Karbür takımlar üzerinde oluşturulan mikrokanalların takım aşınması ve tezgah kuvvetleri üzerine etkisi
Effects of microchannels on carbide cutting tools on tool wear and cutting forces
Yazar: CANER DOKEL
Danışman: DR. ÖĞR. ÜYESİ CANAN GAMZE GÜLERYÜZ PARASIZ
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Makine Mühendisliği Ana Bilim Dalı / Malzeme ve İmalat Bilim Dalı
Derece: Yüksek Lisans, 2022
Konu: Makine Mühendisliği = Mechanical Engineering
Dizin: Aşınma = Wear ; Karbür = Carbide ; Kesici takımlar = Cutting tools ; Mikro kanallar = Micro channels

Özet:
Havacılık motorları endüstrisinde kullanılan malzemeler çoğunlukla işlenmesi zor malzemeler sınıfında yer almaktadır. Uçak motor parçaları yüksek basınç, yüksek sıcaklık ve yüksek hız koşulları altında çalıştıkları için yüksek mekanik özelliklere sahip malzemeler ile üretilmektedir. Nikel esaslı süperalaşımlar, sahip oldukları yüksek mekanik özellikler nedeni ile uçak motoru parçalarında yaygın olarak kullanılmaktadır. Nikel esaslı süperalaşımlar, yüksek yalıtkanlığa sahiptir ve işleme sırasında oluşan yüksek sıcaklıkları kesici takıma ve kesme ortamına verme eğilimindedir. Kesim performansının iyileştirilmesi için, kesim ortamı ve kesici takımın oldukça iyi soğutularak kesim sırasında ortaya çıkan ısının ortamdan uzaklaştırılması gerekmektedir.
Yeterli soğutmanın sağlanmadığı durumda kesici takım aşırı ısınma eğilimi gösterir ve bu durum kesici takımın mukavemetinin azalmasına sebep olur. Aşırı ısınma, kesici takım üzerindeki aşınmanın artmasına ve takımın mukavemetinin azalmasına neden olarak; kesici takım kırılmalarına sebebiyet verdiği bilinmektedir. Talaşlı imalat sırasında meydana gelen takım kırılmaları, özellikle havacılık endüstrisinde istenilen işleme toleransı düşük parçalar üzerinde geri dönülemez hatalara sebep olduğu bilinmektedir. Aynı zamanda ortamdan atılamayan ısı, iş parçası üzerinde boyutsal değişmelere sebebiyet vererek yüzey kalitesini de düşürdüğü bilinmektedir. İşleme ortamında gerekli soğutmanın sağlanması imalat sürecinde her zaman kritik bir öneme sahiptir. Bu soğutmanın sağlanması için genellikle özel amaçlı kimyasal yağlar kullanılmaktadır. Bu yağların gerekli soğutmayı sağlamaları için periyodik olarak yenilenmesi gerekmektedir ve bu durum işletmelere ciddi bir mali gider olarak yansımaktadır. Öte yandan bu tür kimyasal yağları uzun süre solumanın insan sağlığına çeşitli (cilt ve akciğer fonksiyonlarının bozulması vb.) zararları olduğu da bilinen bir durumdur. 
Literatürde; talaşlı imalat süreçlerinde kesme koşullarının iyileştirilmesi, sürtünme ve aşınmanın azaltılması, kesme ortamının soğutulması ve soğutma sıvılarının daha az kullanılması amacı ile çeşitli bilimsel çalışmalar yapıldığı bilinmektedir. Bu çalışmada, talaşlı imalat yöntemleri ile işlenen malzemelerde kesim performansını iyileştirdiği bilinen mikro desenli kesici takımların tornalama işlemi açısından teorik ve deneysel araştırmalarının yapılması hedeflenmiştir. Deneysel çalışmalar TUSAŞ Motor Sanayi A.Ş Eskişehir yerleşkesinde yapılmıştır. Kullanılan CNC torna tezgahı, karbür kesme takımları, mikro kanal işlenmesi için kullanılan lazer markalama tezgahı ve ölçüm cihazları gibi ekipmanlar TUSAŞ Motor Sanayi A.Ş tarafından sağlanmıştır.

Abstract:
The materials used in the aviation engine industry are mostly in the class of materials that are difficult to process. Aircraft engine parts are produced with materials with high mechanical properties because they operate under high pressure, high temperature and high speed conditions. Nickel-based superalloys are widely used in aircraft engine parts due to their high mechanical properties. Nickel-based superalloys have high insulating properties and tend to impart high temperatures during machining to the cutting tool and cutting environment. In order to improve the cutting performance, the cutting environment and the cutting tool must be cooled very well and the heat generated during cutting must be removed from the environment.
