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Thin-walled components, i.e. fuselage frames of airplanes, are prone to an unstable process behavior during milling. Therefore, tools with a chamfer between the cutting edge and the flank face are often used for such machining tasks. During milling, the chamfered area comes into contact with the just cut surface. This contact leads to process damping forces and the induced heat into the workpiece in this contact zone is increased. Furthermore, the amount of induced heat depends on the process parameters. At certain spots on the machined surface this may lead to a local overheating, which can reduce stiffness significantly. When this occurs during milling of a thin-walled component, the component is often regarded as reject. In this paper, the influence of chamfers and process parameters on the induced heat into the workpiece is investigated experimentally. In addition, a simulation which predict the temperature in the workpiece in dependence of the process parameters is presented.

This study is focused on developing and testing a calorimeter to measure the chip heat in drilling of C45EN. Inside the calorimeter, the cut chips fall into a fluid with known heat capacity. Its temperature is measured continuously with thermocouples. Based on calorimeter designs found in the literature, the principal assembly of the calorimeter was adapted to be used in drilling and to minimize heat losses. A modular design with measuring box, process box and top cover was developed. This allows a smooth handling of the calorimeter during experiments as well as the use of the calorimeter to analyze further processes like milling. A horizontal configuration of workpiece and tool was chosen to optimize the chip fall into the fluid, which is a basic requirement for measuring the exact temperature of the chips. The temperature is measured by three thermocouples at different positions of the calorimeter to quantify the temperature distribution in the fluid. To accelerate the process of thermal balance between chip and fluid, the system was dynamically stimulated by jerky movements of the machine axes. This aims to a uniform distribution of the chips within the calorimeter. First experimental tests validated the functionality of the calorimeter and demonstrated that dynamic axes movements accelerate the heat transfer from chip to the fluid substantially.

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