Engineering companies benefit from improved sensor design for tribological machine elements
Submitting InstitutionUniversity of Sheffield
Unit of AssessmentAeronautical, Mechanical, Chemical and Manufacturing Engineering
Summary Impact TypeTechnological
Research Subject Area(s)
Information and Computing Sciences: Artificial Intelligence and Image Processing
Engineering: Manufacturing Engineering
Medical and Health Sciences: Neurosciences
Summary of the impact
This research, performed in the Department of Mechanical Engineering at
Sheffield, has provided
a unique method for measuring oil films in real engineering components
like ball-bearings, thrust
pads, seals, and piston rings. Adopted by leading industrial customers
across Europe, the
resulting benefits include the development of new seal designs and piston
ring-pack products as
well as trouble-shooting pump failure. The spin-out company, Tribosonics
Ltd., which manufactures
the instrumentation under licence and provides consultancy services,
currently employs eight
people and turned over £450k in 2012 (£600k expected in 2013). Customers
include [text removed
for publication] who have seen their new ring pack reduce oil
consumption by up to 40%, saving
$160K per year per engine and [text removed for publication] whose
seals designed and tested
using our methods have 10% of the leakage of conventional seals.
The underlying research consists of methods and devices to determine oil
film thickness from
pulses of ultrasound reflected at lubricated contacts.
All lubricated machinery relies on a thin film of oil to keep surfaces
separated and so reduce friction
and wear. These films are very thin (typically ranging in thickness from
10nm to 100 f06dm) and have
proved difficult to measure. There are several measurement techniques that
have been used in the
past (reflected light, electrical resistance, and capacitance). Without
exception these methods
require significant changes to the machine elements being measured, for
example drilling holes
into cylinder liners, or imbedding probes into surfaces. This is
experimentally difficult to achieve,
costly, and disrupts the very thin oil films. This has meant that in the
past direct oil film
measurement is usually limited to the laboratory. Ultrasound has the key
advantage that it is non-
invasive and can measure the contact through the machine parts.
The underpinning research [R1-R3] used fundamental elastic wave mechanics
to show how an
interface responds to an ultrasonic pulse. For most practical cases the
interface can be modelled
as a simple non-linear spring; and reflection depends on the stiffness of
that spring. In turn the
spring stiffness depends on the thickness of an oil film or the amount of
solid contact. The
significance of this new approach is that simple, cheap, and small
piezo-electric sensors can be
bonded onto the outside of the component for non-invasive measurements.
This has allowed for
the first time measurements on real components in full scale industrial
Pathway from research to impact
(a) 1997-2002: Early work to develop the algorithms and instrumentation
for measuring oil films
was funded by three key EPSRC grants (GR/S46963, GR/M90191, GR/L89020).
were experimentally validated on laboratory based bearings and model
encapsulated in three pioneering papers that describe how ultrasound
responds to tribological
interfaces (i.e. oil films, asperity contact, and mixed lubrication films)
(b) 2002: IP Protection. The scientific concept was patented in three
regional patents (GB
2370354, US7066027, EP1314001) and is jointly held by Sheffield and
Bristol (60:40 royalty
(c) 2003-date: System Refinement. Work focused on making the techniques
and expanding the portfolio of measurement solutions. This has involved
and validation, development of high speed data capture, dealing with harsh
manufacturing simple cheap sensors and instrumentation [R4-R6].
(d) 2005-date: Industry Trials and Technology Transfer. Most of the
technology refinement was
done in collaboration with industrial partners on a consultancy basis. The
learning was carried
out on-site with partners where technical problems were solved as they
arose. Examples of
these on-site trials are: [text removed for publication].
(e) 2012-date: On-going Development. The technology continues to be
enhanced to increase
scope of application. Recent developments have covered the more
challenging applications of
sheet metal rolling and automotive piston rings.
