Improve Tool Life Research Articles

Technology Focus: Bits and Bottomhole Assemblies (December 2020)

Achieving and sustaining performance drilling’s intended benefits - improved drilling efficiency with minimal down-hole tool failures and the associated reductions in project cycle time and operational costs - requires new protocols in drilling-system analysis. Drilling-system components [bits, reamers, bottomhole assemblies (BHAs), drive systems, drilling parameters, and hydraulics] must be analyzed independently for their relevance on the basis of application types and project challenges. Additionally, the drilling system must undergo holistic evaluations to establish functional compatibility and drilling-parameter responses and effects, considering project objectives and key performance indicators. This comprehensive physics-based approach ensures durability and rate-of-penetration (ROP) improvements without compromising stability and downhole tool reliability. The success of this process is strongly dependent on vibration control. Considering the different vibration modes - axial, torsional, lateral, stick/slip, and whirl - and their many dissimilar initiating and amplification factors, their sources always must be identified. Researchers have challenged the usual classification of erratic torque and revolution-rate behavior as stick/slip. BHA design and drilling-parameter ranges, considering blade spacing, can produce unfavorable tubular deformations, contact points, and side loads. This condition creates torque and revolution-rate fluctuations that have been linked to lateral vibrations. Awareness of these vibration modes, particularly their sources and intensifying conditions, ensures development of effective remediation solutions. Improved borehole quality, with regard to tortuosity and rugosity, must always be considered as a critical requirement in performance drilling. This condition reduces borehole drag, enhances drilling-parameter transfer, and improves ROP and overall run lengths. Most importantly, it reduces vibrations, leading to improvements in downhole tool life and directional drilling performance. In addition to formation drillability effects, drilling-systems components and operational practices have strong effects on borehole quality. Consequently, this must be part of the drilling-system analysis. The industry’s advancements at developing physics-based solutions for drilling challenges have matured. Continuing to ask questions that help us understand how and why we fail or succeed puts more wind beneath our wings to accelerate learning and reduce cycle times. Recommended additional reading at OnePetro: www.onepetro.org. SPE 200740 Digital Twins for Well Planning and Bit-Dull-Grade Prediction by Mehrdad Gharib Shirangi, Baker Hughes, et al. SPE 201616 Validating Bottomhole-Assembly Analysis Models With Real-Time Measurements for Improved Drilling Performance by Mark Smith, Premier Directional Drilling, et al. IADC/SPE 199658 Simulation and Measurement of High-Frequency Torsional Oscillation (HFTO)/High-Frequency Axial Oscillation and Downhole HFTO Mitigation: Knowledge Gains Continue by Using Embedded High-Frequency Drilling Dynamics Sensors by Junichi Sugiura, Sanvean Technologies, et al.

An Experimental Investigation on Micro End Milling with High-Speed Up Cut Milling for Hardened Die Steel.

The importance of micromachining using small diameter end mills and the dies used for them has been increasing in the machining of small parts. However, the reality is that there are various requirements to improve the machining surface, machining accuracy, machining efficiency, and tool life. Therefore, this paper discusses the possibility of satisfying these requirements by high-speed up cut milling in side cutting. The goal of this study was to solve the aforementioned problems, by conducting a detailed analysis of the machining phenomena in order to understand their mechanisms. In particular, the effects of high-speed cutting using a high-speed air-turbine spindle with highly stiff rolling bearings were analyzed. Moreover, cutting experiments were conducted by measuring the cutting force and flank wear of the tool, to reveal the differences in the cutting phenomena relative to the cutting direction in high-speed micro end milling. Description of the machined surface and the measurement of its profile were also included in the discussions. On the basis of the results, high-speed up cut milling is a better choice than down cut milling; furthermore, a high-feed rate further increases machining efficiency and improves tool life.

