Dirk Biermann

• Prof. Dr.-Ing. Prof. h.c.
• Head of Department at TU Dortmund University

Disturbance factors, such as self-excited tool vibrations, limit the performance of modern machining processes and thus restrict the quality, productivity, and sustainability of industrially manufactured components. Tools with functional flank-face structures as well as asymmetric dynamic properties represent two approaches that are capable of redu...

The ultimate pressure and efficiency of positive displacement vacuum pumps is limited by the backflow through the gaps within the machines. These gap flows are typically reduced by decreasing the gap height, which is limited for reasons of operational safety. Therefore, this study concentrates on the reduction of rarefied gap flows by means of suit...

Due to complex interrelations between process configurations, tool characteristics and process results, the design of microfinishing operations is challenging. Microfinishing is often conducted to generate high surface qualities and shape accuracies of highly loaded components. For some applications, e.g. bearing seats, the contact surface is desir...

In milling processes in which material removal is performed periodically from solid material, dynamic effects are generally considered to be responsible for instabilities and subsequent productivity limits. Usually, in such applications, the process-inherent complex dynamic load spectrum on machines, tools and workpieces is considered together with...

Using cooling lubricants in metalworking requires a high consumption of energy and resources. However, cooling lubricants serve to increase the productivity and quality of these processes. Accordingly, it is necessary to expand the efficiency of their application. This requires fundamental understanding of the working mechanisms. Driven by this mot...

The clearance flow in dry-running vacuum pumps is the main loss mechanism. To reduce the clearance mass flow rate in rarefied gas flows, sawtooth structures transversing to the direction of flow can be utilized. However, due to the sawtooth’s structure size, micro-machining is necessary, whereby burr formation is a central challenge. First, the eff...

Ejector deep hole drilling achieves high-quality boreholes in production processes. High feed rates are applied to ensure a high productivity level, requiring reliable chip removal from the cutting zone for a stable process. Therefore, a constant metalworking fluid flow under high volume flow rates or high pressure is required. Experimental results...

Cutting edge preparation is an established approach in the field of machining technology for optimizing the performance of cutting tools. However, the potential of asymmetric geometries has not yet been sufficiently utilized for filigree micromilling tools. In this regard, the study presents investigations on the adjustment of asymmetric microgeome...

The surface integrity of machined components affects their fatigue performance and service life. Thus, with a view to sustainability and resource efficiency, aspects that influence the nature of the workpiece surface and sub-surface are increasingly considered in the process design, such as the resulting microhardness or the residual stress state....

Nickel-based alloys are known to mount intense heat around the cutting edges of the cutting tool owing to their high yield strength, comparatively low thermal conductivity, and a significant seizure of the chip at the rake face even at low cutting speeds. Their sustainable machining demands a highly effective heat dissipation system. Due to its ric...

Honing operations, e.g. microfinishing, are resulting in high quality surfaces with a roughness values, e.g., average roughness Ra, of only a few micro- to nanometer [1]. The simulation of honing processes can be beneficial to reduce experimental effort in terms of determining suitable process parameters for such processes. Various aspects of the f...

Machining nickel-based super alloys such as Inconel 718 generates a high thermal load induced via friction and plastic deformation, causing these alloys to be among most difficult-to-cut materials. Localized heat generation occurring in machining induces high temperature gradients. Experimental techniques for determining cutting tool temperature ar...

Disturbance factors, such as self-excited tool vibrations, limit the performance of modern machining processes and thus restrict the quality, productivity and sustainability of industrially manufactured components. The dynamic process stability is subjected to significant variances especially at the beginning of the tool life. To precisely quantify...

In machining, tool temperatures and thus tool wear are significantly influenced by frictional behaviour. Friction tests are used to determine the friction coefficient depending on relative speed, which serves as basis for parameterising friction models as input data for chip formation simulations. Therefore, this paper represents investigations tow...

In the machining process, the buildup of heat around the cutting edge significantly impacts the outcome, causing adverse effects like micro-cracks, heightened tool wear, and diminished surface quality of the workpiece. To counter these challenges, the application of cutting fluids, particularly through flood cooling, is a common practice. However,...

Ultra-short Pulse Laser (USPL) has a wide range of applications in industrial sections. Among them is the workpiece surface pre-structuring before machining to reduce the process forces and temperature. Laser pre-structuring removes a section of workpiece material and induces controlled subsurface damages, improving the achievable Material Removal...

