Functional Micro Research Articles

Enhanced Flexible Mold Lifetime for Roll-to-Roll Scaled-Up Manufacturing of Adhesive Complex Microstructures.

Various functional complex 3D patterned surfaces with micro- or nanostructures have been developed and their superior performances over non-patterned smooth surfaces proven. However, it is challenging to mass-produce such complex micro-/nanopatterned surfaces, which limits their commercialization drastically. Although roll-to-roll (R2R) manufacturing using flexible molds has been implemented for mass-production of such functional surfaces, the poor mold repeatability issue has not been resolved yet. Here, a strategy to significantly improve the repeatability of the micropatterned flexible silicone molds over 1000 cycles against highly adhesive polyurethane acrylates (PUAs) in UV light curing based R2R systems by using a two-step curing process is reported. The mold repeatability is drastically increased from 10s of cycles to over 1000 cycles through the proposed strategy in spite of the complicated 3D undercut geometry and high tackiness of the microstructure. This two-step process would enable scaled-up production of micro-/nanostructured adhesives, such as gecko-inspired microfiber adhesives as demonstrated in this study, as well as various other functional micro-/nanostructured surfaces by enhancing the flexible mold lifetime.

A Review of Microinjection Moulding of Polymeric Micro Devices.

Polymeric micro devices are gaining huge market potential in broad areas of medical devices, diagnostic devices, drug delivery, and optical applications. Current research is focusing on developing functional polymeric micro devices on a mass-production scale. Microinjection moulding is a promising technique suitable for fabricating polymeric micro devices. This review aims to summarise the primary achievements that have been achieved in various aspects of microinjection moulding of polymer micro devices, consisting of micro parts and micro surface structures. The relationships of the machine, process, rheology, tooling, micro/nanoscale replication, morphology, properties, and typical applications are reviewed in detail. Finally, a conclusion and challenges are highlighted.

Size dependent regeneration capacity of functionalized Capra ear-derived micro-tissue scaffolds for treatment of cartilage defects

Regeneration of cartilage still possesses considerable challenge in orthopedic treatment owing to avascular nature and lack of self-healing ability of the tissue. In this context, cartilage defect recovery via engineered functional micro tissue delivery is an emerging trend in musculoskeletal therapeutics. This work explores the efficacy of Capra ear-derived functionalized micro-tissues (FMTs) for regeneration of cartilage defects. For this study, a novel and inexpensive NaOH-based decellularization method was developed and optimized to obtain complete removal of cells without deteriorating the matrix structure of Capra ear cartilage. The decellularized matrix was then processed to generate micro-scaffolds (MSs) with different size distributions. It was established that among those size groups, MSs having 100 µm average size were most effective for adherence, cell proliferation and differentiation. It was assessed that the loose fibrous structure of smaller scaffolds was able to induce chondrogenic differentiation. Further, a frugal system was devised for performing hanging culture on the MSs with adipose tissue derived mesenchymal stem cells (ADMSCs) to generate functionalized micro tissues (FMTs). Finally, FMTs were implanted in rabbit auricular cartilage defects to evaluate their healing efficacy. Histology, FTIR and microCT studies revealed that the implanted FMTs were able to regenerate the defect within 60 days. Thus, this work establishes that the functionalized micro tissues derived from decellularized capra ear cartilage can potentially be used for cartilage regeneration, and the efficacy of regeneration depends on the size along with the fibrous structure of the scaffolds.

A model for predicting the friction of micro patterns fabricated by precision machining

This study aims to construct a model facilitating the design of patterns with desirable friction characteristics by investigating the effects of pattern geometries. By utilizing precision machining, non-uniform asymmetric patterns were machined and then transferred to a polymer. Friction experiments were designed and performed to investigate detailed pattern geometries. Results showed that the effects of all geometries were statistically significant on friction, and anisotropic friction characteristics were discussed. Based on this, the prediction model was constructed using Gaussian regression and then verified with patterns with maximum anisotropy. The experimental and model were in good agreement, showing that it is possible to design and fabricate patterns with desirable friction characteristics. Our results will aid the fabrication of functional micro patterned surfaces.

Direct nanoimprint of chalcogenide glasses with optical functionalities via solvent-based surface softening.

