D. Grandy, P. KoshyMcMaster University, Canada
F. Klocke RWTH Aachen, Germany
Pneumatic Non-Contact Roughness Assessment of Moving Surfaces
2/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Development towards in-process roughness estimation
Issues with machining debris and cutting fluid
Development of a pneumatic sensor
www.taylor-hobson.comwww.taylor-hobson.com
3/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Principle of pneumatic gauging
work
pb
xi
air
Pcontrol orifice
pressure transducerps
Back pressure pb depends on xi
pb
xi
ps
Primarily quasi-static applications
work
air piezoelectricpressure transducer
4/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
5 mm
Surface porosity detection in machined castings
cutting tool
workpiece
nozzle
transducer Sensor integrated into the cutting tool holder for in-process application, in the presence of a flood coolant
Menzies & Koshy (2009)
5/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
US patent 2,417,988 (1947)
US patent 7,325,445 (2004)
Reliability of pneumatic gauging deteriorates as the peak-to-valley height of the surface exceeds about 3 µmRelated previous work
Nicolau (1937)
Hamouda (1979)
Tanner (1982)
Wang & Hsu (1987)
Woolley (1992)
Nozzle is in contact with workpiece, and is hence not suitable for in-process application
6/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
work
pb
xi
air
P
frequencydecomposition
The present work pertains to non-contact roughness assessment of moving surfaces
Roughness is related to the frequency content of the back pressure signal
7/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Working principlenozzle
nozzle traverse
8/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Experiments on plane surfaces
nozzle diameter (dn) 1.5 mm
control orifice diameter (dc) 0.84 mm
supply pressure (ps) 138 kPa
stand-off distance (xi) 50 µm
nozzle feed rate 0.4 m/min
piezo pressuretransducer
nozzle
9/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Comparison of stylus and pneumatic signals from milled and turned surfaces of roughness 3.2 µm Ra
-10
-5
0
5
10
15
0 2 4 6 8 10-1.0
-0.5
0.0
0.5
1.0
0 2 4 6 8 10
Distance (mm) Distance (mm)
Hei
ght
(µm
)V
olta
ge (
V)
milled surface turned surface
stylus
pneumatic
10/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Frequency domain comparison of stylus and pneumatic signals
0
2
4
6
0 1 2 3 4 5 60.00
0.15
0.30
0.45
0 1 2 3 4 5 6
Frequency (mm-1) Frequency (mm-1)
Am
plitu
de (
V)
Am
plitu
de (
µm
) turned surfacemilled surface
stylus
pneumatic
11/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Frequency spectra corresponding to milled surfaces of various roughness values
5 plots shown for each roughness
??
12/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Roughness Ra (µm)
Am
plitu
de (
V)
Are
a (V
/mm
)
Roughness Ra (µm)0 3 6 9 12 15
0.00
0.15
0.30
0.45
0 3 6 9 12 15
0.0
0.5
1.0
1.5
Correlation of pneumatic indices to roughness measured using a stylus instrument
Area under the frequency plot
Amplitude of dominant frequency
13/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Supply pressure (kPa)
Nor
mal
ized
am
plitu
de
0 100 200 300 4000
3
6
9
Effect of supply pressure
work
pb
xi
air
Pdc
ps
dn
14/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Effect of control orifice diameter dc
work
pb
xi
air
dc
ps
dn
Stand-off distance (µm)
Nor
mal
ized
am
plitu
de dc = 0.84 mm
dc = 0.50 mm
dc = 0.50 mm
dc = 0.84 mm
0
1
2
3
0 50 100 150 200 250 300
0
1
2
3
experimental
analytical
15/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Experiments on rotating cylindrical surfaces
quenchant
hardness
nozzle
turned surface
nozzle workpiece diameter ~25 mm
surface speed 30 m/min
nozzle feed rate 0.2 mm/rev
stand-off distance (xi) 50 µm
supply pressure (ps) 138 kPa
nozzle diameter (dn) 1.5 mm
control orifice diameter (dc) 0.84 mm
nozzleworkpiece
16/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Effect of increasing roughness
Frequency (Hz)
Am
plitu
de (
V)
0 8 16 24 32 40 480.0
0.1
0.2
0.3
0.4
0 8 16 24 32 40 48
Frequency (Hz)
quenched endof Jominy specimen
1 mm 1 mm
increasing roughness
1.2 µm Ra 3.8 µm Ra
17/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Effect of relative speed between nozzle and work
0 20 40 60 80
0.00
0.05
0.10
0.15
Frequency (Hz)
Am
plitu
de (
V)60 m/min
100 m/min
200 m/min
Sensor response can be improved by
minimizing the volume of the
variable pressure chamber
18/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Effect of application of cutting fluid
Frequency (Hz)
Am
plitu
de (
V)
0 8 16 24 32 40 48
0.0
0.1
0.2
0.3
0.4
without cutting fluid
with cutting fluid
Flood coolant application has minimal influence on sensor performance
19/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Recent work on extension to fine surfaces
0 5 10 15 20 25 30
0
5
10
15
20
23 24 25 26 27
0
2
4
6 Frequency (mm-1)
Am
plit
ude (
mV
)
0 5 10 15 20 25 30
0
5
10
15
20
20 21 22 23 24
0
2
4
6 Frequency (mm-1)
Am
plit
ude (
mV
)
0 3 6 9 12 15 18 21 24 27 30
0.0
0.3
0.6
0.9
1.2
1.5
Am
plitu
de (
mV
)
Frequency (1/mm)
0 3 6 9 12 15 18 21 24 27 30
0
3
6
9
12
15
Am
plitu
de (
mV
)
vibration
pressure
0.1 µm Ra ground 0.1 µm Ra lapped
Back pressure signals are noisy, and are affected by vibration
X1
X2
X3
P
St1
t2
X1 X2 X3 … …
G1
G2
L1
L2
Variables
Obs
erva
tions
…
20/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Principal Components Analysis
21/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Application of principal components analysis
-20
-10
0
10
20
-40 -30 -20 -10 0 10 20 30 40
tPS
[2]
tPS[1]
WorksetPredictionset
SIMCA-P 11.5 - 5/29/2009 9:40:58 AM
t1
t 2ground
lapped
95% limit
Filled symbols refer to test data not
considered when building the model
22/23
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Proof-of-concept of pneumatic non-contact roughness assessment of moving surfaces has been established
In its present state of development, the system is best suited for in-situ process monitoring based on appropriate calibration
The system exhibits potential for in-process application in the presence of machining debris and cutting fluid that generally obscure the measurement process when using optical instruments
Future work will focus on the physics of jets impinging on laterally moving surfaces, taking roughness into consideration
Conclusions
23/23
Thank you for
your attention!
Pneumatic Non-contact Roughness Assessment of Moving SurfacesD. Grandy, P. Koshy, F. Klocke
59th CIRP General AssemblyBoston, August 26, 2009
Natural Sciences & EngineeringResearch Council of Canada
For more details please see: D. Grandy, P. Koshy, F. Klocke, Pneumatic non-contact roughness assessment of moving surfaces, CIRP Annals 58 (2009) 515-518.