Film thickness in a grease lubricated ball bearing

Hui Cen (Corresponding Author), Piet M. Lugt

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (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.",
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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.

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