1. Early Stage Researcher 1.1 Work Package 1
Claude SANZ
Early Stage Researcher 1.1
Work Package 1
Magnet
Nano-positioning system
Manual pre-alignment system
Stretcher
CMM granite table
Seismic sensor
Wire going through the BPM and the magnet
BPM

2. the SESHAT, the CMM & the Wire
The SESHAT is the ‘Shape Evaluating Sensor: High Accuracy & Touchless’
The CMM is the Leitz Infinity Coordinate Measuring Machine
The Wire is the PACMAN reference wire
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
Requirements:
- Hello, I am the SESHAT, I am looking for an infinite light – No, I am the Leitz Infinity, a Coordinate Measuring Machine… - wire enters: I am looking for a goddess of writing and measurements – There is only the SESHAT and me here. – yes, I am a sensor. Who are you? – I am the PACMAN reference wire, and it is indeed the Seshat I should find. You, the sensor, wear the name of the Egyptian goddess of wisdom, writing and measurement. – Well, it is rather good
Where to go next?
CMM: Coordinate Measuring Machine

3. the SESHAT, the CMM & the Wire
PACMAN reference wire: CuBe, 100 µm in diameter, ~1.2 m long
Form error
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
Linear weight
Tensile strength
Reflectance
Requirements:
X-ray spectroscopy
SEM observation
2.46 µm | 2.93 µm
Micro-hardness
AFM measurements
Resistivity
2 µm
Where to go next?
SEM: Scanning Electron Microscope
AFM: Atomic Force Microscope
NGK: 1.76 µm
CMM: Coordinate Measuring Machine

4. the SESHAT, the CMM & the Wire
Magnet
Nano-positioning system
Manual pre-alignment system
Stretcher
CMM granite table
Seismic sensor
Wire going through the BPM and the magnet
BPM
700mm
1250mm
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
Requirements:
Requirements:
-> Stiffness
-> Weight <1.2 kg
-> Width <100 mm
-> Tight tolerances <2 µm
-> Hardness > = 1175 kg/mm2
-> Stand magnetic field > 15 mT
-> Can be calibrated
->
The requirements for the SESHAT:
Maximum weight: 1.2 kg
Low energy emission
Maximum width: 100 mm
Not disturb the wire
Stand magnetic field
Can be calibrated
Maximum Permissible Error in positioning: MPEE[µm]=0.3 +L/1000
Where to go next?
CMM: Coordinate Measuring Machine

5. The SESHAT’s Sensing element
CMM & PACMAN requirements:
Light
Small
Can stand strong magnetic fields
Highest repeatability
Measuring the form
Do not disturb the wire
Possible to calibrate
Fitting with the CMM translation
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
Sensors available on the market:
Low force touch probes
Eddy current probes
Acoustic probes
Optical sensors
Interferometers
Confocal chromatic (several providers)
Shadow based
Confocal
Fringe pattern recognition
Camera based
Tunnel effect probes
Capacitive
Sensors available on the market:
Low force touch probes
Eddy current probes
Acoustic probes
Optical sensors
Interferometers
Confocal chromatic (several providers)
Shadow based
Confocal
Fringe pattern recognition
Camera based
Tunnel effect probes
Capacitive
Requirements:
-> Stiffness
-> Weight <1.2 kg
-> Width <100 mm
-> Tight tolerances <2 µm
-> Hardness > = 1175 kg/mm2
-> Stand magnetic field > 15 mT
-> Can be calibrated
->
-> Stand magnetic field > 15 mT
-> Can be calibrated
Where to go next?
CMM: Coordinate Measuring Machine

