【正文】 matter 2020 Elsevier Science . All rights reserved.doi:(03)000335management system, which can help to improve the performance of the advanced manufacturing system.Besides the changed requirements on the productionmanagement which were mentioned above, precision forging technology urges modified constraints on productdevelopment. Not only the functional specifications needto be considered for the product development, but thespecifics of precision forging as well, which in many casesforces the adoption of the product design.In a joint BMBF founded project these objectives areaddressed by including product design, organizational andinformation technology aspects in the layout and operationof an advanced forging system which will be achieved byseveral balanced actions described in this paper. Beforeactually describing the efforts of the project, we shortlydescribe precision forging and its modified requirements onthe process design and production control.2. Precision forgingThe majority of forging processes is performed in severalstages to reach the requested final geometry. Basically thosestages can be split up into two main categories. The firstcategory is in general a preforming processes for distributingthe mass of the raw material, followed by the actual forgingprocesses operated on a press or hammer. The preforming ismainly done on a rolling machine.Besides the preforming step, in most cases precisionforging is performed in a single step. However for precisionforging of long flat parts like connecting rods, monlytwo steps are necessary. First an upsetting operation isperformed to flatten the part followed by the final precisionforging operation. The purpose of the upsetting is to reducethe material deformation in the final forging step and todecrease the friction which consequently minimizes thewear of the tool. Gear wheels for example can even beforged in one step without previous preforming the rawmaterial. Therefore gear wheels need only one single stageto be pletely formed from a raw material slug [5,6].For the precision forging of a connecting rod a tool isdesigned in which the preformed and upset slug is inserted inthe die cavity, thereafter the tool is closed and the puncheswhich are included in the die form the material to the finaldesign (Fig. 2).Besides the special requirements concerning the actualdesign of precision forged products, very exact masses of theraw parts with deviations less than % are prerequisites fora successful process. The temperatures of the billets and diesneed to be controlled carefully to facilitate a temperaturedeviation of less than 20 8C. Additionally the materialhandling and forming of the workpiece needs to be performed with a high degree of precision. For this a press andother manufacturing ponents with very small tolerancesregarding geometric deviations are needed.As mentioned above, precision forging processes havecertain special requirements concerning the design of theproduct and as a result to the forging die.For the described research project a conventionally forgedconnecting rod needed to be adapted for the production witha precision forging process. As mentioned above precisionforging is performed without flash (Fig. 3).Fig. 1. Integrated ITsystems 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 (2020) 16–21 17The technology of closed die forging is used with stampsin the eyes and the shaft doing the forming work. To enablethe connecting rod to be forged in that way some changes inthe conventional forging geometry have to be made. In Fig. 4the changes in the area of the shaft are shown.First it is important that the transition between the weband the wad is not smooth like for conventional forging butwith a revolving edge and a vertical side face. This isnecessary to allow the stamp to perate the materialwithout any collision with the die sinking and to avoid anoffset due to deviations in the path of the stamp (Fig. 4).As the mass exactness of the inserted part is only in arange of 1% the area of the stamps is necessary to pensate the mass deviation. This is the reason for thedeviation of the stamp path. The revolving edge is a promise between a smooth transition and an acceptable loadof the die sinking. With FEMsimulation the angle has beenoptimized to . 5 shows the occurring stress for a608 angle is not inflicting the die sinking and therefore thetool life quantity.Additional changes have to be made in the area betweenthe eyes and the shaft. The reasons are the displacement ofthe material between the stamps and the load of the diesinking as mentioned above (Fig. 6).An important requirement for the development of a precision forgeable geometry is that the mass and the stresses ofFig. 4. Design change for precision forging of the shaft crosssection.Fig. 5. FEMsimulation of tool angle. Fig. 6. CAD drawing of connect rod.18 S. Reinsch et al. / Journal of Materials Processing Technology 138 (2020) 16–21the product have to be the same as for the original design.This can be verified by FEMsimulation du