Engineering, 2012, 4, 532-539 http://dx.doi.org/10.4236/eng.2012.49068 Published Online September 2012 (http://www.SciRP.org/journal/eng) Simulation-Based Analysis and Intuitive Visualization of the Cutting Edge Load in Micromilling of Hardened Steel Petra Kersting * , Dirk Biermann, Eugen Krebs Institute of Machining Technology, Dortmund, Germany Email: * pkersting@isf.de Received June 20, 2012; revised July 18, 2012; accepted July 28, 2012 ABSTRACT The precise micromanufacturing of complex dies with small structures for sheet-bulk metal forming is a challenge due to the high hardness of the materials to be machined. Experiments have shown that micromilling of these diffi- cult-to-machine materials is possible despite of their high hardness. Nevertheless, the higher wear of the tools plays a decisive role. When implementing the machining task as five-axis process, it is possible to control the wear distribution by tilting the milling tools. In this paper, a simulation system is presented which determines the loads acting on the cut- ting edge with regard to different criteria, e.g., the machined material or the effective impulse. Based on this knowledge, it is possible to design the milling process to minimize the tool wear and thereby to increase the lifetime of the milling tools. In order to show the applicability of the simulation system, test workpieces were machined and the experimental results are compared to the simulation data. Keywords: Simulation; Visualization; Micromilling; Tool Wear 1. Introduction Workpieces with microstructured elements (Figure 1) [1, 2] are usually manufactured by die sinking, pulsed laser deposition, or micromilling [3-7]. The advantages of mi- cromilling [8,9] are a higher geometric flexibility, a higher material removal rate, and a higher quality of the machined surfaces [10-12]. However, tool wear [13] and the risk of tool failure is an important factor [14]. Especially in case of sheet-bulk metal forming [15], which combines the advantages of sheet and bulk metal forming in order to manufacture complex lightweight components with integrated functional elements, wear- resistant forming tools made of hardened steel and high- speed steel are required. Due to the high hardness of the materials, the machining of these components is a chal- lenge [16]. In previous studies, the applicability of com- mercially available micro end-milling cutters for a manu- facturing of dies from hardened tool steel with a hardness above 60 HRC was presented [17]. The analysis of tool wear—using the Finite Element Analysis (FEA) [18,19] or different empirical or analyti- cal models [20,21]—and the monitoring during the ma- chining process [22] are subject of many research works. During the machining of materials with a high hardness, the abrasive tool wear plays a decisive role which is sub- stantially influenced by the distance travelled by the mil- ling tool in the workpiece material. Therefore, the analy- sis system presented in the following does not use a complex wear model [21,23] or apply a time-consuming FE model. In contrast, it predicts indicator values of the load on the cutting edge which causes the tool wear— like for example the covered distance, removed material volume, or the impulse acting on the cutting edge. These values are stored during the simulation of the machining process, and the data is prepared in an intuitive visualiza- tion [24] in order to allow for an easy visual perception. This knowledge can then be utilized by the NC (Nu- merical Control) software engineer to optimize the pa- rameter values of the manufacturing process. 2. Simulation System for Analyzing the Load on the Cutting Edge The approach for analyzing the load on the cutting edge during the NC milling process is integrated into a geo- metric time-domain milling simulation. This approach computes the material removal and the cutting forces on the basis of a geometric description of the milling tool (e.g., shape (sphere, torus, cylinder), radius, helix angle) as well as the raw stock material (Figure 2) and real NC programs, which include all the required information, e.g., about the position and orientation of the milling tool, the feedrate, and the spindle speed [25,26]. This simulation system [27] s based on the Constructive i * Corresponding author. Copyright © 2012 SciRes. ENG