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High-accuracy three-dimensional miniature components and microstructures are increasingly in demand in the sector of electro-optics,
automotive, biotechnology, aerospace and information-technology industries. A rational approach to mechanical micro machining
is to develop ultra-precision machines with small footprints. In part 1 of this two-part pa...
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... addition to these requirements a critical and comprehensive review was carried out on ultraprecision machines with micro milling capability at the design stage of the UltraMill. There are a number of industrial ultraprecision turning and milling machines available for high precision components manufacture. However, most of them are generally aimed at the optical components market and are not well suited to the manufacture of precision micro components due to high investment costs and lack of flexibility. Fig. 2 shows some examples of industrial precision machines with micro milling capability. They fall into two categories. One is conventional ultraprecision machine tools which are designed as diamond turning machine tools with add-on Z-axis, rotary table and a second high speed milling or grinding spindle. Typical examples are Moore Nanotechnoloy Nanotech 350FG and Precitecch 2 Freeform 700 ultra as shown in Fig. 1 (g) and (h). Both of them require 5-7 m floor space. Their very high cost and low flexibility limit their application to micro components of simple geometries and high added value, such as optical components. Another type of industrial precision micro milling machine tool has emerged in the last decade. A typical example is the Kern micro machine (Fig.1 (a)) which meets many applications but still suffers from its machining accuracy for precision micro machining due to the positioning accuracy of the ball bearings based feed drive mechanism. Kugler MicroMaster (Fig.1(e)) offers higher accuracy and surface finishes, but the relative larger space requirements and the high cost limit its general applications as a micro machine tool. Numerous research efforts to develop miniaturized machines or micro factories have been undertaken for the manufacture of precision micro components [12, 13, 14]. Fig. 3 shows some examples of miniature machine tool. However, most of them are still at the research stage, and only a few of them have so far found their way into industrial applications [15], but their application to high accuracy and fine surface quality are still constrained by low static/dynamic stiffness. Therefore a rational approach to micro manufacturing is to develop compact or bench- top precision machines which offer a good trade-off between conventional ultraprecision machines and micro factory machines. The advantages over the conventional ultraprecision machines may include: Small footprint and ...
Citations
... Micro-machining technologies have versatile applications in several industries like electro-optics, automotive, biotechnology, aerospace and information technology to fabricate high-accuracy miniaturized components. The growing demand of micro-machining technology has facilitated the requirement of high-performance and efficient ultraprecision machines tools [1]. Highly precise complex 3D shapes with mirror finish on different materials can be fabricated in these ultra-precision machine tools in an expeditious and cost-effective way [2,3]. ...
... Vivek Bajpai vivek@iitism.ac.in 1 Department of Mechanical Engineering, Indian Institute of Technology (ISM) Dhanbad, Jharkhand, 826004, India on difficult-to-machine materials [4,5], even on silicon. The major limitation of micro-machining is low tool stiffness and low MRR. ...
... The stiffness of the machine structure plays a very crucial role for machining efficiency and vibration isolation of a machine tool [12]. Hence, the high-speed micromilling machine structure must have good static, dynamic stiffness and damping performance for quality machining performance [1]. ...
The demand of ultra-precision micro-machine tools is growing day by day due to exigent requirements of miniaturized components. High accuracy, good dimensional precision and smooth surface finish are the major characteristics of these ultra-precision machine tools. High-speed machining has been adopted to increase the productivity using high-speed spindles. However, machine tool vibration is a major issue in high-speed machining. Vibration significantly deteriorates the quality of micro-machining in terms of dimensional precision and surface finish. This article describes a design methodology of a closed type machine structure for vibration minimization of a high-speed micro-milling center. The rigid machine structure has provided high stiffness and the damping capability to the machine tool without utilizing vibration absorbers. The models of the machine structures have been generated and assembled in AutoCAD 3D. The performance of the integrated micro-milling machine tools was determined by finite element analysis. The best model has been selected and proposed for manufacturing. Additionally, simulation results were validated by comparing with experimental results. Eventually, after manufacturing and assembly, experiments have been performed and it was observed that the amplitude of vibration was approaching towards nanometer level throughout the working range of the high-speed spindle. The machine tool was capable to fabricate miniaturized components with smooth surface finish.
... The software system used is the leading software that can convert G code into its coordinate system. The built machine can store parameters and guide the machine to programmable requirements, including feed rate, cutting depth, cutting speed, and safety features [3]- [5]. ...
The machine manufacturing industry usually monopolizes CNC-based machine manufacturing technology. These machine tools have world-class manufacturer control systems. Simultaneously, hobbyists, amateurs, and semi-professionals created many solutions for small-scale and low-cost CNC machines. This paper discusses processes for designing and developing a PC-based 3-axis CNC milling machine to meet small-scale and cost-effective machine manufacturing requirements. The following is a review of CNC milling machines built based on the capabilities of similar-sized machines reviewed previously. The milling machine's design is based on a vertical position with a close frame structure. It is assembled with aluminum extrusion profiles to achieve a rigid frame structure. This low cost is achieved by using low-cost off-the-shelf hardware modules that can reduce maintenance costs. The Mach4 software that acts as a PC-based controller communicates G-codes to control the machine. The machining test revealed that the UHMW-PE sample could be cut with different geometric shapes by machining a workpiece under a specific tool path. This machine design shows manufacturing efficiency and flexibility, allowing small facilities to reduce capital costs. Although not intended for mass production or precise machining, this machine can effectively replace expensive commercial CNC machines.
