Some observations on flood and dry finish turning of the Ti-6Al-4V aerospace alloy with carbide and PCD tools (original) (raw)
Related papers
Coatings
Tribological phenomena and tool wear mechanisms during machining of hard-to-cut TiAl6V4 aerospace alloy have been investigated in detail. Since cutting tool wear is directly affected by tribological phenomena occurring between the surfaces of the workpiece and the cutting tool, the performance of the cutting tool is strongly associated with the conditions of the machining process. The present work shows the effect of different machining conditions on the tribological and wear performance of TiB 2-coated cutting tools compared to uncoated carbide tools. FEM modeling of the temperature profile on the friction surface was performed for wet machining conditions under varying cutting parameters. Comprehensive characterization of the TiB 2 coated vs. uncoated cutting tool wear performance was made using optical 3D imaging, SEM/EDX and XPS methods respectively. The results obtained were linked to the FEM modeling. The studies carried out show that during machining of the TiAl6V4 alloy, the efficiency of the TiB 2 coating application for carbide cutting tools strongly depends on cutting conditions. The TiB 2 coating is very efficient under roughing at low speeds (with strong buildup edge formation). In contrast, it shows similar wear performance to the uncoated tool under finishing operations at higher cutting speeds when cratering wear predominates.
Machinalibilty of Ti-6Al-4V Under Dry and Near Dry Condition Using Carbide Tools
The Open Industrial & Manufacturing Engineering Journal, 2009
The effectiveness of the usage of coolant in high speed machining of highly reactive material like titanium and its alloys is still far away uncertain. For this reason, it is wiser to study the effectiveness of Minimum Quantity of Lubricant (MQL) under transient cutting speed before advancing to high speed machining. This paper discusses the effect of MQL on the machinability of Ti-6Al-4V using Physical Vapor Disposition (PVD) coated cemented carbide tools. The machinability studied parameters were the generated cutting force and the tool life. The performance of PVD coated cemented carbide tool was investigated at various cutting condition under dry and near dry (or MQL) machining. For near dry machining, two levels of coolant flow rate of 50 and 100 mL/H were investigated. The effectiveness of mist coolant was tested at three different levels of cutting speed, 120, 135 and 150 m/min. Application of mist coolant is more effective at cutting speed of 135 m/min. At this speed longer tool life was obtained when more coolant was applied. The effect of the cutting speed and coolant flow rate on the surface roughness is not significant. Surface roughness is more sensitive to the feed rate and the depth of cut. No significant effect of MQL on cutting force at early stage of machining was observed. MQL seems to be more effective when tools start to wear out, where greater contact area between tool and work piece occurs to give better lubrication effect.
Wear mechanisms of cutting tools in high-speed turning of Ti6Al4V alloy
The International Journal of Advanced Manufacturing Technology, 2019
Titanium and its alloys are associated with low density and excellent strength/weight ratio, biocompatibility in surgical implants, high mechanical strength at high temperatures and excellent corrosion resistance. The Ti6Al4V alloy is applied in the aerospace, biomedical, chemical, naval and petrochemical industries. However, these alloys present problems during machining and are therefore considered materials of difficult machinability at high cutting speeds. This paper aims to analyse the wear mechanisms in cutting tools using cemented carbide (H13A) and synthetic polycrystalline diamond (PCD) in the high-speed turning of Ti6Al4V alloy, under the following cooling conditions: dry, jet and minimum quantity lubricant (MQL). To measure wear, a microscope was used to measure flank wear in the tools. Next, the images of these tools were obtained using scanning electron microscopy for the identification of the wear mechanisms. According to the results, the variation in the cutting parameters (cutting speed and feed rate), type of tool material, as well as the cooling conditions significantly affects the behaviour of the wear mechanisms. The wear mechanisms presented in the cutting tools are not the result of one single mechanism, but a combination of many mechanisms. Overall, the primary type of wear is flank wear and the mechanisms are abrasion, adhesion and attrition (adherence and drag).
Journal of Materials Processing Technology, 2013
High speed machining Ti-6Al-4V alloy PCD tools High pressure coolant Tool wear Adhesion and attrition wear mechanisms a b s t r a c t Usage of titanium alloys has increased since the past 50 years despite difficulties encountered during machining. Many studies involving different tool materials, cutting parameters, tool geometry and cutting fluids when machining this important aerospace material have been published. However, there are relatively few literatures available on the application of ultra hard tools in the machining of titaniumalloys. The primary objective of this study is to investigate the behaviour of Polycrystalline Diamond (PCD) tools when machining Ti-6Al-4V alloy at high speed conditions using high pressure coolant supplies. Tool performance under different tribological conditions and the dominant wear mechanisms were investigated. Increase in coolant pressure tends to improve tool life and reduce the adhesion tendency, accelerated by the susceptibility of titanium alloy to gall during machining. Adhesion and attrition are the dominant wear mechanisms when machining at the cutting conditions investigated.
Materials, 2021
This paper reports a fundamental investigation consisting of systematic trials into the response of Ti6Al4V alloy to high-speed machining using carbide inserts. It is a useful extension to work previously published, and aims at assessing the impact of the process parameters, depth of cut, cutting speed and feed rate in addition to cutting length, and their interrelations, on observed crater and flank wear and roughness of the machined surface. The results showed that abrasion was the most important flank wear mechanism at high speed. It also showed that increased cutting length accelerated crater wear more than exhibited flank wear and had considerable effect on surface roughness. In particular, crater wear increased by over 150% (on average), and flank wear increased by 40% (on average) when increasing cutting length from 40 to 120 mm. However, cutting the same length increased surface roughness by 50%, which helps explain how progression of tool wear leads to deteriorated surface ...