Chalcogenide glasses are attractive materials for optical applications. However, these applications often require patterning of the surface with functional micro-/ nanostructures. Such patterning is challenging by traditional microfabrication methods. Here, we present a new, to the best of our knowledge, approach of direct imprint via solvent-based surface softening, for the patterning of As2Se3 surface. Our approach is based on an elastomeric stamp soaked in an organic solvent. During the imprint, the solvent diffuses into the imprinted substrate, plasticizes its surface, and thereby allows its imprint at the temperature below its glass transition point. Thus, our approach combines the full pattern transfer with the maintenance of the shape of the imprinted substrate, which is necessary for optical devices. By using this approach, we demonstrated functional antireflective microstructures directly imprinted on As2Se3 surface. Furthermore, we showed that our approach can produce imprinted features sized down to 20 nm scale. We believe that our new approach paves the way for more future applications of chalcogenide glasses.

Highly functional bio-based micro- and nano-structured materials for neodymium recovery

One of the main pillars of sustainable development is the preparation of functional materials derived from renewable resources. Nevertheless, facile methods to convert lignocellulosic biomass into value-added, highly functional materials remain limited. Here, we evaluate the potential of an acid-free method to convert a variety of lignocellulosic biomass into highly charged micro- and nano-structured materials. We show how the sequential oxidation of delignified (e.g., softwood pulp and cotton) or untreated (e.g., corncob and tomato peel) lignocellulosic sources yield three distinct products, including biopolymeric nanoparticles (BNP), solubilized biopolymers (SB), and microproducts (MP), bearing up to 6 mmol of carboxylate groups per gram, which is up to ∼ 500 % beyond the theoretical charge content of conventional cellulose nanocrystals (CNC). The main difference among the products was the type of nanoparticles: delignified sources yielded hairy cellulose nanocrystals, whereas lignin nanoparticles were formed from the untreated sources. As a proof-of-concept for the applications of these materials, we show that carboxylated cotton microproducts remove ∼ 92.5 mg of neodymium ions per gram from a dilute solution in less than 5 min and recover approximately 64 % of it via pH adjustment. This work may provide new opportunities for the conversion of a wide array of lignocellulosic biomass to highly functional biocolloids with extremely high charge density for advanced sustainable applications.

Distinguishing functional exosomes and other extracellular vesicles as a nucleic acid cargo by the anion-exchange method.

The development of a new large‐scale purification protocol is required for research on the reliable bioactivity and drug discovery of extracellular vesicles (EVs). To address this issue, herein, we propose an effective method for preparing high‐performance exosomes (EXOs) by using an anion‐exchange method. Cytotoxic T‐lymphocyte (CTL) EVs from 4 L of culture supernatant through a 220 nm cut‐off filter are divided into two populations at a deproteinization rate of over 99.97%, which are eluted at low (0.15 M–0.3 M) and high (0.3 M–0.5 M) NaCl concentrations (approximately 2 × 1012 and 1.5 × 1012 particles, respectively) through the anion‐exchange column chromatography. The former are abundant in EXO proteins, including late endosome‐associated proteins and rab‐family and integrin‐family proteins, and functional micro (mi) RNAs, and have bioactivity for preventing tumour metastasis by depleting mesenchymal cell populations in the primary tumour lesions. By contrast, the latter is microvesicle (MV)‐like particles including DNA, core histone and ribosomal proteins, and GC‐rich miRNAs with unknown function, and are easily phagocytosed by mannose receptor+ Kupffer cells. Thus, the anion‐exchange method is suitable for the large‐scale separation of bioactive EXOs and MV‐like EVs as a cargo for dangerous nucleic acids at high‐purity.

The dark proteome: translation from noncanonical open reading frames.

Omics-based technologies have revolutionized our understanding of the coding potential of the genome. In particular, these studies revealed widespread unannotated open reading frames (ORFs) throughout genomes and that these regions have the potential to encode novel functional (micro-)proteins and/or hold regulatory roles. However, despite their genomic prevalence, relatively few of these noncanonical ORFs have been functionally characterized, likely in part due to their under-recognition by the broader scientific community. The few that have been investigated in detail have demonstrated their essentiality in critical and divergent biological processes. As such, here we aim to discuss recent advances in understanding the diversity of noncanonical ORFs and their roles, as well as detail biologically important examples within the context of the mammalian genome.

