A review of the techniques for the mold manufacturing of micro/nanostructures for precision glass molding

Micro/nanostructured components play an important role in micro-optics and optical engineering,tribology and surface engineering,and biological and biomedical engineering,among other fields.Precision glass molding technology is the most efficient method of manufacturing micro/nanostructured glass components,the premise of which is meld manufacturing with complementary micro/nanostructures.Numerous mold manufacturing methods have been developed to fabricate extremely small and high-quality micro/nanostructures to satisfy the demands of functional micro/nanostructured glass components for various applications.Moreover,the service performance of the mold should also be carefully considered.This paper reviews a variety of technologies for manufacturing micro/nanostructured molds.The authors begin with an introduction of the extreme requirements of mold materials.The following section provides a detailed survey of the existing micro/nanostructured mold manufacturing techniques and their corresponding mold materials,including nonmechanical and mechanical methods.This paper concludes with a detailed discussion of the authors recent research on nickel-phosphorus(Ni-P)mold manufacturing and its service performance.

Recent advancements in optical microstructure fabrication through glass molding process

Optical microstructures are increasingly applied in several fields, such as optical systems, precision measurement, and microfluid chips. Microstructures include microgrooves, microprisms, and microlenses. This paper presents an overview of optical microstructure fabrication through glass molding and highlights the applications of optical microstructures in mold fabrication and glass molding. The glass-mold interface friction and adhesion are also discussed. Moreover, the latest advance- ments in glass molding technologies are detailed, including new mold materials and their fabrication methods, viscoelastic constitutive modeling of glass, and micro- structure molding process, as well as ultrasonic vibration- assisted molding technology.

Precision glass molding： Toward an optimal fabrication of optical lenses

It is costly and time consuming to use machining processes, such as grinding, polishing and lapping, to produce optical glass lenses with complex features. Precision glass molding （PGM） has thus been developed to realize an efficient manufacture of such optical components in a single step. However, PGM faces various technical challenges. For example, a PGM process must be carded out within the super-cooled region of optical glass above its glass transition temperature, in which the material has an unstable non-equilibrium structure. Within a narrow window of allowable tempera- ture variation, the glass viscosity can change from 10s to 10t2 Pa-s due to the kinetic fragility of the super-cooled liquid. This makes a PGM process sensitive to its molding temperature. In addition, because of the structural relaxa- tion in this temperature window, the atomic structure that governs the material properties is strongly dependent on time and thermal history. Such complexity often leads to residual stresses and shape distortion in a lens molded, causing unexpected changes in density and refractive index. This review will discuss some of the central issues in PGM processes and provide a method based on a manufacturing chain consideration from mold material selection, property and deformation characterization of optical glass to process optimization. The realization of such optimization is a necessary step for the Industry 4.0 of PGM.

High-temperature friction behavior of amorphous carbon coating in glass molding process

In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated temperature.To improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron sputtering.The friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the mold.Therefore,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high temperature.Meanwhile,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction strength.The friction coefficient between the glass and coating depended on the temperature.Besides,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition diffusion.This work provides a better understanding of the application of carbon coatings in the glass molding.

Analysis of Mechanical Properties of Injection Molded Short Glass Fibre (SGF)/Calcite/ABS Composites

Acrylonitrile-butadiene-Styrene (ABS), with and without calcium carbonate (calcite) particles,was used as the matrix for reinforcement with as-received short-glass fibres (were originallytreated by the manufacturer) and sized short-glass fibres with two amino-silane coupling agents.The calcite particle content is 0, 11.7 and 23.5 vol. pct for the matrices. The glass fiber contentis 0, 10 and 15 vol. pct. The matrix materials and corresponding composites were compoundedusing a twin screw extruder and dumbbell-shaped tensile bars were prepared with an injectionmolding process. The tensile and flexural properties as well as the unnotched and notchedCharpy impact energies of short glass fibre/calcite/ABS composites were studied in this paper.The effects of fibres, fibre surface treatments and particles on these mechanical properties ofthe composites were discussed in detail. An importarit information was obtained, which is thatthe tensile and flexural strengths of hybrid SGF/calcite/ABS composites are the same as thoseof corresponding fibre composites when the ratio of the interfacial adhesion strength betweenparticles and matrix to that between fibres and matrix is higher than certain value. otherwise theformer are lower than the latter.