Small Ball End Mill Research Articles

Monitoring method of cutting forces and vibrations by using frequency separation of acceleration sensor signals during milling process with small ball end mills

Recently, there has been a further demand for precise monitoring of milling process with a machine tool by a simple and cost-effective method. One of the ways for monitoring is to install acceleration sensors to the tool spindle and estimate cutting forces from the model of the tool spindle structure. This method generally allows stable monitoring of cutting forces for tools with large diameters. However, in case of using tools with small diameters, it is difficult to estimate the cutting force due to higher frequency vibrations generated near the tool center point. Therefore, to solve the problem, we propose a new monitoring method by signal analysis of acceleration sensors in this research. The problem is that the acceleration sensor signals contain two types of signals, such as ‘acceleration change due to mechanical displacement of a tool spindle generated by cutting load’ and ‘high frequency self-excited and forced vibration’. In our method, we separate these two signals by using an approximation of sequential quadratic regression. From the former, cutting forces are estimated from equation of motions which are obtained in advance from frequency responses of the tool spindle, and from the latter, intensities of vibrations due to milling are estimated. This method was tested several milling patterns such as large cutting loads, fluctuations of cutting loads, and cutting during abnormal vibrations. As a result, we have achieved in-process monitoring of milling process not only in the X and Y directions, but also in the Z direction with a small radius ball end mill.

A study on milling of super elasto-plastic titanium alloy with a small ball end mill tool

A study on milling of super elasto-plastic titanium alloy with a small ball end mill tool

A study on milling of super elastic-plastic titanium alloy with a small ball end mill tool

A study on milling of super elastic-plastic titanium alloy with a small ball end mill tool

A Study on Milling of Niobium-Titanium Alloy with A Small Ball End Mill Tool

A Study on Milling of Niobium-Titanium Alloy with A Small Ball End Mill Tool

小径ボールエンドミルによる超弾塑性型チタニウム合金のミーリング加工に関する研究

小径ボールエンドミルによる超弾塑性型チタニウム合金のミーリング加工に関する研究

小径ボールエンドミルを用いた超弾塑性型チタニウム合金の微細加工に関する研究

β-type titanium alloy exhibiting super-elasticity and super-plasticity was developed. This alloy has high tensile stress and low young's modulus too. The excellent characteristics of this alloy indicate its likely application in the field of dental implant. However, the characteristics of this alloy is lost by severe heat environment and external force. In this study, the effect of cutting temperature and cutting force on the affected layer was investigated by milling with small ball end mill tool in order to decrease the affected layer by cutting process. The thickness of affected layer indicated a tendency to increase with the cutting speed. And at the cutting speed of 16.0m/s, the thickness of the affected layer exceeded 2.5μm because of increasing of cutting temperature. On the other hand, the thickness of affected layer was 0.7μm at the condition of the environment of high cutting force. Thus, the affected layer influenced by cutting temperature.

A25 超弾塑性特性を有するチタニウム合金を対象とした小径ミーリング加工に関する研究 : 工具被膜の最適化に関する検討(OS3 工具・ツーリング(1))

A25 超弾塑性特性を有するチタニウム合金を対象とした小径ミーリング加工に関する研究 : 工具被膜の最適化に関する検討(OS3 工具・ツーリング(1))

S132023 超弾塑性特性を有するチタニウム合金を対象とした小径ボールエンドミル工具によるミーリング加工に関する研究 : 最適切削速度の検討([S132-02]先進切削加工技術(2))

Recently, P-type titanium alloy having super-elasticity and super-plasticity was developed. Since it has the excellent characteristic, such as a mechanical property, corrosion resistance and biocompatibility, application in the oral surgery field is expected. However, super elasto-plastic titanium alloy having a high property of adhering and low thermal conductivity, it is difficult machining. In this study, the effect of cutting speed on tool life was investigated milling with small ball end mill tool. As a result, although a tool wear is small on each cutting speeds, the wear shows a tendency to decrease slightly with increase in a cutting speed. However, surface roughness shows an tendency to increase opposite to wear. Especially, the surface roughness on cutting speed of 4.0m/s becomes large compared with the other conditions. Further, cutting temperature became highest in cutting speed of 4.0m/s and it was about 580K. Moreover, in the cutting speed range of this experiment, the thickness of the affected layer was 500 nm and was very thin. It is clarify that optimum cutting speed is 2.5m/s from the viewpoint of tool life and surface roughness.

