Gisela Lanza

Company-specific quantitative evaluation of lean production methods

Small and medium-sized companies encounter enormous difficulties when trying to implement lean production methods according to the role model of the Toyota Production System. This is caused by the varying effects of lean methods on production figures depending on the production conditions concerning product variety and volumes, variation of process and set-up times, etc. This article presents approaches developed at the Institute of Production Science (wbk), Karlsruhe Institute of Technology, to evaluate and optimize the effects of lean methods in small series productions based on the quantified interdependencies with the relevant target figures. It enables the best combination of lean methods to be identified and recommendations for the efficient implementation of these lean methods.

Produkte und Produktionssysteme integrativ konzipieren: Modellbildung und Analyse in der frühen Phase der Produktentstehung

Unternehmen mussen aufgrund der vorherrschenden Markt- und Wettbewerbssituation Produkte immer schneller und kostengunstiger entwickeln und produzieren. Fertigungstechnologien bestimmen in hohem Mase das Produktkonzept. Die Abhangigkeiten zwischen Produkt und Produktionssystem werden heute jedoch nur unzureichend berucksichtigt. Die Folge sind aufwandige Iterationsschleifen im Entwicklungsprozess. Produkt und Produktionssystem sind daher im Wechselspiel zu konzipieren. Dieses Buch beschreibt das BMBF-geforderte Verbundprojekt VireS, Virtuelle Synchronisation von Produktentwicklung und Produktionssystementwicklung. Es wird ein Instrumentarium zur integrativen Entwicklung von Produkt und Produktionssystem dargestellt. Bestandteile des Instrumentariums sind Vorgehensmodelle, Bewertungsmethoden und eine domanenubergreifende Spezifikationstechnik fur den integrativen Entwurf. Das Buch unterstutzt den Entwickler entlang des Entwicklungsprozesses bei der systematischen Konzipierung von Produkt und Produktionssystem.

Simulation of personnel requirements during production ramp-up

Nowadays the number of product models constantly increases, due to a strong competition to innovate and the reduction of product life cycles, resulting in a more frequent occurrence of production ramp-ups. The production ramp-up combines the product development with the series production and has an impact on the market entry timing. In order to ensure an ideal ramp-up with new developed products being placed on the market as quickly as possible, there has to be an efficient use of existing resources, especially of human resources. Nevertheless, the planning of these resources turns out to be the most important challenge because it is directly related to a great uncertainty. The following article represents an approach that is being developed at the Institute of Production Science (wbk) of the Karlsruhe Institute of Technology (KIT) to optimize the forecast of the personnel requirements during ramp-up by taking into account the dynamic planning variables and organizational basic conditions. Therefore, a method will be developed that provides support to the responsible persons of the respective production ramp-up to calculate the necessary manpower for every single ramp-up phase and to realize the economic optimum. This method focuses on a simulation of the ramp-up process that allows an economically more efficient use of human resources.

Total Cost Analysis of Process Time Reduction as a Green Machining Strategy

Manufacturers have pursued green machining strategies, such as process time reduction, to address the demand for environmental impact reduction. These strategies, though, increase the stresses on the manufacturing system, which can affect availability, service life, achieved part quality, and cost. This study presents a total cost analysis of process time reduction for titanium machining to holistically consider the implications of such strategies. While the results suggest it may not be a viable green machining strategy for titanium machining, the feasibility of process time reduction as a greening solution is highly dependent on the functionality of the finished part.

Criticality analysis of spare parts management: a multi-criteria classification regarding a cross-plant central warehouse strategy

Abstract Today an efficient warehouse and inventory management of spare parts for production machinery is essential for service organizations. Optimal strategies in procurement, stocking and supply play an important role for serviceability in spare parts management. In this context, individual item criticality should be considered, which describes how crucial a spare part is. This paper presents a three-dimensional classification approach for spare parts regarding a cross-plant central warehouse strategy of a service network. The approach uses two dimensions to estimate value and predictability of spare parts with aid of an ABC and XYZ analysis. The third dimension VED analyses a multi-criteria criticality classification and six feasible criteria are identified to describe item criticality. The methodology of the analysis is based on a decision tree, which represents the defined criteria by nodes. In addition, the analytic hierarchy process is used to solve the multi-criteria decision problems at the different nodes of the decision tree. The approach is developed in a research project and evaluation of spare parts is performed based on real inventory and transaction data in cooperation with an industrial company. As a result 15,000 out of 50,000 items could be classified as suitable for central warehousing.

