VMM vs. CMM

Dear mooremarvin,

we need some more information about the parts you measure and if you measure flatness or roundness or diameter or whatelse, how many parts per second and if it is allowed to touch the parts (leaving a fine scratch on a good surface).

There are many more possibilities than you mentioned.

RHABE

Here's a sample of some of the parts we make.

How about a multi-sensor VMM? It has both touch probe, (CMM) and Video, (VMM) capability. You can also have them fitted with a laser scanner, but they're not as accurate as the other sensors. (Best suited for rough profile and surface inspection.)

http://www.ogpnet.com/ogpVidQuest300.jsp?page=594

Have you investigated CMM's for your application? With your stated tolerances, I'm guessing that you will need an very accurate machine. $$$$$$ That is, if you can find one that can Repeat and Reproduce inspection results. (GR&R required.)

Good Answer nomination from milo. DO not purchase anything without having vendor performing a GAGE R&R Repeatability and Reproducibility study.

DO not purchase anything without having vendor performing a GAGE R&R Repeatability and Reproducibility study.

DO not purchase anything without having vendor performing a GAGE R&R Repeatability and Reproducibility study.

THIS IS CRITICAL!

milo

Hi,

these parts look like pretty many produced per day.

If you have to measure 100% then neither CMM nor VMM will do as both are not really fast.

The solution to measure many parts of the same shape is a fixture with a multitude of contacting and/or non-contacting sensors with automatic loading and unloading and alarm if something is wrong.

If you have a few parts per day only and have a lot of different parts than a CMM and or a VMM will be a good choice. Very likely measurement cost will be very high so a comparison with specialised measurement fixtures shall be done for any part.

CMM and VMM are expensive in many aspects: to buy, to operate, to have ever new touch-probes, maintenance of hard- and software, operators and their training. And the room with stabilised temperature and humidity.

Simpler solutions are likely to be better and cheaper and only the measurement fixtures (or one part per day or week) to be remeasured by a CMM.

This Will be more complicated if tolerances of 1 µm and below are required.

Get you informed about the possibilities of simple or sophisticated probes: mechanical touch probes, LVDT touch probes, Laser-triangulation, Laser confocal scanning, Laser projection, wavelength dispersion distance sensing, air-flow distance sensing, inductive sensors, eddy current sensors, capacitive sensors ....

Or get an expert to let you know.

Then decide. Or decide today but lease the expensive equipment to learn with different approaches.

RHABE

Thank you very much!

You have me thinking in a different way, and I like what I am reading. Do you have any suggestions as where to direct my inquiry?

MM

We may have suggestion. Please contact with us. Henryzhang1@hotmail.com

Do your homework - as with any capital purchase you will have to live with your decision for many years.

If you don't already have any hardware and particularly software that you need to standardize with, then you have more flexibility in your decision.

You've received good advice to look at multi-sensor machines from OPG as well as Zeiss equipment although you will find that they are quiet expensive and may be more than you need for your application if the parts in the photo represent you typical parts.

Fixed electronic gages with SPC capabilities may be more cost effective (reliable and fast) if your do long run production although you'll need CMM data on master samples to use as "set masters". A dimensional inspection house can supply that but it will get expensive if you do it often.

Touch probing is currently more accurate than laser scanning or white light technology and also note that some CMM equipment probes "touch" harder than others which could be a surface finish issue.

also visit these sites for general info

www.hexagonmetrology.net

www.xspectsolutions.com

Do your homework - as with any capital purchase you will have to live with your decision for many years.

If you don't already have any hardware and particularly software that you need to standardize with, then you have more flexibility in your decision.

You've received good advice to look at multi-sensor machines from OPG as well as Zeiss equipment although you will find that they are quiet expensive and may be more than you need for your application if the parts in the photo represent you typical parts.

Fixed electronic gages with SPC capabilities may be more cost effective (reliable and fast) if your do long run production although you'll need CMM data on master samples to use as "set masters". A dimensional inspection house can supply that but it will get expensive if you do it often.

Touch probing is currently more accurate than laser scanning or white light technology and also note that some CMM equipment probes "touch" harder than others which could be a surface finish issue.

also visit these sites for general info

www.hexagonmetrology.net

www.xspectsolutions.com