Summary of staff involved
The team that created this impact was led by Professor Dwyer-Joyce
supported by PhD students
and Research Assistants (notably Dr Harper, Dr Reddyhoff, Dr Donohoe, Dr
Mills, Dr Hunter, and
Dr Vail). The first stage of the work was carried out with the University
of Bristol NDT group
(Professor Drinkwater). They provided the basic ultrasonic tools and
instruments that were
implemented in the Sheffield laboratory. The second phase of the work
was carried out solely by the Sheffield team.
References to the research
References that best indicate the quality of the research are
indicated with asterisks (***).
R1.***Dwyer-Joyce, R.S., Drinkwater, B.W., and Donohoe, C.J., (2002), The
Lubricant Film Thickness using Ultrasound, Proceedings of the Royal
Society Series A, Vol.
459, pp 957-976. (doi: 10.1098/rspa.2002.1018).
R2.***Drinkwater, B. W., Dwyer-Joyce, R. S., and Cawley, P., (1996), A
Study of the Interaction
between Ultrasound and a Partially Contacting Solid-Solid Interface,
Proceedings of the
Royal Society Series A, Vol. 452, No. 1955, pp. 2613-2628, London. (doi:
R3.***Dwyer-Joyce, R.S., Reddyhoff, T. and Zhu, J., (2011), Ultrasonic
Measurement for Film
Thickness and Solid Contact in Elastohydrodynamic Lubrication, ASME
Journal of Tribology,
Vol. 133, Issue 3, 031501. (doi:10.1115/1.4004105).
R4. Reddyhoff, T., Dwyer-Joyce, R.S., and Harper, P., (2008) A New
Approach for the
Measurement of Film Thickness in Liquid Face Seals, Tribology
Transactions, Vol. 51, No. 2,
pp. 140 - 149. (doi: 10.1080/10402000801918080).
R5. Kasolang, S. and Dwyer-Joyce, R.S. (2008), Observations of film
thickness profile and
cavitation around a journal bearing circumference, Tribology
Transactions, Vol. 51(2), pp
231-245. (doi: 10.1080/10402000801947717).
R6. Mills, R.S., Avan,E.Y., and Dwyer-Joyce, R.S., (2013), Piezo-electric
sensors to monitor
lubricant film thickness at piston-cylinder contacts in a fired engine,
Proceedings of the
Institution of Mechanical Engineers, Part J, Journal of Engineering
Tribology, Vol. 227, No. 2,
pp. 100-111. (doi: 10.1177/1350650112464833).
Details of the impact
Spin-Out & Commercialisation Activity
A spin-out company called Tribosonics Ltd [S1] was incorporated in 2006,
with a start-up fund of
£40k won competitively from the ERA Foundation and the RAEng. The company
is run by Dr Phil
Harper and is largely staffed by PhD graduates from the Sheffield group.
The business model
covers the manufacture and sales of oil film monitoring equipment and the
provision of testing and
installation services. Tribosonics manufactures full specification
instruments named FMS50,
FMS100, and FMS200 (selling price £18k-£40k) and a cut-down miniaturised
version the T-200
(selling price £0.8k-£2k). The University owned IP is licenced to
Tribosonics who pay a royalty on
each instrument sold.
Since 2009, nine sets of full specification equipment, with a combined
value of £325k, have been
purchased by [text removed for publication]. These span the lubricant,
seal, and bearing
manufacturers, and geographically the UK, Europe and Asia markets.
Customers for whom consultancy test services have been provided include:
[text removed for
publication]. The company has a current (2012 figure) annual turnover of
£450k/year and employs
Critical Impact on Industrial Practice
[text removed for publication]
Sources to corroborate the impact
S1. Corroborating statements available from Managing Director,
Tribosonics Ltd., Sheffield. U.K.
S2. [text removed for publication].
S3. [text removed for publication].
S4. Journal Paper. Smith, O. and Sutton, M. (2011), `Fuel economy in
heavy duty diesel engines.
Part 1: measurement of oil film thickness on an operating engine:
Measurement of oil film
thickness on an operating engine', Proc. Inst. Mech. Eng., Part J: J. Eng.
S5. [text removed for publication].
S6. [text removed for publication].
S7. [text removed for publication].