Tool wear estimation in turning of Inconel 718 based on wavelet sensor signal analysis and machine learning paradigms

In the last years, hard-to-machine nickel-based alloys have been widely employed in the aerospace industry for their properties of high strength, excellent resistance to corrosion and oxidation, and long creep life at elevated temperatures. As the machinability of these materials is quite low due to high cutting forces, high temperature development and strong work hardening, during machining the cutting tool conditions tend to rapidly deteriorate. Thus, tool health monitoring systems are highly desired to improve tool life and increase productivity. This research work focuses on tool wear estimation during turning of Inconel 718 using wavelet packet transform (WPT) signal analysis and machine learning paradigms. A multiple sensor monitoring system, based on the detection of cutting force, acoustic emission and vibration acceleration signals, was employed during experimental turning trials. The detected sensor signals were subjected to WPT decomposition to extract diverse signal features. The most relevant features were then selected, using correlation measurements, in order to be utilized in artificial neural network based machine learning paradigms for tool wear estimation.

Evaluation of Usefulness of AlCrN Coatings for Increased Life of Tools Used in Friction Stir Welding (FSW) of Sheet Aluminum Alloy.

The study presents the results of examinations of wear in tools made of 1.2344 steel without and with an anti-wear coating in the process of welding overlap joints of sheet metal made of 7075-T6 aluminum alloy using friction stir welding (FSW) technology. A commercial anti-wear AlCrN coating (Balinit® Alcrona Pro by Oerlikon Balzers Coating Poland Sp. z o.o., Polkowice, Poland) was examined, applied using physical vapor deposition (PVD) and used to improve tool life in metalworking processes. Wear tests for the tools were conducted in industrial conditions at specific parameters of the friction stir welding process. Tool wear was evaluated through examination of the tool working surface. The results of the static tensile strength tests and metallographic examinations of the joints were used to evaluate the effect of tool wear and the coating impact on joint quality. The results obtained in the study show that the tool made of 1.2344 steel was intensively worn after the welding of a joint with the length of 200 m, increasing the risk associated with further use of the tool and suggesting the tool’s low durability. The use of the AlCrN coating led to an increase in tool life. The coating limits the process of tool wear and can be used as an anti-wear coating for tools used in the FSW of aluminum alloys.

MEJORA DEL MECANIZADO MEDIANTE EL REGISTRO Y ANÁLISIS DE VARIABLES DE PROCESO EN LA NUBE

Manufacturing sector faces the challenge of harnessing digital industry. Responding to this challenge, the present work shows different machining processes, as turning, grinding and milling, that have been optimized following Industry 4.0 paradigm. In all cases, this optimization objective has been reached using data platforms where process variables coming from numerical control or sensors are stored, and where optimization algorithms are ran. These improvements are diverse and specific for each process: quality control, cutting tool life improvement, or defect prevention.

Durability Map for The Friction Stir Welding Tools with Flat Faced Pins

In friction stir welding, tools made with flat faced pins deliver comparatively higher strength joints than circular pins. However, its non-axisymmetric cross section about the rotational axis results in fluctuating stress along its surface that leads to premature tool failure. This requires a systematic definition for process parameter selection domain based on the number of flat faces in the pin to improve tool life. Temperature dependent strength of the material to be joined in the stir zone is the only source of opposing force for the tool movement. To predict opposing force, temperature gradient developed by the different levels of process parameters in the stir zone is numerically quantified with an experimentally validated model. Based on the estimated temperature, maximum stress acting on the tool pin is quantified with a remodified temperature dependent analytical model. The effect of increase in process temperature on the strength of the weld joint is experimentally analysed through the investigation of change in hardness value in heat affected zone. Obtained results are used to develop tool durability maps for tools with flat faced pin in a domain on which higher and lower limits are fixed by considering satisfactory level of joint strength and tool life respectively. These maps provide flexibility in the parameter selection with an acceptable level of compromise in joint strength or in tool life based on the quality requirement of weld joint.

