companies are challenged by an increased number of production ramp-ups in shorter intervals due to shorter product life cycles and dynamically changing customer demands. The complexity of new products and the corresponding production systems, particularly in the value network, adds to this challenge. This complexity leads to an increased number of disruptions during the production ramp-up, to which manufacturing companies must be able to adapt flexibly. Although methodological support is available, there is a lack of data-driven approaches for adapting and reacting to potential disruptions during the production ramp-up in the value network. Therefore, this article presents a concept for a data-driven approach in value networks during production ramp-ups to flexibly adapt to disruptions. First, a method for describing and categorizing disruptions and corresponding mitigation decisions is developed based on the ISO/IEC 20000 1. Second, an application method for a generic simulation model is created to generate synthetic disruption production ramp-up data for a given value network configuration and corresponding disruptions. Third and parallel, a method for assessing a manufacturing company's resilience in the value network during the production ramp-up is developed. In the final step, the synthetic data is used to train a data-driven model. This model selects appropriate mitigation decisions for disruptions based on data and can evaluate the impact of disruptions and mitigation decisions on key performance indicators specific to production ramp-up. The possible increase in company-specific resilience is assessed using the developed assessment method

Manufacturing Change Management - A Case Study-Based Analysis Of Change Processes In Industrial Practice

In the constantly changing landscape of modern manufacturing, companies face numerous challenges that require a continuous adaptation of their factories. As a result, the number and variety of Manufacturing Changes (MCs) are increasing, making proficient Manufacturing Change Management (MCM) critical to the long-term competitiveness of manufacturing companies. In particular, the change process, i.e. the sequence of steps for dealing with MCs, is important, as its effectiveness and efficiency are essential to a functioning MCM system. Several broad-based surveys have provided initial insights into the application of MCM in practice, but no studies examine MCM processes in detail. This contribution presents an in-depth analysis of MCM processes in an industrial context through a case study involving three manufacturing companies from various industries. The study provides clarity on the organizational relevance of MCM and the differences between processes and data management in different companies in industrial practice. This contribution thus develops the basis for further research activities in the field of MCM

A Concept For The Development Of A Maturity Model For The Holistic Assessment Of Lean, Digital, and Sustainable Production Systems

Manufacturing companies today face a volatile environment with a variety of challenges. Particularly, external factors such as the climate change, the digitalization, the material scarcity, or the shortage of skilled workers can be noted. At the same time, these factors are forcing companies to take measures to remain competitive and ensure their production system's future viability. In this context, established paradigms such as Lean Production and Industry 4.0 promise optimization potentials in terms of efficiency, quality, and costs. A new paradigm has gained importance with the emergence of the topic of sustainability, which aims to improve companies' use of resources and the recyclability of their products. However, there is no transparent model that enables companies to assess the status quo of their production system regarding these three paradigms, considering the interdependencies between the paradigms, and at the same time showing the implementation potential of methods or technologies within these paradigms. To support companies in rationalizing, digitalizing, and making their production processes more sustainable, this scientific paper presents a three-stage concept for a holistic maturity model. By providing transparency about the status quo of production systems in terms of Lean Production, digitalization, and sustainability, the model contributes to ensuring the future viability of such production systems in this highly competitive environment and under the political, social, and regulatory challenges

Towards Additively Manufactured Metamaterials with Powder Inclusions for Controllable Dissipation: The Critical Influence of Packing Density

Particle dampers represent a simple yet effective means to reduce unwanted oscillations when attached to structural components. Powder bed fusion additive manufacturing of metals allows to integrate particle inclusions of arbitrary shape, size and spatial distribution directly into bulk material, giving rise to novel metamaterials with controllable dissipation without the need for additional external damping devices. At present, however, it is not well understood how the degree of dissipation is influenced by the properties of the enclosed powder packing. In the present work, a two-way coupled discrete element - finite element model is proposed allowing for the first time to consistently describe the interaction between oscillating deformable structures and enclosed powder packings. As fundamental test case, the free oscillations of a hollow cantilever beam filled with various powder packings differing in packing density, particle size, and surface properties are considered to systematically study these factors of influence. Critically, it is found that the damping characteristics strongly depend on the packing density of the enclosed powder and that an optimal packing density exists at which the dissipation is maximized. Moreover, it is found that the influence of (absolute) particle size on dissipation is rather small. First-order analytical models for different deformation modes of such powder cavities are derived to shed light on this observation

