1. SP80
Ultra-high accuracy scanning probe with long stylus capacity for measuring deep features
This presentation outlines the key choices facing a CMM user who needs to specify a probing system.
Key questions:
Do my measurement applications require a scanning solution?
If so, what is the scanning performance of the system?
Scanning accuracy at high speeds
Total measurement cycle time, including stylus changes
If I also need to measure discrete points, how fast can I do this?
Will I benefit from the flexibility of an articulating head
Access to the component
Sensor and stylus changing
What are the lifetime costs?
Purchase price
What are the likely failure modes and what protection is provided?
Repair / replacement costs and speed of service
Issue 2

2. Agenda SP80 ultra-high accuracy scanning probe
1. What should an ideal scanning system offer?
2. What type of scanning probe is SP80?
3. Where can SP80 be used?
4. What's components make up the SP80 system?
5. Comparing SP80 with competitor offerings?
- PASSIVE sensors v ACTIVE sensors
6. SP80 key design characteristics
This presentation outlines the key choices facing a CMM user who needs to specify a probing system.
Key questions:
Do my measurement applications require a scanning solution?
If so, what is the scanning performance of the system?
Scanning accuracy at high speeds
Total measurement cycle time, including stylus changes
If I also need to measure discrete points, how fast can I do this?
Will I benefit from the flexibility of an articulating head
Access to the component
Sensor and stylus changing
What are the lifetime costs?
Purchase price
What are the likely failure modes and what protection is provided?
Repair / replacement costs and speed of service

3. What should an ideal scanning system offer?
High accuracy scanning of the form of known and unknown parts
Rapid discrete point measurement when measuring feature position
Easy interchange between stylus arrangements
Minimum stylus wear
Reliability, productivity and low cost of ownership
The typical manufacturer will require a combination of high speed, accurate scanning for critical features where form measurement is essential, plus discrete point measurement for features that require just size or position control Scanning systems can do both of these things, although they are not the optimum solution for fast measurement of discrete points. The ideal scanning system therefore has the following characteristics. For more information on how Renishaw scanning systems are designed to meet these criteria, explore the Renishaw scanning topic in the Quick links below.
Ideal scanning system characteristics
High speed, accurate scanning of the form of known and unknown parts
Rapid point measurement to capture discrete data points when measuring feature position
Flexible access to the component to allow rapid measurement of all critical features on the part
Easy interchange with other types of sensor, including touch-trigger probes and non-contact sensors. This allows users to optimise their sensor choice for each measurement application.
Renishaw’s SP80 scanning probe gives you all this functionality

4. What type of scanning probe is SP80?
SP80 is a PASSIVE sensor (as opposed to an ACTIVE sensor type) - so SP80 features are:
simple, accurate and high-performance design
robustness and high resistance to most collision damage
use of long, heavy, complex and rapidly interchangeable styli
long service life, reliability and low cost of ownership
SP80 is an ANALOGUE scanning probe:
a probe that gives a continuous reading at any time while in contact with the part
an integral part of the CMMs motion control system - giving real time response X, Y and Z outputs
a probe whose output is proportional to its deflection 

5. Where can SP80 be used? SCANNING applications
controlling the form or profile of complex surfaces or features that form functional fits with other parts
determining the feature position, accurately measuring the feature size and identifying errors in the feature’s form or shape
data capture speeds of up to 500 points per second (with UCC1) giving significantly improved productivity over other sensing methods
Scanning allows you to gather a lot of data very quickly. This data can be used to determine not just the size and position of features on your components, but their form as well With a scanning inspection system you can acquire several hundred points per second, rapidly gaining an accurate understanding of the surface of your components. This is ideally suited to features where the tolerance of form is a significant proportion of the total tolerance Features which must form a functional fit with another component benefit most from scanning. Where form is not important (on clearance features, for instance), discrete point measurement is generally preferred.

6. Where can SP80 be used? DISCRETE POINT MEASUREMENT applications
not quite as fast as using a dedicated touch trigger probe but still very viable where requirement is secondary to scanning work
extrapolate to zero routines have no need to pause and give averaging for best measurement results
most features on most parts are best measured with discrete point measurement so ability to do this effectively with a scanning probe is of great benefit
Scanning allows you to gather a lot of data very quickly. This data can be used to determine not just the size and position of features on your components, but their form as well With a scanning inspection system you can acquire several hundred points per second, rapidly gaining an accurate understanding of the surface of your components. This is ideally suited to features where the tolerance of form is a significant proportion of the total tolerance Features which must form a functional fit with another component benefit most from scanning. Where form is not important (on clearance features, for instance), discrete point measurement is generally preferred.