This article presents a patented approach for the fluid-mechanical and thermodynamic improvement of screw spindle vacuum pumps [Brü21]. These machines belong to the group of rotary positive displacement vacuum pumps and have two parallel rotors that convey the gas along the rotor axes. Chambers are formed between the rotors and the surrounding hous...

Micromilling tools face significant challenges in achieving cutting edge preparation by mechanical processes due to their small size. To address these limitations, a new approach for cutting edge preparation of micro end mills by physical vapor deposition (PVD) etching technology is presented. By adapting the etching strategy, which is conventional...

When bores with high length-to-diameter ratios (l/D > 10) and large diameters (D > 40 mm) are required, usually, the Boring and Trepanning Association (BTA) deep hole drilling process is used. Common industrial applications of this process are aerospace engineering and petrol exploration, where drilled components range from landing gears and engine...

Inhalt Bisher ist es nicht möglich, Innenkonturen in Bauteilen mit kleinen Bohrungen auch in großer Bohrungstiefe einzubringen. Insbesondere das Innendrehen ist nur in geringen Bearbeitungstiefen umsetzbar, größere Tiefen können mit anderen Systemen lediglich ab einem Durchmesser von D = 40 mm erreicht werden. Aus diesem Grund erfolgten die Konstru...

The process design for the manufacturing of surface structures with functional tribological properties is a major challenge when machining workpieces with freeform surfaces. Distortion effects of the structures and limitation of CAD/CAM-systems require the development of novel technological solutions. The paper presents a new approach for designing...

The manufacturing of internal thread using the helical thread forming process (Punch Tap) as a novel high-performance manufacturing technology provides high productivity by reducing the tool path, which can save manufacturing time up to 75% compared to the conventional thread forming process. For instance, cast gearboxes in the transport sector con...

Both conventional processes such as internal turning and special processes such as bottle boring do not allow complex internal machining of small bores at large depths. For this reason, a new type of tool system is being developed for internal contouring of small diameters even at large machining depths. In a first development step, preliminary inv...

The application of sensor technology for monitoring and analysing manufacturing processes is becoming increasingly important and is well established for manufacturing processes with geometrically defined cutting edges. However, in grinding processes such as internal grinding, the use of sensor-based tool holders reaches its limits. Especially in th...

In context of industrial mass production, innovative machining technologies offer a potential for significant gain of efficiency and sustainability. Whereas in conventional tapping processes the tool moves in and out in sync with the thread pitch, the kinematics of the novel helical thread forming technology allows to reduce the process time by hal...

The productivity of machining processes is often limited by the occurrence of dynamic effects. The investigated approach intends to counteract tool deflections, and thus to damp and disrupt chatter vibrations by using milling tools with defined functional structures on the flank faces at the frontal cutting edges. For the fundamental investigation...

Heat accumulated around the cutting edge significantly impacts the machining process. It results in microcracks development, tool wear enhancement, and work surface quality deterioration. These issues can be somewhat counteracted by applying a cutting fluid at the cutting zones through flood cooling. Cutting fluid waste, however, can be significant...

Metalworking operations rely on the successful application of metalworking fluids (MWFs) for effective and efficient operation. Processes such as grinding or drilling often require the use of MWFs for cooling, lubrication, and chip removal. Electrochemical machining processes require electrolyte flow to operate. However, in those machining operatio...

With respect to post-processing techniques in the field of surface engineering, it was recently found that machine hammer peening (MHP) represents a promising approach to functionalizing thermally sprayed coatings as the MHP contributes to a compression of the coating, enabling the potential to reduce the coating porosity as well as the protruding...

The effect of process damping in machining is an effective influencing factor for the suppression of regenerative chatter vibrations. Although process damping is typically associated with process configurations at low cutting speeds, the use of tools with flank face chamfers is a suitable strategy to specifically increase process stability over a w...

The novel process strategy of discontinuous drilling of Inconel 718 was designed to reduce thermomechanical wear at the cutting edges. The development is supported by creating a CFD simulation predicting the characteristics of the coolant flow during the drilling process. In this context, a validation of this simulation is required to build the fou...

