Konrad Wegener

• ETH Zurich

Coating thickness is considered to be one of the most important characteristics of thermal spray coatings. Therefore, it has long been the goal to be able to predict the coating thickness that ensues when coating an arbitrary part. A commonly applied approach is to determine the coating deposit based on a series of spray spot tests and use that for...

Finishing machining of Ti6Al4V, known for its high strength and heat conduction resistance, demands optimisation to achieve high-quality end products. This study explores modifying the chip contact length on the rake face and altering the flank face with a cavity to minimise process forces and temperatures while maintaining cutting edge integrity....

The numerical simulation of metal cutting processes requires material data for constitutive equations, which cannot be obtained with standard material testing procedures. Instead, inverse identifications of material parameters within numerical simulation models of the cutting experiment itself are necessary. This report presents the findings from a...

Machining of Ti6Al4V is considered difficult because the material removal rates are relatively small if the tool wear shall be low. In recent years the reduction of process forces as well as tool wear have been investigated by introducing textures (pockets) into the tool surface. To advance the understanding how those textured tools function and to...

This research investigates the anisotropic behavior of single crystalline diamonds (SCD) during ultra-short pulse (USP) laser machining. The ablation behavior of SCD synthesized by high-pressure high-temperature (HPHT) and chemical vapor deposition (CVD) methods is studied on their primary crystallographic planes: {100}, {110}, and {111}. The resul...

The fraction of materials that does not reach the target product in discrete manufacturing is very significant. Directing secondary material streams towards other manufacturing processes, possibly after intermediate pre-processing, offers opportunities for more energy and resource efficient recycling routes. This paper contributes to the exploratio...

The article presents the research findings on the process of machining with a pulsating water jet. The study determined the influence of water velocity and pressure, providing insights into the dynamics of pulsating water jets. An evaluation of the generation process of pulsating water jets was conducted for various models of self-excited pulsating...

In the context of directed energy deposition (DED), the production of complex components necessitates precise control of all processing parameters while mitigating undesirable factors like heat accumulation. This research seeks to explore and validate with various materials the impact of a geometry-based analytical model for minimizing heat input o...

The combination of Direct Metal Deposition (DMD) with milling offers numerous advantages for the manufacturing of complex geometry parts demanding high dimensional accuracy and surface quality. To reach this, a process strategy alternation between both processes is often required, leaving the milled surface with a layer of cooling fluid before addi...

This paper presents a physics-free Bayesian approach for the learning and inference of probabilistic stability charts in milling operations. The approach does not require any information from machine tool structural dynamics or cutting force coefficients, and the underlying learning algorithm can operate with limited training data. A Fully Bayesian...

Finishing machining of Ti6Al4V, known for its high strength and heat conduction resistance, demands optimisation to achieve high-quality end products. This study explores modifying the chip contact length on the rake face and altering the flank face with a cavity to minimise process forces and temperatures, while maintaining cutting edge integrity....

The selection of growth substrate geometries for the mechanical dry transfer of carbon nanotubes to device substrates depends on the precision of the assembly equipment. Since these geometries play a decisive role in the overall efficiency of the process, an investigation of the most important geometry parameters is carried out. The substrate geome...

Coating thickness is considered to be one of the most important characteristics of thermal spray coatings. Therefore, it has long been the goal to be able to predict the coating thickness that ensues when coating an arbitrary part. A commonly applied approach is to determine the coating deposit based on a series of spray spot tests and use that for...

The production of materials with a high affinity for oxidation using the direct metal deposition (DMD) process requires an extended process examination that goes beyond the usual, purely energetic consideration, with the aim of providing sufficient energy to melt the substrate and the powder material supplied. This is because the DMD process does n...

Short and ultrashort pulse lasers can ablate the vast majority of materials compared to other machining methods, making them the preferred tool in many niche applications. For the use in precision machining, such laser systems need to reach machining accuracy in the range of 1 µm. Usually, a galvanometric scanner is used in such laser systems to sc...

Additive manufacturing (AM) by using direct metal deposition (DMD) often causes erratic distortion patterns, especially on large parts. This study presents a systematic distortion analysis by employing numerical approaches using transient–thermal and structural simulations, experimental approaches using tomography, X-ray diffraction (XRD), and an a...

Nickel–titanium (NiTi) is a versatile material with unique inherent properties, such as shape recovery, superelasticity, and biocompatibility, that makes it suitable for various engineering applications. While NiTi can be additively manufactured using powder bed fusion for metals (PBF-LB/M), challenges arise due to the material sensitivity to proce...

Powder bed fusion of metals (PBF-LB/M) is currently the most widely adopted additive manufacturing technology for the fabrication of metal parts. However, the inconsistent quality of PBF-LB/M-manufactured parts and high costs for part certification are impeding wider industrial adoption. In-situ monitoring technologies are expected to enable proces...

The article provides a analysis of pulsating water jets, utilizing three distinct head models. It research the impact of tool geometry on water velocity and pressure scientifically. The emergence of vortices due to increased flow through additional holes is identified as the primary cause of the observed pulsations. Laboratory tests contributed mea...