7. Where can SP80 be used? DIGITISING applications
capturing large amounts of data about an unknown surface
creation of CAD models
uses many of the same techniques as scanning
REVERSE ENGINEERING applications
digitised data can be exported to CAD for reverse engineering purposes
used to generate a machining program for re-manufacture
Like scanning, digitising is best performed using a scanning probe since the amount of data required is very high. Whilst discrete point measurement techniques can be used, these are very much slower Digitising uses many of the techniques needed for scanning, except that the motion of the CMM is controlled in a different manner On described parts, the probe can move in a pre-defined path, accommodating any surface deviations. By contrast, on an unknown part the probe is moved within a pre-defined area and the probe deflection vector is used to determine which way to move the CMM to keep the probe stylus in constant contact with the surface Digitising is used for re-manufacture and reverse engineering where a master part must either be replicated or converted into digital form.

8. What's components make up the SP80 system?
Standard SP80 probe kit contains:
SP80 - probe body
KM quill to probe kimematic adaptor plate
SH80 - stylus holder with kinematic mounting to probe body
KM80
SP80
No heat soak
The SP80 has no motors for driving or locking its axes, and therefore has no heat sources within it. 'Active' probes have up to 6 motors inside them, resulting in heat soak that can affect measurement performance.
Mechanical simplicity and longevity
‘Active’ probes are effectively measuring machines, featuring powered motion of the axes. Such sensors add complexity to the scanning system, calling for more control and more maintenance. There are many more powered components that could fail By contrast, the SP80 probe is a ‘passive’ device, acting merely as a means of position feedback. It is much simpler than an ‘active’ probe - the only power required is for the readheads. This makes for inherent reliability, leading to much lower lifetime costs The life expectancy of SP80 is likely to significantly exceed that of its ‘active’ sensor competitors due to the simplicity of design and superior robustness.
Reduced vibration
With no motors and hence no servo control within the probe itself, ‘passive’ sensors rely only on the machine’s servo performance. ‘Active’ sensors have another set of servo controlled axes to contend with, adding to overall servo noise during scanning.
SH80

9. What's components make up the SP80 system?
SH80 - stylus holder
Permits optimised stylus arrangement for each feature
Repeatable kinematic re-location means no need for re-qualification
Rotational alignment of stylus via 5-way M5 stylus cube
Renishaw scanning sensors are equipped with a unique kinematic stylus changing system, allowing for rapid swapping between styli and crash protection for the scanning probe.
Using Renishaw’s new modular rack system (MRS), any number of stylus changing ports (SCP80) can be fitted to a CMM, allowing great flexibility in your choice of styli. This allows you to select the best stylus for each measurement task, resulting in more repeatable measurements.
SH80

10. What's components make up the SP80 system?
KM80 - standard quill mount
fits directly to 80mm square quill
probe mounts to KM80 via quick release kinematic joint
KM optional quill mount
as KM80 but adapts down to suit 60mm square quill
SM80 - optional shank mount
non-preferred mounting method
compatible with all 5 hole CMM shanks
has Touchel connector incorported (as PH10)
Mating part of locking cam mechanism
KM80
M4 / M3 csk holes
Standard 5 hole shank
SM80
The quill mount is the preferred method.
Shank mount has the same electrical connector as the PH10.

11. What's components make up the SP80 system?
SCP80 - stylus changing ports
MRS
repeatable automatic stylus changing of SH80's
no need for re-qualification
passive design
no signal cables
easy installation
fits to MRS (modular rack system)
size of rail to suit application
permits flexible port system
leverage system reduces pull off force required to just 20N
SCP80

12. ??? PASSIVE ACTIVE SENSORS SENSORS (SP80) (competitors)
Comparing SP80 with competitor offerings
???
PASSIVE
SENSORS
(SP80)
ACTIVE
SENSORS
(competitors)
VERSES
This presentation outlines the key choices facing a CMM user who needs to specify a probing system.
Key questions:
Do my measurement applications require a scanning solution?
If so, what is the scanning performance of the system?
Scanning accuracy at high speeds
Total measurement cycle time, including stylus changes
If I also need to measure discrete points, how fast can I do this?
Will I benefit from the flexibility of an articulating head
Access to the component
Sensor and stylus changing
What are the lifetime costs?
Purchase price
What are the likely failure modes and what protection is provided?
Repair / replacement costs and speed of service
Q. How do I compare SP80 with competitor offerings?
A. The following slides will help explain the justification for choosing a SP80 probe...

