Cutting performance and wear mechanisms of Sialon–Si3N4 graded nano-composite ceramic cutting tools

Sialon–Si₃N₄ graded nano-composite ceramic tool materials were fabricated by using hot-pressing technique. The residual stresses in the surface layer of the graded ceramic tool materials were calculated by the indentation method. The cutting performance and wear mechanisms of the graded tools were investigated via turning of Inconel 718 alloy in comparison with common reference tools. The surface roughness of the finish hard turning of Inconel 718 and the microstructures of the chips were also examined. Worn and fractured surfaces of the cutting tools were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results showed that graded structure in Sialon–Si₃N₄ graded ceramic tool materials can induce residual compressive stresses in the surface layer during fabrication process. Tool lifetime of graded ceramic tool was higher than that of the common reference tool. The longer tool life of the graded nano-composite ceramic tool was attributed to its synergistic strengthening and toughening mechanisms induced by the optimum graded compositional structure of the tool and the addition of nano-sized particles. Wear mechanisms identified in the machining tests involved adhesive wear and abrasive wear. The mechanisms responsible for the higher tool life were determined to be the formation of compressive residual stress in the surface layer of the graded tools, which led to an increase in the resistance to fracture.     

加工含镍球墨铸铁时梯度陶瓷刀具的失效机理

研究了Al2O3／TiC梯度陶瓷刀具干切削含镍球墨铸铁的切削性能及损坏机理。结果表明,梯度陶瓷刀具的寿命约为硬质合金YS10刀具的1—2倍,且切削速度愈高,梯度陶瓷刀具的优越性愈显著;其损坏形式：低速切削时,为磨粒磨损;高速切削时,为剥落及粘结磨损。     

Al2O3基纳米复合陶瓷刀具切削不锈钢的实验研究

实验研究了Al2O3基纳米复合陶瓷刀具ASs与LTN连续干切削奥氏体不锈钢1Cr18Ni9Ti时的切削性能。结果表明,在相对较高的切削速度下,两种刀具表现出较好的切削性能,其中ASs刀具的主要磨损机制是粘结磨损和微崩刃,而LTN刀具则主要是粘着剥落;在相对低速下切削时,两种刀具都发生粘结破损失效。     

Performance of ceramic tools in high-speed cutting iron-based superalloys

A series of turning tests were conducted to investigate the cutting performance of ceramic tools in high-speed turning iron-based superalloys GH2132 (A286). Three kinds of ceramic tools, KY1540, CC650, and CC670 were used and their materials are Sialon, Al₂O₃–Ti(C,N), and Al₂O₃–SiC_w, respectively. The cutting forces, cutting temperatures, tool wear morphologies, and tool failure mechanisms are discussed. The experimental results show that with the increase in cutting speed, the resultant cutting forces with KY1540 and CC670 tools show a tendency to increase first and then decrease while those for CC650 increase gradually. The cutting temperature increases monotonically with the increase in cutting speed. The optimum cutting speeds for KY1540 and CC650 when turning GH2132 are less than 100 m/min, while those for CC670 are between 100 and 200 m/min. Flank wear is the main reason that leads to tool failure of KY1540 and CC670 while notch wear is the main factor that leads to tool failure of CC650. Tool failure mechanisms of ceramic tools when machining GH2132 include adhesion, chipping, abrasion, and notching. Better surface roughness can be got using CC670 ceramic tools.     

The computer simulation of the temperature distribution on the surface of ceramic cutting tools

The temperature distributions on the surface of Si₃N₄ and Ti(CN) ceramic cutting tools for turning different metallic materials were calculated and plotted using computer simulation based on a mathematic model of heat sources. The results showed that the temperature on the rake face of the ceramic cutting tools for turning 18-8 stainless steel was much higher than that for turning 1045 plain carbon steel due to the much lower thermal conductivity of the former, the temperature increased with increasing cutting speed. This observation is important in explaining the wear resistance and wear mechanisms of the two ceramic cutting tools. The computed temperature distributions on the surface of the ceramic cutting tools were checked by measurement with a thermal video system (TVS), and showed good agreement.     

