Probe pressure on the part

[[Ma...]]

How much pressure is applied from the probe to the part during scanning with an Vast XXT system?

[[Al...]]

My recommendations;

Default is between 50-200 mN. You can change that per feature or to the entire measurement plan.
I always change the default to 50-100. (tick Measurement Plan radio button and you can change it for the whole plan)

Resources > Feature Settings Editor
Drop Down > Probing > Elastic Parts [Force in mN]

You also want to change the touch approach speed. This is handled with the Probing Dynamic option in the same list.
Resources > Feature Settings Editor
Drop Down > Probing > Probing dynamic [in %]
Vast XXT: My default is 50% for features and 25% for Datum Features.
(Unless using a DuraMax, then cut those in half: 25% and 12.5%)

ElasticForce_Default.PNG

[[Da...]]

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Alexander, if I'm reading correctly Mark is interested in XXT sensor.

Mark, searching around forum gives -> viewtopic.php?p=53198#p53198

[[Al...]]

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I see what you're saying.

The actual sensor pressure is irrelevant, regardless of type (TL1, TL2, etc.). You'll also achieve extremely high sensitivity with longer styli because the fulcrum is further from the point of contact. If he is aiming at measuring very thin materials, I recommend a long stylus (70-100mm length) with a force of (50-100 mN) and probing dynamic (<= 25%) and an acute stylus angle (not perpendicular, 0-30 degrees parallel with the surface).

You'll have the most accurate results if you reduce the touch speed (Probing Dynamic). I've tested it on a DuraMax. At 100% the stylus bounces off the part and I saw 40-50 micron error in repeatability. At lower touch speeds, I saw a 2-3 micron repeatability. Using a G2-G5 Contura, I could see a 12-25 micron repeatability at 100% and I can get it to 0-2 microns at 50%. The XXT also has a delay in sensor action, it will wait for minimum force before starting the measurement, but at lower touch speeds, the force required is much lower than advertised.

[[Da...]]

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Thanks for additional info.

[[Da...]]

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Alexander, so lowering Probing Dynamics on XXT has no impact on scanning? You can only see the difference with single points?

[[Al...]]

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That is correct. Probing Dynamic only controls the approach / touch speed. The CMM will drive full speed (or less if programmed) to the clearance plane, it will drive full speed to the retract distance, and then reduce speed to the default touch speed or a percentage of that if you adjust it. Does that make sense? All I can suggest is to try it, measure a feature twice, once at 100% and then adjust the second down to 12.5% and watch the difference.

Scanning is not affected by Probing Dynamic during the scan, but reducing the probing dynamic for a scanned feature will reduce the initial touch speed therefore reducing potential noise at the start of the scan. Calypso scans a little differently, it will start moving almost as soon as it touches the surface, so if the stylus is still noisy and bouncing around, you'll have bad data. Also, the part (if small enough or thin enough) could move when touching at 100%, and that will also affect scanning. Even if it's just microns, sometimes that's your tolerance, and eating tolerance with error is what we aim to avoid.

[[Je...]]

https://portal.zeiss.com/knowledge-base ... &id=523557 - Probing Dynamic
https://portal.zeiss.com/knowledge-base ... id=1572069 - XXT Sensor specs