13. Passive v Active? - overview
Passive sensors
Active sensors
Complexity
Drive motors
3 Dampers
LVDTs mounted on stacked axes
Simplicity
no motor drives
no locking mechanism
no tare system
no electromagnets
no electronic damping
Design
Active sensors are large, heavy and complex
Passive sensors are small and relatively simple

14. Passive v Active? - method of control
Passive sensors
Active sensors
simple device senses deflection
no powered motion
measurements taken using machine to control stylus deflection
3 axes under servo control
effectively a miniature CMM
motors control the deflection to minimise the force on the stylus
6 axes under servo control
Compact passive sensor
Complex active sensor

15. Passive v Active? - sensor design and calibration
Passive sensors
Active sensors
smaller axis travels required
at 300 mm/sec, deflections can be held within a 100 µm range*
stylus bending compensated by sophisticated calibration routine
large probe travel needed to keep the contact force steady during scanning
direction- dependent stylus bending variations minimised by controlling the contact force
Compact passive sensor
Complex active sensor
* using adaptive scanning

16. Passive v Active? - dynamic response
Passive sensors
Active sensors
Light weight
high natural frequency suspension system
Motorised stylus carrier
driven on internal servo loop
Modern CMMs are able to move very quickly - often faster than 500 mm/sec - and can generate high accelerations - sometimes more than 0.5g. Yet scanning on conventional scanning systems is typically performed at a tiny fraction (less than 5%) of this potential.
These slow scanning moves offset most of the gains in cycle time made by having a fast measuring machine. Clearly there is scope for significant cycle time improvements if some of this untapped potential can be released.
Renishaw has met this challenge with its innovative Renscan DCTM technology. This is explained in the Renishaw CMM motion control presentation.
Probe suspension must respond whilst scan vector is adjusted
Motors adjust stylus position to keep contact force within set limits

17. Passive v Active? - measurement performance
Passive sensors
Active sensors
low inertia probe holds surface at high speeds
fast discrete point measurement cycles with 'extrapolate to zero' routines
no heat sources for improved stability
500 mW power consumption
< 1ºC temperature change inside probe
motorised probe mechanism enables high speed scanning
slow discrete point measurement cycles due to the need to servo and static average probe data
heat sources: motors and control circuits generate heat
Probe inertia
A high natural frequency can be achieved, even with low spring rates, due to the low suspended mass of Renishaw’s compact scanning probes. In active sensors, masses are much higher but not suspended on springs, so motorised control is used to allow the stylus to track the surface quickly.
Discrete point measurement
Active sensors measure discrete points by driving the stylus against the surface, holding machine position steady and then using the probe’s motors to modulate the contact force. With six axes under simultaneous servo control, there are oscillations that must be accounted for by averaging the probe output for a period of time. Only then can the probe be moved off the surface. This whole process can take several seconds.
Passive sensors do not need to go through such a complex or time-consuming process. The probe is simply moved so that the stylus meets the surface and reaches a specified deflection. The probe’s deflection is monitored throughout. As the probe moves off the surface, the probe’s readings during the period of contact can be examined to find the true surface position by ‘extrapolating back to zero’ - effectively the same as static averaging except that it is done on the move. This process typically takes less than one second per point.
Heat soak
Renishaw scanning probes consume little electrical power since there is no requirement to drive the stylus carrier, or lock the axes. With a peak power consumption of less than 1W, the SP80 family do not have significant internal heat sources. Experiments show that temperature variations inside the probe are less then 1 ºC.

18. Passive v Active? - robustness
Passive sensors
Active sensors
no motors
position feedback system is only electro-mechanical element
kinematic stylus changing and Z over-travel bump stop provides robust crash protection
probe will survive most accidents
simpler motion control
more things to go wrong
motor drives
locking mechanism
tare system
electromagnets
electronic damping
control hardware for the above
limited crash protection if the stylus is deflected beyond its limits
more complex motion control
Kinematic stylus changing provides a low force ‘break joint’ which causes the stylus to detach in XY collisions. In the Z direction, a patented ‘bump stop’ prevents damage to the probe mechanism.
The chances are, a Renishaw scanning probe will survive most crashes and still work to spec. In more than 8 years of sales, no SP80 field failures returned the Renishaw can be attributed to crash damage.
The same cannot be said for active sensors that do not provide robust crash protection features. Plus, crash damage to active sensors tends to be more costly due to their complexity and high repair charges.

