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Advanced manufacturing system for forging products Steffen Reinsch * , Bernd Mu¨ssig, Bernd Schmidt, Kirsten Tracht IPH—Institut fu¨r Integrierte Produktion Hannover gGmbH, Hollerithallee 6, 30419 Hannover, Germany Abstract The demand of the industry for high quality parts that are provided with a high-level delivery performance is constantly growing. For increasing the product quality without raising the cost in many cases new processes have to be introduced. For providing those products flexible and responsive to the market advanced manufacturing systems need to be introduced to quickly and reliably deliver to customers in-time. Using precision forging combined with an advanced manufacturing system for forging parts that used to be forged traditionally requires changes in the design of products and processes. Not only the different stages need to be formed with a high precision, the positioning of the inserted parts in the tool needs to be performed with a high-level of accuracy as well. In the best-case this is done with an automated positioning gear. For gaining flexibility the tools are supposed to be replaced quickly by a changing system as well. Besides a flexible and automated forging line for the production of precision forging parts, a high-performance production management system is required that is specifically tailored to the individual requirements of the advanced manufacturing system for precision forging. Therefore a bi-directional integration of the software modules tool management, production planning and material management needs to be realized. It is essential for the precision forging process to monitor a number of process data which can be processed by the production management system. This facilitates the linkage of technical process data to logistical data of the product management system to increase the logistical performance concerning efficiency, lead-time and in-time delivery of the advanced manufacturing system. # 2003 Elsevier Science B.V. All rights reserved. Keywords: Advanced manufacturing system； Flexible forging line； Integrated production management 1. Introduction In the last decade supply chains and supplier companies have gained a growing significance for the German industry. Especially in the German automobile industry, large com- panies such as Volkswagen, Mercedes-Benz, BMW, Audi etc. reduced their scope of in-house manufacturing drasti- cally and started to rely increasingly on external supply chains. In particular forging products which are the basis for many key components in the automotive industry such as different types of shafts, connecting rods, gear wheels or stub-axles and so on are affected by that development. As of today 80% of these parts are bought from external suppliers, whereas many of them are medium-sized enterprises with 200–1500 employees. To meet the requirements of the customer, the forging industry is facing new challenges regarding product quality, logistical performance, flexibility and reliability. The result- ing problems are well known in the German forging industry which is the largest in Europe and which had to adapt to those challenges [1]. Not only the need for a high product quality, but for a steadily increasing precision of the products is gaining importance in the forging industry. Hence forging companies are urged to implement advanced forging processes, like precision forging for example. Compared with traditional processes, precision forging requires a higher accuracy and a significantly improved process monitoring and control. Moreover, the tools needed for precision forging and the process conditions have to be monitored carefully because of the stricter product tolerances that need to be achieved. Thus a couple of process parameters, like forces, temperature, product type, process-times need to be monitored. Thus the data can be used in an integrated production management system for improving the logistical performance concerning scrap rates, lead-times, work-in-process, etc. as well. The goal of a high product quality combined with a high-level delivery performance demands the integration of advanced information and manufacturing technologies. Besides a flexible and automated forging line for the pro- duction of precision forging parts, a high-performance production management system is required, that enables an improved tool management which is directly linked to the production management and vice versa (Fig. 1). This results in specific requirements for a tailored production Journal of Materials Processing Technology 138 (2003) 16–21 * Corresponding author. E-mail address: reinsch@iph-hannover.de (S. Reinsch). 0924-0136/03/$ – see front matter # 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0924-0136(03)00033-5management system, which can help to improve the perfor- mance of the advanced manufacturing system. Besides the changed requirements on the production management which were mentioned above, precision for- ging technology urges modified constraints on product development. Not only the functional specifications need to be considered for the product development, but the specifics of precision forging as well, which in many cases forces the adoption of the product design. In a joint BMBF founded project these objectives are addressed by including product design, organizational and information technology aspects in the layout and operation of an advanced forging system which will be achieved by several balanced actions described in this paper. Before actually describing the efforts of the project, we shortly describe precision forging and its modified requirements on the process design and production control. 2. Precision forging The majority of forging processes is performed in several stages to reach the requested final geometry. Basically those stages can be split up into two main categories. The first category is in general a preforming processes for distributing the mass of the raw material, followed by the actual forging processes operated on a press or hammer. The preforming is mainly done on a rolling machine. Besides the preforming step, in most cases precision forging is performed in a single step. However for precision forging of long flat parts like connecting rods, commonly two steps are necessary. First an upsetting operation is performed to flatten the part followed by the final precision forging operation. The purpose of the upsetting is to reduce the material deformation in the final forging step and to decrease the friction which consequently minimizes the wear of the tool. Gear wheels for example can even be forged in one step without previous preforming the raw material. Therefore gear wheels need only one single stage to be completely formed from a raw material slug [5,6]. For the precision forging of a connecting rod a tool is designed in which the preformed and upset slug is inserted in the die cavity, thereafter the tool is closed and the punches which are included in the die form the material to the final design (Fig. 2). Besides the special requirements concerning the actual design of precision forged products, very exact masses of the raw parts with deviations less than 0.5% are prerequisites for a successful process. The temperatures of the billets and dies need to be controlled carefully to facilitate a temperature deviation of less than 20 8C. Additionally the material handling and forming of the workpiece needs to be per- formed with a high degree of precision. For this a press and other manufacturing components with very small tolerances regarding geometric deviations are needed. As mentioned above, precision forging processes have certain special requirements concerning the design of the product and as a result to the forging die. For the described research project a conventionally forged connecting rod needed to be adapted for the production with a precision forging process. As mentioned above precision forging is performed without flash (Fig. 3). Fig. 1. Integrated IT-systems and organization. Fig. 2. Precision forging of connecting rod. Fig. 3. Precision forged connecting rod. S. Reinsch et al. / Journal of Materials Processing Technology 138 (2003) 16–21 17