Film thickness in a grease lubricated ball bearing

Hui Cen* (Corresponding Author), Piet M. Lugt

*Corresponding author for this work

    Research output: Contribution to journalArticleAcademicpeer-review

    5 Citations (Scopus)
    2 Downloads (Pure)

    Abstract

    The film thickness for grease lubricated bearings is normally calculated using the base oil viscosity, where it is assumed that the bearing is running under fully flooded conditions. It is well known that this is not accurate since grease lubricated bearings are usually running under starved lubrication conditions leading to thinner films. Single contact measurements have shown that, in the case of starvation, the film thickness decreases with increasing speed. It is shown in this paper that this effect seems to be very small though. The film thickness measurements, for three types of thickener material and base oil, show that the film thickness is almost independent of speed. To quantify this starvation effect, the film thickness can be expressed as the ratio between real film thickness and calculated film thickness using the base oil viscosity, hg/hff. The measurements in this paper show that hg/hff > 1 for very low speeds but decreases with speed asymptomatically reaching a constant value. It is shown here that hg/hff depends on speed, load and temperature and on the grease properties. It is not only the base oil viscosity that determines the film thickness. It is also governed by other grease properties that are today not known.

    Original languageEnglish
    Pages (from-to)26-35
    Number of pages10
    JournalTribology international
    Volume134
    Early online date25 Jan 2019
    DOIs
    Publication statusPublished - 1 Jun 2019

    Fingerprint

    ball bearings
    greases
    Ball bearings
    Lubricating greases
    Film thickness
    film thickness
    Bearings (structural)
    Oils
    oils
    Viscosity
    viscosity
    Thickness measurement
    lubrication
    low speed
    Lubrication
    Thin films

    Keywords

    • Bearings
    • Film thickness
    • Grease lubrication
    • Starvation

    Cite this

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    title = "Film thickness in a grease lubricated ball bearing",
    abstract = "The film thickness for grease lubricated bearings is normally calculated using the base oil viscosity, where it is assumed that the bearing is running under fully flooded conditions. It is well known that this is not accurate since grease lubricated bearings are usually running under starved lubrication conditions leading to thinner films. Single contact measurements have shown that, in the case of starvation, the film thickness decreases with increasing speed. It is shown in this paper that this effect seems to be very small though. The film thickness measurements, for three types of thickener material and base oil, show that the film thickness is almost independent of speed. To quantify this starvation effect, the film thickness can be expressed as the ratio between real film thickness and calculated film thickness using the base oil viscosity, hg/hff. The measurements in this paper show that hg/hff > 1 for very low speeds but decreases with speed asymptomatically reaching a constant value. It is shown here that hg/hff depends on speed, load and temperature and on the grease properties. It is not only the base oil viscosity that determines the film thickness. It is also governed by other grease properties that are today not known.",
    keywords = "Bearings, Film thickness, Grease lubrication, Starvation",
    author = "Hui Cen and Lugt, {Piet M.}",
    year = "2019",
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    doi = "10.1016/j.triboint.2019.01.032",
    language = "English",
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    Film thickness in a grease lubricated ball bearing. / Cen, Hui (Corresponding Author); Lugt, Piet M.

    In: Tribology international, Vol. 134, 01.06.2019, p. 26-35.

    Research output: Contribution to journalArticleAcademicpeer-review

    TY - JOUR

    T1 - Film thickness in a grease lubricated ball bearing

    AU - Cen, Hui

    AU - Lugt, Piet M.

    PY - 2019/6/1

    Y1 - 2019/6/1

    N2 - The film thickness for grease lubricated bearings is normally calculated using the base oil viscosity, where it is assumed that the bearing is running under fully flooded conditions. It is well known that this is not accurate since grease lubricated bearings are usually running under starved lubrication conditions leading to thinner films. Single contact measurements have shown that, in the case of starvation, the film thickness decreases with increasing speed. It is shown in this paper that this effect seems to be very small though. The film thickness measurements, for three types of thickener material and base oil, show that the film thickness is almost independent of speed. To quantify this starvation effect, the film thickness can be expressed as the ratio between real film thickness and calculated film thickness using the base oil viscosity, hg/hff. The measurements in this paper show that hg/hff > 1 for very low speeds but decreases with speed asymptomatically reaching a constant value. It is shown here that hg/hff depends on speed, load and temperature and on the grease properties. It is not only the base oil viscosity that determines the film thickness. It is also governed by other grease properties that are today not known.

    AB - The film thickness for grease lubricated bearings is normally calculated using the base oil viscosity, where it is assumed that the bearing is running under fully flooded conditions. It is well known that this is not accurate since grease lubricated bearings are usually running under starved lubrication conditions leading to thinner films. Single contact measurements have shown that, in the case of starvation, the film thickness decreases with increasing speed. It is shown in this paper that this effect seems to be very small though. The film thickness measurements, for three types of thickener material and base oil, show that the film thickness is almost independent of speed. To quantify this starvation effect, the film thickness can be expressed as the ratio between real film thickness and calculated film thickness using the base oil viscosity, hg/hff. The measurements in this paper show that hg/hff > 1 for very low speeds but decreases with speed asymptomatically reaching a constant value. It is shown here that hg/hff depends on speed, load and temperature and on the grease properties. It is not only the base oil viscosity that determines the film thickness. It is also governed by other grease properties that are today not known.

    KW - Bearings

    KW - Film thickness

    KW - Grease lubrication

    KW - Starvation

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