Evaluation of the Machinability of Nickel-Base,Inconel 718, Alloy with Nano-Ceramic Cutting Tools

The machinability of difficult-to-cut aerospace alloys can be enhanced by the rapid development of cutting tool materials that can withstand machining at high-speed conditions. The performance of nano-grain size ceramic tool materials were evaluated when machining nickel base, Inconel 718, in terms of tool life, tool failure modes and wear mechanisms as well as component forces generated under different roughing conditions. Comparison tests were carried out with commercially available ceramic tool materials of micron-grain composition.

The test results show that the micron grain size commercially available tool materials generally gave the longest tool life. The dominant failure mode is nose wear, while some of the nano-ceramic tools were rejected mainly due to chipping at the cutting edge. This suggests that physical properties and mechanical stability of the cutting edge of the ceramic tools influence their overall performance. It is also evident that chemical compositions of the tool materials played a significant role in their failure. The alumina base ceramics are more susceptible to premature fracture than the silicon nitride base ceramics with higher fracture toughness.     

铁基粉末冶金材料的高速干切削试验研究

用陶瓷刀具、涂层刀具和硬质合金刀具进行了铁基粉末冶金零件的干切削对比试验,研究了切削速度、切削深度以及进给速度与刀具耐用度和加工表面粗糙度的关系,分析了陶瓷刀具的磨损机理。结果表明所选用陶瓷刀具的切削性能明显优于涂层刀具和硬质合金刀具;陶瓷刀具前刀面主要磨损形式为月牙洼磨损与剥落,后刀面的主要磨损原因为磨粒磨损;认为陶瓷刀具更适合用于粉末冶金零件的切削加工。     

陶瓷涂层刀具切削灰铸铁的试验研究

为了探究陶瓷涂层刀具涂层材质、基体材质对切削性能的影响,试验采用四种陶瓷涂层刀具连续干切削灰铸铁,测试了切削力和切削温度的变化情况以及后刀面的磨损量和已加工表面的粗糙度。结果表明,在刀具基体同为Si_3N_4的条件下,涂层材质为Ti N/Al_2O_3/Ti C的刀具比Ti N/Al_2O_3的切削性能好;在涂层材质同为Ti N的条件下,刀具基体Al_2O_3/Ti CN比Al_2O_3/Ti C的切削性能好。研究发现:四种陶瓷涂层刀具前刀面磨损形式均为微崩刃和月牙洼,后刀面磨损形式均为磨粒磨损和粘着磨损,涂层的磨损形式均为剥落和扩散磨损。     

Experimental investigations on the failure mechanism and self-sharpening of a graded tool

To solve the urgent needs of high-performance cutting tool and high-efficient cutting process for nickel-based super alloy, a graded ceramic tool was manufactured and a series machining experiments were performed in high-speed (HS) conditions. The failure mechanisms of the graded tool were revealed by analysis the micro-structure and failure morphology. The experimental results exhibited that the primary failure mechanisms were adhesive wear, micro-chipping and flaking. For the graded tool, the step-shaped flaking surfaces and some narrow flaking strips were found on the rake face and along the cutting edge, respectively, which were the self-sharpening cutting characteristics. These characteristics should be attributed to the synergistic mechanisms of strengthening and toughening resulted from the reasonably graded structure. In addition, during the HS milling process, this characteristic was also presented on the failure faces of homogeneous tool with SiC whisker reinforced. Therefore, it is concluded that the characteristics were in a close relation to the cutting parameters and tool mechanical properties.     

