Milling Depth Research Articles

Investigation on specific milling energy and energy efficiency in high-speed milling based on energy flow theory

Manufacturing energy consumption affects both the environment and manufacturing costs. Therefore, evaluating the energy consumption of the metal cutting processes is required. Accordingly, the idle power and total power were separately measured with a multimeter. A mechanical milling force model was constructed and validated by high-speed milling experiments with the dynamometer. The specific milling force coefficients (with respect to different cutting parameters) were obtained through high-speed milling experiments and a mechanical milling force model. The specific milling coefficients show size effect, with the feed per tooth, axial milling depth and radial milling width decreasing owing to the size effect of the specific cutting force. A general mechanical milling power model considering the size effect was established and validated by the milling power measurements in the milling experiments. The specific milling energy shows the same trend as the specific milling energy coefficients. The specific removing energy increases with rotation speed, feed rate per tooth, axial cutting depth and cutting width decreasing, owing to the idle energy of spindle. The energy efficiency increases as the milling parameters increase, owing to the larger material removal rate (MRR) and the reduced consumption of idle power in specific removing volume. A larger feed per tooth is recommended in high-speed milling, owing to the higher energy efficiency and marginal utility.

Prediction model of the depth of the femtosecond laser micro-milling of PMMA

The femtosecond laser technology is emerging as a powerful and flexible tool for the fabrication of miniaturized polymeric devices, thanks to the micrometric precision and the minimum thermal damage on the workpiece obtainable through ultrafast laser ablation. However, parametrization of femtosecond laser processes is often based on a trial and error approach, which requires a lot of expensive experimental efforts. The design of experiment (DoE) approach can offer a methodical way to quickly determine the laser process settings limiting the use of resources. In this work, we define an accurate DoE procedure to estimate the influence of the laser repetition rate, pulse energy, scanning speed, and hatch distance on the fs-laser micromilling process of PMMA specimens in terms of depth of removed material (Dh). We show that the laser pulse energy is the parameter that mainly affects the milling depth. A predictive model describing the relationship between the response variable depth and the main laser parameters is defined and then validated.

Spatially Engraving Morphological Structure on a Polymeric Surface by Ion Beam Milling.

Polymer surface patterning and modification at the micro/nano scale has been discovered with great impact in applications such as microfluidics and biomedical technologies. We propose a highly efficient fabricating strategy, to achieve a functional polymer surface, which has control over the surface roughness. The key development in this fabrication method is the polymer positive diffusion effect (PDE) for an ion-bombarded polymeric hybrid surface through focused ion beam (FIB) technology. The PDE is theoretically explored by introducing a positive diffusion term into the classic theory. The conductivity-induced PDE constant is discussed as functions of substrates conductivity, ion energy and flux. The theoretical results agree well with the experiential results on the conductivity-induced PDE, and thus yield good control over roughness and patterning milling depth on the fabricated surface. Moreover, we demonstrate a controllable surface wettability in hydrophobic and superhydrophobic surfaces (contact angles (CA) range from 108.3° to 150.8°) with different CA hysteresis values ranging from 31.4° to 8.3°.

Study on Surface Roughness in Micro Milling of Single Crystal Materials

Micro milling is a machining method of high precision and efficiency for micro components and features. In order to study the surface quality of single crystal materials in micro milling, the two-edged cemented carbide tool milling cutter with 0.4 mm diameter was used, and the orthogonal experiment was completed on the micro-milling of single crystal aluminum material. Through the analysis of statistical results, the primary and secondary factor which impacting on surface quality were found as follows: spindle speed, feed rate, milling depth. The ideal combination of optimized process parameters were obtained, when the spindle speed was 36000 r/min, the milling depth was 10 μm, the feed rate was 80 μm/s, which made the milling surface roughness is 0.782 μm and minimal. Single crystal materials removal mechanism were revealed, and the influence of cutting parameters on micro-milling surface were discussed, the reason of tool wear was analyzed. Those provide a certain theoretical and experimental basis for micro milling of single crystal materials.

Investigation on tool wear process of milling wave-transmitting Si3N4 ceramics

ABSTRACTDue to the low fracture toughness of wave-transmitting Si3N4 ceramics, the special material removal mechanism causes the tool wear to be different. The paper presents the tool wear forms and mechanism under different milling depth. The effect of tool wear on cutting force and machined surface morphology is discussed. Tests have been performed under typical conditions of cutting depth of 0.3 mm (in plastic-domain processing) and 0.4 mm (in brittle-domain processing). The results show that the abrasive wear caused by the chips is the main mechanism of the cutting edge wear and the flank wear, the increase of the side edge rear angle with tool wear is the main cause of the chipping phenomenon. The cutting depth is a significant influence parameter to the wear characteristics, and two types have been distinguished. As the material removal volume ascending, the cutting edge wear and the flank face wear has a stable period, and the root-mean-square deviation of processing surface increases to 1.6 μm, while that increase with the material removal volume continuously, and the processing surface decreases to 1.4 μm. It has been proved that the cutting force tends to increase first and then decrease as the material removal volume is about 4320 mm3.