Investigation on the roll-to-plate imprinting of metallic surface micro dimples

Large-area functional metallic surface microstructures have been increasingly utilized in various industrial fields. As an efficient and economical method in fabricating large-area functional metallic surface microstructures, the roll-to-plate (R2P) imprinting process with the flat die was proposed to experimentally fabricate functional micro dimple arrays on the surface of the metallic substrate. The effects of the rolling direction, die cavity aspect ratio, die feature density and grain sizes on the forming results were investigated using pure copper specimens with different grain sizes. The transfer ratio of surface structures decreases with the increase of the die feature density and die cavity aspect ratio, respectively. The flowing differences of material in the rolling direction and transverse directions lead to the inconformity of section profile of formed dimples in the two directions. The depth of dimples in the rolling direction is prominently greater than that in the transverse direction. The depth difference of dimples in the two directions increases with the increase of rolling depth and reduces with the increase of die cavity width. The surface morphology of formed specimens obviously depends on the material flowing direction, grain sizes and rolling depth. The surface roughness, surface roughness scatter and flatness of the formed specimens increase with the grain size. The symmetry of cross sectional micro hardness distribution on both sides of the formed dimple in the rolling direction is poorer than that on both sides of the formed dimple in the transverse direction. The asymmetry of cross sectional micro hardness distribution on both sides of the formed dimple in the rolling direction becomes more prominent with the increase of grain sizes.

Additive-Free All-Carbon Composite: A Two-Photon Material System for Nanopatterning of Fluorescent Sub-Wavelength Structures.

The major bottleneck in fabrication of engineered 3D nanostructures is the choice of materials. Adding functionality to these nanostructures is a daunting task. In order to mitigate these issues, we report a two-photon patternable all carbon material system which can be used to fabricate fluorescent 3D micro/nanostructures using two-photon lithography, with subwavelength resolution. The synthesized material system eliminates the need to use conventional two-photon absorbing materials such as two-photon dyes or two-photon initiators. We have used two different trifunctional acrylate monomers and carbon dots, synthesized hydrothermally from a polyphenolic precursor, to formulate a two-photon processable resin. Upon two-photon excitation, photogenerated electrons in the excited states of the carbon dots facilitate the free radical formation at the surface of the carbon dots. These radicals, upon interaction with vinyl moieties, enable cross-linking of acrylate monomers. Free-radical induced two-photon polymerization of acrylate monomers without any conventional proprietary two-photon absorbing materials was accomplished at an ultrafine subwavelength resolution of 250 nm using 800 nm laser excitation. The effect of critical parameters such as average laser power, carbon dot concentration, and radiation exposure were determined for the fabrication of one-, two-, and three-dimensional functional nanostructures, applicable in a range of domains where fluorescence and toxicity are of the utmost importance. A fabrication speed as high as 100 mm/s was achieved. The ability to fabricate functional 3D micro-/nanostructures is anticipated to instigate a paradigm shift in various areas such as metamaterials, energy storage, drug delivery, and optoelectronics to name a few.

Tuning electron correlations of RuO2 by co-doping of Mo and Ce for boosting electrocatalytic water oxidation in acidic media

Designing highly efficient electrocatalysts in acidic media is considered as a promising strategy for improving the wide applications of proton exchange membrane (PEM) electrolyzers. Especially, oxygen evolution reaction (OER) requires high overpotentials (η) to overcome the high thermodynamic energy barrier toward water splitting. Herein, both Mo and Ce with large ionic radius are incorporated into RuO2 to redistribute electronic structures around Ru‒O bonds, promoting the activity and stability of RuO2. The representative Ru3MoCeOx exhibits superior activity with an overpotential of 164 mV at 10 mA cm−2 and excellent stability of 100 h (100 mA cm−2) in acidic media. Density functional theory (DFT) calculations and micro characterizations reveal that introduction of Mo and Ce into RuO2 effectively tune Ru–O bonds covalency, modulate electron correlations and reduce energy barrier of the intermediates from 0.78 to 0.60 eV. The outstanding activity and long-term stability indicate that Ru3MoCeOx could be acted as efficient anode catalyst in PEM electrolyzers for water splitting.