EXPERIMENTAL INVESTIGATION OF EFFECT OF CRYO-TREATMENT ON MICROMILLING OF INCONEL 718

In this paper, the effect of cutting parameters during micromilling on surface finish and material removal rate is presented. Inconel 718 alloy and high-speed steel micro end mill are used as work material and cutting tool, respectively. High-speed steel end mill of 1 mm diameter is subjected to cryogenic treatment. Machining studies are performed on Inconel alloy using untreated and cryogenic treated cutters. The milling tests are conducted at three different values of feed rate, cutting speed and depth of cut. Also, tool wear, microstructure and microhardness of different treated and untreated end mill are investigated and discussed in detail. The results showed that cryogenic treatment significantly improved the tool wear. The surface finish produced on machining the work-piece is better with the cryogenic treated tools than when compared with the untreated tools. The material removal rate is better with the cryogenic treated tools than when compared with the untreated tools. Improvement in tool life was up to 53.16% for Inconel 718 material when machined with cryogenically treated micro end mill.

Environmentally conscious machining of Inconel 718 with solid lubricant assisted minimum quantity lubrication

The use of conventional cutting fluid in metal cutting may increase total production cost and also a threat to the environment and health of the operator. Thus, sustainable and cost-effective measures are to be envisaged to overcome the ill effects of conventional cutting fluids. In this regard, the current study aims to develop an experimental setup for solid lubricant assisted minimum quantity lubrication during machining of Inconel 718. PVD and CVD coated tools are employed for the machining under dry, flood cooling, MQL, and solid lubricant (molybdenum disulfide and graphite) assisted MQL. The influence of these techniques is examined by considering surface roughness, tool wear, chip morphology, and microhardness of the machined surface. Experimental results revealed the effectiveness of molybdenum disulfide assisted MQL in the form of improved tool life and surface finish compared to other machining environments. The results also demonstrated the effectiveness of PVD coated by improving the tool life and surface finish in combination with MQSL compared to selected machining conditions. The presented work may help the metal cutting industries to select the combination of most suitable tool material and lubrication conditions leading towards sustainable machining.

CO2 cryogenic milling of Inconel 718: cutting forces and tool wear

Machining Inconel 718 alloy is a challenge due to its low machinability. This thermal resistant alloy combines high strength even at high temperatures with strain hardening tendency that causes high forces and extreme cutting temperatures during the machining. These issues force industries to achieve suitable machining processes to deal with this kind of alloys and the high worldwide competitiveness. Nevertheless, environmental considerations must to be taken into account due to growing environmental concerns. In the work here presented, cryogenic cooling with external MQL lubrication (CryoMQL) working along with CO2 as internal coolant is proposed for milling Inconel 718 with the aim of not only improving from a technical point of view but also environmental. This technique was compared with other lubricooling techniques. The results show that internal CryoMQL improves tool life by 57% in comparison with emulsion coolant, achieving 120% if it is compared with MQL in stand-alone mode.

Dry turning performance of TiN–WSx/TiN hard-lubricious bilayer composite coating

Dry machining is receiving immense attention worldwide to eliminate or minimize the harmful environmental effects of cutting fluids. The present work investigates dry machining performance of a bilayer coating with top-layer of hard-lubricious TiN–WSx, supported by a hard TiN under layer. During dry turning of AISI 1060 steel, the bilayer coated carbide tool registered significantly less cutting forces as compared to its TiN coated counterpart in the cutting velocity range of 77–230 m/min. In prolonged turning test at cutting velocity of 200 m/min, it also exhibited notably higher tool life on the order of 13 and 2.17 times respectively as compared to the uncoated WC and monolayer TiN coated tool. Such improved performance of bilayer coating was found to be associated with its microstructure, mechanical and tribological properties. Existence of lubricious WS2 phase in the composite TiN–WSx layer along with superior coating adhesion and equivalent nanohardness as compared to TiN resulted in low cutting forces. Formation of W–O tribo layer on surface of worn-out coating on flank surface of tool aided in improving tool life during prolonged turning test.

