Filter Methods &/or Waviness

[[Ke...]]

So, a few questions:

What are the primary uses for Band-pass and High-pass filters? (please give real-world examples)

Has anyone used the (Maximum) Waviness form result, and (if so) do you have any tips/tricks?

It is suggested by one of the engineers that I work with that Waviness can be evaluated using the Roundness evaluation, with a 500 upr filter setting.

Thoughts?

[[Ri...]]

I thought that Waviness required something like a profilometer that is able to detect much higher frequencies?

I know that there is a Waviness characteristic inside of Calypso, but that looks to be more of a Fourier Analysis (maybe that's the same thing, IDK).

I hope someone knowledgeable in the field can shed some light.

[[Er...]]

We evaluate a lot of "waviness" (its not actual waviness, more like variation/harmonics in surface per lenght) on airfoils.

Sort of what the curve jump characteristic does, but we dont use that since it has limited function and dont cover the reqirements of our drawings.

The method we use has Been developed under ~3 years and its finally "stable and accurate".

One thing I have learned it that you must take the machine it self in to consideration. For us, it was impossible to just say thats this or that filter is good. We measured the same curve 150 times without any filter and in the same way as in production. Then I calculated the max, min and median deviation point by point. Then I was able to see how much "waviness" the machine caused. First then we could say what was considered noise from machine/friction and what the real surface looked like.

How ever, band-pass is used if you are looking for something specific. Then you can "cut" both high and low harmonics, and leave the "middle". High-pass removes form errors. And can revele things as machine marks and scratches. Its typical not used when you are checking dimensions.

Normally you look for form errors, so you wish to keep the big waves and remove the noise. Thats what low-pass does.

My opinion is that you can check waviness with a CMM. Just use a really small probe, be very caution with filters, and measure slowly.

[[Kl...]]

A short overview of my contact with waviness evaluation

Special thanks to Eric. By the "non documented" PCM found in Mimir
getActual("Waviness").allAmplitude
it is possible to get results of all harmonics at CALYPSO and therefore at PiWeb

P1_1119_20_SE21.pdfWaviness.docx

[[Da...]]

For the most part, waviness can be measured on a CMM. The website, Digital Metrology, has an excellent article which evaluates exactly this. Hope this helps.
https://digitalmetrology.com/can-i-meas ... -on-a-cmm/

[[SH...]]

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English version of the waviness document is available??