FARO Applications Engineer Ryan Dant explores contact and non-contact measurement technologies, and explains the advantages of each to the design engineer, OEM manufacturer and others. Attendees gain a greater understanding of the advantages and drawbacks for both, and ultimately are able to decide which is best for their unique application. In addition, Ryan: Discusses, in-depth, the process of contact measurement including the types of probing methods – hard-probing and touch-trigger methods Explains laser probing as it relates to articulated arm CMMs; covering point cloud spread, volume, and the effects of color and reflectivity on the target item Details the uses of each type of measurement in different applications, and explain the specific benefits to users

1. Better Design Through Measurement:
Contact vs. Non-Contact Technologies

2. Before We Start
 This webinar will be available afterwards at
designworldonline.com & email
 Q&A at the end of the presentation
 Hashtag for this webinar: #DWwebinar

3. Moderator
Presenter
Leslie Langnau
Ryan Dant
Design World
FARO Technologies

4. Better Design Through Measurement:
Contact vs. Non-Contact Technologies
Ryan Dant, Applications Engineer, FARO Technologies

5. Agenda
•
Introduction
•
Single Point Repeatability and Volumetric Accuracy
•
Contact Measurements
o
•
Non-Contact
o
•
•
Strengths and Weaknesses
Strengths and Weaknesses
How can You Benefit?
Q and A

6. What Is Contact Measurement
In terms of articulated arm CMM’s, contact measurement includes any probes that
require the probe to be physically touching the surface of the part being digitized.
•
This includes hard probes and touch-trigger probes

7. Non-Contact Measurement
A type of digitization that uses lasers or light systems
to capture data without touching the part.
• Includes white and blue light systems, as well as laser line
probes, used with portable CMM’s.
• We will focus on those types of probes that can be used in
tandem with an articulated arm (e.g. Laser Line Probes (LLPs)

8. Single Point Repeatability and Volumetric
Accuracy
Two ways to compare different measurement methods:
•
•
Single Point Repeatability, or precision, is how close the same
measurements are together.
Volumetric Accuracy: How close a point can be in 3D space to
it’s nominal (or correct) position.

9. Contact Measurement
Hard Probing
Touch-Trigger Probing

10. Contact Measurement: Hard Probing
•
Hard Probing is a subset of those types
of probes that require contact with the
desired surface and a manual trigger.
•
Hard probes come in a variety of
different shapes and sizes, ranging from
large ball-type probes down to a needle
point.

11. Contact Measurement:
Hard Probing - Calibration
•
When a probe is switched it is important to “teach” the arm the location of the
tip (point probe), or the center of the sphere (ball probe).
o Known as calibration
•
There are different types of calibration, each used for a specific case of probe
type. Videos available at www.faro.com/site/resources/supportvideos

12. Contact Measurement:
Hard Probing – Ball Compensation
•
When measuring a surface with a ball
probe, the radius of the probe (4) must be
considered.
•
This is because the point is taken at the
center of the probe (3) which was found
during compensation.
•
But the ball contacts the surface at the
tangent point (2).

13. Contact Measurement:
Hard Probing - Accuracy
•
The accuracy of a hard probe is entirely
determined by the accuracy of the articulated
arm CMM that it is mounted to.
•
Modern “Arms” range in accuracy from <.001” to
around .005”

14. Contact Measurement:
Hard Probing – Capturing Data
When capturing data with a hard probe, the probe is placed up against the desired surface
and a manual trigger is depressed which records the 3D location of the probe at the moment
of the trigger.
Single Point – Trigger for every reading
Interval – Press and hold for either distance
based or time based readings

15. Contact Measurement:
Hard Probing – Points Taken vs. Accuracy
To accurately represent a feature,
enough points must be taken to
improve the best fit.
How many is enough?

16. Contact Measurement:
Best Fit
•
When accurate readings for surface inspection are needed it is important to
take a high volume of points to account for any deviation on the surface of the
part.
•
It can be a lengthy process to cover a surface in a high volume of points
necessary for detailed surface inspection.

17. Hard Probing
•
Accurate
o As high accuracy as .0005”
•
Low volume of points
•
Quick Measurement of Geometric
Primitives

18. Contact Measurement:
Touch Trigger Probes
•
With a touch-trigger probe the articulated arm will record a point when the
probe contacts the surface.
o Thus, the x,y,z data of the point will be recorded at very low pressures.
•
This can be beneficial when measuring parts consisting of material that
deflects under low amounts of pressure.
o e.g. Molded or formed plastic, sheet metal

19. Non-Contact
Measurement
Laser Line Probes

20. Non-Contact Measurement:
What is an LLP?
• (1) Laser Emitter
• (2) Camera
• (3) Calibration Plate

21. Non-Contact Measurement:
LLP Calibration
As with the hard probe, we need to teach the
arm the 3D distance from the laser emitter
to the points being taken.

22. Non-Contact Measurement:
Calibration Considerations
•
When calibrating a laser probe, it is first necessary to use a properly
calibrated contact probe to define a feature.
•
When dealing with an attached LLP the accuracy of the LLP must be added
to the accuracy of the Arm; the resultant “system” accuracy will be what is
measured to.

23. Non-Contact Measurement:
Acquiring Data
Takes ~45,000 points per second along a line

24. Non-Contact Measurement: Point Clouds
A scan with an LLP will produce a point cloud, which is just a large 3D group of
points that correspond to the geometry measured.
•
Point clouds can be exported to CAD and turned into models
•
They can also be used for inspection

25. Non-Contact Measurement:
Point Cloud Color Contour Map
Laying a point cloud over a CAD model we can obtain
a color map that shows us the deviation of the part
scanned.

26. Non-Contact Measurement:
Measurement Considerations
•
Part Color
o The easiest colors to capture start at white and the difficulty increases as the
color darkens.
•
Darker colors absorb more light
•
Part Reflectivity
o As a part reaches a certain threshold of reflectivity, the part will scatter the laser
and make reading hard to acquire
o e.g. high machine finish and chrome parts

27. Non-Contact Measurement:
Resolving the Reflectivity Problem
•
Paint the part.
•
Coat the part in a solvent, which can
counteract the effects of reflectivity.

28. How Can You Benefit?
Industry Comparison & Conclusions

29. Conclusions:
Hard Probing
Good for doing simple measurements quickly on rigid parts.
•
•
•
Machine Shops
Fabrication Shops
Welding

30. Conclusions:
Touch-Trigger Probes
Applications where simple feature based
measurements suffice, but material will deform if
pressed on by a hard probe.
•
•
Plastics
Formed Sheet Metal

31. Conclusions:
Laser Line Probe
•
Ideal for complete reverse engineering projects
o Point Clouds can be exported into CAD and turned into
IGES, STP, or X_T (to name a few)
•
Inspection of complex geometry not suited for feature
based inspection
o Can compare to CAD and provide color contour maps

32. Thank You
For more information: www.faro.com

33. Questions?
Design World
Leslie Langnau
llangnau@wtwhmedia.com
Phone: 440.234.4531
Twitter: @DW_RapidMfg
FARO Technologies
Ryan Dant
Ryan.Dant@faro.com
Phone: 630.862.4752
- Can call or text

34. Thank You
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 Tweet with hashtag #DWwebinar
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