Realization of High Efficiency and Low Damage Machining of Anisotropic KDP Crystal by Grinding

Meina Qu, Guizhi Xie, Tan Jin, Rui Cai, Ange Lu

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    21 Citations (Scopus)
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    Potassium dihydrogen phosphate (KDP) is a non-linear material used in various opto-electronic applications including Q-switches, high-speed photography shutters, frequency harmonic generation lens and Pockels cells in the Inertial Confinement Fusion (ICF) devices. KDP belongs to the most difficult-to-cut material, due to its delicate and unique characteristics including the combination of softness with brittleness, anisotropic performances, tendency for deliquescence and sensitivity to temperature change. Single point diamond turning (SPDT) is considered to be the ideal method for machining KDP components. However, the process efficiency is rather low and often accompanied with severe tool wear issues. This paper studies the feasibility using grinding method to remove the surface material of KDP components with high process efficiency and low damage, fulfilling the task of re-aligning the surface orientation to the crystalline axis. The grinding tests were carried out on a common CNC grinder, using resin bonded diamond grinding wheel, whilst the diamond abrasives are coated with Ni-P alloy. The direction of precision grinding was determined by studying the anisotropy of KDP, including its elastic modulus E, Vickers hardness HV and fracture toughness KIC, to reduce the influence of material anisotropy on machining quality. The grinding process parameters were preliminarily determined based on the experimental results investigating the effects of peripheral speed of the grinding wheel, worktable feed rate and grinding depth on the ground surface roughness. The surface defects, surface morphology and sub-surface damage under different process parameters were investigated. Surface roughness Ra ≤ 0.3 μm and sub-surface damage depth SSD ≤ 6 μm were obtained. The machining efficiency can be improved by nearly ten times using the proposed precision grinding method, producing nearly the same surface quality (Ra ≤ 0.2 μm, SSD ≤ 6 μm) as that in the axis fixing phase in SPDT.
    Original languageEnglish
    Pages (from-to)464-473
    Number of pages10
    JournalPrecision Engineering
    Early online date5 Nov 2018
    Publication statusPublished - Jan 2019

    Bibliographical note

    NOTICE: this is the author’s version of a work that was accepted for publication in Precision Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control
    mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Precision Engineering, 2018

    DOI:10.1016/j.precisioneng.2018.10.016 © 2017, Elsevier. Licensed under the Creative Commons AttributionNonCommercial-NoDerivatives
    4.0 International


    • Crystal axis fixing
    • Grinding
    • KDP crystal
    • Machining efficiency
    • Sub-surface damage
    • Typical impurities embedded

    ASJC Scopus subject areas

    • Engineering(all)


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