The previous research on machined surface topography in milling processes usually focuses on simple and single machining features such as free flat and form surfaces. However, the industrial ...components are composed of complex machining features such as slots and grooves finished by profile milling cutters. The formation mechanism and prediction method of machined surface topography for the complex milling features are required in industrial applications. Firstly, the machined side surface topography formation mechanism in profile milling straight slot machined by single-pass processing with a solid end mill is presented. Then, the numerical prediction models for machined side surface roughness in straight slot profile end milling are proposed. The proposed model can accurately predict the surface topography, and the relative prediction errors of the surface roughness (
S
a
) are within 6.34% for the whole cases in this research. Finally, the effect of cutting parameters on the residual heights of the machined side surface is analyzed. The formation mechanisms of machined two side surface topographies on the straight slot are distinct, for which one side surface is machined by up milling while another is by down milling. It is shown that the different tool trajectories cause the distinction for milling each slot side. The machined side surface topography can be controlled by selecting optimized tool motion parameters and cutting parameters. The influences of tool deflection and tool wear on the surface topography are ignored in the current research, which will be considered in the future.
Abstract
Microchannels are utilised on material surfaces of a body, allowing coolant to pass through them and enabling heat dissipation by increased contact area. Fabrication of metal surface ...microchannels is primarily achieved by employing a micro-milling process, which has drawbacks such as excessive cutting forces, top burrs, tool wear, and lower tool life. Alternatively, it is also realised by using Laser micro milling, which has problems associated with lower quality of surface finish, un-desired taper, heat-affected zone, and spatters. The existing literature, after due review of the current state of the art, has brought out gaps needing attention. These gaps are limited capability to reduce surface roughness, unaddressed burr width, and irregular bottom surface morphology, which affect microchannel quality. These gaps motivate this research work to improve and sustain the microchannel quality. To achieve the goals, this research work performs the fabrication of microchannels by micro-milling with automated laser assistance being achieved in two ways (a) sequentially, (b) non-sequentially, termed as LASMM and LPCMM, which are novel for the scientific community. The effects of micro milling parameters, spindle speed and feed on the quality were analysed while machining commercially pure titanium (cp-Ti). Results show that laser assistance to micro-milling provides a lower generation of undesired forces and lesser top burrs compared to micro-milling alone. In sequential laser assistance, the channels have a mean down burr width ~ 58% lower and a maximum down burr width ~ 38% lower than the channels done non-sequentially. In the case of up-burr width, a mean value ~ 60% lower and a maximum value ~ 73% lower is achieved in channels done non-sequentially as compared to those done sequentially. In the case of surface roughness, channels done sequentially have a maximum Sa value of 1.508 µm, a maximum Sq value of 1.912 µm whereas non-sequentially, they show a maximum Sa value of 3.495 µm, maximum Sq value of 4.59 µm. Steady tool wear is observed sequentially, whereas in non-sequential, rapid tool wear occurs after 500 mm of cutting length.
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•End milling of hybrid magnesium MMC (Mg + E-Waste CRT + BN).•Cutting forces, temperature and surface roughness were measured.•Effect of reinforcement, tool and machining factors in ...milling is explained.•Multi objective optimization through GRA and TOPSIS.•Amount of reinforcement and its size have noteworthy effect in MMC machining.
Present study investigates the effect of material and machining parameters on cutting force, surface roughness and temperature in end milling of Magnesium (Mg) Metal Matrix Composite (MMC) using carbide tool. Mg hybrid composite was fabricated by reinforcing Cathode Ray Tube (CRT) panel glass, an intensifying E-waste and Boron Nitride (BN) particles through powder metallurgy method. The milling experiments were conducted based on L27 orthogonal array designed by considering CRT glass particle size and weight percentage, tool diameter, speed, feed and depth of cut as input process parameters. Multi objective optimization was done through Grey Relational Analysis (GRA) and Techniques for Order Preferences by Similarity to Ideal Solution (TOPSIS). Both of the techniques provided a similar optimum parameter condition i.e. 10 µm particle size, 5% reinforcement, 8 mm diameter tool, 710 rpm speed, 20 mm/min feed and 0.5 mm depth of cut that outcomes in 139.48 N in-feed force, 63.92 N cross-feed force, 42.6 N thrust force, 68.96 °C temperature and 0.198 µm surface roughness. ANOVA is performed to identify significance and also the effect of each process variables on response parameters. Though all the parameters were found to be significant, reinforcement weight% and particle size affects the response parameters as that of machining parameters whereas speed turned to be the least significant factor.
•Established a generic tool flank wear model with adjustable coefficients.•Identified the relationship of the critical times to the adjustable coefficients in the model.•Defined a method to predicate ...tool life with the wear model.•Compared and validated milling forces per tooth obtained both from the model and the experimental data.
Tool wear is an important factor that influence machining precision and part quality in high speed milling, and it is essential to seek a convenient method to monitor and predict tool conditions. A generic wear model with adjustable coefficients is proposed and validated in this study. In this model, three wear zones of an entire tool life are divided by critical times considering the nature of different wear stages. Additionally, the intrinsic amplitude and growth frequencies in earlier and later milling stages are explicated and elaborated to determine the tool flank wear over whole milling process. The relationship between milling force against tool flank wear is studied and identified, which provides a technical foundation for online force modeling and wear monitoring. It is shown that with inclusion of the wear factor the milling force can be predicted accurately, with 98.5% agreement with the instantaneous force model. In addition, tool life can be predicted conveniently based on the wear model. Due to adjustability of coefficients in the model, it can be generalized to various machining types and conditions.