Manufacturing the internal thread in lightweight components using chipless flow drilling and internal thread forming processes can reduce material and time consumption. Furthermore, using these methods imposes a further work-hardening into the subsurface of the formed thread profiles and consequently improves the thread strength. While the required...

The development of an optimized discontinuous drilling process of Inconel 718 with reduced thermal loads is supported by a CFD simulation, whose application already resulted in improvements of coolant flow. To consider the heat flow from the chip formation into the tool and the fluid, the numerical model must be expanded by a FEM chip formation sim...

In machining, high mechanical and thermal loads are exerted on a small area of the tool where it interacts with the workpiece. Despite limited interaction space, extensive use of cutting fluids (CFs) is inefficiently used to improve the machining process and increase productivity. In order to minimize CFs’ negative impact on health, environment and...

Continuous technological advancements in the field of grinding technology and improved grinding tools have contributed to the development of high performance grinding processes. One example of such a process is internal traverse grinding (ITG) with electroplated cBN grinding wheels, where the tool consists of a conical roughing zone and a cylindric...

Nickel‐based alloys, like Inconel 718, are widely used in industrial applications due to their high‐temperature strength and high toughness. However, machining such alloys is a challenging task because of high thermal loads at the cutting edge and thus extensive tool wear is expected. Consequently, the development of new process strategies is neede...

Sustainability is an increasingly important trend, giving great potential in industrial production to save resources and energy. This paper presents fundamental research results on the reduction of cutting-tool consumption and saving on workpiece-material. For the basis of a new wear model, explicit knowledge of the thermo-mechanical loads and rela...

In modern manufacturing processes, the environmental impact becomes an increasingly important aspect. The aim of developing new coolant strategies is therefore an approach to increase the efficiency of the machining process while reducing coolant consumption. The priority is to optimize the supply of coolant to the tool-workpiece interface. In case...

Due to the attractive material properties such as high specific strength and very good corrosion resistance, titanium and its alloys are frequently used in the aerospace, automotive and chemical industries. However, the low thermal conductivity leads to high thermomechanical tool loads during machining, making an optimal cooling lubricant supply to...

The difficulties in the mechanical micro-machining process regarding the tool deflection, size effect and tool wear are much more pronounced than those in mechanical macro-machining. However, the role of mechanical micro-machining cannot be overestimated as an alternative against the non-traditional machining methods in manufacturing complex micro-...

Today, simulation of cutting processes still relies, in most cases, on the phenomenological representation of flow stress properties of workpiece materials. This investigation presents a physics-based (dislocation-based) constitutive model to simulate the flow stress properties of Ti6Al4V titanium alloy at elevated temperatures and a large range of...

Die Untersuchungen vergleichen das Einlaufverhalten metallisch gebundener Diamant-Microfinishwerkzeuge in unterschiedlichen Konditionierzuständen. Die Analyse erfolgt werkstück-, prozess- als auch werkzeugseitig anhand von Oberflächengüte, Prozesskräften und Werkzeugtopographie. Hierdurch wird die Wirkung der Konditionierzustände auf das Einlaufver...

The increasing demand for functional lightweight components, in order to reduce CO2 emissions in the automotive and aerospace industries, for example, inevitably involves the use of high performance materials or increased component complexity. This is equally accompanied by increased demands on the cutting tools and the machine tools to ensure a co...

In micromachining, the manufacturing quality of the cutting tools as well as the condition of the cutting edges play a major role. However, achieving the desired quality of the micro cutting tools has been very challenging in the conventional grinding processes. A new approach for manufacturing micro cutting tools by precise electrochemical machini...

The large tool length in BTA deep hole drilling often leads to strong torsional vibrations of the tool system, leading to a reduced bore hole quality failures. When substituting steel drill tubes with tubes from composite material, the laminate structure dampens these vibrations. Secondly, the integration of sensors allow to monitor process vibrati...

The aim of this study is to evaluate impact of varying core hole diameters on resulting thread quality for helical thread forming. Regarding to common applications in mass production of engine casings in automotive industy, the experiments were performed in AlSi10MnMg cast alloy and thread size M6. Regarding the forming process by analysis of mecha...

The characteristic segmented chip formation of titanium alloy Ti6Al4V leads to a periodic excitation and therefore to vibrations during the process. One way to avoid these chip formation induced vibrations is to position a counter element, the constraint, in front of the primary shear zone which suppresses the segmentation mechanism. In this paper,...

