Henrik Prinzhorn

Project engineer
Practice Areas:
Production planning & control, operation research, simulation of material flow
+49 (0)511 279 76-446


Assembling large-scale products involves frequent process interruptions why in order to reduce the impact of interruptions, a short-term response is necessary to reduce delivery delays and idle times of resources. An approach to challenge this represents the flexibility of a production system. Regarding the environment of large-scale product assembly, it has to be shown which potentials of flexibility are able to be used in a short-term manner.

assembly, production management, disruption management

Considering production planning and control, lot sizing is a very important task. Lot sizes are usually resorted to lot size dependent order and storage costs. However, models for lot sizes ignore the aspect of lot size dependent maintenance costs. For forging companies the tool wear has a great economic importance, because the tooling costs represents a major factor in production costs.

production planning and control, lot sizing, process stability

Assembling large-scale products, such as airplanes, locomotives, or wind turbines, involves frequent process interruptions induced by e.g. delayed material deliveries or missing availability of resources. This leads to a negative impact on the logistical performance of a producer of xxl-products. In industrial practice, in case of interruptions, the identification, evaluation and eventually the selection of an alternative order of assembly activities (‘assembly alternative’) leads to an enormous challenge, especially if an optimized logistical decision should be reached. Therefore, in this paper, an innovative, optimization model for the identification of assembly alternatives that addresses the given problem is presented. It describes make-to-order, large-scale product assembly processes as a resource constrained project scheduling (RCPS) problem which follows given restrictions in practice. For the evaluation of the assembly alternative, a cost-based definition of the logistical objectives (delivery reliability, inventory, make-span and workload) is presented.

assembly sequencing, logistical objectivs, optimization modell

Disassembling of large-scale products (e. g. wind energy plants, crane and conveyor systems which are known as XXL-Products) becomes increasingly important, as the operating time is limited. The challenge is to optimize the positioning of the complex and expensive disassembling on the operation site on the one hand and the costly transportation of modules to the disassembling factories. For this reason the location and allocation problem will be pictured in a mathematical model within the research project “DemoNet”. This model supports companies to create a XXL-disassembly-network. The research hypothesis assumes: a disassembly under ecological, economical and logistical aspects constitutes the optimum. The extension of a location planning tool forms the basis of the mathematical optimization model for the disassembly of XXL-Products. For solving the problem a genetic algorithms will be used. The result helps companies to arrange disassembling networks for XXL-Products efficiently.

dismantling planing, dismantling networks, impact model

Assembling large-scale products involves frequent process interruptions. To reduce the duration of an assembly stop, the WZL of RWTH Aachen University and the IPH Hannover developed an approach which is able to identify alternative assembly plans and to evaluate them on the basis of the logistic performance objectives. Stock, capacity utilization, lead time and adherence to schedule are transferred into costs and assembly plans are thus comparable based on one parameter.

production planning and control, assembly, logistical objectives

The assembly of large-scale products is usually organized in the construction-site principle. For each assembled product, the area requirement increases with assembly time. So for each product a defined area is reserved, that corresponds to the maximum expansion of the product. As the existing area is limited, the single products are competing for it. This results in an increased area requirement and a poor use of area. Therefore time-variable and competing area requirements should be considered in the facility layout planning.

layout problem, time dynamics, competing areas

Assembling large-scale products involves frequent process interruptions induced by e.g. delayed material deliveries or missing availability of resources. Our approach for identifying alternative assembly sequences by analyzing the product structure and process dependencies allows for continuing with the assembly process in case of interruptions and therefore increases the process efficiency.

large-scale product, adaptive assembly, alternative assembly process

By leveraging the production factor "human" it is possible by taking into account human performance fluctuations during the day to reduce product-related defect costs and increase quality. To this end, the integration of human performance variations in methods of production planning and control must be carried out. This article introduces a method by which a quality-oriented job shop schedule can be created, taking into account human performance fluctuations.

produktion planning, job shop scheduling, human performance fluctuation, optimization problem

A xxl-product is defined as product, whose production costs increase disproportionately in relation to further growth of a characteristic product feature. Existing models of supply chain design are not designed for xxl-products. For this reason a method was developed to create a supply chain for a xxl-product. The supply chain design works in due consideration of the most relevant xxl-product specific features. The created supply chain can be evaluated for their logistical quality. Therefore a comparison between different supply chain variants is possible.

xxl-product, supply chain design, logistical objectives

The assembly of complex, large-scale products is often characterized by poor date availability, limited process standardization, frequent product modifications and flexible usage of resources, which often leads to interruptions in the assembling process. Therefore, in a research project between the IPH Hannover and the WZL of RWTH Aachen University, a methodology for assembly processes is developed which allows the identification and evaluation of process alternatives in case of interruptions. For the evaluation of those process alternatives logistical objectives are used.

xxl-product, adaptive assembly scheduling, interruption assembly process, logistical objectives

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