No abstract

Hybrid material composites can meet the increasing demands for high strength and low weight due to their different workpiece properties. Usually, hybrid components require post-machining after their fabrication. Due to the different material properties, new challenges arise in the machining process. It is essential to recognize the course of the material boundary in order to adapt the process planning accordingly and to enable a uniform material transition during machining. This paper presents a method for automated material recognition and automatic adaptation of the process parameters considering a uniform force level during the milling of hybrid materials. This way, the load on the milling tool in the material transition area can be reduced by up to 71%, which prevents premature tool failure. An optical laser line scanner is used to localize of material transitions within hybrid components. This enables a digital mapping of the material distribution in the discretized workpiece model. In combination with an empirical force model, it is possible to predict the cutting forces of the different materials and determine the material transition area for adapting them to specified target values.

In manufacturing of cylindrical cemented carbide tools, helical flute grinding is an important process step. Process planning and the use of cooling lubricants are defining factors for process performance. Therefore, finding optimal parameters and cooling conditions is essential because they characterize the properties of the boundary zone, e.g. residual stresses. In this paper, grinding oil droplet experiments are compared with simulation results to describe the wetting behavior of different grinding wheel based on their specifications (grain size, bonding structure, and wetting status). More specifically, finite element simulations of the thin-film equation are used to identify corresponding slip parameters that will be used in more complex 3D fluid-dynamic simulations via the Joseph-Beavers condition. The results show that both the bonding and, to a lesser degree, the grain size have an influence on the wetting behavior. This presents an intermediate step in getting a better understanding of the cooling properties of lubricants in grinding processes, where the wetting effectiveness plays an important role for the heat transport.

Helical flute grinding is an important process step in the manufacturing of cylindrical cemented carbide tools where the use of cooling lubricants is a defining factor determining process performance. Finding optimal parameters and cooling conditions for the efficient use of lubricant is essential in reducing energy consumption and in controlling properties of the boundary zone like residual stresses. Any mathematical model describing the interactions between grinding wheel, lubricant and workpiece during the process has to account for the complex microstructure of the wheel; however, this renders the identification of parameters like slip or heat exchange coefficients numerically prohibitively expensive. In this paper, results from grinding oil droplet experiments are compared with simulation results for the wetting behavior of grinding wheels. More specifically, finite element simulations of the thin-film equation are used to identify slip parameters for different grinding wheel specifications (grain size, bonding structure, wetting status). Our results show that both the bonding and the grain size have an influence on the wetting behavior. The slip parameters that we identified account for the fluid-microstructure interactions and will be used to effectively model those interactions in more complex 3D fluid-dynamic simulations via the Beavers-Joseph condition.