Static & dynamic performance analysis and modal simulations of single point cutting tool

Tool manufacturers’ aims to produce quality tools to with stand higher cutting forces, thermal resistivity with increased wear resistance to improve tool life and to produce better surface finish maintaining dimensional accuracy of the finished product. The paper analyses the machining performances of single point cutting tool made from high speed steel and tungsten carbide in dry machining of mild steel and aluminium. Varying cutting speeds, feed rates and depth of cuts were taken into consideration for the experimental performance, using lath tool dynamometer. The data obtained from the experiments are used for the static, modal and steady state dynamic analysis using FEA package ABAQUS solver. From the static analysis, it was found that WC has a higher stiffness and durability as compared to the HSS. The natural frequencies and the mode shapes of the HSS and WC tools were identified and plotted. The analysis showed WC tool has higher natural frequencies as compared to the HSS tool for each of the six mode shapes. The dynamic analysis of the tools showed the deformation was least for WC. The stress induced in WC was found to be around 50% of that of HSS and the factor of safety was almost double to that of HSS. Thus this paper shows that static and dynamic performance analysis of the WC tools is better than the HSS tools.

Dataset and methodology on identification and correlation of secondary carbides with microstructure, wear mechanism, and tool performance for different CERMET grades during high-speed dry finish turning of AISI 304 stainless steel.

The aim of this research is to utilize reverse engineering approach for the identification of the elements and phases available in the commercial CERMET inserts with the help of characterization techniques such as Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), and X-Ray Deposition (XRD). Four commercial CERMET inserts were investigated in this research work, and the effect of the composition and phases are related to its tool wear mechanism and performance. Each CERMET insert is used to perform a turning process on a CNC lathe for machining stainless steel (SS) under the dry condition at a fixed cutting length interval. Once it completes machining for a fixed cutting length, the CERMET insert is taken out to investigate its wear mechanism with the help of SEM, EDS, XRD and using a focus-variation microscope (Alicona). A correlation analysis is performed to relate progressive tool wear mechanisms with elements and their relevant phases of various carbides. The approach of correlating wear property with the phase content will contribute to the understanding of the wear mechanism under such extreme machining conditions. It will serve as a reference for the improvement of the performance of these CERMET inserts for such harsh machining conditions by the development of protective coatings for these CERMET inserts based on the identification of the composition and phases that improves tool life and reduces wear. The data related research work can be found at “https://doi.org/10.1016/j.wear.2020.203285” [1].

A Universal Pocket Plunge Milling Method to Decrease the Maximum Engagement Angle

Abstract Plunge milling has been proven to be an efficient strategy for machining of pockets with deep cavities and difficult-to-cut material. Previous work generates the plunge toolpath mainly by controlling the radial cutting width within the given value. However, uneven tool engagement angles may lead to excessive tool load and tool load fluctuations, which has a negative influence on tool life. In this study, a universal plunge milling toolpath generation method is proposed to improve tool life by decreasing the maximum tool engagement angle. A series of concentric circles with constant radius increment is utilized to generate a toolpath with constant cutting radial depth. Center of the concentric circle is determined based on the pocket contour. New detailed algorithms to generate plunge toolpath for basic cases have been developed. An automatic pocket subdivision algorithm has been developed by dividing the pocket into several subregions that are easy to be machined. Without loss of generality, the method is applicable for both open and closed pockets. It also works for pockets with and without islands inside. The method is implemented and verified successfully by machining experiments. The results provide strong evidence that the proposed method can reduce the maximum engagement angle over the entire toolpath and thus improve the tool life.