Experimental investigation on cutting mechanism of laser sintered material using small ball end mill

This paper describes an experimental investigation on the cutting mechanism of laser sintered material using small ball end mill focusing on the temperature of the cutting edge. Sintered material was produced by irradiating a laser beam on a layer of loose fine SCM–Ni–Cu powder. Bulk carbon steel AISI 1055 was selected as reference steel. The influence of cutting conditions, tools diameter and unsintered metallic powder on the cutting edge temperature were examined. Comparison of the cutting edge temperature between the peripheral and surface milling were investigated. Investigations of the tool life and wear mechanisms in cutting the sintered material and AISI 1055 were also carried out. Results indicated that the cutting edge temperature for sintered material was higher than for bulk AISI 1055. Cutting at the outer surface of sintered material produced higher temperature than at the inner surface. The temperature of the cutting edge was greatly influenced by the cutting speed followed by depth of cut and feed per tooth. Cutting temperature for different tool's diameter was almost similar under the same rotational speeds and cutting conditions. Cutting tool temperature in peripheral milling was higher than in surface milling. Adhesion of the work material and chipping were the main wear mechanisms of the ball end mill in cutting sintered material.

Tool Life of Small Diameter Ball End Mill for High Speed Milling of Hardened Steel - Effects of the Machining Method and the Tool Materials -

We studied tool life, flank wear, and machined surface roughness in the high-speed milling of hardened steel on a small ball end mill using a high-speed milling machine. We found that: (1) Cutting edge flank wear increases in proportion to cutting length and the flank wear shape gradually has a resembalance to the shape of the actual cutting length. (2) Long tool life depends on stepdown pick-feed and down-milling conditions. (3) Surface roughness increases in proportion to cutting length, but a low surface roughness of 1.4 μm is obtainable for a 3,800 m cutting length in down-milling. (4) CBN tool flank wear is very low -- at least 1/15 th that of carbide tools under down-milling conditions, and a surface roughness of 1.6 μm is obtainable for a 67.2 km cutting length. We verified the effectiveness of CBN tools in high-speed milling of hardened steel under cutting conditions.

610 小径ボールエンドミル多軸曲面加工の高精度化 : 創成点固定法の提案(G.S.設計・工作2,九州支部 第58期総会・講演会)

610 小径ボールエンドミル多軸曲面加工の高精度化 : 創成点固定法の提案(G.S.設計・工作2,九州支部 第58期総会・講演会)

Studies on High-Speed Milling with Small Ball End Mill

A new three-color infrared radiation pyrometer using an optical fiber is developed for measuring cutting temperature in high speed machining by small ball end mill. The high speed air spindle unit is adopted to the ordinary milling machine so that the maximum spindle revolution of 40000rpm is attainable. The ball radius of the carbide cutter is 3mm and the side cutting of carbon steel with ballnose is executed without cutting fluid. Cutting temperature distribution along the ball-nosed cutting-edge is measured. The influences of spindle rotational speed, radial depth of cut and feed per tooth on the temperature distribution at the flank face are examined. The maximum temperature of peripheral cutting edge about 700°C is obtained even at the rotation angle of 180° after cutting, and it drops along the ballnose toward the ball tip. Relatively large temperature gradient arises along the ball cutting-edge at higher spindle revolution because cutting speed depends on the local tool radius. Depth of cut and feed per tooth, at the same time, affect the overall temperature at the ball cutting edges. The cooling characteristics in air cutting reveals that the temperature difference during one cycle of intermittent cutting increases as spindle speed decreases. The relationship between the peripheral cutting speed and the tool temperature varies from tool shank to ball tip because the interactions between cutting edge and workpiece change along the ballnose.

Effect of tool stiffness upon tool wear in high spindle speed milling using small ball end mill

Longer tool life can be tentatively achieved at a higher feed rate using a small ball end mill in high spindle speed milling (over several tens of thousands of revolutions per minute), although the mechanism by which tool life is improved has not yet been clarified. In the present paper, the mechanism of tool wear is investigated with respect to the deviation in cutting force and the deflection of a ball end mill with two cutting edges. The vector loci of the cutting forces are shown to correlate strongly with wear on both cutting edges of ball end mills having various tool stiffnesses related to the tool length. The results clarified that tool life can be prolonged by reducing tool stiffness, because the cutting forces are balanced, resulting in even tool wear on both cutting edges as tool stiffness is lowered to almost the breakage limit of the end mill. A ball end mill with an optimal tool length showed significant improvement in tool life in the milling of forging die models.

小径ボールエンドミルを用いた高回転ミーリングにおける動的切削力

小径ボールエンドミルを用いた高回転ミーリングにおける動的切削力