Benjamin Döbbeler

Assessment of Energy and Resource Consumption of Processes and Process Chains within the Automotive Sector

Within this paper a methodology for the assessment of energy and resource consumption within manufacturing processes is described and two case studies from the automotive sector were evaluated. On basis of the Life Cycle Assessment approach the energy and material flows within single manufacturing processes were acquired concerning the two selected case studies. With the generated knowledge about energy and material use it was possible to show up optimisation potentials for the reduction of the ecological impact of the determined products within the manufacturing phase. The work shown in the paper was conducted within the project BEAT which is kindly financed by the Federal Ministry of Education and Research in Germany (BMBF).

Ecological lifecycle assessment of an electric drive for the automotive industry

The growing consequences of global warming and rising prices for fossil fuels are calling for a broad substitution of combustion engines by electrical machines and an energy- and resource-efficient design of manufacturing systems. The present work proposes a conceptual approach for the holistic product lifecycle assessment (LCA) of an electric drive for the automotive industry. The proceeding is part of the NRW Bank funded Project KERME (engl.: Competitive Electro-Mobility through Resource Efficiently and Modularly Designed E-Drives). KERME aims at the eco-efficient production of a scalable E-Drive, which finally enables the manufacturers to realize economies of scale, which in return is a key condition for a successful adaption of environmentally friendly transportation concepts by the end users due to reduced sale prices. The investigated electric drive will be designed to meet the load spectrum of a compact vehicle for close-by traffic in an urban environment. Accordingly, the engine is supposed to provide short but intensive phases of acceleration followed by long downtimes. Suitable engine concepts are the synchronous and asynchronous layout with an internal rotor and liquid cooling (P = 30 kW, nmax = 9000-12000 rpm, V = 300-400 V, dimensions (length × external diameter of box): 480 × 270 mm). Following the guidelines in ISO 14040/44, the analysis will determine the ecological impact of an E-Drive during all of the following lifecycle stages: Production of raw materials, manufacturing phase (including final assembly) and utilization phase. However, the focus of the analysis will be the manufacturing processes, completed by assumptions and mathematical models about the remaining phases. The analysis will break down the absorbed flows of resources and energy to the applied manufacturing processes per manufactured E-Drive. By doing so, the contribution of each production step to the over-all energy consumption, global warming potential or any other factor of ecological impact (e.g. eutrophication, eco- and human-toxicity) can be determined. Accordingly, those processes can be identified, which are the most promising to be modified in order to improve the energy efficiency of the production system and thus to lower the manufacturing costs while protecting the environment at the same time. In detail, the proposed work investigates the manufacturing and assembly of the main engine parts lamination stack, housing, rotor, stator and shaft. Thus, the E-Drive production includes a great variety of manufacturing technologies mentioned in DIN 8580: Primary forming (e.g. casting of housing), forming (e.g. stamping of magnetic strips in lamination stack), cutting (e.g. machining of shaft), joining (e.g. adhesive joint of box and stator), coating (electrical insulation of stator-grooves), modifying material properties (e.g. heat treatment of shaft). Physical measurement techniques will later be applied in order to determine the absorbed flows of electrical power, cutting fluids and material of each machine tool. By implementing and validating the production chain into a software tool (GaBi 5) possible scenarios with alternative manufacturing processes or materials can be analyzed concerning their impact on the ecological impact of the engine without conducting costly and time-consuming experiments.

Simplified Life Cycle Analysis of a Forming Tool in the Automotive Industry

Since climate protection and reduction of carbon emissions have gained increasing significance in research, industry and legislation, it is not only important to reduce energy consumption and emissions of vehicles during the use stage, but throughout the whole life cycle. In the sub-project “Resource-Efficient Tool Manufacturing” of the Green Carbody Technologies Innovation Alliance the life cycle of an integrated forming tool for the manufacturing of car body parts has been analysed. From casting to tool manufacturing and use stage until recycling processes have been considered and energy and material consumptions have been measured and analysed in a life cycle perspective.

Self-optimizing Production Technologies

Customer demands have become more individual and complex, requiring a highly flexible production. In high-wage countries, efficient and robust manufacturing processes are vital to ensure global competitiveness. One approach to solve the conflict between individualized products and high automation is Model-based Self-optimization (MBSO). It uses surrogate models to combine process measures and expert knowledge, enabling the technical system to determine its current operating point and thus optimize it accordingly. The objective is an autonomous and reliable process at its productivity limit. The MBSO concept is implemented in eight demonstrators of different production technologies such as metal cutting, plastics processing, textile processing and inspection. They all have a different focus according to their specific production process, but share in common the use of models for optimization. Different approaches to generate suitable models are developed. With respect to implementation of MBSO, the challenge is the broad range of technologies, materials, scales and optimization variables. The results encourage further examination regarding industry applications.

Impact of the Heat Treatment Condition of Steel AISI 4140 on Its Frictional Contact Behavior in Dry Metal Cutting

In this work, the impact of the heat treatment condition of steel AISI 4140 on its frictional contact behavior with coated cemented carbide and cubic boron nitride (CBN) in dry metal cutting is experimentally investigated. Two different kinds of tests were performed. The frictional behavior was investigated under conditions very similar to metal cutting on a frictional test bench, which was installed on a broaching machine. Additionally, orthogonal cutting processes with linear workpiece geometries were conducted on the same machine. The cutting experiments included observations of cutting forces, high-speed filming of chip formation, chip thickness ratio analysis as well as a comprehensive metallographic characterization of the chips and workpiece surfaces. The impacts of the undeformed chip thickness and cutting speed were investigated individually for coated cemented carbide and CBN as cutting materials. The frictional examinations delivered the Coulomb friction coefficients for all four combinations of work and cutting materials as a function of the relative velocity. The identified frictional behaviors explain the dependencies of forces, chip thicknesses, and surface microstructures on the tool and process conditions during the cutting tests.

