Controlling Temperature and Humidity in the CMM Room and does anyone use Artifacts?

J

Jcowan - 2010

I work at a AS9100 certified Manufacturing company we were just audited by Boeing and they were not satified with the controlls we have in the CMM room. Now we keep our CMM in a room by itself with temperature controlls but I am also not satified with the level of controll the temperature does not remain entirely constant. The heat source we use is very small and the AC unit is way up high near the ceiling. How is everyone controlling their temperature ??


Secondly, we were advised that we needed an Artifact to check our CMM periodically for any common features we may be checking i.e. ellipses, rads ect. Now I have seen some of them which are the ball on stick format but are there others out there or did anyone make their own ??

Thank you in advance,
 
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J

Jcowan - 2010

Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

Not even a wee opinion...:confused:
 

AndyN

Moved On
Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

Sorry! I was thinking about this one!

The auditor issue needs to be addressed by data recording of your conditions otherwise it looks like an opinion, albeit one based on some experience. You should put a recorder and some thermocouples around the room and see what you get. Your not really required to control the environmental conditions, simply monitor them so that when they start to change in a way that could affect the measurement result, you can make a decision about continuing etc. That's all.

The artifact can be an ANSI ball bar, or a Renishaw machine checking gauge or similar. The cost of making one and having it checked out is probably going to be prohibitive. When I worked at a metrology equipment manufacturer, the artifact nearly ended up costing as much to design and make/certify as the product it was designed to check!!
 
J

Jcowan - 2010

Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

No worries, Ok so the temperature issue seems pretty simple. Now, the auditor said that I needed to have some way to verify that the features the CMM was checking were correct and he said we could get an artifact that had all the common or regularly used features like pockets with rads and that sort of thing but I have not seen any like he talks about. I have seen the ball bar as you mention and some clindrical one with holes on it but thats it so I am not sure what hes talking about ?? Any Ideas or maybe get some clarification...
 

AndyN

Moved On
Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

He's pushing the limit - especially if he can't give you an example or place where you can obtain one. You can validate many features by checking them on an alternate item of equipment - like a shadograph for example.

Sounds like a personal bias of his.......
 
T

True Position

Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

Also, your artifact doesn't necessarily need to prove your programs ability to measure a particular part, simply a group of tooling balls set at known positions and with different diameters could be used.

A company selling something like I am describing:
http://www.metronom.com.au/TetronomTextPage.htm

You could have something like this made, say 6 tooling balls arranged in a triangle pattern at different heights. If you know the positions accurately you can check linearity in all 3 axis and if you use different size balls you can also check it for diameter accuracy.

I'd assume you could have something made with mostly off the shelf components pretty cheap, especially if you have an in house tool shop.
 
K

Ken K

Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

He's pushing the limit - especially if he can't give you an example or place where you can obtain one

Andy, where in the post did you read the auditor was asked for a source? :notme:

We monitor our CMM room with a Dickson Chart Recorder. All of the charts are dated and kept on file. We also put the readings taken every two hours and chart them in Excel for an average temp/humidity for the day. Pretty simple stuff.
 

AndyN

Moved On
Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

No worries, Ok so the temperature issue seems pretty simple. Now, the auditor said that I needed to have some way to verify that the features the CMM was checking were correct and he said we could get an artifact that had all the common or regularly used features like pockets with rads and that sort of thing but I have not seen any like he talks about. I have seen the ball bar as you mention and some clindrical one with holes on it but thats it so I am not sure what hes talking about ?? Any Ideas or maybe get some clarification...

I'm a bit perturbed by the idea that 'the auditor said'. What requirement is he referencing when he says you have to do these things? Is this his personal opinion? Do you have a history of not meeting some specification due to not validating these features? Why is it that your regular calibration isn't acceptable to him? Does he even know how a cmm works? I wonder if the work you do for this customer is worth the effort........maybe if you charge them back or at least send them a quote for his demands, he might be told to back off........
 
J

JHagani

Re: Controlling Temperature and Humidity in the CMM Room and does anyone use Artifact

Per Boeing's internal procedures, the CMM room temprature does not have to be necessarily controlled.

You need to be able to measure, verify and compensate for temprature change effects on the machine, and your part.

We have accomplished this by creating Scale Bars, "3 +/- Feet bar of different materials, Aluminum, SS, titanium,... Calibrated the length in 68 +/-2 F and 50% humidity controlled environment. each bar is identified with the measured length.

Our CMM is supposedly compensating for temp variations, and I verify this compensation by measuring these bars at different temperatures and humidities.

Our procedure was approved by Boeing.
 
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