Papers by Keyword: High Speed Milling (HSM)

Abstract: This paper presents an experimental study of wear mechanism on high speed milling of FC300 gray cast iron using TiAlN coated carbide cutting tool. The experiment was carried out under dry cutting condition with different cutting speed (95-143m/min) and feed rate (4000-7000 mm/min). The cutting tool for machining FC300 gray cast iron is a ball nose end mill ø32 mm coated with TiAlN. Wear mechanism was analyzed at VB 0.08mm after 60 minute machining. The flank wear increased when the spindle speed and feed rate increased caused by the generated high shearing force and high cutting temperature. The dominant wear mechanisms appear to be the abrasion, adhesion, chipping and delaminating of coating at the contact surface of cutting tool. Formation of built-up edge (BUE) was evidence for most of the cutting trials.

Abstract: Machining technique using high spindle speed, high feed rate and shallow depth of cut utilize in High Speed Milling (HSM) machines offer several benefits such as increase of productivity, elimination of secondary and semi-finishing process, reduce tool load and small chips produced. By adjusting some of the machining parameters, non-HSM machine having lower spindle speed and feed rate could also take advantages some of the benefits mentioned above when applying the HSM technique. This experiment investigate the effects of varying combination of depth of cut and feed rate to tool wear rate and surface roughness during end milling of Aluminum and P20 tool steel in dry condition. The criterion for tool wear before it gets rejected is based on maximum flank wear, Vb of 0.6mm. Material removal rate, spindle speed and radial depth of cut are constant in this experiment. After preliminary machining trials, the combination starts with depth of cut of 2mm and feed rate of 45mm/min until the smallest depth of cut and highest feed rate of 0.03mm and 3000mm/min respectively. The obtained result shows that for both materials, feed rate significantly influences the surface roughness value while depth of cut does not as the surface roughness value keep increasing with the increase of feed rate and decreasing depth of cut. Whereas, tool wear rate almost remain unchanged indicates that material removal rate strongly contribute the wear rate. With no significant tool wear rate, this study demonstrates that HSM technique is possible to be applied in non-HSM machine with extra benefits of eliminating semi-finishing operation, reducing tool load for finishing, machining without coolant and producing smaller chip for ease of cleaning.

Abstract: According to the weak rigidity characteristics of thin-walled parts, the material parameters and deformation tools are taken into account. In this paper, the finite element model of high-speed milling process is systematically studied by a large-scale finite element analysis (FEA) software DEFORM-3D with the modified Johnson-Cook model. The simulated results of cutting force, chip morphology, effective stress, effective strain and cutting temperature in deformation zones of thin-wall part are analyzed. On the basis of simulation results, cutting force of high speed milling on thin-wall part is verified. Comparing to the experimental results, the simulated results of cutting force, chip morphology, effective stress and cutting temperature in deformation zones of high speed peripheral milling indicate good consistence and the models established can be used to accurately predict the thin wall deformation. Therefore, numerical simulation method for the thin wall milling deformation control and provide a new way of compensation.

Abstract: The eco-friendly and economic challenges are driving more and more aerostructure components with thin wall and deep pocket features. These features are getting thinner and deeper and become impractical during part manufacturing. Therefore, there is a need to better understand the mechanics, kinematics and dynamics of thin wall machining (which is the focus in this paper). In this paper, the application of a newly discovered relationship between the workpiece geometry and its damping parameters in the machining of aerospace structures is presented. This relationship allows for the prediction of damping ratios, without the use of experimental results for any wall with a different thickness compared to a reference wall. A previously proposed ‘improved stability lobes model’ is used to validate the damping model, as this model considers the nonlinearity of the cutting force coefficients. While a finite element method (FEM) is used to obtain natural frequencies and modal stiffness’s at different locations along the workpiece or toolpath, required in the stability model. The advantage of this new damping model is that, it alleviates the burden of having to carry out modal experiments to obtain the damping parameters required for subsequent stability margin predictions, as the work-piece thickness changes during machining.