Shape Memory Alloys and Polymers for MEMS/NEMS Applications: Review on Recent Findings and Challenges in Design, Preparation, and Characterization

Rapid progress in material science and nanotechnology has led to the development of the shape memory alloys (SMA) and the shape memory polymers (SMP) based functional multilayered structures that, due to their capability to achieve the properties not feasible by most natural materials, have attracted a significant attention from the scientific community. These shape memory materials can sustain large deformations, which can be recovered once the appropriate value of an external stimulus is applied. Moreover, the SMAs and SMPs can be reprogrammed to meet several desired functional properties. As a result, SMAs and SMPs multilayered structures benefit from the unprecedented physical and material properties such as the shape memory effect, superelasticity, large displacement actuation, changeable mechanical properties, and the high energy density. They hold promises in the design of advanced functional micro- and nano-electro-mechanical systems (MEMS/NEMS). In this review, we discuss the recent understanding and progress in the fields of the SMAs and SMPs. Particular attention will be given to the existing challenges, critical issues, limitations, and achievements in the preparation and characterization of the SMPs and NiTi-based SMAs thin films, and their heterostructures for MEMS/NEMS applications including both experimental and computational approaches. Examples of the recent MEMS/NEMS devices utilizing the unique properties of SMAs and SMPs such as micropumps, microsensors or tunable metamaterial resonators are highlighted. In addition, we also introduce the prospective future research directions in the fields of SMAs and SMPs for the nanotechnology applications.

Ultra-precision direct diamond shaping of functional micro features

• Direct Diamond Shaping is presented as a novel machining method, producing unique features using the UPM. • Rotary and linear features can now be machined continuously with a turning tool. • 2D and 3D complex functional micro features can now be realized using the Virtual Rotating Tool Shaping algorithm. • Successfully machined a Bi-focal segmented Fresnel lens by Direct Diamond Shaping without the need for assembly. • Successfully machined a serpentine microfluidic channel with linear and rotary features by Direct Diamond Shaping. • Comprehensive geometrical analysis on tool limitations during shaping of channels is presented. As technological components continue to utilize space effectively within devices without compromise to their operational efficiency, the relevance of accurate and precise parts with good tolerances and surface finishing has shot to prominence. Ultra-Precision Machining (UPM) technology has constantly risen to the challenge by realizing components with superior geometrical accuracies and mirror-like surface finishes, much of which are required in the optical industry. However, conventional diamond shaping processes are usually limited to rotary symmetric components or linear gratings. Thus, the developed Virtual Rotating Tool Shaping (VRTS) addresses these issues by enabling the UPM to fabricate non-rotary symmetric, intricate and freeform elements by Direct Diamond Shaping (DDS). VRTS synchronizes the linear and rotational motions of the ultra-precision machine to constantly align the tool with the cutting direction, while compensating in the linear axes for the run-off. As such, DDS can now achieve a combination of linear and rotary features by planing. In this paper, the developed DDS technique is presented with experimental verifications of the algorithm on a segmented bi-focal Fresnel lens and a serpentine micro-channel, followed by the corresponding analyses.

Piezo-Actuated One-Axis Vibrational Patterning for Mold-Free Continuous Fabrication of High-Precision Period-Programmable Micro- and Nanopatterns.

We present a mold-free high-resolution nanopatterning technology named piezo-actuated one-axis vibrational patterning (POP) that enables continuous and scalable fabrication of micro- and nanopatterns with precisely programmable periods and dimensions. POP utilizes the piezoelectric stack-actuated high-precision uniaxial vibration of a flat, pattern-free rigid tool edge to conduct sub-50 nm-periodic indentations on various compliant substrates laterally fed underneath. By controlling the tool vibration frequency, tool temperature, and substrate feed rate and by combining sequential tool strokes along multiple directions, diverse functional micro- and nanopatterns with variable periods and depths and multidimensional profiles can be continuously created without resorting to mold prefabrication. With its simple but universal principle, excellent scalability, and versatile processability, POP can be practically applied to many functional devices particularly requiring large-area micro- and nanopatterns with specifically designed periods and dimensions.

