Citation: Schumski, L.; Guba, N.;
Espenhahn, B.; Stöbener, D.; Fischer,
A.; Meyer, D. Characterization of the
Interaction of Metalworking Fluids
with Grinding Wheels. J. Manuf.
Mater. Process. 2022, 6, 51. https://
doi.org/10.3390/jmmp6030051
Academic Editors: Arkadiusz Gola,
Izabela Nielsen and Patrik Grznár
Received: 7 March 2022
Accepted: 12 April 2022
Published: 21 April 2022
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Manufacturing and
Materials Processing
Journal of
Article
Characterization of the Interaction of Metalworking Fluids with
Grinding Wheels
Lukas Schumski
1,2,
*, Nikolai Guba
1,2
, Björn Espenhahn
2,3
, Dirk Stöbener
2,3
, Andreas Fischer
2,3
and Daniel Meyer
1,2
1
Division Manufacturing Technologies, Leibniz Institute for Materials Engineering, Badgasteiner Str. 3,
28359 Bremen, Germany; guba@iwt-bremen.de (N.G.); dmeyer@iwt-bremen.de (D.M.)
2
MAPEX Center for Materials and Processes, University of Bremen, Bibliothekstr. 1, 28359 Bremen, Germany;
b.espenhahn@bimaq.de (B.E.); d.stoebener@bimaq.de (D.S.); andreas.fischer@bimaq.de (A.F.)
3
Bremen Institute for Metrology, Automation and Quality Science (BIMAQ), University of Bremen,
Linzer Straße 13, 28359 Bremen, Germany
* Correspondence: schumski@iwt.uni-bremen.de; Tel.: +49-421-218-51152
Abstract:
The thermal load that occurs during grinding can be reduced with the aid of an optimized
metalworking fluid (MWF) supply. In previous work, mainly the free jet was considered for the
determination of the conditions required for an optimized MWF supply. An investigation of the
interaction area between the MWF and the grinding wheel has not yet been carried out due to the
lack of suitable measurement techniques. In the presented work, both the free jet and the interaction
area are analyzed with the aid of new metrological analysis and evaluation methods based on high-
speed records (shadowgraphy and shadogram imaging velocimetry) in order to assess the free jet
geometry and velocities, as well as the velocity distribution and the MWF amount in the interaction
area. Using this approach, the following main results were derived: (1) The free jet velocity remains
approximately constant in a defined free jet cross-section even at high distances from the nozzle
outlet. (2) The velocity distribution in the interaction area is mainly influenced by the flow rate. (3) A
new image parameter (black pixel fraction) was derived for the evaluation of the MWF supply to the
contact zone.
Keywords: metalworking fluids; supply conditions; grinding; shadowgraphy; velocimetry
1. Introduction
Grinding processes are characterized by a thermomechanical load, whereby the ther-
mal load is generally more dominant [
1
,
2
]. Thus, grinding involves an increased risk of
thermal damage to the machined workpieces due to high temperatures and larger contact
zones compared to other manufacturing processes. The thermal damage, commonly re-
ferred to as grinding burn, leads to the formation of tensile residual stresses or a drop in
hardness in the surface layer of the ground workpieces [
3
–
6
]. Numerous approaches at
minimizing the thermal effects during the grinding process can be found in the literature.
Metalworking fluids (MWF) reduce the thermal load by (i) lubricating the contact zone
between the grinding wheel and workpiece, thus reducing the amount of generated heat as
well as (ii) cooling the tool and the workpiece by dissipating generated heat. In addition
to the selection of a suitable metalworking fluid, an approach that is easy to implement
even in an industrial environment and yet very effective is the optimization of the MWF
supply [
7
–
11
]. With the help of an optimized MWF supply, a sufficient MWF supply in the
contact zone should be ensured. As shown in Figure 1, a number of influencing parameters,
such as the nozzle geometry, e.g., [
12
–
14
], the nozzle position, e.g., [
15
–
17
], the selected
flow rate Q
MWF
, e.g., [
18
–
20
], and the velocity ratio between the MWF free jet v
jet
and the
grinding wheel velocity v
s
, e.g., [
21
–
23
], have to be taken into account in order to realize an
optimized MWF supply.
J. Manuf. Mater. Process. 2022, 6, 51. https://doi.org/10.3390/jmmp6030051 https://www.mdpi.com/journal/jmmp