6. The SESHAT’s Mount for the chromatic confocal sensor
The parts constituting the SESHAT:
The chromatic confocal sensor
A rotor
A stator which can be linked to the CMM
A rotary mechanical connection between the stator and the rotor
Something mastering the rotor’s move
Something giving information on the position with high accuracy
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
: aluminium is well modelled, cheap and easy to handle, rather light
: with a three ball plate, in aluminium
: a bearing
: a motor
: an encoder
Requirements:
-> Stiffness
-> Weight <1.2 kg
-> Width <100 mm
-> Tight tolerances <2 µm
-> Hardness > = 1175 kg/mm2
-> Stand magnetic field > 15 mT
-> Can be calibrated
->
How to reach high Accuracy?
Lowest random motion
Highest stiffness for the assembly
Low impact of the bearing surfaces
Isostaticity (or reduced hyperstaticity)
A well mastered move
Reduced vibrations
High damping effect
Fitting Eigen frequencies
Well known position and high accuracy positioning
Reduced Abbe offset
Accurate positioning of the rotor
Air bearings: 12 pads, mounted on ball screws, opposite each other
I just read that the bearings with lowest random motion error are the air pads – air pads? – yes, now you can find air pads made out of a porous media and they are stiffer. On top of this, they could go over the opening. – What opening? – Well, I will be stretched from both ends, so you will need to open your rotor in order to let me enter by the bottom – yes, you are right, this will not simplify our quest ! – OK, let’s take as many air pads as possible, to have a very stable and stiff motion – no, you should not, you will be hyperstatic – oh – yes, it induces stresses inside your body and you cannot know how to move properly, which frightens the accuracy. 12 pads: 4 pads with two opposite along y and z, arranged at 120°
: a piezo motor
High damping effect
Where to go next?
: the motor’s vibrations frequency should fit
: the encoder is as close as possible to the sensor
: the motor does nanometric steps
CMM: Coordinate Measuring Machine

7. The SESHAT’s Mount for the chromatic confocal sensor
The parts constituting the SESHAT:
The chromatic confocal sensor
An aluminium rotor
An aluminium stator with the right plate
Air bearing bringing high stiffness and high quality for the rotation
A piezo motor fitting with the miscellaneous requirements
A high accuracy encoder as close as possible to the sensor
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
The aluminium part of the stator should be stiff enough
The air pads require very tight tolerances on form and surface quality: the form error should be less than 2.5 µm on the open rotor (due the air gap size of 5µm)
The piezo motor requires a hard material to walk on: typically alumina ceramic
The encoder has a minimum bending radius of 200 mm
Requirements:
The stator is quite large
-> Stiffness
-> Weight <1.2 kg
-> Width <100 mm
-> Tight tolerances <2 µm
-> Hardness > = 1175 kg/mm2
-> Stand magnetic field > 15 mT
-> Can be calibrated
-> The rotor must be open
-> Stiffness
The weight is higher
-> Weight <1.2 kg
-> Tight tolerances <2 µm
A company must be able to reach these tolerances!
I just read that the bearings with lowest random motion error are the air pads – air pads? – yes, now you can find air pads made out of a porous media and they are stiffer. On top of this, they could go over the opening. – What opening? – Well, I will be stretched from both ends, so you will need to open your rotor in order to let me enter by the bottom – yes, you are right, this will not simplify our quest ! – OK, let’s take as many air pads as possible, to have a very stable and stiff motion – no, you should not, you will be hyperstatic – oh – yes, it induces stresses inside your body and you cannot know how to move properly, which frightens the accuracy. 12 pads: 4 pads with two opposite along y and z, arranged at 120°
The machine tool should make it
An alumina ring must be inserted in the aluminium rotor and opened
Where to go next?
There is a high risk of breaking the ring with the motor
Let’s have a look at the SESHAT!
The rotor has a minimum radius
The minimum weight is higher

8. The SESHAT’s Mount for the chromatic confocal sensor
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
Requirements:
-> Stiffness
-> Weight <1.2 kg
-> Width <100 mm
-> Tight tolerances <2 µm
-> Hardness > = 1175 kg/mm2
-> Stand magnetic field > 15 mT
-> Can be calibrated
-> …
-> Stiffness
-> Width <100 mm
I just read that the bearings with lowest random motion error are the air pads – air pads? – yes, now you can find air pads made out of a porous media and they are stiffer. On top of this, they could go over the opening. – What opening? – Well, I will be stretched from both ends, so you will need to open your rotor in order to let me enter by the bottom – yes, you are right, this will not simplify our quest ! – OK, let’s take as many air pads as possible, to have a very stable and stiff motion – no, you should not, you will be hyperstatic – oh – yes, it induces stresses inside your body and you cannot know how to move properly, which frightens the accuracy. 12 pads: 4 pads with two opposite along y and z, arranged at 120°
Where to go next?
**CMM: Coordinate Measuring Machine

