Papers by Keyword: High-Speed Milling

Abstract: AMS 6260 alloy is a nickel-chromium-molybdenum steel containing Ni, Cr, Mo, with Fe as the main component, and is one of AMS (aerospace materials specifications) in the United States. This material has high hardenability and high toughness. For this reason, it is used as a material for parts that require high toughness, such as gears in aircraft engines. However, while AMS 6260 alloy after heat-treatment has high hardness, it significantly reduced machinability. Therefore, it is extremely difficult to achieve high efficiency and high accuracy in the cutting process of AMS 6260 after heat-treatment. In this paper, the experimental milling of the hardened AMS 6260 alloy after heat-treatment is conducted under some cutting conditions using a coated cemented carbide radius end mill, and the effect of cutting conditions on the flank wear and surface roughness is investigated. As a result, optimal cutting conditions on the tool wear and surface roughness were clarified.

Abstract: The present work aims to optimize the processing parameters to minimize the geometric deviations of thin-walled parts machined from 6061-T651 aluminum alloy by high-speed milling (HSM). The experimental tests were carried based on a factorial design of experiments, which included as input factors axial cutting depth, cutting speed, and feed per tooth, resulting in shape deviations but also roughness and hardness of machined surfaces. After machining, the residual stresses were determined to establish, if possible, a cause-effect relationship between parts deviations and the magnitude of stresses involved. The experimental tests allowed us to obtain the optimum machining parameters under maximum productivity conditions that ensure the required geometric precision of parts.

Abstract: Nowadays, increasing the productivity and the quality of machining become major challenges of the metal cutting process. Due to the complexity of the chip formation process, in particular, at high cutting speeds, finite element model (FEM) has been frequently used as an alternative solution. Chip shrinkage coefficient and cutting force are the two basic parameters of the cutting process, which determines the productivity and quality of the workpiece. This study uses a Grey correlation relationship to analyze and select the common set of parameters for cutting force and chip shrinkage coefficient of the chip. Simulation of the A6061 aluminum alloy high-speed milling is done by Bao-Wierzbicki's (B-W) model. The optimal parameters are determined cutting depth 1 mm, clearance angle 6^o and rake angle 10^o. This parameter set adjusts the cut parameters so that the cutting process achieves the highest machining efficiency.

Abstract: Stainless steel is an excellent material that has properties such as heat and corrosion resistance. Thus, stainless steel is used as a material in steam turbine blades. Steam turbine blades are mainly manufactured using two methods. One is the cutting of unforged metal ingots. Another is the cutting of forged parts. Small blades are made by cutting metal ingots. Large blades are made by cutting forged parts. The mechanical characteristics of a metal ingot and a forged part, such as hardness and toughness, are almost the same. There were not researches related to a relationship between “an unforged ingot and a forged part of stainless steel” and “the differences of the tool wear and the finished surface by high-speed milling”.In this study, the high-speed milling of stainless steel was attempted for high-efficiency cutting of a steam turbine blade. The differences of the tool wear and the finished surface in the cuttings of an unforged ingot and a forged part were investigated. In the experiment, the cutting tool was a TiAlN coating radius solid end mill made of cemented carbide. The diameter of the end mill was 5 mm, and the corner radius was 0.2 mm. The cutting speed were 100 m/min-600 m/min. The workpieces used were a metal ingot and a forged part of stainless steel. In the results, it was found that the differences of the tool wear and the finished surface in the cuttings of an unforged ingot and a forged part. In the case of the unforged ingot, the flank wear became large with increasing cutting speed. On the other hand, in the case of forged part, the flank wear rapidly increased at a cutting speed of 100 m/min. In addition, the flank wear became smaller than the cutting speed 100 m/min at the cutting speed 200 m/min. Further, the flank wear became large with increasing cutting speed at cutting speeds higher than 200 m/min. That is, the flank wear was at a minimum at a cutting speed of 200 m/min. Although it could not be confirmed the characteristic of high speed milling at an unforged ingot, it has been identified at a forged part.