THE STUDY OF WEAR PROCESS ON UNCOATED CARBIDE CUTTING TOOL IN MACHINING TITANIUM ALLOY
The uncoated carbide cutting tools were used in turning titanium alloy Ti6Al4V bar with hardness of 340 HV. The main objective to find the wear behaviour of the cutting tool based on the flank wear data. The experiments were performed under dry cutting condition at various combinations of cutting speed and feed rate. The cutting speeds selected in the experiment were 15, 25, 35 and 45 m/min. Meanwhile the feed rates were used at 0.02 and 0.04 mm/rev. In this research depth of cut, doc was kept constant at 0.5 mm for all combinations of cutting parameters. Tool wear was measured under optical microscope and the data of flank wear which was gained through the experiment has been analysed. According to these graph shown that the affected of cutting parameters onto tool wear. The experiment’s result showed that the flank wear increased with the cutting speed and feed rate. The flank wear occurs gradually at beginning of machining and at the end of failure when Vbavg reached 0.3 mm where flank wear occurs.
Effect of High-speed Parameters on Uncoated Carbide Tool in Finish Turning Titanium Ti-6Al-4V ELI
In this work, the Sandvik uncoated carbide insert, CNGG 120408-SGF-H13A was used as a cutting tool in high-speed turning of titanium alloy Ti-6Al-4V ELI (extra-low interstitial) with hardness of 32 HRC. Wear is one of the problems that cannot be avoided in machining process. Therefore, the objective of this paper was to investigate tool-wear behavior of various cutting-speed values (high-speed range) on the tool life of the cutting tools, especially in finishing titanium alloy. The experiments were performed under flooded coolant condition using water-based mineral-oil. The cutting speeds employed were 120, 170 and 220 m/min. The feed rate was constant at 0.2 mm/rev and the depth of cut was 0.4 mm. Based on the results, the highest cutting speed of 220 m/min caused the highest wear rate. By linking the machine operations and the tool life curves obtained using flank wear data, the wear behavior of uncoated carbide was described.
Wear, 2009
Dry machining is an extreme environment within which the rake and flank faces of the cutting tool experiences increased pressure, intense friction, high temperatures, and severe thermal flux loads. The contact zone between the tool and the workpiece material under these severe conditions exhibits the formation of an adhesive layer. When the junctions between the adhesive layer and the tool material are removed adhesive wear takes place. In order to avoid the negative effects of this phenomenon, and to enhance the tool performance, thin layers of hard coatings are applied to the tool faces. While the application of the hard coating is thought to protect the tool substrate, coatings themselves experience delamination. This paper presents a study that aimed at comprehending the physico-chemical mechanisms of coating delamination when dry machining aerospace materials. The study employs a synergetic approach that teams finite element-based computations to experimental observations to examine the failure modes and wear mechanisms for two groups of alloyed carbide inserts, (coated and uncoated). The results presented in this study pertain to cutting experiments performed at cutting speeds of 100-125 m/min and feed rates of 0.15 to 0.20 mm/tooth. Post experimental SEM micro-graphical analysis reveal that while delamination is the primary wear mechanism for different cutting conditions, the major portion of delamination takes place at the very initial moments of cutting (first few seconds). Through combining finite element-based computations and metallographic observations a proposal concerning the mechanistic stages of the coating delamination is reached. This proposal takes into account both the thermo-mechanical interactions as well as the physico-chemical mechanisms at the early stages of cutting. Consequences of delamination on wear and the implications on the dry machining process of titanium and titanium based alloys are discussed.
2016
The cutting of titanium alloys is usually associated with low productivity, poor surface quality, short tool life and high machining costs. This is due to the excessive generation of heat in the cutting zone and difficulties in heat dissipation due to the relatively low heat conductivity of this metal. Cooling applications in machining processes are crucial, since many operations cannot be performed efficiently without cooling. Improving machinability, increasing productivity, and enhancing surface integrity and part accuracy are the main advantages of the use of cutting fluids (CFs). Conventional cutting fluids such as mineral oil-based, synthetic and semisynthetic fluids are the most common types used in the machining industry. Although these cutting fluids can be beneficial, they pose a great threat to human health and to ecosystems. Vegetable oils (VOs) are being investigated as a potential source of environmentally favourable lubricants, due to a combination of biodegradability, good lubrication properties, low toxicity, high flash points, low volatility, high viscosity indices and thermal stability. The fatty acids of vegetable oils are known to provide thick, strong, and durable lubricant films. These strong lubricating films give the vegetable oil base stock a greater capability to absorb pressure and a high load carrying capacity. This paper details the main experimental results from an investigation of the impact of various vegetable oil-based cutting fluids, cutting tool materials and working conditions when turning Ti-6Al-4V. A full factorial experimental design was employed involving 24 trials to evaluate the influence of process variables on average surface roughness (Ra), tool wear and chip formation. In general, values of Ra varied between 0.5 µm and 1.56 µm and the Vasco1000 cutting fluid exhibited a level of performance comparable to other fluids in terms of surface roughness, while the uncoated coarse grain WC carbide tool achieved lower flank wear at all cutting speeds. On the other hand, all tools tips were subject to uniform flank wear during the cutting trials. Additionally, formed chip thickness (tc) ranged between 0.1 mm and 0.14 mm with a noticeable decrease in chip size when higher cutting speeds were used.