Wire electrical discharge machining (WEDM) is a process that removes material from conductive workpieces by using sequential electrical discharges. The morphology of the craters formed by these discharges is influenced by various process parameters and affects the quality and efficiency of the machining. To understand and optimize the WEDM process,...

As the machine tool dynamics at the tooltip is a crucial input for chatter prediction, obtaining these dynamics for industrial applications is neither feasible through experimental impact testing for numerous tool-holder-spindle combinations nor feasible through physics-based modeling of the entire machine tool due to their sophisticated complexiti...

The efficient fabrication of titanium components using laser direct metal deposition (DMD) is gaining significant importance in the aerospace and medical sectors. The DMD process must be appropriately designed to address the issue of oxidation, as titanium exhibits a high affinity for oxygen. The carrier gas flow and shield gas flow, which have bee...

The ability of direct metal deposition (DMD) to fabricate complex geometries is still limited. Especially in thin-walled structures heat accumulation can lead to intolerable geometric deviation and which has to be avoided. Combining thin walls and massive sections in one layer requires parameter adapting for each section within a layer. An existing...

This study investigates the feasibility of using ultra-short pulsed (USP) lasers to fabricate single crystalline diamond (SCD) tools. SCD has exceptional mechanical, tribological, and thermal properties and offers excellent performance in the precision machining of hard and brittle materials over polycrystalline diamond and diamond-coated tools. Ho...

This study presents a comprehensive investigation and modeling of the ignition delay time (td) in wire-EDM (WEDM). The research focuses on the influence of gap distance, discharge energy, and piece height on the stochastic distributions of td, providing important insights into the complex properties of these distributions. Observations indicate tha...

Achieving target coating thickness is one of the main objectives in thermal spraying. Despite this, there is a lack of measurement methods that could evaluate in situ the coating thickness with a sufficient accuracy that could be used as a robust feedback signal for online, closed-loop process control. This paper presents a novel approach for in si...

Laser-based Powder Bed Fusion (LPBF) of oxide ceramics enables fabrication of objects with complex three-dimensional shapes. However, mechanical properties of dense LPBF-manufactured ceramics are poor due to large amount of structural defects. Here, we perform the operando tomographic microscopy during LPBF of a magnetite-modified alumina to gain a...

NiTi is a versatile material with a broad range of functional properties such as shape memory effect and superelasticity in combination with high internal damping capabilities and biocompatibility. Processing NiTi with powder bed fusion for metals (PBF-LB/M) enables new potential to solve engineering problems. Due to the layerwise manufacturing tec...

Additive manufacturing processes are among the most innovative manufacturing processes of this century. Powder-based direct metal deposition (DMD) is one of these processes. In the DMD process, local shielding takes place via the powder nozzle. The process is therefore critical for oxidation, especially for materials with an affinity for oxidation...

Rolling noise is a significant contributor to railway noise. Wheel and rail roughness are decisive for the emitted noise level. An optical measurement method installed on a moving train is suitable for closer monitoring of the rail surface condition. A measurement setup based on the chord method requires the sensors to be positioned in a straight l...

Hybrid additive manufacturing (AM) by direct metal deposition (DMD) and milling combines the advantages of both additive and subtractive processes for part fabrication. While the additive process ensures a high level of design flexibility and material efficiency, the consecutive milling steps realize the final surface quality. However, the great en...

Thermal errors are among the most significant contributors to deviations of products manufactured on modern machine tools (MTs). Reducing them is typically achieved through either design adaptation, active cooling of the MT and its environment, or compensation using measurements or model-based predictions. Model-based compensation strategies promis...

The Swiss-type lathe is a specialized turning machine of Swiss-origin with a wide range of applications across the precision machining industry. Its unique features enable it to mass produce parts at high speeds and with high precision. However, the complex non-symmetric structure of the machine tool makes it particularly susceptible to the adverse...

The aim of this publication is to develop a physical-rotordynamic model of a turbocompressor used in gas and oil production and to use it for predictive maintenance (pdM) purposes. The publication based on the programming of a suitable pdM algorithm. Real machine measurement data with a frequency of 0.0167Hz are used to infer the acting forces. The...

Coating thickness is considered to be one of the most important characteristics of thermally sprayed coatings. Despite this, there is a lack of a measurement method that could evaluate in situ the coating thickness with a sufficient accuracy that could be used as a feedback signal for online, closed-loop control. Offline methods that produce spatia...

This paper presents a hybrid Smoothed Particle Hydrodynamics (SPH) – Finite Element Method (FEM) solver for metal cutting simulations on Graphics Processing Units (GPU). For the first time in chip formation simulation, the heat transfer between an SPH model of the workpiece, and a transient FEM temperature model for the cutting tool, is established...

Silicon alumina nitride (SiAlON) and alumina toughened zirconia (ATZ) ceramics are applied for ceramic cutting tools to machine, e.g., cast iron, nickel base alloys and other difficult-to-machine materials. The state of the art technology for manufacturing of the cutting tool geometry is grinding. Laser processing of ceramics is already studied in...