In the absence of adequate cooling, the cutting tool tends to overheat and this leads to a decrease in the strength of the cutting tool. Overheating causes an increase in the wear on the cutting tool and a decrease in the strength of the tool; It is known to cause cutting tool breakage. Tool breaks during machining are known to cause irreversible errors, especially on parts with low machining tolerances, especially in the aerospace industry. At the same time, it is known that the heat that cannot be removed from the environment causes dimensional changes on the workpiece and reduces the surface quality. Ensuring the necessary cooling in the machining environment is always critical in the manufacturing process. Special purpose chemical oils are generally used to provide this cooling. These oils need to be renewed periodically in order to provide the necessary cooling, and this is reflected as a serious financial expense to the enterprises. On the other hand, it is also known that inhaling such chemical oils for a long time has various harms to human health (deterioration of skin and lung functions, etc.).
In the literature; It is known that various scientific studies have been carried out with the aim of improving cutting conditions, reducing friction and wear, cooling the cutting environment and using less cooling fluids in machining processes. In this study, it is aimed to carry out experimental research of micro-patterned cutting tools, which are known to improve cutting performance in materials processed by machining methods, in terms of turning process.
With the aim to improve cutting performances in machining of super alloys in terms of decreases in cutting forces and tool wear, as a beginning, a literature survey on the implementation of micro patterns was performed. All experiments were performed at Turkish Engine Industries (TEI-TUSAŞ) Facilities, work piece metal as a bar of Inconel 625, tungsten carbide tool inserts coded  as TNGN 220416 were also provided by TEI. In the experimental part, micro channels having various orientation with the cutting edge of the turning insert was selected as the micro pattern, as it was shown to present benefit in literature. Micro channels were formed on the cutting inserts with a marking laser equipment, Gravograph LS100ex fiber laser machine. Three different micro channel orientations were used: The first orientation of channel was parallel to the cutting edge of the insert, the second orientation had an angle of 90 degrees with the cutting edge and the third orientation had an angle of 45 degrees with the cutting edge. The width of the channels was 50 micron, and the depth of the channels was 4 m. The distance between the micro channels was 80 micron. Achieved dimensions were also measured by Leica optical microscobe and the distribution of dimensions for each pattern orientation was presented. 
Same machining parameters as feed rate, cutting velocity and depth-of-cut were used in experiments. Energy requirements for these experiments were compared using chuck sprindle load. Forces in the X axis and Z axis directions were also measured and provided using MT Connect Protocol of the HNK vertical CNC lathe. Wear on the inserts was measured by optical means via Leica optical microscobe after 50 mm machining. Flank wear and the width of the wear on the rake face were recorded.
When compared to cutting tests with inserts having no micro channels, depending on the orientation, using inserts with micro channels can decrease X axis load can be up to 90%, Z axis load up to 44% and chuck spindle load up to 9%. Flank wear on the inserts can be decreased up to 55% and the width of wear on the rake face can be decreased up to 19%. Micro channel orientation has a substantial effect on the test  results.
Data received from CNC lathe via MT Connect Protocal represents how difficult to perform each cutting operation with laser processed inserts having micro channel with different orientations. Energy required to achieve the CNC operation is expected to decrease when decreases in chuck spindle load, X axis and/or Z axis load decrease. It is possible to perform cutting operations using less energy using inserts with patterns on their rake face. Because it is becoming more and more important and vital to implement manufacturing processes with lower energies, improvements achieved can be one of the useful applications to follow for industry. It can also prolong parts of the engine lathe by increasing fatigue life of the machine. 
Possible reasons for the decrease in X axis load and/or Z axis load and chuck spindle load were discussed. The only parameter changed was the direction of the micro pattern formed on the insert rake face. Therefore, an ease of surface interaction of the chip and the tool insert that may occurred when specific micro channels applied on the tool. 
Although a decrease in Z axis load was observed for the tool with a micro channel direction of an angle of 45 degrees with cutting edge, an increase in X-axis load with respect to machining with a tool with no surface pattern. It is discussed that carried load on X-direction of surface interaction on the tool surface with the chip may increase under these conditions. Because it is related to surface interactions, it may also increase friction between tool and the work piece accompanying a temperature increase. 
Because increases of the width of the wear on the rake surface for the inserts with micro channels parallel or vertical to the cutting edge were observed, a discussion of a difficulty to flow on the rake surface for the chip that may occurred for these cases. Flank wears on the cutting tools used to machine hard metals such as super alloys have been pronunciated more frequently to decide their useful life. Increases in flank wear shows the dimensions of work parts will be away from to be in the range of acceptable tolerances. Flank wear values were decreased by the application of micro channels for all orientation cases. Reasons for the decrease in flank wear by having micro channels independent of orientation may be one or several of the followings: Improves of surface conditions by decreasing friction between tool and the chip and increasing the effect of cooling fluids by keeping them in the channels. All of these reasons will prevent chemical and mechanical interaction of tool and the work piece and protect the cutting tool insert. Average decrease in wear types measured for patterned tools with respect to tool without any pattern
For a company producing airplane engine parts, tool expenses will decrease, when wear in cutting tool inserts decreased or postponed with patterned rake face applications. Tool changes are more prominent for machining of super alloys with high hardnesses where tools should work under difficult conditions. When a tool can be used a longer period of time, machining operation of a part will be accomplished faster. 
Under the light of studies on patterned tools and the results of this thesis, it is possible to expect substantial economic opportunities for companies heavily involved in machining operations when micro patterned tools are preferred.