19. Passive v Active? - lifetime costs
Passive sensors
Active sensors
lower purchase costs
simple and cost-effective to purchase
lower running costs
crash protection for greater reliability
50,000+ hours MTBF
advance replacement service at discounted price
customer-replacement on site due to simple fittings
less downtime
cost-effective repair
higher purchase costs
complex and high cost sensor
higher running costs
complex sensor
limited crash protection
vendor technician needed to remove damaged sensor
more downtime
high repair charges
Renishaw service
Renishaw’s RBE facility enables customers to quickly replace faulty product with one that is rebuilt to factory specification, at a heavily discounted price. Renishaw’s objective is to make the cost of ownership affordable, both in terms of service charges and in terms of costly downtime.
Robustness
SP80 probes have exceeded 50,000 hours of service with no failures. This is more than twice the MTBF claimed for active sensors.

20. SP80 - key design characteristics
Renishaw's design brief for SP80:
very accurate position sensing
long reach into parts
passive design to avoid unnecessary system complexity
design to avoid stacked axis errors
stylus changing capability for reduced cycle times
Renishaw’s SP80 adheres to all the design principles of Renishaw’s ‘passive’ sensor technology

21. SP80 - key design characteristics
Passive sensor - no motors
minimal heat source for greater stability
no electro-mechanical wear
reduced vibration during discrete point measurement
Box spring mechanism
unique design
compact and robust mechanism
low inertia
rapid dynamic response
low spring rates
single 3D ferro-fluid damper
avoids stacked axis errors
Compact dimensions - 50 mm diameter, 89 mm length
Compact dimensions are valuable since they allow the probe itself to enter deep features, thus reducing the length of stylus needed to access the surface. It is always sensible to minimise stylus length to reduce stylus bending and to minimise suspended mass, thus maximising the dynamic response of the probe.
The SP80 is much smaller than probes fitted to conventional scanning systems.
Light weight - SP80M weighs just 216g (7.6 oz)
The light overall weight of Renishaw scanning probes means that versions can be mounted on articulating heads for flexible part access. Renishaw's SP80M is the only scanning probe that can be mounted on an articulating head. When mounted on a PH10 indexing head, the combined weight is less than 1 kg (2.2 lbs).
Even on fixed probes, a light mass reduces the dynamic loads on the CMM quill during scanning. Here, the compact size of the SP80Q makes it ideal for use on small CMMs where the measurement volume is limited. The SP80Q weighs 299g (10.5 oz).
By contrast, 'active' probes are heavy - some weigh more than 5 kg (11 lbs). This can increase the inertial loads on the machine quill, limiting scanning accuracy at higher speeds.
Parallel acting springs

22. SP80 - key design characteristics
Isolated optical metrology
readheads attached to probe housing
measures deflection of whole mechanism, not just one axis
eliminates inter-axis errors
picks up thermal and dynamic effects
probes with stacked axes cannot measure inter-axis errors directly
A scanning probe has three axes of deflection - X, Y and Z. The probes use parallel-acting springs to allow each axis to move relative to one another. Each axis moves in an arc, resulting in a small amount of motion in a direction perpendicular to the axis that is moving. This small deflection - or inter-axis error - must be accounted for to ensure that the position of the stylus is accurately known.
In a Renishaw scanning probe, the three axes are arranged to form a unique 'box spring', making for a very compact design. The transduction (position sensing) system is located behind the spring assembly. By contrast, a tower probe features stacked axes, making the probe much longer. A position sensing device is mounted on each axis.
Isolated optical metrology
Renishaw's SP600 probe mechanism features a transduction system with readheads fixed to the body of the probe, measuring the deflection in each direction on a target mounted to the moving mechanism. This arrangement means that any inter-axis errors caused by the arc motion of each pair of parallel-acting springs are directly measured by the sensor system - the deflection in each direction is measured 'back to earth'. The motion of the stylus is measured directly by the readheads, meaning that the system is not reliant on the mechanical design of the structure for its accuracy.
The illustration on this slide shows a schematic of an SP600 mechanism featuring position sensitive detectors (PSDs) lit by LEDs shining through precision slits.
By contrast, probes that feature position sensing devices mounted to each axis can only measure linear deflections relative to the axis above. They cannot detect inter-axis errors, nor errors of squareness of the probe axes. Whilst these errors can be compensated, this is not necessary for a Renishaw scanning probe.
Isolated optical metrology systems can detect sources of variable error such as thermal and dynamic effects. Stacked axis probes cannot detect these and so perform less well in real world conditions, or when scanning quickly.
Inter-axis error

