Tool Performance in High Speed Finish Milling of Ti6Al4V

Author(s):  
D. Barnett-Ritcey ◽  
M. A. Elbestawi

High feed rates may be achieved when finish milling titanium (Ti6AI4V) alloy (300HB) at speeds of 152–305 m/min (500–1000sfm). Three tool materials (micro-grain C2 carbide, fine-grained C2 carbide, and a TiAIN coated carbide) were tested using liquid (flood and through-spindle coolant (TSC) at pressures of 2.07 MPa), pressurized air (69–689 kPa (10–100psi)), and dry (no coolant) coolant conditions to prolong tool life. Tool wear manifested itself in two distinct patterns, gradual flank wear or micro-chipping leading to gross fracture. Which of these will lead to tool failure, will depend largely on the ability of the coolant to cool the tool (retard flank wear) without inducing thermal shock. Typically, under pressurized air, speeds up to 267 m/min (875sfm) and chip loads of 0.057–0.114 mm (0.00225–0.0045") may be attained.

2019 ◽  
Vol 825 ◽  
pp. 31-38
Author(s):  
Hisaaki Nakai ◽  
Takekazu Sawa ◽  
Masahiro Anzai

In order to improve efficiency of high speed milling, effects of pick feeds of up cutting and down cutting on tool wear and processing characteristics were investigated after cutting pre-hardened steel NAK 55 by TiAlN-coated carbide radius end mill. Flank wear of the tools after up cutting was less than down cutting when the pick feed was smaller than 0.1 mm, which tendency changed when the pick feed was larger than 0.3 mm.


1970 ◽  
Vol 92 (1) ◽  
pp. 109-114 ◽  
Author(s):  
A. Bhattacharyya ◽  
A. Ghosh ◽  
Inyong Ham

For machining with cemented carbides and ceramics, a quantitative assessment of tool failure at the flank for establishing “limit criterion” is necessary. The arbitrarily chosen flank wear limit for all cutting speeds is not valid at higher cutting speeds because of the earlier appearance of the “inflection point” which is often taken as criterion of flank-failure. In this paper, proceeding from the basic physical model of flank wear described in Part I of the paper (ASME Paper No. 68—WA/Prod-5), tool-life relations in the form of Taylor’s equations have been theoretically developed, the parameters of which have been compared with, experimental results. Further, the critical points of inflexion where the flank-wear characteristic enters temperature sensitive region resulting in accelerated wear have been uniquely defined. The location of these critical points have also been verified experimentally.


Author(s):  
W. Li ◽  
Y. B. Guo

Inconel 718 is among the most widely used superalloys in many industries. It is often used in very harsh conditions such as jet engines, combustors and nuclear reactors due to its high strength at elevated temperatures, high oxidation and corrosion resistance. Machining superalloy Inconel 718 has always been a challenging task due to its poor machinability including rapid work hardening, low thermal conductivity, and relatively short cutting tool life. The fast tool wear during cutting Inconel 718 results in longer production time, deteriorated surface integrity, and higher manufacturing cost. In this paper, an on-line optical tool monitoring system integrated with a CNC machine tool has been developed to examine tool wear evolutions in end milling Inconel 718 with PVD (Ti, Al) N/TiN-coated carbide insert. Three basic types of tool wear: flank wear, nose wear, and crater wear were examined and analyzed. A two-parameter method has been proposed to evaluate both flank wear and nose wear vs. cutting time.


2012 ◽  
Vol 499 ◽  
pp. 348-352 ◽  
Author(s):  
Xiao Li Zhu ◽  
Song Zhang ◽  
X.L. Xu ◽  
H.G. Lv

In the present study, an experimental investigation has been carried out in an attempt to monitor tool wear progress in turning Inconel 718 with coated carbide inserts under the wet cutting condition. First, each experimental test was conducted with a new cutting edge and the turning process was stopped at a certain interval of time. Secondly, the indexable insert was removed from the tool holder and the flank wear of the insert was measured using a three-dimensional digital microscopy (VHX-600E); and then the insert was clamped into the tool holder for the next turning experiment. The final failure of tool wear surfaces were examined under a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). It is indicated that significant flank wear was the predominant failure mode, and the abrasive, adhesive and oxidation wear were the most dominant wear mechanisms which directly control the deterioration and final failure of the cutting tools.


