Deep hole drilling processes for high-alloyed materials are characterised by worn guide pads and chatter vibrations. In order to increase feed rates, process stability and bore quality in STS deep ...hole drilling, various investigations were carried out with adjustments to the tool. First, a new process chain for the production of tribologically optimised guide pads and their effects on the guide pad shape is described in detail. The results of these studies show that the shape change in the area of the axial run-in chamfer through a micro finishing process leads to a better bore hole quality. Furthermore, the influence of guide pad coating and cooling lubricant on the deep hole drilling process was investigated. In addition, the machining of the austenitic steel AISI 304 is analysed by using a conventional steel boring bar and an innovative carbon fibre reinforced plastic (CFRP)-boring bar. While the conventional drill tube oscillates with different eigenfrequencies, the CFRP-boring bar damps chatter vibrations of the drill head and stabilises the process. Even at higher feed rates up to
f
= 0.3 mm, it is possible to machine austenitic, difficult-to-cut-materials with significantly reduced vibrations.
In order to increase the cooling effect when drilling the nickel-based alloy Inconel 718, low-temperature emulsion below the freezing point is used as cooling lubricant in a novel concept. For this ...purpose, a freeze-resistant emulsion and an adapted coolant circuit were developed for the use on a machining centre. The technological analyses of drilling with a solid carbide drill include the influence on the tool, the workpiece and the machine periphery at different coolant temperatures.
Due to their low thermal conductivity, nickel-based alloys can cause an increased thermal energy flow to the cutting tool during machining. This may result in intensive tool wear and a poor bore ...quality. In order to increase the process cooling during drilling, a new concept has been developed to supply a cooled emulsion at temperatures of T ≈ -20 °C to the process under high pressure. Therefore, a low-temperature emulsion itself and a circuit for the supply of the emulsion were developed. This should enable a higher productivity as well as component quality.
High interstitial austenitic stainless CrMn steels are characterised by significantly increased work hardening ability and strength compared with conventional CrNi austenites, yet maintaining very ...high ductility and toughness. The machining of high interstitial CrMnCN steels is challenging in terms of process stability and economic efficiency. In this context, unfavourable chip forms, high thermomechanical loads and the superposition of different wear mechanisms in particular lead to challenges in turning operations. In the following article, different lubricant strategies are analysed for machining of CrMnN and CrMnCN austenitic stainless steels regarding chip form, mechanical tool loads and wear. Furthermore, the workpiece properties are considered with regard to surface roughness and microstructural changes.
High interstitial austenitic stainless CrMn steels are characterised by significantly increased work hardening ability and strength compared with conventional CrNi austenites, yet maintaining very ...high ductility and toughness. The machining of high interstitial CrMnCN steels is challenging in terms of process stability and economic efficiency. In this context, unfavourable chip forms, high thermomechanical loads and the superposition of different wear mechanisms in particular lead to challenges in turning operations. In the following article, different lubricant strategies are analysed for machining of CrMnN and CrMnCN austenitic stainless steels regarding chip form, mechanical tool loads and wear. Furthermore, the workpiece properties are considered with regard to surface roughness and microstructural changes. Keywords High-strength materials; stainless austenitic steels; cooling lubricants; corrosion resistance; Interstitials; work hardening; turning Nichtrostende, austenitische CrMn-Stahle zeichnen sich durch ein deutlich hoheres Kaltverfestigungsvermogen und sowie eine gesteigerte Festigkeit im Vergleich zu konventionellen CrNi-Austeniten aus, wobei sie eine sehr hohe Duktilitat und Zahigkeit aufweisen. Die Zerspanung von CrMnCN-Stahlen gestaltet sich in Bezug auf Prozessstabilitat und Wirtschaftlichkeit dabei als sehr herausfordernd. In diesem Zusammenhang fuhren insbesondere ungunstige Spanformen, hohe thermomechanische Belastungen und die Uberlagerung verschiedener Verschleissmechanismen zu Herausforderungen bei der Drehbearbeitung. Nachfolgend werden zwei unterschiedliche Schmierstoffstrategien fur die Zerspanung von austenitischen CrMnN--und CrMnCNEdelstahlen hinsichtlich Spanform, mechanischer Werkzeugbelastung und Verschleiss analysiert. Daruber hinaus werden die Werkstuckeigenschaften im Hinblick auf Oberflachenrauheit und Gefugeveranderungen betrachtet. Schlusselworter Hochfeste Werkstoffe; Nichtrostender, austenitischer Stahl; Kuhlschmierstoffe; Korrosionsbestandigkeit; Interstitielle Elemente; Kaltverfestigung; Drehbearbeitung
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