Threading Performance of Different Coatings for High Speed Steel Tapping

Threading holes using tapping tools is a widely used machining operation in the industry. This manufacturing process involves a great tool immersion in the part, which involves both friction and cutting. This makes the use of coatings critical to improving tool life. Four coatings are used based on Physical vapor deposition (PVD) technology—TiN, TiCN, TiAlN and TiAlN+WC/C are compared to uncoated tool performance. The effect of various coatings on the life of M12 × 1.5 tapping tools during threading of through holes 20 mm deep, in GG25 casting plates, dry and applying cutting speed of 50 m/min. The end-of-life criterion has been established based on a cutting torque of 16 N-m. Taking the uncoated tap as a basis for comparison, it is observed that coatings based on PVD technologies increase tool life doubling in the most advantageous case with the TiAlN coating. PVD type coatings provide better protection to wear at cylindrical area of the tool, where the thread profile is finished, than uncoated taps. The teeth located in the cone-cylinder transition zone of the taps suffer the most wear regardless of the coating. However, taps coated with TiAlN+WC/C wear level values is lowest of all the coatings tested, which indicates a strong reinforcement in these teeth.

Investigation on the effect of cryogenic treatment on tungsten carbide milling insert with 11% cobalt (WC–11%Co)

The objective of this research is to evaluate the performance of cryogenically treated cemented carbide milling inserts with 11% cobalt content in face milling of EN19 steel. Two different deep cryogenic treatments at temperature of around − 193 °C were performed on the inserts, namely cryogenic treatment and cryogenic treatment and tempering. Uncoated tungsten carbide face milling inserts with 11% cobalt content were used in this research. Machining tests were conducted at the catalog recommended cutting parameters, and flank wear and nose wear of untreated, cryogenically treated and cryogenically treated and tempered inserts were compared to study the performance. The experimental investigation revealed that both cryogenic treated and cryogenic treated and tempered inserts showed 4–7% lesser flank and nose wear than the untreated inserts. The metallurgical examinations using indirect measurement technique revealed the phase transformation of cobalt from FCC to HCP which could have resulted in increased hardness, reduced friction coefficient and improved tool life.

Experimental investigation on influence of engagement angle and tool geometry on plunge milling

Taking advantage of the superior cutter axial stiffness, plunge milling provides a higher material removal rate in rough milling for components with deep cavities. Tool wear depending on cutting parameters of radial cutting width, axial cutting depth, step interval, feedrate, and spindle speed has been studied by several researchers. For a more comprehensive understanding of the wear mechanism, this study investigates the influences of tool engagement angle and tool geometry on tool wear based on multiple sets of machining tests. The development of tool wear during plunge milling is monitored. Results show that tool wear of insert with large engagement angle mainly exists on minor edge, which is caused by increased tool deflection. When the radial distance equals to tool radius, optimal engagement angle can be achieved while considering both tool life and machining efficiency. The experimental results show that tool life of insert with rake angle of 22° is 6.5% higher than rake angle of 15°. Smaller corner radius has positive influences on tool life improvement. Surprisingly, tool life of insert without cutting edge chamfer is 3.6 times than insert with cutting edge chamfer. The best tool geometric parameters of plunge insert can then be identified among a variety of inserts. This work is useful for cutting tool producers and manufacturers to optimize tool geometry and machining parameters.

Evaluation of tool wear, energy consumption, and surface roughness during turning of inconel 718 using sustainable machining technique

Heat resistant alloys such as Inconel 718 present challenges to manufacturing industries during its machining. Machinability of such alloys can be improved using smart cutting conditions. Further, to seek improvements in the machinability of Inconel 718, this assessment evaluates industry-relevant machinability indicator, i.e., tool wear in terms of both flank and crater wear under indigenously developed cryogenic turning technique and compares the results with conventional dry and wet turning techniques. Experimental results show a massive improvement (133%) in tool life under cryogenic turning as compared with the dry turning. However, tool life obtained under wet and cryogenic turning is comparable. In the second part of this paper, industry-relevant machinability indicators namely energy consumption, chip reduction coefficient (CRC), and average surface roughness (Ra) were critically examined at different material removal rates (MRR) for turning of Inconel 718 under different cutting environments. A total 24 number of experiments were designed using full factorial considering two levels of cutting speed (vc) i.e., 45 and 60 m/min, four levels of feed (fr) i.e., 0.03, 0.06, 0.12, and 0.24 mm/rev, and three cutting conditions (dry, wet, and cryogenic). The results show that energy consumption in cryogenic turning reduced up to 8–17% when compared with dry and wet turning. Ra values for cryogenic turning also reduced up to 20–37% in comparison to dry and wet turning at various MRR. Improved tool life, reduced energy consumption, and Ra values obtained under cryogenic turning echo its potential to replace unsustainable conventional machining practices.

