To improve machining processes concerning the usage of lubricants, knowledge of the thermo-mechanical and thermo-fluid interactions at the cutting zone is of great importance. This study focuses on the description of the convective heat transfer which occurs during circular sawing when the lubricant is provided via an internal coolant supply. The highly complex flow field inside the cavity of the sawing process is separated into two distinct flow forms, an impingement and a channel flow. With the aid of experimental and numerical studies, the heat transfer characteristics of these two flow forms have been examined for water and a lubricant used in the circular sawing process. Studies have been conducted over a wide range of Reynolds numbers (impingement flow: $2\times {10}^3<\mathrm{Re}<17\times {10}^3$, channel flow: $1\times {10}^3<\mathrm{Re}<30\times {10}^3$). Additionally, the variation in the inlet temperature of the fluid, as well as the variation in heating power, has been studied. Overall, the impingement flow yields a significantly higher heat transfer than the channel flow with Nußelt-numbers ranging from 120 to 230, whereas the Nußelt-numbers in the case of the channel flow range from 20 to 160. For both flow forms, the use of the lubricant results in a better heat transfer compared with the usage of water. With the aid of these studies, correlations to describe the heat transfer have been derived. The provided correlations are to be used in a coupled numerical model of the chip formation process which also includes the effects of the heat transfer to the coolant lubricant.

The mechanical energy resulting from cutting processes is turned almost completely in thermal energy, which encourages thermal procedures, such as diffusion, leading to higher wear in the cutting tool and thus to higher temperatures. Furthermore, high temperatures influence the properties of the marginal zones in the workpiece. In this presented work, the in-process temperature of a cutting insert during single-lip deep hole drilling (SLD) is investigated. Therefore, a sensor-integrated tool with resistance temperature detectors (RTD) placed beneath the cutting insert is developed. First, the thermal properties of the cutting insert are adjusted to fit the assembled tool. Afterwards, a CEL-Simulation is obtained to examine the temperature distribution at the cutting edge of the SLD-tool. The temperatures calculated by simulation can be compared to the in-process temperatures of the sensor integrated tool. Because of the usage of a cooling lubricant, simulated temperatures can be varied with a factor to fit the experimentally measured temperature curves. The highest temperature during the process appears at the outer edge of the cutting insert. By knowing the thermal properties, the maximum process temperatures for the deep hole drilling operation are to be calculated. The results represent a contribution to an interdisciplinary research project “Surface Conditioning in Machining Processes” (SPP 2086) of the German Research Foundation (DFG).

The increasing demands in manufacturing technology require continuous improvement of machining processes. The use of internal coolant supply (ICS) has led to enhanced efficiency in circular sawing by enabling more uniform chip cooling, particularly when machining difficult-to-cut materials. However, integrating coolant channels into the thin-walled core bodies of the circular saw blade poses significant manufacturing challenges and introduces additional risks in circular saw blade production. To reduce manufacturing effort, this study aims to improve the geometry of circular saw blades for ICS-based machining using numerical flow simulation. In particular, the investigation focuses on modifying the inflow geometry to reduce the number of coolant channels required to improve the process and establish an enhanced fluid flow between the chip spaces of the saw blade. Various inlet conditions and geometric configurations are analyzed and evaluated regarding the ability to supply chip spaces with no direct cooling channel with respect to their manufacturing complexity.

Circular sawing of Ti6Al4V presents significant challenges due to high tool wear and unstable chip formation, both of which are strongly influenced by frictional conditions at the tool-workpiece interface. As the friction coefficient is known to impact the contact length, temperature at the tool-chip interface and chip morphology, friction coefficients are of great interest. First, a two-dimensional cutting simulation was performed to estimate contact pressures and sliding speeds occurring during the cutting process. The friction coefficients were then identified for the secondary shear zone at machining-relevant sliding speeds and contact pressure using a pin-on-disk tribometer. A velocity dependent friction model is identified for uncoated carbide and Ti6Al4V serving as input for a three-dimensional sawing simulation, in which friction at the upper tool wall is varied systematically. The simulations revealed that changes in the local friction coefficient significantly affected chip morphology until the process reliability is also affected by oscillating chip formation. These results highlight the critical role of frictional properties in determining process stability during circular sawing of titanium alloys and they provide a foundation for improving tool design and cutting conditions in high-performance machining applications.