9. The SESHAT’s Mount for the chromatic confocal sensor
The parts constituting the SESHAT:
The chromatic confocal sensor
An aluminium rotor
An aluminium stator with the right plate
Air bearing bringing high stiffness and high quality for the rotation
A piezo motor fitting with the miscellaneous requirements
A high accuracy encoder as close as possible to the sensor
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
Requirements:
The weight is too high
Weight optimization should be performed
Stiff and light: Carbon and honey comb structure + peek
The structure is larger than the maximum width allowed
Peek is very unstable with temperature variations
-> Stiffness
-> Weight <1.2 kg
-> Width <100 mm
-> Tight tolerances <2 µm
-> Hardness > = 1175 kg/mm2
-> Stand magnetic field > 15 mT
-> Can be calibrated
-> …
I just read that the bearings with lowest random motion error are the air pads – air pads? – yes, now you can find air pads made out of a porous media and they are stiffer. On top of this, they could go over the opening. – What opening? – Well, I will be stretched from both ends, so you will need to open your rotor in order to let me enter by the bottom – yes, you are right, this will not simplify our quest ! – OK, let’s take as many air pads as possible, to have a very stable and stiff motion – no, you should not, you will be hyperstatic – oh – yes, it induces stresses inside your body and you cannot know how to move properly, which frightens the accuracy. 12 pads: 4 pads with two opposite along y and z, arranged at 120°
There is a high risk of breaking the ring with the motor
The hard material should be very well bounded to the rotor
For the prototype and the proof of concept, it will be plain alumina
Where to go next?
Optimisation is under process: 3D printed titanium or Scalmalloy with an alumina ring is being considered (Ti and Al2O3 behave similarly)
CMM: Coordinate Measuring Machine

10. Where to go next…
Check independently the parts constituting the SESHAT:
The chromatic confocal sensor
A rotor
A stator with the right plate
Air bearing bringing high stiffness and high quality for the rotation
A piezo motor fitting with the miscellaneous requirements
A high accuracy encoder as close as possible to the sensor
Assemble the SESHAT prototype and proof the concept
Measure the influence of the air pad’s air stream on the wire
Find the optimal material and technique to lighten the SESHAT
Adapt the sensor on the CMM
Determine and apply the best method for the sensor calibration
Determine and apply the integration strategy for using the sensor with Q7
Compare the results with the simulations being performed
Understand the gap between the contact & non-contact from measurements
SESHAT, CMM & Wire
-> Shape Evaluating Sensor: High Accuracy & Touchless
-> MPEE [µm]= 0.3+L/1000
-> CuBe Φ100 mm
-> 3σ < 0.5 µm for the wire axis positioning
Requirements:
-> Stiffness
-> Weight <1.2 kg
-> Width <100 mm
-> Tight tolerances <2 µm
-> Hardness > = 1175 kg/mm2
-> Stand magnetic field > 15 mT
-> Can be calibrated
-> …
I just read that the bearings with lowest random motion error are the air pads – air pads? – yes, now you can find air pads made out of a porous media and they are stiffer. On top of this, they could go over the opening. – What opening? – Well, I will be stretched from both ends, so you will need to open your rotor in order to let me enter by the bottom – yes, you are right, this will not simplify our quest ! – OK, let’s take as many air pads as possible, to have a very stable and stiff motion – no, you should not, you will be hyperstatic – oh – yes, it induces stresses inside your body and you cannot know how to move properly, which frightens the accuracy. 12 pads: 4 pads with two opposite along y and z, arranged at 120°
Where to go next?
CMM: Coordinate Measuring Machine

11. Thank you for your attention… Do you have questions?
@ Deviant Art, Seshat drawn by Mme Kikue

12. PACMAN’s Reference Wire
Choice of the wire provider
Good Fellow
California Fine Wire company
NGK
Form error measurement 1 [µm]
22.47
1.37
1.44
Form error measurement 2 [µm]
1.74
2.31
2.75
Form error measurement 3 [µm]
2.88
2.39
2.10
Form error measurement 4 [µm]
3.37
2.89
1.56
Form error measurement 5 [µm]
3.79
2.00
1.85
Form error measurement 6 [µm]
8.17
2.08
1.82
Form error measurement 7 [µm]
1.26
1.47
Form error measurement 8 [µm]
0.96
1.25
Form error measurement 9 [µm]
1.88
3.50
1.38
Form error measurement 10 [µm]
1.52
5.53
1.48
Mean [µm]
2.93
2.46
1.76
Standard deviation [µm]
2.04
1.23
0.39
The environmental noise measured on the same day as these measurements had a standard deviation of 81 nm.

13. Choices of sensor and wire providers

14. The SESHAT and the Quest of the Accuracy
The result of a partnership