Batch size optimized use of tools in hot bulk forming

Theme
Tool- and Mold-Making
Project title Batch size optimized use of tools in hot bulk forming (LöWe)
Project duration 01.09.2015 – 31.08.2017
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Press release
Ways to minimize tool wear consist among other things in the change of tool, workpiece or forming machine. However, these changes are associated with a great effort. An alternative way to change tool stresses is to adjust the batch size. For the forging technical production of a lot a so-called thermal cycle is passed through. The more thermal cycles are passed through, the greater the thermal stress and thus the tool wear and the associated maintenance costs. However, a one-sided optimization of batch size with respect to an reduction of maintenance costs is not effective. Rather, the central logistic objectives in terms of logistics costs and logistics performance need to be considered. A change of the lot size, among other things, directly affects inventory and order costs. It also arises indirect logistics costs, such as adherence to delivery dates and throughput time costs. A low logistic performance of a company can lead to extra work and additional costs on the part of its customers. The outlined version indicates the need for a cost-effective batch size formation in compliance with the maintenance costs as well as the direct and indirect logistics costs. If the expansion of an existing procedure for batch size formation succeeds, a reduction in the total production costs in hot forming is possible.
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  • 01.12.2016
  • Lindenhof 32, 42657 Solingen
  • 26.04.2016, 09:00 h - 11:00 h
  • IPH – Institut für Integrierte Produktion Hannover gGmbH, Hannover

Publications about the project

Lot sizing is an important task of production planning and control: basis of lot sizes are order change costs and costs for storage. Models for lot sizing do not consider lot size dependent maintenance costs. However, for a forging company the tool wear is very important, because the tooling costs represent a major part in the production cost. In this article, the deter-ministic lot size model of Andler is extended with lot size dependent maintenance costs. For this purpose, the correlation between lot size and the tool wear is ?rst derived in order to develop a lot size dependent wear function. The linking of a lot size dependent wear function with maintenance costs results in a lot size dependent maintenance cost function, which can be integrated into existing lot size models with a customized total cost function. The validation of the extended lot size model consists of two parts. In the ?rst part, the functionality of the extended lot size model is validated. In the second part, a sensitivity analysis of the lot size is carried out with regard to lot size dependent costs and unit costs.

lot sizing, tool wear, forging industry, sensitivity analysis

High temperatures up to 1280 °C and high pressures during the forming opperation lead to strong tool wear in forging processes. Increasing tool wear can lead to very high costs. By experiments conducted at the Institut für Integrierte Produktion in Hanover the correlation between tool wear and lot size in hot forging processes was verfied. The findings will help companies to optimise maintenance procedures and therefore reduce cost in the future.

forging, steel, tool wear, lot size

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

Sponsor

The IGF project 18780 N of the Association for Traffic Management and Logistics (GVB) was funded via the German Federation of Industrial Research Associations (AiF) in the programme of Industrial Collective Research (IGF) by the Federal Ministry for Economic Affairs and Energy (BMWi) based on a decision of the German Bundestag.

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