Tool life monitoring during the diamond turning of electroless Ni–P

“…Electroless nickel-phosphor is a commonly used mold material for an ultra-low-T g PGM, because this material is hard, and has high wear and corrosion resistance at a moderate temperature [52][53][54]. It has also a high machinability for single point turning [55,56]. However, this material can be crystallized and annealed at a temperature above 400°C; after which its properties are deteriorated [57].…”

Section: Mold Materialsmentioning

confidence: 99%

Precision glass molding: Toward an optimal fabrication of optical lenses

Zhang

Liu

2017

Front. Mech. Eng.

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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 carried 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 temperature variation, the glass viscosity can change from 10 5 to 10 12 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 relaxation 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.

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“…In process measurement of cutting forces (e.g. [11]) or acoustic emission [12] enable process monitoring but give only indirect information about the tool condition.…”

Section: Measurement Of Diamond Tool Wearmentioning

confidence: 99%