MEMBRANE MATERIALS BASED ON POROUS ANODIC ALUMINIUM OXIDE

Anodized aluminum oxide (AOA) is applied in many technological areas such as formation of decorative or anticorrosive coating, hydrophobic and hydrophilic surfaces, development of functional micro- and nanomaterials. Due to unique properties of porous structure (most direct, regular and through pores with size in a narrow range) AOA films can be used for membrane separation. The morphological features of such films mainly depend on synthesis conditions. This review consists of the models of pore formation on the aluminum surface and the correlation parameters of films with anodizing conditions. Particular attention is paid to the influence of synthesis factors (electrolyte composition, voltage, temperature conditions, etc) on the porous structure of AOA and the film thickness that determines the mechanical strength of membranes. The optimal voltage values for the porous structure arraingment of anodized aluminum oxide were indicated for each electrolyte. It is noted formation of cylindrical shaped pores with controllable pore diameters, periodicity and density distribution can be produced during two-stage anodizing. The pre-treatment of the metal surface and stage of separation of the formed film from its surface are also considered. Modern research are mainly aimed to synthesis of porous AOA membranes in new anodizing electrolytes and determining pore formation factors on the aluminum surface. The new anodizing conditions in most popular electrolytes (oxalic, sulfuric, phosphoric acids) for obtaining of porous AOA with the required morphological features is also under investigation. Such conditions include, for example, a lower voltage or higher temperature in case for a particular electrolyte. To avoid of local heating the electrolytes with additional components, for example, organic additives is also studied. Some practical aspects of AOA membrane utilization obtained under certain conditions are considered.

Enhancing biochar sorption properties through self-templating strategy and ultrasonic fore-modified pre-treatment: Characteristic, kinetic and mechanism studies

The traditional anaerobic sewage treatment facilities are unsuitable for the widely uncontrolled spread of antibiotic residues in hospital or on livestock farm, which have raised the risk levels of high concentrations of antibiotic residues leakages and seriously threatened the aquatic ecology safeties. Thus, to develop an effective adsorbent with safe, low cost, and high firmly adsorptive capacity are imminent required. In this investigated, a self-templating hydrothermal alkali fore-modified & ultrasonic treatment was developed to achieve the highly adsorptive capacity and low desorption rate of biochar. As expected, the prepared biochar adsorbents present plenty of surface functional groups and micro pores. The BET value is raised up 1452 cm2·g−1 for biochar treated by the associated alkali fore-modified and ultrasonic treatment (UFB), whereas it is only 415.8 cm2·g−1 for the biochar treated by traditional carbonization (AC) and 1205 cm2·g−1 for the biochar by further hydrothermal alkali fore-modification (FB). Congruously, UFB exhibits the removal abilities of 397.70 mg·g−1 of levofloxacin (LEV) and 320.99 mg·g−1 of chlorotetracycline (CTC), 3.5–6.3 times absorbability towards familiar antibiotics than traditional biochar. Moreover, the corresponding the lowest desorption of 1.30 mg·g−1 (LEV) and 0.43 mg·g−1 (CTC) mg·g−1 by UFB have been confirmed. Meanwhile, Furthermore, both the adsorption and desorption mechanisms have been addressed by kinetic studies, pore width distributions, XPS and FTIR surveys. It is proposed the fore-modified treatment is more helpful for carbon functionalization while the ultrasonic treatment dedicates to the largely microporous structures. Consequently, the adsorption's capacity and stability of UFB adsorbents is large promoted due to its more micro- and meso-porous structure through a jointly hydrothermal alkali fore-modified and ultrasonic treatment. The present investigation will provide a novel alternative preparation strategy of the highly efficient adsorbent for emergency medical wastewater treatment.

Frustrated Microparticle Morphologies of a Semicrystalline Triblock Terpolymer in 3D Soft Confinement.

Self-assembly of block copolymers (BCPs) in three-dimensional (3D) confinement of emulsion droplets has emerged as a versatile route for the formation of functional micro- and nanoparticles. While the self-assembly of amorphous coil-coil BCPs is fairly well documented, less is known about the behavior of crystalline-coil BCPs. Here, we demonstrate that confining a linear ABC triblock terpolymer with a crystallizable middle block in oil-in-water (O/W) emulsions results in a range of microparticles with frustrated inner structure originating from the conflict between crystallization and curved interfaces. Polystyrene-block-polyethylene-block-poly(methyl methacrylate) (PS-b-PE-b-PMMA, S32E36M3293) in toluene droplets was subjected to different preparation protocols. If evaporation was performed well above the bulk crystallization temperature of the PE block (Tevap > Tc), S32E36M3293 first microphase-separated into microparticles with lamella morphology followed by crystallization into a variety of frustrated morphologies (e.g., bud-like, double staircase, spherocone). By evaporating at significantly lower temperatures that allow the PE block to crystallize from solution (Tevap < Tc), S32E36M3293 underwent crystallization-driven self-assembly into patchy crystalline-core micelles, followed by confinement assembly into lenticular microparticles with compartmentalized hexagonal cylinder lattices. The frequency of these frustrated morphologies depends on polymer concentration and the evaporation protocol. These results provide a preliminary understanding of the morphological behavior of semicrystalline block copolymers in 3D soft confinement and may provide alternative routes to structure multicompartment microparticles from a broader range of polymer properties.