Processing microchannels inside laminated aluminum nitride high-temperature co-fired ceramics (AlN HTCC) packaging, a typical difficult-to-cut ceramic, can effectively solve the heat-dissipation ...problem of integrated chips used in smart skin. In order to improve the processing efficiency and quality of AlN, the machinability of AlN after laser chemical milling (LCM) was studied through the milling force, machined surface quality, surface defects, formation mechanism, and tool wear. This study established a milling force model that can predict the milling forces of AlN and analyses the reasons for the improvements in the milling force based on experimental data and predicted data. The results from the model and experiments demonstrated that the milling force of the laser chemical milling assisted micro milling (LCAMM) decreased by 85%–90% and 85%–95%, respectively, due to the amount of removal of a single edge was more uniform and the actual inclination angle increased during the cutting process in LCAMM. Moreover, the machined surface quality improved by 65%–76% after LCM because of less tool wear, fewer downward-propagating cracks generated during each feed, and the surface removal mode transformed from intergranular fracture to transgranular fracture, which effectively reducing tool wear and improving tool life. Finally, when feed per tooth and depth of cut were 0.4 μm/z and 5 μm, the optimal machined surface quality was obtained, with a roughness of 64.6 nm Therefore, milling after LCM can improve the machinability of AlN and providing a feasibility for the high-quality and efficient machining of microchannels.
Titanium alloy is widely used for manufacturing structural parts of high-end equipment due to its excellent mechanical properties, despite difficulty in being machined. Nowadays, titanium alloy parts ...are mostly machined by ball-end milling cutters (BEMC), but the cutting edge structure of the BEMC limits the improvement in machining efficiency and surface quality of the parts. In this paper, a circular-arc milling cutter (CAMC) with large-curvature cutting edge was proposed; the differential geometry method was used for establishing the geometric model for the contour surface of the CAMC and the mathematical model for the spiral cutting edge line; the conversion matrix between grinding wheel and workpiece coordinates was introduced to derive the equation of grinding wheel trajectory when the rake face of the CAMC was ground; the self-designed CAMC was ground and tested in accuracy. The comparative research was conducted experimentally on the side milling of titanium alloy TC4 with the CAMC and BEMC, and consequently the variation laws of milling forces, wear morphology, and machined surface quality were obtained about the two types of milling cutters. The results indicated that the CAMC can effectively reduce the main milling force and keep the milling process stable. Moreover, the CAMC was worn slower and produced better surface quality than the BEMC.
Highly flexible and costly gas turbine and compressor blades, machined with ball-ended mills from thermally resistant alloys on five-axis CNC machines, face challenges like chatter and deflection ...marks during machining. This paper introduces an algorithm to automatically segment stock removal, considering tool flexibility and position-dependent blade dynamics. Employing variable thickness but constant feed and spindle speed in an optimally planned tool path reduces chatter, minimizing machining time and dimensional and surface finish errors. The algorithm is experimentally validated in the five-axis machining of blades, and its effectiveness over conventional toolpath generation with a uniform stock removal strategy is demonstrated.
Ball-end milling cutters are commonly used in the finishing processes of curved-side milling for titanium alloys; however, several issues arise during machining, such as poor cutting conditions at ...the bottom of the end teeth, low cutting speeds, and limited chip space. Given the above issues, the research on the design and manufacture of conical arc side-edge milling cutter for titanium alloy processing was carried out in this paper; the mathematical model of the vital structure of conical arc side-edge milling cutter was established; the grinding trajectory equations of tool front and flank were deduced; the tool-workpiece kinematics of ultrasonic vibration applied to conical arc side edge was studied; and the comparative experimental study of the conical arc side-edge milling cutter cutting titanium alloy with and without ultrasonic vibration was carried out. The experiment results indicate that in comparison to conventional milling techniques, ultrasonic vibration cutting significantly decreases cutting force, plastic deformation of the chip, and wear rate of the flank face. The tool wear band is both longer and more uniform, bonding phenomena in titanium alloys are distinctly reduced, and tool performance is improved.
Milling involves the application of mechanical energy to physically break down coarse particles to finer ones and is regarded as a “top–down” approach in the production of fine particles. Fine drug ...particulates are especially desired in formulations designed for parenteral, respiratory and transdermal use. Most drugs after crystallization may have to be comminuted and this physical transformation is required to various extents, often to enhance processability or solubility especially for drugs with limited aqueous solubility. The mechanisms by which milling enhances drug dissolution and solubility include alterations in the size, specific surface area and shape of the drug particles as well as milling-induced amorphization and/or structural disordering of the drug crystal (mechanochemical activation). Technology advancements in milling now enable the production of drug micro- and nano-particles on a commercial scale with relative ease. This review will provide a background on milling followed by the introduction of common milling techniques employed for the micronization and nanonization of drugs. Salient information contained in the cited examples are further extracted and summarized for ease of reference by researchers keen on employing these techniques for drug solubility and bioavailability enhancement.
Ball-end cutters are widely used in industries of dies, molds, and aerospace, which have the problem of poor machined surface quality due to the low cutting speed near the tool-tip. With the increase ...in the complexity of parts, it will become more and more difficult to avoid the tool-tip participating in the cutting. In this paper, the velocity effect sensitivity of the ball-end cutter is analyzed, and several key positions, including the intersection points of the CWE boundaries, are selected to describe the cutting speed in three dimensions. The relationships between the cutting speed of the critical points and important variables such as the machining inclination angle and the feed direction were investigated. The optimal range of feed direction is obtained when the tool-tip engages in the contact circle. The core aim of the feed direction selection is to make the tool engagement area in a high position by changing the feed direction, to avoid surface damage and improve the quality of the machined surface. Finally, an experimental study was carried out, and the results corroborate the effectiveness of the selection method. In the experiment, it was also found that cutting-out from the cutter contact position can improve the surface quality in the directions of non-optimal range, and the milling force and chips shape will vary with the change of the feed direction.
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