Research on milling forces during high-speed milling of wood-plastic composites

To analyze the influence of the milling parameters, including the spindle speed, feed rate, axial cutting depth, and radial cutting depth, on the milling force during high-speed milling of wood-plastic composites, an orthogonal test was performed with carbide cutting tools. The results showed that the tangential (Fx) and radial forces (Fy) decreased with an increase in the spindle speed, increased with an increase in the feed rate, and increased with an increase in the axial milling depth. Also, both were influenced by a relatively small amount of change in the axial milling depth. Mathematical models of Fx and Fy during the high-speed milling of wood-plastic composites were established with a multiple linear regression method. The variance analysis showed that the two mathematical models of the milling forces were significant overall.

Quality Assessment of Milling Pavement Surface Using 3D Line Laser Technology

To ensure that a regular milled surface texture provides good bonding without residual distress, a new specification of milling surface assessment has been established for quantitatively evaluating the milled surface quality. This research explores the possibility of using three-dimensional (3D) laser scanning technology to develop an algorithm to obtain a milled surface model that can measure evaluating indicators, milling depth and texture depth, and identify poorly milled areas. A case study was conducted by using a laser scanning vehicular system to collect 3D continuous pavement transverse profiles data in a 500 m long segment of Highway S107. The results show that the proposed method is very promising and can measure the milling depth and texture depth to effectively and quantitatively differentiate between good- (milling depth between 47 mm and 53 mm and texture depth exceeding 2 mm) and poor-quality work. Moreover, the poorly milled areas such as those with residual distress and unmilled areas that will lead to premature failure can also be identified using the proposed method. The proposed method can effectively support remilling work and ensure the quality of the overlay pavement.

Performance of reclaimed asphalt pavement reinforced with Bamboo geogrid and Bamboo geocell

ABSTRACTPerformance of reclaimed asphalt pavement (RAP) reinforced with Bamboo geogrid and Bamboo geocells based on laboratory model tests are presented in this paper. RAP materials are obtained as waste materials during milling and/or full depth reconstruction of bituminous pavement. Generally, very high-quality uniform RAP is used in the preparation of hot mix asphalt (HMA). RAP materials not suitable for preparation of HMA can be economically utilised for the construction of sub-base/base course of flexible pavement. However, the load-settlement behaviour of unreinforced RAP used in base/sub-base of flexible pavement especially placed over softer subgrade is not very encouraging. The same has been improved by reinforcing it with Bamboo geogrid having tensile strength of 100 kN/m and Bamboo geocells in the present study. A series of laboratory model experiments have been conducted using RAP materials with and without the use of reinforcements and placing it over soft marine clay with low california bearing ratio value. Based on model tests results, it is observed that load carrying capacity of RAP increases by about 80% when RAP is reinforced with Bamboo geogrid and Bamboo geocells.

Prediction of Milling Force Based on Actual Radial Cutting Depth in Peripheral Milling of Complex Curved Surface

In order to predict the milling forces in the process of peripheral milling of complex curved surface with high efficiency and precision, this paper make a description on the workpiece contour and tool path through parametric curved surface. New methods are proposed to calculate actual feed per tooth and actual radial cutting depth, and calculation equations are derived. And then, a model for instantaneous milling force is established. Through simulation, this paper prove that curvature has little or even no effect on feed per tooth. Curvature mainly influences actual radial cutting depth. Also, when tool diameter is greater, curvature has more significant influences on actual radial cutting depth. Then, a method to predict milling force based on actual radial cutting depth is proposed. Moreover, this paper make a prediction on the milling force in peripheral milling of complex curved surface and conducted tests for validation. The predicted and experimental results have a good consistency both in variation tendency and amplitude, and time cost of simulation is significantly reduced, which show that the presented method has high precision and calculation efficiency.

Layer coefficients of cold in-place recycled layers from performance data

ABSTRACTWith cold in-place recycled (CIR) pavements becoming an increasingly popular treatment for pavement life extension, it is important for local agencies to have data that justifies the design parameters that influence the effectiveness of such treatments. Studies have shown that the effectiveness of CIR depends on its milling depth, and in order for agencies to better decide the pavement design, depth of CIR to be milled and placed, the authors have developed a procedure to back-calculate the structural layer coefficient of CIR layers based on performance data, in order to evaluate their structural capacity. This paper attempts to establish a relation between the structural capacity of the CIR layer and the international roughness index (IRI) of the pavement over time, using the results of previous research determining a definite differential between the IRI of pavements with different CIR thicknesses.

