Measurement of grinding wheel waviness

[Anand Nambiar]

I have done experiements on a grinding machine and have collected the data of grinding wheel profile (using a laser sensor). The raw data consists of info on grinding wheel profile, waviness and roughness (because of abrasive grains).
I would like to process the colelcted raw data. I want to filter out the high frequency and low frequency data. (I want to appply a simple band pass filter). Each cycle consists of about 200,000 data units and I have them in an excel file(csv data) and would like to perform digital filtering.
How do I filter out the waviness data separately and analyze, from this?

 

[Ranger Mike]

Surface texture is divided into 5 segments. Roughness, Waviness, Total profile and flaws.
Lay or " grain" of the surface.

Flaws are surface irregularities like cracks, checks, blow holes etc.…

Total profile is the profile of the surface that includes both roughness and waviness and can be measured with a dial indicator.

Only when you can scrutinize the surface and electrically filter out the short term roughness for the waviness, will you be able to determine Waviness per the ISO or ANSI Standards.

Typically the instrument is an LVDT transducer with applicable .0004” diameter radius stylus.Roughness is easily and cheaply measured as you can use a skid mount on the surface to be inspected. Waviness is a very expensive parameter to measure as you need an instrument with a very high accuracy reference datum.We are talking magnitude of measurement of sub-micron waviness.

If you are thinking about using a laser, forget it. It is not accurate enough not repeatable enough.I was a Product Manager for a major supplier of these instruments for over ten years.

 

[Anand Nambiar]

Thank you, Ranger Mike, for the reply.
But I am talking about surface texture of the grinding wheel (the tool as such) rather than the ground surface.
Will it still hold good?

https://mail.google.com/mail/u/0/?ui=2&ik=06c822f8eb&view=fimg&th=15a115bb4e403fe6&attid=0.1&disp=emb&realattid=ii_15a1157f5f5748da&attbid=ANGjdJ9MoHBGsbSnffjz97MPHbcGO34ZKv6gzzncS13XPjS23zU2o_qSqy_dBWbreiwnttRICf4zb_lXUSzh99ONadiWIdCJuiFHSTQCPw2Lc3c0QOFOdqvLUYm8Zdw&sz=w870-h286&ats=1486685753652&rm=15a115bb4e403fe6&zw&atsh=1

↑　This is what I had in mind. The raw data that I collected also showed similar patterns.
I wish i could share my data, but I can't upload any file on this (or atleast I don't know how to!)

Anyway, each cycle is for 2 seconds and each the data shown is for 4 seconds (2 cycles and 2 seconds per rotation)

 

[Anand Nambiar]

 

[Ranger Mike]

same principles apply to a diameter as well as flat surface. A a minimum you need to have one grinding wheel measured for the parameter with the traditional method and then you will have a base line to compare your method to actual measurement.
your laser method is not accurate enough and can not repeat to give meaningful information.

 

[Anand Nambiar]

Oh! So laser measurement techniques arent trustworthy enough?

Okay, is there any other method I may use to find out the waviness? Is it so difficult that it hasnt been extensively measured until now?
I understand the need for having a master (ideal grinding wheel surface) and a deformed grinding wheel to be able to compare.
Which I have done using the laser method too (measured before and after dressing operation)

 

[Ranger Mike]

For the third time, Lasers are not good enough to do what you ask - Measure Waviness.

Lasers are not trust worth if your job depends on it to measure Waviness on a dressing wheel.

Lasers are simply amplified light. It is how you sense the light on the surface that is the variable. Lasers hate shiny surfaces, Lasers hate rough non uniform surfaces. You cannot get a repeatable signal.As far as you comment - Is it so difficult that it hasn’t been extensively measured until now?The technology to measure Waviness has been out since 1938 and is proven technology. There are even ANSI and ISO standards on this subject .

The question shows a lack of research on this subject on your part. I recommend you do some homework. Many companies sell systems to measure Waviness. Lasers have been tried since the 1960s to measure waviness and none have been successful. You may use a laser on a very precise machined surface under laboratory conditions to do some surface texture assessments but the range is very narrow and very impractical for industrial application.