Ecological evaluation of consumptions in manufacturing within the automotive sector

Nowadays the necessity to improve the transparency of consumptions origins of electrical energy as well as auxiliary materials (e.g., lubricoolants, pressurised air, etc.) in the industrial manufacturing environment is increasing more than ever. Methodologies for measuring, predicting and estimating consumptions are being developed in order to assess the environmental impacts during the production. This paper presents a detailed analysis of all energy and material flows for the manufacturing of two different demonstrator products using a bottom-up measurement approach. In order to identify potential savings and to reduce the complexity of the data gathering, an assessment of the main origins of consumptions on the one hand as well as the most resource intensive process inputs on the other hand has been conducted. Based on the initial technology chain and its evaluation, an alternative technology chain with several changes in the processes has been investigated in order to reveal potential savings and demo...

Life Cycle Based Evaluation and Interpretation of Technology Chains in Manufacturing

This chapter describes a methodology to gather, assess and interpret the ecological impact of technology chains within industrial manufacturing. The explained methodology leads to significant information about high consuming processes and important energy and material flows. Industrial companies cannot allocate the exact consumptions in the manufacturing processes. Especially costs and consumptions for media like compressed air or centrally provided lubricants are mostly distributed by means of the number of machines rather than by actual consumption figures. By utilising the presented methodology not only information about real consumptions, but furthermore ecological data can be generated for various purposes such as ecological product declarations and evaluation of alternative production chains. The methodology is exemplarily applied in two industrial case studies and results of these studies are shown in this chapter.

Ecological Assessment of Coated Cemented Carbide Tools and Their Behavior during Machining

In the last years and even decades the research on ecological evaluation models has grown. Both procedures for entire companies or plants as well as methods for describing single processes have been developed. Therefore the demand for process oriented approaches which can be aggregated into considerations of higher levels is prevailing.

Influence of the coolant nozzle orientation and size on the tool temperature under high-pressure coolant supply using an analogy test bench

In many examinations, high-pressure coolant supply showed its’ great potential to improve the productivity when machining difficult to cut materials. However, most examinations regarding the supply of metalworking fluid at elevated pressure were performed in turning. Accordingly, a profound knowledge of the fundamental mechanisms of the focused high-pressure coolant supply in milling is vital for an optimal process and tool design and mostly still missing. However, especially the sensor-based examination of the cooling effect on the tool temperature in milling under coolant supply is highly challenging, because the rotation of the tool prevents the direct application of temperature sensors in the tool. Therefore, an analogy test bench for lathes was developed to generate an interrupted cut and chips with a non-constant undeformed chip thickness h. With this test bench, different coolant supply strategies with different coolant nozzle orientation, coolant supply pressure and volumetric flow rate were examined. The results show, that the coolant supply pressure, volumetric flow rate and coolant nozzle orientation have a major influence on the tool temperature. As opposed to this, no major influence was found on the cutting force.

Analysis of surface integrity in machining of AISI 304 stainless steel under various cooling and cutting conditions

Recent studies have shown that machining under specific cooling and cutting conditions can be used to induce a nanocrystalline surface layer in the workspiece. This layer has beneficial properties, such as improved fatigue strength, wear resistance and tribological behavior. In machining, a promising approach for achieving grain refinement in the surface layer is the application of cryogenic cooling. The aim is to use the last step of the machining operation to induce the desired surface quality to save time-consuming and expensive post machining surface treatments. The material used in this study was AISI 304 stainless steel. This austenitic steel suffers from low yield strength that limits its technological applications. In this paper, liquid nitrogen (LN2) as cryogenic coolant, as well as minimum quantity lubrication (MQL), was applied and investigated. As a reference, conventional flood cooling was examined. Besides the cooling conditions, the feed rate was varied in four steps. A large rounded cutting edge radius and finishing cutting parameters were chosen to increase the mechanical load on the machined surface. The surface integrity was evaluated at both, the microstructural and the topographical levels. After turning experiments, a detailed analysis of the microstructure was carried out including the imaging of the surface layer and hardness measurements at varying depths within the machined layer. Along with microstructural investigations, different topological aspects, e.g., the surface roughness, were analyzed. It was shown that the resulting microstructure strongly depends on the cooling condition. This study also shows that it was possible to increase the micro hardness in the top surface layer significantly.Recent studies have shown that machining under specific cooling and cutting conditions can be used to induce a nanocrystalline surface layer in the workspiece. This layer has beneficial properties, such as improved fatigue strength, wear resistance and tribological behavior. In machining, a promising approach for achieving grain refinement in the surface layer is the application of cryogenic cooling. The aim is to use the last step of the machining operation to induce the desired surface quality to save time-consuming and expensive post machining surface treatments. The material used in this study was AISI 304 stainless steel. This austenitic steel suffers from low yield strength that limits its technological applications. In this paper, liquid nitrogen (LN2) as cryogenic coolant, as well as minimum quantity lubrication (MQL), was applied and investigated. As a reference, conventional flood cooling was examined. Besides the cooling conditions, the feed rate was varied in four steps. A large rounded cuttin...