Author(s):  
Emel Kuram

Tool coatings can improve the machinability performance of difficult-to-cut materials such as titanium alloys. Therefore, in the current work, high-speed milling of Ti6Al4V titanium alloy was carried out to determine the performance of various coated cutting tools. Five types of coated carbide inserts – monolayer TiCN, AlTiN, TiAlN and two layers TiCN + TiN and AlTiN + TiN, which were deposited by physical vapour deposition – were employed in the experiments. Tool wear, cutting force, surface roughness and chip morphology were evaluated and compared for different coated tools. To understand the tool wear modes and mechanisms, detailed scanning electron microscope analysis combined with energy dispersive X-ray of the worn inserts were conducted. Abrasion, adhesion, chipping and mechanical crack on flank face and coating delamination, adhesion and crater wear on rake face were observed during high-speed milling of Ti6Al4V titanium alloy. In terms of tool wear, the lowest value was obtained with TiCN-coated insert. It was also found that at the beginning of the machining pass TiAlN-coated insert and at the end of machining TiCN-coated insert gave the lowest cutting force and surface roughness values. No change in chip morphology was observed with different coated inserts.


Author(s):  
M. Hassan ◽  
A. Sadek ◽  
A. Damir ◽  
M. H. Attia ◽  
V. Thomson

Tool failure remains one of the most challenging phenomena in machining that affects the productivity and product quality, and hence the cost. In high feed rough milling operations of hard-to-cut materials, chipping and breakage have been observed as the dominant failure modes of the end mill cutters. Most of the work in the open literature is focusing on either detecting the complete tool breakage after it takes place or detecting the progressive tool wear. Detecting the abrupt/sudden tool failure due to tool chipping before it takes place, which is essential to avoid any damage to the machined part, has not been addressed. Therefore, the main objective of this research work is to investigate the ability of using the process monitoring signals in order to detect the tool pre-failure and failure by chipping/breakage in intermittent cutting operations. A method was devised to induce impact load on the cutting tool tip to study the features of signals collected by various sensors due to unstable crack propagation and chipping, while ensuring minimal tool wear effect. The acoustic emission (AE) signal features were able to successfully capture tool pre-failure, while other signals could detect the failure occurrence only.


2020 ◽  
Vol 21 (2) ◽  
pp. 177-185
Author(s):  
Natasha A. Raof ◽  
Nur Sofwati Daud @Ab Aziz ◽  
Abdul Rahman A. Ghani ◽  
Aishah Najiah Dahnel ◽  
Suhaily Mokhtar ◽  
...  