Abstract: This paper presents an experimental verification of the alternative options for using by-products or mineral waste materials applied to cold recycled mixtures with low level of stabilisation intended for low-volume road structures. To achieve the necessary refinement and a certain level of reactivity potential, the by-products were activated mechanically, i.e. pulverized in a high-speed disintegrator with respect to the lowest possible energy demands of the process and to the level of wear-and-tear of the working components in the milling machine. Such refined material, with average particle size of 10-15 μm, is applies as an active filler component allowing to partly substitute hydraulic binder in cold recycled mixtures. The application of such materials in structural pavement layers should increase the environmental benefits and result in added economic value. The experimental measurements taken focused on cold recycled mixtures with low level of stabilisation, modified by a combination of binders, or namely cement, mechanically activated concrete from reclaimed concrete pavement slabs originating from the Czech backbone D1 highway modernisation, mechanical-chemically activated fluid ashes from the Pilsen heat plant and foamed bitumen. Both basic volumetric properties and strength and deformation parameters were set for the purposes of evaluation of the characteristic measured in the experimental mixes.

Abstract: This article was focused on the influence of the micronized waste marble powder on mechanical properties of cement pastes. Resulting blended cement was composed of Portland cement CEM I 42.5 R and micronized marble powder with different percentage amounts (0 wt. %, 5 wt. %, 10 wt. % and 15 wt. %). Testing was carried at prismatic samples of dimension 40 × 40 × 160 mm. The investigated mechanical properties were dynamic modulus of elasticity, dynamic shear modulus, flexural strength and compressive strength for the 28 days old samples. The results obtained from these materials were compared with reference material.

Abstract: For production of the samples were used several types of aggregate: the standard sand from Zalezlice, the standard sand from Gaza, waste crushed limestone, waste marble sludge and waste micronized marble powder. The Portland cement CEM I 42.5 R produced in Radotín was used as binder. Testing was carried at prismatic samples of dimension 40 × 40 × 160 mm. Another approach than previously used solutions consists primarily in micronization marble sludge with a high-speed mill, this modified micronized filler may also an impact on the final properties of composite materials based on cement. The micronized powder may have binding properties that are activated in this way. Dynamic modulus of elasticity, dynamic shear modulus, flexural strength and compressive strength were determined for the 28 days old samples.

Abstract: In order to obtain better surface quality after high speed milling high hardness mold steel, and reduce tool wear in cutting process, prolong the service life of cutting tools, obtain superior levels and optimal combination of cutting parameters in the test range. Through the design of orthogonal experiment, the use of Taguchi method, and noise ratio analysis and variance analysis of dry cutting high hardness mould steel PM60 under different cutting parameters; and finally, the optimal cutting parameters of surface roughness and cutting force value were predicted and verified. Research showed that: the worst cutting parameters influenced the surface roughness R_a was radial depth of cut a_e, its influence was highly significant, followed by spindle speed n and depth of axial cut a_p; the most serious impact cutting parameter of cutting force F was the feed speed v_f, followed by the spindle speed n and radial depth of cut a_e; verification test showed that the optimal cutting parameters combination were reasonable and the calculation errors of the predicted values and experimental values were very small, indicating that Taguchi method in cutting parameters optimization of cutting mould steel PM60 was valid.

Abstract: When milling corners in high speed, it will lead the mutation of cutting force that affects the processing quality and processing efficiency. In order to study the influence of milling parameters on milling force in the corner. Firstly, an orthogonal experimental of corner is designed to study the influence of various cutting parameters on cutting force. Axial cutting depth, radial depth, spindle speed and feed speed, as the major influence factors, impact on cutting force in corner milling. Then, a cutting force model of corner is established based on a method of orthogonal experiment linear regression. The significance test of regression equation and regression coefficient shows that cutting force model is accurate. The cutting force model is used to predict the cutting force, and then select the appropriate cutting parameters.

Abstract: A series of research on the interactions among tool wear, cutting force and cutting vibration were conducted through high speed milling experiment in this paper, which objected the titanium alloy as difficult-to-cut materials. The results showed that the increasing of tool wear led to enlarging the cutting force and cutting vibration; and vice versa, the increasing of cutting force and cutting vibration aggravated the tool wear in the process of machining. Besides, the variation trend of tool wear with cutting was similar to the trend of cutting force, while the variation trend between cutting vibration and tool wear was different. Especially in the sharply cutting tool wear stage, the influence of tool wear on cutting vibration became more complicated.