镍基粉末冶金零件的切削试验研究

对陶瓷刀具和硬质合金刀具进行了镍基粉末冶金零件的干切削对比试验,测量了切削力和加工表面粗糙度,分析了刀具的磨损机理。试验结果表明:陶瓷刀具的切削性能明显优于硬质合金,适合于粉末冶金零件的切削加工。     

Al_2O_3-TiB_2 刀具的磨损特性

对ＴｉＢ２颗粒增强Ａｌ２Ｏ３刀具在车削正火态、调质态４５＃钢和球墨铸铁齿轮坯时的刀具磨损性能、磨损机理进行了研究，并与硬质合金刀具的耐磨性能进行了对比。结果表明：Ａｌ２Ｏ３┐ＴｉＢ２陶瓷刀具具有良好的耐磨性能。刀具磨损主要以脆性剥离为主，同时存在着犁耕和塑性流变过程，陶瓷刀具表面形成的粘结层结构疏松，与基体结合力较弱，较易脱落，不易形成粘结磨损。     

陶瓷刀具和PCBN刀具磨损形态的研究

对陶瓷刀具(CC650)和PCBN刀具(CB20)精车淬硬GCr15轴承钢时的刀具磨损形态及性能进行了对比试验；结合扫描电镜对刀具的磨损形态作观察；分析了刀具磨损特征及磨损机理。结果表明：刀具损坏的形态主要为前刀面磨损、后刀面磨损、微崩刃及破损等；陶瓷刀具和PCBN刀具的前后刀面磨损形态不同于典型的磨损形态，陶瓷刀具主后刀面的磨损量要比PCBN刀具的磨损量小。但两种刀具均适合于淬硬钢的精加工工序。     

Wear behaviour of alumina based ceramic cutting tools on machining steels

The advanced ceramic cutting tools have very good wear resistance, high refractoriness, good mechanical strength and hot hardness. Alumina based ceramic cutting tools have very high abrasion resistance and hot hardness. Chemically they are more stable than high-speed steels and carbides, thus having less tendency to adhere to metals during machining and less tendency to form built-up edge. This results in good surface finish and dimensional accuracy in machining steels. In this paper wear behaviour of alumina based ceramic cutting tools is investigated. The machining tests were conducted using SiC whisker reinforced alumina ceramic cutting tool and Ti[C,N] mixed alumina ceramic cutting tool on martensitic stainless steel-grade 410 and EN 24 steel work pieces. Flank wear in Ti[C,N] mixed alumina ceramic cutting tool is lower than that of the SiC whisker reinforced alumina cutting tool. SiC whisker reinforced alumina cutting tool exhibits poor crater wear resistance while machining. Notch wear in SiC whisker reinforced alumina cutting tool is lower than that of the Ti[C,N] mixed alumina ceramic cutting tool. The flank wear, crater wear and notch wear are higher on machining martensitic stainless steel than on machining hardened steel. In summary Ti[C,N] mixed alumina cutting tool performs better than SiC whisker reinforced alumina cutting tool on machining martensitic stainless steel.     

陶瓷刀具高速干切削等温淬火球铁(ADI)磨损性能研究

采用陶瓷刀具(CC650)对等温淬火球墨铸铁(以下简称AD I)进行干式高速切削试验,用带有X射线能谱分析的扫描电镜观察刀具表面的磨损形貌,并对刀具磨损微区和工件表面成分进行定性分析,用X射线衍射仪对刀具、工件和切屑等试样进行物相分析,研究高速切削时陶瓷刀具磨损性能及磨损机制。结果表明:切削速度是影响刀具寿命的主要因素;CC650刀具高速干切削AD I时形成的刀具主后刀面和前刀面的磨损形态基本类似中、低速条件下磨损形态,主要区别在其磨损区域紧靠切削刃,最大磨损部位位于切削刃附近;CC650刀具高速切削AD I时切削温度高,其磨损是机械磨损与化学磨损综合作用的结果,磨损机制主要包括磨料磨损、扩散磨损、粘结磨损和微崩。     

Effect of cutting speed on cutting forces and wear mechanisms in high-speed face milling of Inconel 718 with Sialon ceramic tools