Abstract: With FEM software of AdvantEdge, a model was created to analyze cutting force and thermal in the high-speed milling process, this model included a complete milling process of cutter radius. Combined with experiments validation, in high-speed milling, the normal force is greater than the tangential force and result in greater residual stress of that direction, which indicates that mechanical force play an essential part on the formation of residual stress. When the speed is over certain scope, the cutting force decreases, but the cutting temperature has been rising. In Roughing, by limiting the range of high-speed the residual tensile stress impact can be reduced. While in finishing, as the feed rate reducing the residual tensile stress will decrease greatly, improving the surface quality of thin-walled parts.

Abstract: Taking the machining efficiency and surface quality as the optimization objective, a multi-objective and multi-constrained optimization model of the high-speed milling parameters based on the matching of lengthened shrink-fit holder (LSFH) and cutter was established using fuzzy optimization theory. In this model, the contact performance, grip rigidity and dynamic characteristics of the matching of LSFH and cutter were taken into account. Subsequently, the optimization problem of the fuzzy domain was transformed into the optimization problem of the ordinary domain using the Optimal Level Cut Set Method. The optimization results show that the processing time reduced by 5.95% and 8.54%, the surface roughness decreased by 5.42% and 6.85% compared to conventional optimization model and the parameters recommended by the tool manual respectively. The effectiveness and practicality of this optimization method was further proved by processing examples.

Abstract: Analytical and experimental identifications on the characteristics of the acceleration signal in high speed milling (HSM) process using ball end mill were studied. Three parts of harden steel with different hardness were assembled together, as opposed to the single harden steel in general HSM process. Dynamic model of ball end milling was established, tests with new and worn cutter were carried out respectively. Time domain analysis on the acceleration signal showed that the amplitude varies with the hardness through the whole cutting path. Furthermore, frequency domain analysis using fast Fourier transform (FFT) technique shows that the spectrum of the vibration signal using new cutter contain the tool spindle rotation speed as fundamental frequency and its harmonics. On the other hand, the spectrum of vibration signal under tool wear state contain other frequencies in addition to the fundamental frequency and harmonics, and this feature of spectrum can be used to monitor the state of the cutter during HSM.

Abstract: Cutting force can response changes in cutting process deeply, so it is important for studying cutting force on revealing the milling mechanism. For this reason, based on the support of finite element theory, a mesh adaptation method is used to establish the simulation model on die tool Cr12MoV during high-speed milling by simulation software ThirdWave, and the effects of different cutting conditions on cutting force are studied by simulation method, which has verified the simulation results by experiments. The results of research also have certain reference significance on the optimization of cutting process and hard milling mechanism.

Abstract: For the instability of ball-end milling cutter in high speed milling, instantaneous cutting process of high speed milling hardened steel was studied. The model of instantaneous cutting layer parameters of high speed ball-end cutter was established, and the influence of cutting speed and inclination angles on instantaneous cutting layer parameters were obtained. Using the model, instantaneous cutting force was studied, and high speed milling experiment was processed. Results show that the increase of cutting speed makes the change rate of cutting layer parameters increasing, leads to the energy concentration in cutting process, and increases the impact on milling cutter. The increase of inclination angle makes the instantaneous cutting layer parameters show a trend of decrease and the decrease of cutting thickness more rapidly, which caused instantaneous unit cutting force to increase and the instantaneous main cutting force appears increasing trend, and the cutting process become unstable.

Abstract: High-speed cutting is a complexity and uncertainty process .The cutting parameters optimization is ambiguous. In this paper, based on the orthogonal experiment of high-speed milling aluminum alloy 7475, we use fuzzy comprehensive evaluation to optimize the parameters high-speed milling of aluminum alloy 7475 in the indication of surface roughness, cutting force, material removal rate. We have got cutting parameters optimal that is highly processing quality and productivity. Compared optimal results with orthogonal experimental results, we found that the optimal result is reliable. The study shows that fuzzy comprehensive evaluation method can optimize the parameters of high-speed milling of aluminum alloy 7475 accurately. This method has also a good application effect to other materials and great significance to guide actual production.