Surface structuring offers great potential for modifying frictional properties for various applications, such as complex forming processes like sheet-bulk metal forming. The production of surface structures in micrometre range is challenging for manufacturing processes in particular when machining hard-to-cut materials like hardened tool steels. Pr...

Hot forming processes of complex parts with small cavities demand high-performance tools made of hardened steels. Their surface can be tribologically modified in order to control the material flow for improving the mold filling of functional elements. Surface structuring here offers great potential for adjusting the frictional properties and thus c...

Continuous technological advancements in the field of grinding technology have led to the development of high performance processes. One example of such a process is internal traverse grinding (ITG), where the tool consists of a conical roughing zone and a cylindrical finishing zone. The tool is fed in axial direction into a revolving workpiece, re...

Deep drilling with smallest diameters is used for applications such as automotive, aerospace and medicine. Especially difficult to cut materials require an efficient tool design to realize an economical production. Therefore, combined simulation methods are used in this paper to analyze the fluid behavior under consideration of the transient chip p...

The residual stress state in the subsurface is a key element of surface integrity. It is well known to have a significant impact on a component’s properties in terms of fatigue behavior and resistance to wear and corrosion. For this reason, adjusting residual stresses during manufacturing is a major challenge in modern production engineering, to im...

For single-lip drills with small diameters, the cutting fluid is supplied through a kidney-shaped cooling channel inside the tool. In addition to reducing friction, the cutting fluid is also important for the dissipation of heat at the cutting edge and for the chip removal. However, in previous investigations of single-lip drills, it was observed t...

The surface integrity of components is decisive for their fatigue strength and is significantly influenced by applied machining processes. Particularly in drilling, the used coolant strategy affects the process stability and the surface quality produced due to its contribution to chip evacuation and the cooling and lubricating effect of the cutting...

The surface integrity is crucial for the capability of machined parts; therefore, a detailed characterization of the obtained microstructure is very important for the assessment of machining processes. In this paper, the microstructure of single-lip deep drilled specimen, especially the formation of white etching layers (WEL), is considered by micr...

The BTA deep hole drilling process is used to machine deep bores with a large diameter. The cutting process, consisting of the material removal by cutting edge and the surface burnishing by the guidepads influence the surface of the bore. To separate the impact of the cutting edge from that of the guidepads on the surface of the bore and the subsur...

Ejector deep hole drilling is required for a variety of drilling applications with length-to-diameter-ratios larger than l/D > 10 and high quality demands, e.g. on roundness, diameter accuracy and surface quality. The ejector effect is essential for the process and decisive for a stable ejector deep hole drilling process by supplying the working zo...

To machine bores with larger diameters (D > 40mm) and a length to diameter ratio greater than ten (lb/D > 10) the BTA deep hole drilling process is often used. The cutting action of the cutting edge and the burnishing of the guide pads influence the resulting surface and the subsurface zone of the machined bore. The guide pads support the BTA drill...

Diamond impregnated tools for core drilling consist of segments in which synthetical diamonds are bounded in a metal matrix. The wear of these tools depends on the time points when active diamonds breakout and new diamonds from deeper layers of the metal matrix become active. Up to now, these time points were measured only by visual inspection at g...

High flexibility of the micro-milling process compared to nontraditional methods has led to its growing application in manufacturing complex micro-parts with tight tolerances and high accuracies. However, difficulties such as tool deflection, size effect, and tool wear limit the application of micro-milling. In this regard, the role of laser-assist...

Additional to the conventional requirements for the component quality, the residual stress state of the sub-surface is becoming increasingly important as it affects the fatigue and wear behaviour of the component. First results indicate that micromilling allows the induction of high residual compressive stresses to increase the component's service...

Anchorage to concrete is a recurring application in construction. For such applications, bonded anchors, formed by means of a polymer adhesive injection into a borehole, are a widely used product due to their flexibility in regards to the construction logistics and positioning of the attached element as well as high load capacities. At the same tim...

The Boring Trepanning Association (BTA) deep hole drilling process is frequently employed for machining bores with a high length-to-diameter ratio and diameters larger than 6 mm. Typical applications of BTA deep hole-drilled components include the production of drill collars, hydraulic cylinders and highly safety-critical parts like the landing gea...