23. SP80 - key design characteristics
Isolated optical metrology
SP80 features digital readheads with m resolution reading precision gratings
accuracy defined by straightness of lines on each grating and calibrated squareness of gratings, not by probe mechanical design
ISO test data:
ISO Diff: 0.6 m
ISO Tij: 1.0 m
CMM spec L / 1000
Test time 61 secs
Controller UCC1
Filter None
Stylus length 50 mm, 9 mm, ceramic
The SP80 quill-mounted probe also features isolated optical metrology. The larger size of this probe allows for a more sophisticated sensor system - the SP80 uses digital readheads and precision gratings as the basis for its position feedback. This allows for even greater precision.
The digital readheads are each matched to a grating, which contains a series of precisely straight and parallel lines. Three gratings are attached to the moving mechanism, each one aligned with an axis of motion. The squareness of these gratings is calibrated, so that any slight misalignments are corrected in the probe output. The readheads interpolate the signal from the gratings to produce a digital output at 20 nm resolution.
The accuracy of the overall {x.y.z} deflection of the probe is reliant on the straightness of the lines on the grating surface, and on the performance of the readheads, not on the design of the probe mechanism. The performance results speak for themselves.
Note: ISO Tij is the result generally quoted for scanning probes. It is the the total span of readings in the measured data set. Renishaw also quotes ISO Diff values - the maximum radial error from the calibrated perfect sphere to the measured values.
Note that these results are for unknown path scans and are raw data with no filter applied. When a 60Hz harmonic filter is used, the Tij value for SP80 in this test fell to 0.6 microns.
Other details for the ISO test:
Scanning speed = 5 mm/sec
Scanning deflection = 0.5 mm
Total points taken = 2,619
Note - results quoted are for unknown path scans.

24. SP80 - key design characteristics
Crash protection
stylus change joint has low release force
over-travel in XY causes stylus holder to detach
patented Z crash protection
outer housing provides a ‘bump stop’ to prevent damage to probe mechanism and readhead
Renishaw's kinematic stylus changing system provides crash protections when the stylus travel is exceeded in a lateral direction (X or Y). However, this does not provide full protection for crashes in the Z direction A feature of Renishaw scanning probes is a Z 'bump stop' that transfers any compression forces into the probe body before the Z travel of the scanning mechanism is exceeded. This means that in the event of an uncontrolled Z movement of the machine, the probe stylus and the probe body take the load whilst protecting the box spring and readheads from damage.
Stylus deforms in a severe Z crash, whilst probe mechanism is protected

25. SP80 - key design characteristics
Stylus carrying capability
max unidirectional length 500mm
max load 400g with no compromise
500g reduces -Z range slightly
styli thread M5
Up to 500mm
The SP80 enables long styli to be carried.

26. SP80 - key design characteristics
Feature access - SP80
deep bore measurement - cranked / star styli
VDI / VDE test data:
CMM spec: L / 1000
Test speed: 5 mm/sec
Controller: UCC1
Filter: 50 Hz
Values: Unknown path
V2 m
1.75
1.5
1.25
1.0
The chart shows how the scanning performance of the SP80 varies with stylus length using a variety of cranked styli. In this test, a 50 mm diameter ring gauge, orientated at 90 degrees to the CMM quill, was measured with styli of different lengths.
Styli up to 400 mm in length were used, in all cases showing V2 performance of better than 2 microns.
0.75
0.5
0.25 50
100
150
200
250
Stylus length (mm)

27. SP80 summary Very accurate scanning Flexible and productive solution
passive scanning probe with superior mechanism
scale and read head technology
class leading accuracy
Flexible and productive solution
carries styli up to 500mm in length
carries up to 500g in weight.
rapid stylus changing
Low cost of ownership
innovative hardware and scanning techniques reduce complexity
robust designs and responsive service for lower lifetime costs
Renishaw’s approach to scanning system design delivers the best performing and most cost-effective solution available.

28. Questions?
apply innovation