(Invited) Printing Optical Materials

Will future of smart lighting and window coatings enable energy-efficient cooling in smart buildings? Can printed color converters lead to next generation micro displays with high brightness, sharp image resolution, and ultra‐low power consumption? Recently, exciting new physics of nanoscale optical materials has inspired a series of key explorations to manipulate, store and control the flow of information and energy at unprecedented dimensions. In this talk we will report our recent efforts on controlling light harvesting and conversion process using scalable micro/nanofabrication. These emerging optical materials show promise to a range of important applications, from optical networks and chip-scale photonic sensors to lasers, LEDs, and solar technology.For example, pixelated color converters are envisioned to achieve full-color high-resolution display through down conversion of blue micro-LEDs. Quantum dots (QDs) are promising narrow-band converters of high quantum efficiency and brightness enabling saturated colors. However, challenges still remain to produce high resolution color-selective patterns compatible with the advanced blue micro-LEDs with pitch and pixel size approaching 1 µm. Here we demonstrate our preliminary study on scalable printing of high-resolution pixelated red and green color converters patterned through projection lithography. We will also discuss potential applications such as high-resolution wide-gamut microdisplay for mixed reality and high speed visible light communication.In this talk, We will also introduce versatile 3D shape transformations of nanoscale structures by deliberate engineering of the topography-guided stress of gold nanostructures. By using the topography-guided stress equilibrium, rich 3D shape transformation such as buckling, rotation, and twisting of nanostructures is precisely achieved, which can be predicted by our mechanical modeling. Benefiting from the nanoscale 3D twisting features, giant optical chirality is achieved in an intuitively designed 3D pinwheel-like structure, in strong contrast to the achiral 2D precursor without nano-kirigami. The demonstrated nano-kirigami, as well as the exotic 3D nanostructures, could be adopted in broad nanofabrication platforms and could open up new possibilities for the exploration of functional micro-/nanophotonic and mechanical devices.

Optical Fiber Integrated Functional Micro-/Nanostructure Induced by Two-Photon Polymerization

Owing to the limitation of optical fiber materials and conventional fabrication methods, the development of optical fiber devices has encountered a bottleneck. Recently, two-photon polymerization technology are attracting increasing research interest due to its superiorities of high precision, flexibility and diversity of polymer materials. The optical fiber integrated micro-/nanostructures realized by two-photon polymerization have become a research hotspot due to the great application expansion of optical fiber device. In this paper, we review the research progress in the field of optical fiber integrated micro-/nanostructure induced by two-photon polymerization in the last ten years, which are classified by micro-optics, optical waveguide device and optical micro-cavity. Furthermore, we briefly discussed the future prospects of this exciting research field.

Influences of machining parameters on tool performance when high-speed ultrasonic vibration cutting titanium alloys

Tool performance is a key factor in evaluating machining processes. To improve machining productivity and part quality, researchers have conducted numerous studies on improving tool performance, such as tool design, coatings, functional micro textures, cooling/lubrication conditions, cutting parameter optimization, and intermittent cutting. Focusing on materials that are difficult to cut (i.e., Ti alloys), this paper explores a high-speed ultrasonic vibration cutting method that combines intermittent cutting, cooling, and lubrication. Through theoretical analysis and experiments on tool wear, cutting force, temperature, etc., the influence of machining parameters on tool performance is investigated. The results show that a large separation effect coupled with good cooling and lubrication conditions is key to improving tool performance. Among these, the feedrate and phase shift resulting from the rotary (spindle) speed are the core machining parameters. On this basis, the choice of machining parameters is summarized to provide a reference for the high-efficient machining of Ti alloys for scholars and engineers. First, cooling and lubrication conditions, such as dry machining and fluids, are determined. The duty cycle is then set from 0.5 to 0.6 via a relatively small feedrate value (i.e. 0.005 mm/r) and a π phase shift. Finally, the cutting speed and depth of cut are chosen according to the requirements of machining efficiency and cost.