Evaluating Trade-Offs Between Sustainability, Performance, and Cost of Green Machining Technologies

The growing demand to reduce environmental impacts has encouraged manufacturers to pursue various green manufacturing technologies and strategies. These solutions, though, may have a direct impact on several productivity metrics including availability, quality, service life, and cost. This study presents an approach to evaluate the trade-offs between the environmental, performance, and financial impacts of green machining technologies by combining green manufacturing principles into life cycle performance evaluation. The approach is validated by investigating the implications of reducing the processing time by increasing the cutting speed and chip load to green a horizontal milling process.

Befähigungs- und Einführungsstrategien für Industrie 4.0

Kurzfassung Oftmals mangelt es Unternehmen bei der Integration von Industrie 4.0 auf dem Hallenboden an geeigneten Vorbildern sowie nachvollziehbaren Vorgehensweisen und Einführungsstrategien. Dieser Beitrag stellt einen Ansatz vor, der Unternehmen, insbesondere den deutschen Mittelstand, mithilfe eines reifegradbasierten Handlungsleitfadens bei der Einführung individuell zugeschnittener Industrie 4.0-Methoden und der Bewältigung der dabei entstehenden Herausforderungen unterstützt.

Assessment of lamination stack production

The economic production of automotive electric drives challenges manufacturers and OEMs. In order to support the cost optimal technology choice, a real lamination stack production is assessed with respect to quantity and variant flexibility. Therefore the process chain of a sample product is analyzed from the coil material to the finished stack. The cost interdependencies are analytically modeled in order to calculate the production costs from a bottom-up perspective. The cost calculation is done for a punching as well as a laser-cutting line. Based on this evaluation manufacturing processes can be chosen and volume-flexible series production lines can be designed. Furthermore, the achievable quality is a key aspect in the production of electric drives. The geometric features of the single sheet and the lamination stack, respectively, influence the performance of the electric drive significantly. Therefore, the perspective on suitable evaluation criteria for the process-dependent quality characteristics of the individual components is given in this paper.

Behavior of dynamic preventive maintenance optimization for machine tools

This paper presents an approach to the dynamic optimization of the preventive maintenance schedule for machine tool components during operation based on the actual operating life and the respective load profile. Therefore, a stochastic model based on the Weibull Cumulative Damage Generalized Log-Linear Model and the Monte Carlo Simulation is used. Furthermore, the effect of the dynamic optimization on component selection for different maintenance strategies is taken into consideration. The ideal strategy can be selected from corrective, preventive and condition-based maintenance for every component of a complex system.

Statistical modelling of process parameters in micro cutting

Micro production, with an annual forecasted growth rate of 20 per cent will clearly be a key technology of the 21st century. High-precision engineering, which uses miniaturized conventional manufacturing techniques, e.g. milling, turning, and drilling, has significant potential for application to the manufacture of micro-sized products with exacting precision and accuracy requirements. Owing to its flexibility and its ability to produce complex three-dimensional geometric shapes in a broad variety of different materials, micro cutting is of special importance both for small scale and mass production environments. However, cutting in micro dimensions follows special rules caused by size effects. Successful micro cutting depends on statistically reliable and robust processes and therefore on knowledge about parameter adjustments and process characterization. Statistical analyses of experimental micro cutting data and modelling studies are used to study the effects and interactions of process parameter variations for workpiece material, cutting edge radii, cutting speed, depth of cut, and application of a lubricant. The results show a significant influence of most of the mentioned factors on the response variable surface roughness and specific cutting force. Based on the experimental data and the statistical modelling studies, linear models for the specific cutting force and surface roughness are proposed. In addition, the outcome is compared to the empirical cutting model of Victor-Kienzle derived for application in macro dimensions.