Papers by Keyword: CBN Tool

Abstract: Nickel-based superalloys such as Inconel 718 are known as one of the most difficult-to-cut materials due to their mechanical and chemical properties and the tool life is extremely short. Recently, Cubic-Boron-Nitride (CBN) has received a considerable attention as a material for cutting tools and has been considered to be a major candidate for high performance cutting of Inconel 718. However, the detailed wear behavior of CBN tools in cutting of Inconel 718 is not sufficiently understood yet, and the performances of CBN tools are still insufficient in practical use. To overcome this problem, we first conducted orthogonal cutting experiments on Inconel 718 at low (20 m/min) and high (100 m/min) cutting speeds employing CBN cutting tools to clarify the detailed wear mechanisms. Moreover, relationship between surface microstructures of the cutting tool and wear resistance was investigated. As a result, it was found that a rake face with micro grooves significantly suppressed the crater wear at low cutting speed, although polished surface rake face reduced the initial crater wear by approximately 40 % compared to the non-polished tool in high speed cutting of Inconel 718.

Abstract: Machining efficiency of titanium alloys is crucial to the aerospace industry especially in the manufacture of bladed discs (blisks) where over 80% of titanium alloy material is roughed out to generate the complex shapes and contours of components. The choice of the right tool materials for machining titanium alloys contributes enormously to reducing the overall machining time by significantly lowering the cycle time and indexing of the cutting edges. These improvements lead to a reduction of the manufacturing cost by up to 30%. Uncoated and coated carbide tools have demonstrated encouraging performances when turning Ti-6Al-4V alloy, especially under roughing operations complemented by high pressure cooling technology, at high cutting speed and depth of cut conditions that increase the metal removal rate. Under such cutting conditions there is no significant difference in performance between coated or uncoated carbide tools when turning Ti-6Al-4V alloy. Super abrasives like ceramics and cubic boron nitride (CBN) tools are not suitable for machining titanium alloys as low tool life with no economic benefit is achieved because of severe chipping and fracture of the cutting edge. Machined surfaces produced with ceramic tools have very low surface integrity status because of loss of form as a result of accelerated tool wear and the consequent chipping and fracture encountered during machining. Polycrystalline diamond (PCD) tools are suitable for finish turning Ti-6Al-4V alloy at cutting speeds up to 250 m/min.

Abstract: The wear morphology of rake face and flank face of tool is investigated by turning titanium alloy TC4 with CBN solid tool. It has been observed that the main wear form of rake face and flank face of tool is groove wear. The relation between tool flank wear and cutting speeds, feed rate, and cutting depth obtained from experimental data is given.

Abstract: In this paper, the cutting experiment was used to study the influence of various cutting parameters on cutting force when rough turning titanium alloy (TC4) with the whole CBN tool. The results indicate that among the cutting speed, feed rate and cutting depth, the influence of the cutting depth is the most significant on cutting force; the next is the feed rate and the cutting speed is at least.

Abstract: CBN cutting tool is used to cut hardened GCr15 bearing steel. Based on the surface roughness under different cutting parameters, people built the prediction model of surface roughness by Linear Regression algorithm, and carried on the significance test of it, the results show that the surface roughness forecast model set up by linear regression algorithm has a certain reliability and its linear regression equation is significant; among the cutting parameters, cutting speed and feed rate make great impact to the surface roughness and back engagement of the cutting edge has little impact to the surface roughness of test specimen.

Abstract: Coatings were turned by two tools: a) ISO 2R 2525K10, geometry and cutting parameters recommended by Messner Eutectic Castolin Company (tool angle β = 90^o, approach angle κ_r = 45^o, nose radius r_ε =0,8 mm, clearance angle α = 6^o, rake angle γ = -5^o) b) bit tool with CBN WNGA080408S01030A insert mounted in DWLNRL-2525M08 holder (cutting inserts β = 80^o, approach angle κ_r = 95^o, nose radius 0,8 mm, clearance angle α = 6^o, rake angle γ = -6^o). The influence of cutting speed, feed rate, depth of turning on the coating surface roughness was estimated. The following cutting parameters: cutting speed V_c = 45 214 m/min, feed rate f = 0,04 0,196 mm/rev, depth of cut a_p = 0,05 0,3 mm. The lowest value of the roughness R_a = 0,5μm of the coatings were obtained by using cutting tools and parameters and bit tool: V_c = 214 m/min, f = 0,06 mm/rev, a_p = 0,3 mm.

Abstract: Compositions of cutting tools based on cubic boron nitride phase added with different ceramics as binders have been the subject of several works. A major problem of these tools during machining of steel is the loss of cutting efficiency due the "chemical weathering" generated by the reaction between iron and cBN at the high temperatures reached by the machining operations. Aiming to eliminate these problems, this paper presents results on the development of composites obtained by sintering process at high pressures and high temperatures in association with a cyclic operation. Si₃N₄ was used as the binder agent. The compacts were analysed by x-ray diffraction as well as optical and scanning electron microscopy. The mechanical properties were evaluated by means of microhardness and fracture toughness tests. The degree of phase transformation of the Si₃N₄, the chemical reaction during the cyclic sintering process, and the sintering mechanism of the additive were discussed.

Abstract: In this work a factorial planning had been used to evaluate the CBN tool life during cut-ting SAE 8620 steel. Part U2222 of a TPGW 160408 insert of TX-LS TB650 and 2NU-SHMA6942 S7182BN300 classes from two manufacturers were used in this experiment. A 23 factorial design was used In cutting process to evaluate the behavior of the tool life and reason of the exchange of the part on influences of the chamfer (in S and T+S), the advancing speeds (0.09, 0.10 and 0.11 mm/rpm) at a cutting speed of 91.2 m/min. Model have been fit by variance analysis (ANOVA) and the processing optimization was done by response surface methodology (RSM). Results showed that a hyperbolic model had more adjusting than other models and the optimization showed a high life time for the TX-LS TB650 tool from A manufacturer on 0.09 mm/rpm of advancing speed, where it was observed that the pre-cranking was the reason of the exchange.

Abstract: This paper describes ultrasonically assisted fly cutting for finishing advanced ceramics for hot-press dies used to fabricate glass lenses. Fly cutting can perform shallow machining, which realizes ductile-mode cutting of hard, brittle materials. Ultrasonically assisted machining can increase the critical cutting depth (i.e., the maximum cutting depth for ductile-mode machining of a surface). The technique proposed in this paper combines both techniques and enables precise finishing of advanced ceramics at a high machining efficiency. Ultrasonic assisted fly cutting was found to reduce tool fracture and improve the finished surface quality compared with conventional fly cutting.