Effect of deep and shallow cryogenic treatment on high speed steel grade M2 drilling tool

Every element in existence will have to undergo a manufacturing process. One of the more challenging processes would be material removal especially with respect to metal. Single point cutting tools and drill bits are observed to have a shorter lifespan due to early wear or breakage. Advancements in the field of tool manufacturing have shown drastic improvements with respect to tool life; these advancements have been done in the form of surface treatments but are known to be superficial, not showing any major improvements in tool life. Experimentation was done by means of treating the tool at shallow cooling temperature and deep cooling temperatures at varying timeframes. Deep treatment of the tool to −196 °C has shown to have a 92% increase in life when cryogenically treated with liquid nitrogen. The corroboration of the aforementioned statements can be verified by tests conducted showing a reduction of 11.2% in surface roughness in comparison with an untreated drill bit.

EFFECTS OF DIFFERENT CRYOGENIC TREATMENTS ON DRILLING PERFORMANCE OF HSS DRILLS

Cryogenic processing is a heat treatment which has been widely used in recent years to improve the properties of tool materials. This process has been reported in the literature as it provides significant contributions to wear resistance and tool life of tool steels. This study presents the differences in tool performance between untreated and cryogenically treated M2 high speed steel (HSS) drill bits in terms of their tool wear, tool life, hardness and chip formation properties. Also, the effects of two different tempering temperatures (200 oC and 250 oC) in cryogenic treatment on tool performance are discussed. Drilling performances were studied on different workpieces of SAE 1050, lamellar cast iron and sphero cast iron, and the type of wear is characterized by a high resolution camera. Moreover, fracture tests were performed on a steel workpiece using a constant drilling speed of 1100 m/min and a feed rate of 0.5mm/rev. The microstructures of the samples were characterized using optical microscopy and SEM. The Vickers micro-hardness tests of the samples were performed using 100 g load. Microstructural studies showed that cryogenically treated samples exhibit better microstructure with finer and more homogeneous carbides which yields better tool wear and hardness properties. In paralel, cryogenically treated drills showed improved tool life than untreated drills during fracture tests. When tempering temperatures are compared, tempering at 250 °C resulted in better performance than 200 °C of tempering temperature. Also, the reduction in diameter values during drilling tests were consistent with the tool life tests.

Performance Evaluation of Cryogenic Treated and Untreated Carbide Inserts during Machining of AISI 304 Steel

The cutting tool in the machining process plays an important role as it acts on the working material. There are a few methodologies have been persued to improve tool life, for example traditional cooling, single layer coating, multilayer coating, heat treatment process, nitrogen cooling and latest being the cryogenic treatment which reported a significant improvement in cutting tool life, chip morphology, reduction in heat generation. Hence, the cryogenic treatment is emerged as the sustainable machining process. This paper presents machining of AISI 304 steel using both cryogenic treated (CT) and untreated (UT) cutting tool insert. The commercially available uncoated carbide insert has been cryogenically treated at -196°C for 24 hours soaking period. The machining test has been conducted under four different cutting speeds. The material characterization of cutting insert is studied by using scanning electron microscopy (SEM), hardness test, and microscopic image analysis has been carried out before and after cryogenic treatment. The cutting tool performance is assessed in terms of of wear, cutting temperature, chip morphology, surface roughness under the influence of cryogenic machining and the results are contrast with UT one. The exploratory findings reveals that the deep cryogenic treatment (DCT) with 24 hours soaking period, performed better wear resistance and improved surface roughness of the cutting tool. Also considerable reduction in the flank wear, crater wear, cutting temperature is obtained and found improved chip morphology.