Effect of High Speed Milling Process Parameters on the Milling Force and Surface Topography of AM50A Magnesium Alloy

Within the scope of high speed milling process parameters, analyzed and discussed the effects of spindle speed, feed rate, milling depth and milling width on milling forces in the process of high speed milling of AM50A magnesium alloy. At the same time, the influence of milling parameters on the surface roughness of AM50A magnesium alloy has been revealed by means of the measurement of surface roughness and surface micro topography. High speed milling experiments of AM50A magnesium alloy were carried out by factorial design. Form the analysis of experimental results, The milling parameters, which have significant influence on milling force in high speed milling of AM50A magnesium alloy, are milling depth, milling width and feed speed, and the nonlinear characteristics of milling force and milling parameters. The milling force decreases with the increase of spindle in the given mill parameters. For the effects of milling parameters on surface quality of the performance, in the milling depth and feeding speed under certain conditions with the spindle speed increases the surface quality of AM50A magnesium alloy becomes better with the feed speed increases the surface quality becomes poor. When the spindle speed is greater than 12000r/min, the milling depth is less than 0.2mm, and the feed speed is less than 400mm/min, the milling surface quality can be obtained easily.

Inverse analysis of the cutting force in laser-assisted milling on Inconel 718

Inverse analysis is of value identifying viable solutions of process parameters that can achieve specified process performance. In this study, an inverse analysis method is proposed for the cutting force in laser-assisted milling on Inconel 718. The method uses the analytical model to solve the direct problem and applies a variance-based recursive method to guide the inverse analysis. The half-slot milling is simplified as an orthogonal cutting at each instant, forces in cutting and radial directions are calculated under microstructure evolution, and the axial force is predicted according to tool geometry and coordinates transformation. The inverse analysis identifies five process parameters including feed rate, axial depth of milling, laser preheating temperature, spindle speed, and rake angle, and finds the optimal solution for target performance, the resultant cutting force. Four experiments verified the effectiveness of the proposed method because of a maximum error less than 8% between predicted forces and experimental measurements. The proposed method is valuable in terms of providing a reference for the selection of process parameters under certain cutting force requirements.

Modelling the loading of the nose-free cutting edges of face mill with a spiral-stepped arrangement of inserts

A mathematical model of loading of the nose-free cutting edges of each insert of the face mill with a spiral-stepped cutting scheme was created. It was established that the size of the cut elements depends on the feed magnitude, the design parameters of the mill and the position of inserts on the contact arc. Variable factors of simulation included the feed magnitude, the clearance angle of the inserts and slope angles of the cutter assemblies. This made it possible to determine the chip thickness and width of cut, the depth of cut, the maximum value of the main cutting edge angle and the cut area at an arbitrary position of the face mill on the contact arc. Simulation in the SolidWorks Motion environment has confirmed reliability of mathematical modeling of loading of the cutting edges of the mill. The relative error in determination of the cut area was in the range from 1.8 % to 5.7 %. Calculation of the cut elements in the arbitrary position of the cutter insert on the contact arc was made in the Maple environment. Analysis of influence of the design parameters of the cutter and the magnitude of feed on the values of the cut elements was made. It has been established that an increase in feed caused a linear increase in the chip thickness and width of cut and the depth of cut for the inserts of all steps. Optimal values of the clearance angle of the mill inserts (16°) and slope of the cutting assemblies (6°) were determined for the milling depth of 3 mm. Recommendations on the choice of rational values of design parameters of the face mill for its effective operation at various depths of cut were given. Thus, there are grounds to assert the possibility of improving productivity of machining flat surfaces at a required quality due to the use of nose-free face mills with a spiral-stepped cutting scheme.

The effect of milling parameters on surface integrity in high-speed milling of ultrahigh strength steel

Ultrahigh strength steel with high specific strength, high thermal strength, good corrosion resistance and other characteristics are widely used in aerospace field. However, these characteristics coupled with its poor thermal conductivity, making it hard to machine, and causes high cutting temperature, serious tool wear can adversely affect the machined surface integrity, ultimately affecting the fatigue performance of the machined part. Therefore, the research on the machined surface integrity of ultrahigh strength steel has very important theoretical significance and engineering application value. The effect of milling parameters on surface integrity in high speed milling of 16Co14Ni10Cr2Mo ultrahigh strength steel is studied. The results show that the influence of milling speed and feed per tooth on two-dimensional and three-dimensional surface roughness is significant, but the milling depth has little effect. Surface roughness increases with milling speed and feed per tooth. The surface residual stresses are in the state of tensile stress, and the surface residual stresses increase with the milling speed, the feed per tooth and the milling depth. The influence of feed per tooth on residual stresses is the most significant. Surface microhardness decreases with milling speed and feed per tooth, but increases with milling depth.