... Huo et al. presented a holistic approach to design bench-top ultraprecision machine tools for manufacturing high-accuracy micromechanical components. A five-axis bench-top ultraprecision miromilling machine tool was developed [22,23]. The design methodology will be helpful in designing and developing our prototype and its validation. ...
A microfluidic chip requires micro-channels to be created on a substrate. This paper focuses on the design and development of a precision hot embossing machine for replication of microstructures on a PMMA substrate. Kinematic coupling using three spherical balls in radial v-grooves is used to achieve precise positioning of the mold insert with the base. Flexure based parallel guidance mechanism is used for one DOF motion required for the embossing process. The mechanism allows the motion of the mold normal to the substrate surface. Flexure based kinematic coupling with the thermal center is designed to mitigate thermal stress build-up during heating and cooling of the mold insert. An Arduino-based micro-controller is developed to control the temperature profile during the process. A prototype is fabricated and experiments are performed with an aluminium mold insert on a PMMA substrate. The result shows the feasibility of the concept and the set-up can be used to develop a cost-effective precision hot embossing machine for creating micro-patterns for microfluidic applications.
... Micro-machining technologies have versatile applications in several industries like electro-optics, automotive, biotechnology, aerospace, information technology etc to fabricate high accuracy miniaturized components. The growing demand of micro-machining technology has facilitated the requirement of highperformance and efficient ultra-precision machines tools [1]. Highly precise complex 3D shapes with mirror finish on different materials can be fabricated in those ultra-precision machine tools in a expeditious and cost-effective way [2,3]. ...
... The stiffness of the machine structure plays a very crucial role for machining efficiency and vibration isolation of a machine tool [13]. Hence, the high-speed micro-milling machine structure must have good static, dynamic stiffness and damping performance for quality machining performance [1]. ...
The demand of ultra-precision micro-machine tools is growing day by day due to exigent requirements of miniaturized components. High accuracy, good dimensional precision and smooth surface finish are the major characteristics of these ultra-precision machine tools. High-speed machining has been adopted to increase the productivity using high-speed spindles. However, machine tool vibration is a major issue in high-speed machining. Vibration significantly deteriorates the quality of micro-machining in terms of dimensional precision and surface finish. This paper describes a design methodology of a closed type machine structure for vibration minimization of a high-speed micro-milling center. The rigid machine structure has provided plenty of stiffness and the damping capability to the machine tool without utilizing vibration absorbers . The models of the machine structures have been generated and assembled in AutoCAD 3D . The performances of the integrated micro-milling machine tools were determined by finite element analysis. The best model has been selected and proposed for manufacturing. Additionally, simulation results were validated by comparing with experimental results. Eventually, after manufacturing and assembly, experiments have been performed and determined that the amplitude of vibration was approaching towards nanometer level throughout the working range of the high-speed spindle. The machine tool was capable to fabricate miniaturized components with fine surface finish.
... Micro-milling accuracy depends significantly on the key elements of the machine tool (e.g. spindle, motion axes) [293,294]. According to Luo et al. [295], bench-type ultraprecision machines will be one of the future development tendencies. ...
Recently, mechanical micro-milling is one of the most promising micro-manufacturing processes for productive and accurate complex-feature generation in various materials including metals, ceramics, polymers and composites. The micro-milling technology is widely adapted already in many high-tech industrial sectors; however, its reliability and predictability require further developments. In this paper, micro-milling related recent results and developments are reviewed and discussed including micro-chip removal and micro-burr formation mechanisms, cutting forces, cutting temperature, vibrations, surface roughness, cutting fluids, workpiece materials, process monitoring, micro-tools and coatings, and process-modelling. Finally, possible future trends and research directions are highlighted in the micro-milling and micro-machining areas.
... Manufacturers who want to gain new customers must constantly improve the quality and attractiveness of their products. As far as machine tool manufacturers are concerned, this most often refers to ensuring the desired static stiffness, which corresponds directly with machining accuracy and machine tool performance [1,2]. The higher the static stiffness, the higher the dimensional and shape accuracy can be obtained. ...
The subject of the research was Underfloor Wheel Lathes de-signed to regenerate the profiles of the running wheels and brake discs of heavy rail vehicles without removing the wheelsets. These machines can also be used to regenerate wheel sets in trolleys dismantled from vehicles or the wheel sets themselves. The machine tools operate in a pass-through system. Two machine tools differing in the structure of the supporting sys-tem were tested: monolithic and folding. Conclusions are based on the re-sults of the FEA simulation. They concerned the influence of the type of supporting structure and connection between the bodies on the static stiff-ness, forms of vibrations and dynamic stiffness of machine tools.