Methodology to Determine Melt Pool Anomalies in Powder Bed Fusion of Metals Using a Laser Beam by Means of Process Monitoring and Sensor Data Fusion

Additive manufacturing, in particular the powder bed fusion of metals using a laser beam, has a wide range of possible technical applications. Especially for safety-critical applications, a quality assurance of the components is indispensable. However, time-consuming and costly quality assurance measures, such as computer tomography, represent a barrier for further industrial spreading. For this reason, alternative methods for process anomaly detection using process monitoring systems have been developed. However, the defect detection quality of current methods is limited, as single monitoring systems only detect specific process anomalies. Therefore, a new methodology to evaluate the data of multiple monitoring systems is derived using sensor data fusion. Focus was placed on the causes and the appearance of defects in different monitoring systems (photodiodes, on- and off-axis high-speed cameras, and thermography). Based on this, indicators representing characteristics of the process were developed to reduce the data. Finally, deterministic models for the data fusion within a monitoring system and between the monitoring systems were developed. The result was a defect detection of up to 92% of the melt track defects. The methodology was thus able to determine process anomalies and to evaluate the suitability of a specific process monitoring system for the defect detection

Development of Microstructure and Mechanical Properties of TiAl6V4 Processed by Wire and Arc Additive Manufacturing

Wire and arc additive manufacturing (WAAM) has the potential to significantly reduce material waste due to the milling of components made of TiAl6V4 (Ti‐64). To keep up with the market development, this resource‐efficient technology is becoming increasingly important to achieve climate policy goals. Therefore, this study not only focuses on the influence of different process parameters, such as torch and wire feed speed, but also different gas mixtures on the microstructure and related mechanical properties, as well as on the scalability by investigating single‐ to multilayer welded structures. The wire feed speed is found to have a major influence on the geometry and mechanical properties. The use of different process gases, i.e., argon (Ar), helium (He), and a mixture of 70% He and 30% Ar neither significantly affect the microstructure nor the mechanical properties. It is also found that a solution heat treatment followed by an annealing step degrades mechanical properties, while an ordinary stress‐relief heat treatment leads to improved mechanical properties. It is shown that by adapting WAAM process and heat treatment parameters, mechanical properties of additively produced specimens can be achieved, which are fully comparable to milled components

Influence of process temperature on hardness of friction stir welded high strength aluminum alloys for aerospace applications

AbstractThe increasing application of innovative materials, such as high strength aluminum alloys, is challenging the manufacturing processes of the Aerospace and Aeronautics Industries. Despite this challenge the processes need to comply with high requirements regarding the reproducibility and the quality of the products. For this reason the adaption of conventional welding technologies to the new materials is considered to be difficult. Therefore, innovative welding technologies such as Friction Stir Welding (FSW) have been developed [1].This paper deals with the implementation of FSW into a new production process for lightweight dome structures of fuel tanks: Starting at temper condition O two AA 2219 plates are joined using FSW technology to form a larger blank. After that, the blanks are formed to shape using spinforming technology. The manufacturing process is accompanied by several steps of heat treatment to accomplish a finished tank-dome in temper condition T8.The studies presented in this paper aimed on finding a correlation between the process parameters and the properties of the welding seam, which are essential for the following spinforming process. For this purpose the experiments were conducted using design of experiments (DoE). The resulting hardness increase of the welding seam was chosen as target variable. Based on the acquired data a regression model was established and used to estimate optimal parameters for dome production

FINITE ELEMENT FORMULATION OF PRE-STRESSED BALL SCREW DRIVES

Keywords: Ball screw drive, finite element method, machine tool, mechatronic system. INTRODUCTION In the field of CNC drive technology for machine tools rotatory servo drive systems with ball screw transmission remain the predominantly used solution for generating linear feed motions, despite the increasing application of linear direct drives. Reasons for this include, in comparison to linear direct drives, their lower purchasing costs, greater feed forces in relation to the installation dimensions, higher efficiency, better heat dissipation, and reduced susceptibility to disturbance due to the thread transmission ratio. However, compliances are unavoidably given by the mechanical transmission system between the motor and the linear carriage and cause vibrations within the control path. For speed controlled servo drives, this limits the utilizable dynamic range of the control loop