The relationships between cutting parameters, tool wear, cutting force and vibration

To study the influences of processes factors on cutting force and vibration in cutting processes, milling tests were carried out on 022Cr17Ni12Mo2 stainless steel under different process conditions using a coated carbide end mill insert. The cutting force and vibration acceleration signals were recorded, and the wear depth on the flank face of the tool was measured. This study observed tool wear morphology using a scanning electron microscope and investigated distributions of surface elements on the damaged tools by energy spectrum analysis. Based on the revelations of tool wear mechanisms, the influence of milling parameters and tool wear on cutting force and vibration were further investigated. The research shows that oxidation, adhesion and diffusion wear mainly appear on the rake face, along with mechanical and thermal cracking, while adhesive and diffusion wear occur on the flank face. Among process factors, tool wear and milling depth significantly affect cutting force and vibration. Therefore, in actual machining processes, on the premise of meeting the requirements for rigidity and surface roughness of a machine tool, properly increasing the cutting velocity and milling depth can improve productivity and control cutting force and vibration.

Underwater Laser Micromilling of Commercially-Pure Titanium Using Different Scan Overlaps

Underwater laser milling process is a technique for minimizing the thermal damage and gaining a higher material removal rate than processing in air. This paper presents the effect of laser scan overlap on cavity width, depth and surface roughness in the laser milling of commercially-pure titanium in water. The effects of laser pulse energy and pulse repetition rate were also examined, in which a nanosecond pulse laser emitting a 1064-nm wavelength was used in this study. The experimental results indicated that a wide and deep cavity was achievable under high laser energy and large scan overlap. According to the surface roughness, the use of high pulse repetition rate together with low laser energy can promote a smooth laser-milled surface particularly at 50% scan overlap. These findings can further suggest a suitable laser micromilling condition for titanium in roughing and finishing operations.

Narrow-aperture electron beam in the forevacuum pressure range as a tool for dimensional processing of silica glass

The paper gives overview of the results of using narrow-aperture electron beam generated by a forevacuum plasma electron source as a tool for treatment of electrically non-conductive materials, such as technical glass. Effectiveness of electron beam treatment of non-conductive materials is caused by almost complete neutralization of target charge on the treated surface. Charge neutralization occurs due to ion flow from beam plasma generated while transporting the beam through forevacuum pressure area. The study demonstrates the possibility to control depth and form of milling by changing modes of electron beam treatment. Combined use of electron beam and automated system for beam deflection and sweep makes possible to perform dimensional processing, particularly cutting and milling with complex trajectory. Milling rates were experimentally found depending on treatment time and mode. The suggested method of silica glass treatment represents an alternative for traditional treatment methods.

Power Spectral Density Evaluation of Laser Milled Surfaces

Ablating surfaces with a pulsed laser system in milling processes often leads to surface changes depending on the milling depth. Especially if a constant surface roughness and evenness is essential to the process, structural degradation may advance until the process fails. The process investigated is the generation of precise thrust by laser ablation. Here, it is essential to predict or rather control the evolution of the surfaces roughness. Laser ablative milling with a short pulse laser system in vacuum (≈1 Pa) were performed over depths of several 10 µm documenting the evolution of surface roughness and unevenness with a white light interference microscope. Power spectral density analysis of the generated surface data reveals a strong influence of the crystalline structure of the solid. Furthermore, it was possible to demonstrate that this effect could be suppressed for gold.

Theoretical and experimental analysis of the impact on ablation depth of microchannel milling using femtosecond laser

The plasma brightness cannot be used as a direct indicator of ablation depth detection by femtosecond laser was experimentally demonstrated, which led to the difficulty of depth measurement in the maching process. The tests of microchannel milling on the silicon wafer were carried out in the micromachining center in order to obtain the influences of parameters on the ablation depth. The test results showed that the defocusing distance had no significant impact on ablation depth in LAV effective range. Meanwhile, the reason of this was explained in this paper based on the theoretical analysis and simulation calculation. Then it was proven that the ablation depth mainly depends on laser fluence, step distance and scanning velocity. Finally, a research was further carried out to study the laser parameters which relate with the microchannel ablation depth inside the quartz glass for more efficiency and less cost in processing by femtosecond laser.

Orthogonal Experimental Study on Tool Lifein Milling TB6 Titanium Alloy

The tool wear was studied using orthogonal experiment method while milling titanium alloy TB6 in different milling parameters. The flank face wear was measured by the photomicrograph after a certain period of milling During the milling process. It can be seen from the difference results of the experiment that the most significant factor affecting the durability of titanium alloy TB6 cutter is the cutting speed, which difference is 130.67. Followed by the feed, the difference is 106.33; Next is the milling depth and its difference is 61.33; The least significant factor is the milling width.