Precision machinery employs a variety of materials for their structures: cast iron, welded steel, natural stone, ultra-high performance concrete (UHPC), and mineral cast (MC). Mineral cast is a composite material with an epoxy matrix and various aggregates as a filler, and has been successfully employed for precision machinery structures for over 3...

Production enterprises increasingly revert to digitization and data to gain insights and transparency in manufacturing environments. With the growing adoption of the Industrie 4.0 paradigm, the digital transformation of factories is in full swing. IIoT platforms, production management and manufacturing execution systems are installed in more and mo...

Single-objective multi-variable rotor dynamics optimization promotes the design of spindles in sustainable production. The goal is efficient partial automation of the design process and the optimization of the spindle shaft. The Timoshenko-Ehrenfest beam theory together with the Latin hypercube sampling and direct optimization methods are selected...

Since diamond-impregnated tools have a big share on tools for construction, the development of more efficient ones is necessary in the near future. The drilling speed performance is one of the concerns during the development of new diamond-impregnated segments in concrete core drilling. However, observations only based on experiments can be very co...

Coating thickness is considered to be one of the most important characteristics of thermally sprayed coatings. Therefore, it has long been the goal to be able to control it. This could be achieved by implementing an online, closed-loop control. A prerequisite for such a control mechanism is a feedback signal of the coating thickness with sufficient...

Burckhardt Compression Holding AG, based in Winterthur, is an internationally active manufacturer of reciprocating compressors who uses three-piece pistons in its Laby® reciprocating compressors. Due to their design for casting, the pistons have a high weight, which limits the size of the piston, particularly for the large diameters. For this reaso...

In-flight particle state parameters (PSPs) have been shown to play a crucial role in determining the properties of atmospheric plasma-sprayed coatings. Therefore, PSPs are frequently measured before starting a coating run as part of process control. This paper shows the importance of the measurement procedure used and subsequent data processing app...

Featured Application Rail roughness is measured optically to allow such a non-contact measuring system to be operated from the moving train. Abstract A large part of the noise emissions from rail traffic originates from rolling noise. This is significantly determined by the surface roughness of the wheel and the rail. To quantitatively assess the...

Grinding with metal-bonded cBN grinding tools enables a long lifetime without any need for redressing. However, the lifetime strongly varies and a precise estimation of the remaining number of parts to be machined is an essential contribution to efficient industrial manufacturing. Previous studies focus mainly on the separation of two or three tool...

The aim of this work is to present a new methodology for the automated analysis of the cross-sections of experimental chip shapes from orthogonal cutting experiments. It enables, based on image processing methods, the determination of average chip thicknesses, chip curling radii and for segmented chips the extraction of chip segmentation lengths, a...

Powder bed fusion of metals (PBF-LB/M) is the most commonly used additive manufacturing process for the layerwise production of metal parts. Although the technology has developed rapidly in recent years, manufactured parts still lack consistent quality primarily owing to process-inherent variability, and the lack of effective sensing technologies e...

An accurate description of machine tool dynamics is essential for health monitoring, chatter prevention, and improvement of manufacturing accuracy. The standard identification approach of experimental modal analysis at the standstill of the machine does not realize the possible variations in the dynamics due to operational conditions. The in-proces...

Superabrasives like synthetic diamonds are indispensable in today’s construction industry, particularly for core drilling applications in reinforced concrete. The increase of the cutting efficiency of such core bits strongly depends on the material removal behavior of single diamond grains placed in a diamond segment acting as cutting elements. The...

Mobility and artificial intelligence are the key drivers for the semiconductor industry. The requirements for high-performance chips are constantly increasing and technologies, such as ultra-precision machining, are necessary for this value chain of manufacturing. The exact bearing of rotating axes is one of the main tasks to produce precision work...

The study presents a coupled cellular automata (CA) approach for a single track microstructure simulation for laser conduction welding. A high-power CO2 laser beam (1000 W) traverses the substrate, with the beam shaped by conventional optics, which produces a Gaussian profile. The process parameters produce a shallow melt phase maintaining a conduc...

In Wire Electrical Discharge Machining (WEDM) the erosion process is based on the superposition of craters. The plasma channel and the craters’ shape have an impact on the process and on the characteristics of the machined surface. This impact goes from the cutting speed to the surface roughness passing through workpiece temperature gradient during...

Powder bed fusion is a layer-wise manufacturing technique and emerging technology capable of manufacturing highly customized and complex shapes. Due to the layerwise process characteristic, powder bed fusion has high potential to enable access to each cross section during the manufacturing process. Thus, the integration of 3-dimensional objects can...

Numerical simulation of melt pool behavior during laser powder bed fusion (LPBF) is essential to provide more effective control of the process and choose an optimal set of input parameters for defect-free fabrication. In this work, we use the smoothed particle hydrodynamics (SPH) method to investigate the impact of laser power and scan speed on the...

The conference on electro, physical and chemical machining happened as ISEM XXI again in Zurich and was actually meant to become a full presence conference. The COVID-19 situation enforced again at least a hybrid conference, where approximately 40% of the contributions were made via internet. ISEM covers different manufacturing processes that have...