Alexander Krämer

Bio: Alexander Krämer is an academic researcher from RWTH Aachen University. The author has contributed to research in topics: Tool wear & Machining. The author has an hindex of 7, co-authored 18 publications receiving 212 citations.

Influence of a High-Pressure Lubricoolant Supply on Thermo-Mechanical Tool Load and Tool Wear Behaviour in the Turning of Aerospace Materials:

Abstract: In the field of machining difficult-to-cut materials like titanium or nickel-based alloys, the use of a high-pressure lubricoolant supply may result in a significant increase of productivity and pr...

Influence of the lubricoolant strategy on thermo-mechanical tool load

Abstract: This paper deals with the influence of the cooling strategy on thermo-mechanical tool load during turning of different hard-to-cut materials. The aim is to describe how to control the complex of loads acting on the cutting edge to achieve suitable conditions for different combinations of cutting tool material and workpiece material. As an introduction, measurements and analysis of tool temperature, cutting forces and wear behaviour during turning of TiAl6V4 and Inconel 718 with cemented carbide and high-pressure lubricoolant supply are presented. Based on these results the tool wear behaviour of whisker reinforced cutting ceramics during turning of Inconel 718 with high-pressure lubricoolant supply and conventional flood cooling is evaluated. Additionally this paper presents results of tool temperature, cutting forces and wear behaviour during turning of TiAl6V4 with cemented carbide under cryogenic conditions (LN2 and CO2-snow). The results of the tests under cryogenic conditions will be brought in line with the results of the high-pressure coolant supply. Thereby it is possible to qualify the amount of different wear mechanisms onto the total tool wear under different cooling conditions and to show how they can be influenced specifically.

Potential of Modern Lubricoolant Strategies on Cutting Performance

Abstract: Besides developments in the area of dry machining and minimum quantity lubrication, the use of coolant lubricants is still essential when machining high alloyed steels or heat resistant materials like titanium and nickel based alloys. Experts agree that this fact will not change in the next decade. For this reason it is necessary to use coolant lubricants as effectively as possible to maximise their positive effect on productivity and process stability. High-performance cooling strategies like high-pressure cooling and cooling with cold gases (cryogenic cooling) have received increased attention in the last years. Through the targeted supply of coolant lubricants to the cutting site it is possible to decrease tool wear, increase cutting speeds, guarantee defined chip breakage and chip transport and – in terms of cryogenic cooling – waive part cleaning. This paper shows current research results in the above mentioned field. Since the performance of a high-pressure coolant lubricant supply in turning difficult to cut materials has been shown in many previous papers, this paper focuses on the quantification of the potential in turning different steels, namely quenched and tempered but also stainless steel in comparison to the conventional flood cooling. Since energy efficiency is very crucial, pressure and flow rate have to be adjusted carefully and in accordance with the cutting parameters to guarantee best results with less energy. Moreover the effects of cryogenic cooling will be evaluated in comparison to high-pressure cooling and conventional flood cooling. In latter field, cutting tests were carried out under variation of the flow rate in order to find the minimum required value for a certain machining task with the overall aim to prevent waste of the media used. Especially in cryogenic cooling technologies, many fundamental research regarding the working mechanisms but also further developments in cutting tool and machine tool technology are still necessary to make this technology ready for industrial use.

High performance cutting of advanced aerospace alloys and composite materials

Abstract: This paper presents an overview of the recent advances in high performance cutting of aerospace alloys and composite currently used in aeroengine and aerostructure applications. Progress in cutting tool development and its effect on tool wear and surface integrity characteristics of difficult to machine materials such as nickel based alloys, titanium and composites is presented. Further, advances in cutting technologies are discussed, focusing on the role of hybrid machining processes and cooling strategies (MQL, high pressure coolant, cryogenic) on machining performance. Finally, industrial perspectives are provided in the context of machining specific components where future challenges are discussed.

Cryogenic manufacturing processes

Abstract: Cryogenically assisted manufacturing processes are emerging as environmentally-benign, toxic-free, hazardless operations, producing functionally superior products. This paper presents an overview of major cryogenic manufacturing processes, summarizing the state-of-the-art and significant developments during the last few decades. It begins with a summary of historic perspectives, including definitions, scope, and proceeds to analysis of process mechanics and material performance covering tribological and thermo-mechanical interactions, followed by surface integrity, product quality and performance in cryogenic manufacturing. Process analysis and applications includes machining, forming and grinding. Economic, safety and health issues are then discussed. Finally, progress in developing predictive performance models and future outlook are presented.