In this paper, a series of milling tests were carried out in order to identify the effects of cutting speed on cutting forces and tool wear when high-speed face milling Inconel 718 with Sialon ceramic tools. Both down-milling and up-milling operations were conducted. The cutting forces, tool wear morphologies, and the tool failure mechanisms in a wide range of cutting speeds (600–3,000 m/min) were discussed. Results showed that the resultant cutting forces firstly decrease and then increase with the increase of cutting speed. Under relatively lower cutting speeds (600 and 1,000 m/min), the dominant wear patterns is notching. Further increasing the speed to more than 1,400 m/min, the notching decreases a lot and flank wear becomes the dominant wear pattern. In general, at the same cutting speed, flaking on the rake face and notching on the flank face are more serious in down-milling operation than that in up-milling operation with the same metal removal volume. However, the surface roughness values for down-milling are lower than that for up-milling.     

Effect of cutting atmosphere on dry machining performance with Al2O3/ZrB2/ZrO2 ceramic tool

In this paper, Al₂O₃/ZrB₂/ZrO₂ ceramic cutting tool was produced by hot pressing. Dry cutting tests in air and nitrogen atmospheres were carried out on normalized AISI 1045 steel. The tool wear, cutting temperature, cutting force, and friction coefficient were measured. Compared in nitrogen, the friction coefficient in air was reduced when the cutting speed was higher than 160 m/min. Scanning electron microscopy and energy dispersive X-ray analysis techniques were employed to observe the worn surfaces of the ceramic tools, and the wear mechanisms were simultaneously discussed. Experimental data and observations revealed the formation of oxide film under air in dry machining, which related to the decrease of the friction coefficient and the improvement of cutting performance.     

The effect of cutting parameters and cutting tools on machining performance of carbon graphite material

Abstract

The present study focuses on the effects of cutting speed, feed rate and cutting tool material on the machining performance of carbon graphite material. Polycrystalline Diamond (PCD) cutting tools are used in machining experiments and its performance is compared with the tungsten carbide (WC) and Cubic Boron Nitride (CBN) tools. Machining performance criteria such as flank and nose wear and resulting surface topography and roughness of machined parts were studied. This study illustrates that feed rate and cutting tool material play a dominant role in the progressive wear of the cutting tool. The highest feed rate and cutting speed profoundly reduce the tool wear progression. The surface roughness and topography of specimens are remarkably influenced from the tool wear. Major differences are found in the wear mechanisms of PCD and WC and CBN cutting tools.     

陶瓷刀具低速切削时的有限元分析

采用有限元方法对梯度功能陶瓷刀具和普通陶瓷刀具的机械应力场进行了计算和分析 ,结果表明 :梯度功能陶瓷刀具和普通陶瓷刀具的机械应力基本相等 ,在低速切削时梯度功能陶瓷刀具的抗破损能力与普通陶瓷刀具相比并无太大优势     

高速干切削铁基粉末冶金零件时细晶粒硬质合金刀具的切削性能研究

用细晶粒硬质合金刀具进行了铁基粉末冶金零件的高速干切削试验。研究了切削参数与刀具耐用度以及加工表面粗糙度的关系,给出了刀具的主要磨损形态,通过能谱分析研究了刀具的磨损机理。结果表明:所选用细晶粒硬质合金刀具具有较高的刀具耐用度和较好的加工表面粗糙度,适合于铁基粉末冶金的加工;细晶粒硬质合金的主要磨损形态是前刀面的月牙洼磨损;主要磨损机理是扩散磨损、粘结磨损。     

Al2O3基陶瓷刀具车削300M超高强度钢的刀具寿命研究

采用对角正交回归试验法,求得Al2O3基陶瓷刀具切削300M超高强度钢的刀具寿命经验公式,并分析了切削用量对刀具寿命的影响.通过扫描电子显微镜的观察和能谱分析仪的分析,对Al2O3基陶瓷刀具的损坏形态和磨损机理进行了研究.研究表明:Al2O3基陶瓷刀具车削300M超高强度钢时,粘结磨损和磨粒磨损是主要的磨损机理;合理的切削参数为:切削速度200～300 m/min、切削深度0.1～0.15 mm、进给量0.05～0.1 mm/r.