 Recently, almost 70% of a commercial jetliner’s airframe is made of aluminium alloys. It is predicted that the application of aluminium alloy is to increase up to 65% by the year 2025. They are typically used because of their high strength to weight ratio. However, there are some drawbacks during machining aluminium alloy such as the adhesion wear and built-up edge (BUE) formation that can shorten tool life. As the tool wears, the machining performance, surface roughness, and cutting tool life are affected significantly. A lot of studies were conducted in order to minimize this critical issue. This project presents a study of the cutting tool performance of an uncoated carbide tool in dry turning operation on Al 7075-T651, in which the tool wear rate, volume of material removed, wear mechanism, and surface roughness were investigated. The machining tests were conducted on a CNC lathe machine to obtain the tool wear and surface roughness of the machined work piece. The average flank wear was measured using a digital microscope, whereas the wear mechanism was observed using a Scanning Electron Microscope (SEM). The average surface roughness (Ra) was measured using a surface roughness tester. The cutting time for this experiment was fixed at 40 minutes and all the results were analysed within this time range to evaluate the tool performance in the turning of Al 7075-T651. The results revealed that the tool performs better at low cutting speed, 250 m/min, by reducing the tool wear rate by 33%. The cutting speed of 250 m/min also contributed to 71% higher volume of material removed during the machining tests. The dominant type of wear found was flank wear, while the main principal of wear mechanism is adhesion. At higher cutting speed, the surface roughness was improved. Based on the results, it can be concluded that high cutting tool performance is achieved when low tool wear growth rate, high volume of material removal, and low surface roughness during turning operation are obtained. ABSTRAK: Kebelakangan ini, hampir 70% kerangka pesawat udara komersil diperbuat daripada aloi aluminium. Penggunaan aloi aluminum ini dijangka meningkat sehingga 65% pada tahun 2025. Ia biasa digunakan kerana nisbah kekuatan kepada berat yang tinggi. Walau bagaimanapun, terdapat beberapa kekurangan semasa pemesinan aloi aluminum ini iaitu pemakaian pelekat dan pembentukan binaan tepi (BUE) yang mengurangkan jangka hayat mata alat. Apabila mata alat menjadi haus, prestasi mesin, kekasaran permukaan, dan jangka hayat mata alat pemotong terjejas dengan ketara. Banyak kajian telah dijalankan bagi mengurangkan isu kritikal ini. Projek ini mengkaji prestasi mata alat pemotong karbida tidak bersalut dalam operasi mesin larik kering pada Al 7075-T651, di mana kadar haus mata alat, kuantiti bahan yang dibuang, mekanisme haus dan kekasaran permukaan telah diselidiki. Ujian pemesinan dijalankan pada mesin CNC mesin larik bagi mendapatkan kadar haus mata alat dan kekasaran permukaan material yang dimesin. Purata haus pengapit mata alat diukur dengan menggunakan mikroskop digital, manakala mekanisme haus dipantau menggunakan Mikroskop Elektronik Pengimbas (SEM). Purata kekasaran permukaan (Ra) diukur menggunakan alat penguji kekasaran permukaan. Tempoh masa pemotongan bagi eksperimen ini telah ditetapkan pada 40 minit dan semua keputusan telah dianalisa dalam tempoh masa ini bagi menilai prestasi mata alat dalam melarik Al 7075-T651. Hasil menunjukkan prestasi mata alat lebih baik pada kelajuan pemotongan rendah, 250 m/min dengan mengurangkan kadar haus mata alat sehingga 33%. Kelajuan pemotongan 250 m/min juga menyumbang kepada 71% peningkatan ke atas jumlah bahan yang dibuang semasa ujian pemesinan. Jenis haus yang dominan telah ditemui pada pengapit mata alat, manakala mekanisme haus yang utama adalah lekatan. Pada kelajuan pemotongan yang tinggi, kekasaran permukaan didapati lebih baik. Berdasarkan keputusan, dapat disimpulkan bahawa prestasi mata alat pemotong yang bagus dapat dicapai apabila kadar haus mata alat adalah rendah, jumlah penyingkiran bahan yang tinggi dan kekasaran permukaan yang rendah semasa operasi pelarikan dijalankan. ABSTRAK: Kebelakangan ini, hampir 70% kerangka pesawat udara komersil diperbuat daripada aloi aluminium. Penggunaan aloi aluminum ini dijangka meningkat sehingga 65% pada tahun 2025. Ia biasa digunakan kerana nisbah kekuatan kepada berat yang tinggi. Walau bagaimanapun, terdapat beberapa kekurangan semasa pemesinan aloi aluminum ini iaitu pemakaian pelekat dan pembentukan binaan tepi (BUE) yang mengurangkan jangka hayat mata alat. Apabila mata alat menjadi haus, prestasi mesin, kekasaran permukaan, dan jangka hayat mata alat pemotong terjejas dengan ketara. Banyak kajian telah dijalankan bagi mengurangkan isu kritikal ini. Projek ini mengkaji prestasi mata alat pemotong karbida tidak bersalut dalam operasi mesin larik kering pada Al 7075-T651, di mana kadar haus mata alat, kuantiti bahan yang dibuang, mekanisme haus dan kekasaran permukaan telah diselidiki. Ujian pemesinan dijalankan pada mesin CNC mesin larik bagi mendapatkan kadar haus mata alat dan kekasaran permukaan material yang dimesin. Purata haus pengapit mata alat diukur dengan menggunakan mikroskop digital, manakala mekanisme haus dipantau menggunakan Mikroskop Elektronik Pengimbas (SEM). Purata kekasaran permukaan (Ra) diukur menggunakan alat penguji kekasaran permukaan. Tempoh masa pemotongan bagi eksperimen ini telah ditetapkan pada 40 minit dan semua keputusan telah dianalisa dalam tempoh masa ini bagi menilai prestasi mata alat dalam melarik Al 7075-T651. Hasil menunjukkan prestasi mata alat lebih baik pada kelajuan pemotongan rendah, 250 m/min dengan mengurangkan kadar haus mata alat sehingga 33%. Kelajuan pemotongan 250 m/min juga menyumbang kepada 71% peningkatan ke atas jumlah bahan yang dibuang semasa ujian pemesinan. Jenis haus yang dominan telah ditemui pada pengapit mata alat, manakala mekanisme haus yang utama adalah lekatan. Pada kelajuan pemotongan yang tinggi, kekasaran permukaan didapati lebih baik. Berdasarkan keputusan, dapat disimpulkan bahawa prestasi mata alat pemotong yang bagus dapat dicapai apabila kadar haus mata alat adalah rendah, jumlah penyingkiran bahan yang tinggi dan kekasaran permukaan yang rendah semasa operasi pelarikan dijalankan.


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