Dynamic Jamming in Dense Suspensions: Machining Applications

Dynamic Jamming in Dense Suspensions:
Surface Finishing and Edge Honing Applications
Joseph Span, Philip Koshy
McMaster University
Fritz Klocke, Sebastian Mueller
RWTH Aachen University
Reginaldo Coelho
University of Sao Paulo

1/20
67th CIRP General Assembly
Lugano, August 22, 2017
Dynamic Jamming in Dense Suspensions: Surface Finishing & Edge Honing Applications
J. Span, P. Koshy, F. Klocke, S. Mueller, R. Coelho
Belmont
… surface finishing and edge honing
corn starch
Ideal for sauces, soups and puddings …

2/20
Belmont
Discovery Channel

3/20
Belmont
qedmrf
magnetorheological polishing
electrorheological polishing
Kuriyagawa et al (2002)
In the present work,
the interaction
between abrasives
and workpiece is
regulated by
controlling the
process kinematics

Crawford et al (2013)
4/20
Belmont
| cornstarch water systemShear thickening fluid
shear thinningequilibrium shear thickening
Wagner & Brady (2009)

5/20
Belmont
Shear thickening polishing
polymer water
Li et al (2015)

6/20
Belmont
strain rate 8 to 230 s-1
Finishing performance was proportional to the resultant force
on the coupon
cornstarch

7/20
Belmont
Hypothesis: surface finishing is due to dynamic jamming
rather than shear thickening
Waitukaitis

8/20
Belmont
Dynamic jamming refers to the
formation of a transient, localized,
solid-like domain in a suspension,
at packing densities well below that
required for global jamming

stop-go cycles
velocity(m/s)
time (s)
9/20
Belmont
molding clay
Liu et al (2010)
Kann et al (2013)

10/20

11/20
0
20
40
60
80
resultantforce(N)
couponboundary suspension
2 s
jammed domain
Surface finishing is indeed due to jamming

12/20
Jamming was initially attributed
to compression of the particles
(Waitukaitis, 2015)
Ultrasound imaging of the
jammed region has however
indicated no appreciable
increase in particle density
(Han et al, 2016)
Jamming occurs also
under extensional loading
(Majumdar et al, 2017)
Jamming by shear
(Bi, 2011)

13/20
strain rate
axial
radial
Velocity and strain rate distribution due to impact
velocity
Han et al (2016)
Peters & Jaeger (2014)

14/20
coupon
suspension
abrasive
Mechanism of material removal
On stopping the coupon, the stresses are insufficient to maintain frictional
contacts between particles, which collapses the load bearing network,
returning the suspension to its fluid-like state
cornstarch particle
Transient network of
force chains
transmit stresses
without an increase
in packing density
Stresses in the jammed
domain enable particles to
overcome viscous forces and
establish frictional contacts
Jamming front that
corresponds to the
maximum local
shear strain rate

15/20
Belmont
Introduction of abrasives
much larger in size than
the cornstarch particles
tends to structurally
interfere with their
consolidation into a
load-bearing network
Crawford et al (2013)
~15 µm
corn starch
size distribution

16/20
Belmont
Interaction of the jammed domain with a rigid boundary establishes
a solid-like link in-between, which translates into higher forces
Range of normal stresses are similar to that in magnetic
abrasive finishing

17/20
Belmont
Finishing performance of abrasive-cornstarch suspension

18/20
Application to edge honing of cutting tools
As the finishing medium closely conforms to the
shape of the object, the process may be applied
to finish, deburr, hone complex-shaped
surfaces, edges and tools

19/20
Belmont
Conclusions
Proof-of-concept of a novel process involving a dense aqueous
suspension of cornstarch for surface finishing and edge honing
The mechanism of material removal was shown to be related to
shear-induced, localized, dynamic jamming of the suspension
Parameters such as the translation speed, composition of the
medium and the influence of a rigid boundary on process forces
offer enhanced prospects for control and optimization
The finishing medium has the potential to augment productivity
in such processes as vibratory/drag finishing
RoslerWaitukaitis

Thank you
for your kind attention!
Natural Sciences & Engineering
Research Council of Canada
Canadian Network for
Research & Innovation in
Machining Technology

Dynamic Jamming in Dense Suspensions: Machining Applications

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