Performance of carbide tools in high-speed dry turning iron-based superalloys

Machining quality and productivity of superalloys are limited due to their poor machinability, and fewer studies have focused on the cutting of iron-based superalloys. In this study, the cutting performance of coated and uncoated carbide tools in high-speed dry turning iron-based superalloy GH2132 was investigated by performing a series of cutting experiments. The experimental results indicated that cutting temperature and cutting forces increased, while tool life decreased with the increase in the cutting speed from 30 to 100 m/min. Under relatively low cutting speeds, flank face wear was dominated by abrasion and adhesion, while rake face wear mainly involved built-up edge (BUE), built-up layer (BUL), adhesion, and breakage near the depth of cut. Under higher cutting speed, adhesion wear was more serious on the flank face, and peeling off of the coatings and substrate occurred on the rake face. Owing to the protective effect of (Ti, Al)N + TiN coating, the coated tools exhibited better wear resistance and thus longer tool life, in particular, under higher cutting speeds. Analysis of the tool wear gap in the horizontal direction indicates that better dimensional accuracy could be obtained when coated tools are used. In dry turning of GH2132 with carbide tools, a favorable surface finish could be obtained. The surface roughness roughly showed a tendency to first decrease and then increase with the increase in average flank wear. The coated tools should be avoided to machine GH2132 at higher cutting speed due to the poor surface finish.

The Effect of Cutting Speed on the Ploughing Forces

The ploughing forces (PFs) are one of the important parameters for calculating the tool life. They directly affect the stress on the tool flank face and are responsible for wear and tear conditions of the cutting tool as well. In this study we attempted to find the impact of cutting speed on PFs, that is, the relation between cutting speed and PFs. In this paper, the ploughing forces were estimated by a new comparison method in which forces at different point of contact areas are added (sum of forces) to get the PFs accurately. The accuracy of PFs estimated with this method will be better than previously used methods. This paper presents the measurement results of the PFs when turning stainless steel, structural steel and aluminum alloy materials. The results of experimental studies showed that an increase in cutting speed ranging from 50 to 200 m/min resulted in increase in PFs by 1.4–3.2 times when turning with different flank wears.

Research on the Cutting Principle and Tool Design of Gear Skiving Based on the Theory of Conjugate Surface

Tool design is one of the key factors that restrict the development of gear skiving technology since the design principle does not correspond to the cutting principle. The existing skiving tool cannot achieve ideal machining accuracy and reasonable cutting angles. In view of this, some research has been done in this paper. Firstly, the skiving principle is investigated essentially according to the skiving motions. Then, the principle of tool design is analyzed based on the theory of conjugate surface, and a new tool design method is proposed to match the skiving principle. For this, all the skiving patterns for various kinds of workpieces are enumerated and summarized to abstract a normalized skiving model. Based on this, the mathematical model of the conjugate surface is then derived to lay the foundation for tool design. Then, the design methods of cutting edge, rake face, and flank face are proposed. An example is presented at last, and the cutting simulation is conducted. The result proves that the proposed methods are correct and valid. The theoretical research in this paper could promote the improvement of skiving tools.

The Research of Tool Wear Mechanism for High-Speed Milling ADC12 Aluminum Alloy Considering the Cutting Force Effect

Tool wear is a major cause of accelerated tool failure during the milling of aluminum alloy. The periodically cutting force directly affect the cutting heat and tool wear due to the intermittent cutting characteristics of the milling process. The focus of this paper is to analyze the influence of the variation of cutting force on tool wear behavior. The change law of cutting force by cutting parameters was analyzed firstly. Secondly, the variation of the wear land width (VB) of tool flank face by the milling length was analyzed. Thirdly, the wear morphology and the energy dispersive spectrometer (EDS) results of tool rake face and flank face in different cutting parameters were observed by tungsten filament scanning electron microscope. Finally, considering the cutting force effect, the tool wear mechanism during high-speed milling of Aluminum-Alloy Die Castings 12 (ADC12, 12 means aluminum number 12) was analyzed. The cutting force in tangential direction is predominant during high-speed milling aluminum alloy, which decreases gradually with the increase of cutting speed but increases gradually with the feed rising. The adhesion-oxidation wear was main wear mechanism of tool rake face during high-speed milling. While adhesive wear was the main wear mechanism of the tool flank face during high-speed milling. It is found that the formation of adhesive wear is the process from particle adhesion to melting until the formation of adhesive layer, which related to the change of cutting force.

Additive surface texturing of cutting tools using pulsed laser implantation with hard ceramic particles

In recent years surface texturing of the cutting tools has proved to improve tribological characteristics at tool/chip and tool/workpiece interface and help to reduce cutting and feed forces as well as tool wear. Most, if not all, of the studies have focused on subtractively made textures whereby the material is removed from the surface. This study investigates the performance of additively made surface structures whereby hard ceramic particles are dispersed in the form of dome shaped textures on the surface of the cutting tools using solid state millisecond pulsed laser (pulsed laser implantation). Dry cutting tests were performed on ductile cast iron. The results show a greater reduction of process forces with implantation of flank face as compared to rake face. Both cutting and feed forces were reduced by 10% compared to the non-structured tool. In addition, the tool life increased by a factor of 3 whereas the average flank wear reduced by as much as 80% and cutting edge rounding by up to 60%.

On-Machine Diamond Tool Shaping to Realize Highly Efficient Ultraprecision Machining System

Tool wear is one of the critical issues which deteriorate machining accuracy in ultraprecision machining. However, tool setting errors caused by the change of worn tool during a machining operation should be carefully compensated by identifying the gaps between the ideal tool center point and the actual tool center point, which inevitably lead to low machining efficiency. Because of the long consumption time of actual tool center point detection, this study aims at achieving on-machine shaping of a diamond tool which is commonly used in ultraprecision machining. In the previous study, shaping conditions without tool chipping are investigated by using various shaping materials. Then, in order to create a flank face that is necessary to realize preferable cutting, a pin gauge made of cemented carbide is adopted as the shaper. From the conducted experiments, it is found that the proposed on-machine shaping can create a specific cutting edge and a flank face on an ultraprecision machine tool.