... However, the processing cost of parts increases in this method. In contrast, several economical methods such as lubrication conditions, tool geometry parameters, and tool coatings have been proposed to optimize cutting parameters [9][10][11][12][13][14][15][16]. Ni Chen and Xinlei Zhang contributed equally to this work and should be considered co-first authors. ...
High aspect ratio (HAR) structures are widely utilized in diverse applications, including the defense industries, medical treatment, and aerospace. Studies show that the micro-milling has superiorities such as high efficiency and high flexibility over other methods. Currently, the biggest problem of micro-milling is the influence of burrs on the milling performance, which is an enormous challenge to remove. In the present study, numerical simulations through the finite element method (FEM) and experiments are carried out to optimize cutting parameters of the specimen made of Cr12MoV alloy. Moreover, an improved constitutive model is proposed by considering the size effect of the micro-milling. The proposed model is based on the J-C constitutive model, and it is concluded that the cutting force error is 4.6% through the comparison of experiment and FEM, which further proves the convergence of the improved constitutive model. It is also found that the side burr of HAR slots and the top burr of shallow slots are the biggest factors affecting the surface quality. The depth of cut (DoC) affects the maximum bending angle of the tool, the feed per tooth (FpT) affects the size of the unremoved area, and the spindle speed (SpS) affects the dynamic balance of the micro-mill, through the exploration of the above cutting parameters which can effectively improve the cutting state of the tool and finally achieve the purpose of curbing burr.
... The size effect becomes even more significant at the nanoscale, particularly for nanometric cutting, where ploughing of material dominates, rather than shearing and chip formation [64]. Consequently, this variation from the general behavior of both the tool and the workpiece microstructure at the microscale during machining will depend on many factors, such as the material properties and microstructure [39], micro-milling tool parameters [59], machining parameters [65], as well as tool specifications [1,66]. The physical mechanisms that govern the size effect will be discussed in the following section, including the specific energy, shearing and ploughing-dominant modes of material removal, as well as the effect of tool edge radius. ...
Micro-milling is a precision manufacturing process with broad applications across the biomedical, electronics, aerospace, and aeronautical industries owing to its versatility, capability, economy, and efficiency in a wide range of materials. In particular, the micro-milling process is highly suitable for very precise and accurate machining of mold prototypes with high aspect ratios in the microdomain, as well as for rapid micro-texturing and micro-patterning, which will have great importance in the near future in bio-implant manufacturing. This is particularly true for machining of typical difficult-to-machine materials commonly found in both the mold and orthopedic implant industries. However, inherent physical process constraints of machining arise as macro-milling is scaled down to the microdomain. This leads to some physical phenomena during micro-milling such as chip formation, size effect, and process instabilities. These dynamic physical process phenomena are introduced and discussed in detail. It is important to remember that these phenomena have multifactor effects during micro-milling, which must be taken into consideration to maximize the performance of the process. The most recent research on the micro-milling process inputs is discussed in detail from a process output perspective to determine how the process as a whole can be improved. Additionally, newly developed processes that combine conventional micro-milling with other technologies, which have great prospects in reducing the issues related to the physical process phenomena, are also introduced. Finally, the major applications of this versatile precision machining process are discussed with important insights into how the application range may be further broadened.
... Aside from high-frequency main spindles, means for higher position accuracy, higher stiffness and improved thermal stability of the machine system are decisive. Consequently, machine tools for micro-milling rely on technologies such as hydrostatic bearings, linear direct drives, precision scales, active cooling and controlled compensation of thermal expansion [Che10]. In contrast to conventional cutting, which employs a variety of cutting materials, micro-cutting and particularly micro-milling are almost solely performed with cemented carbide tools. ...
Forming as a shaping process, in which the tool is used as an analog memory for the workpiece geometry, requires precise tools. Especially in micro forming, it is not only the geometry of the basic tool bodies that plays a role, but also their surface topology, since it can be used considerably to control the material flow.
... Material upgrades are one of the optimizations of the product that can make it stronger and more efficient. The characteristics of the micro products are including functional sizes in the range of 1 to 100 m, high levels of precision, generally less than 1 m of tolerances, very small surface roughness with less than 0.5 m of R a , a complex shape and design, and uses heat resistance materials such as ceramics, titanium alloys etc [1]. ...
The demand for micro-scale products is increasing rapidly in various fields of industries such as electronics, bio-medical, optical industry, and so on. Titanium alloys especially Ti-6Al-4V is one of the commonly used in bio-medical industries because of its biocompability properties. However, poor surface quality in terms of surface roughness commonly occurs because of unappropriate cutting parameters to machine this hard to cut material. This study aims to investigate the influencing machining parameters to produce micro-products with a low level of surface roughness in Titanium Alloy (Ti-6Al-4V) material using a miniaturized micro-milling machine. Experiments carried out by micromilling process with variations in low rpm spindle speed and feed rate with a constant depth of cut using a carbide cutting tool of with a diameter of 1 mm. The machining results in the form of a 4 mm slot with a depth of 10 μm, which then measures its surface roughness. It was found that as the feed rate increases, the surface roughness also accordingly increases. On the other hand, the surface roughness decreases as the spindle speed increases.
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