effect of thermal shock

[THEE THAINZ™]

My CNC machines where moved about a year ago to an area that has the shipping bay door within 30 feet of me. With winter coming I want to be able to convince the powers at be that the sudden drop in temp is counter productive to the machining process (both machines and parts). The plan is to move me again next year by building an addition for machining. I want to make sure climit control and proper footing is planned well in advance. The recent thread on anchoring machines down should help with what the machine sits on now all I need is some input on climite control and the effects that the lack of can have.

Thanks

THainz

[peon]

Every tool stamping and mold shop I have worked at had machines located within the distance you mentioned. I have never witnessed an issue with the doors opening and closing. If they leave the door open for a long time, I'm sure you will have an issue. I have seen summer months with a broken AC unit cause more grief than opening doors in the winter as well as losing all heat in the winter for an extended period of time.

[K2csq7]

Unless you are trying to split tenths on a regular basis..... A door being open for 5 minutes shouldn't be a problem...

[djstedman]

I think it totally depends on what the tolerances you are trying to hold are.. generally I think machine movement from being shutoff to having run for a few hours cause a lot more variation than a door being open..

 

It takes a long time for parts / equipment to actually change temperature .. since part growth is going to be based on a measurement like 0.0000131 inch of an inch Per inch per Degree F for Aluminum..

 

Then a ten inch long part that was cooled from 70 degree to 60 degrees (10 degrees of cooling) would shrink by .. 0.0000131 * 10 * 10 or .0013 inches..

 

At first glance that seems like a lot, but you have to think that in reality .. the part wont cool 10 degrees in 5 minutes.. if you take a temp sensor and attach it to a part you will see it takes quite a long time for a part to normalize to the new room temperature...

 

Since its a thermal coefficient which depends on part size as well as material its really dependent on what your working with.. and the size of the part.. and what your tolerances are.

 

Bigger parts will be affected more by temperature variations than smaller ones, however it will take much longer for bigger parts to normalize to a new temperature, smaller parts will be effected less since the amount of growth or contraction is a function of the size of the part.. generally this means short term changes in temperature wont be nearly as detrimental to process stability as changes in temperature that last a sustained period of time.

[THEE THAINZ™]

That is the problem it is for extended periods of time ambiant temp outside yesterday was around 52 deg F. temp inside was about the same within 5 min of the door being open. Then it stays open for up to 30 minutes at a time. It has not caused any problems to date yet. I just want to make sure that if they are going to build a new area that it is as stable as it can be. And yes I do have several tolerences that are +0.0 / -.0005" with a true position of .004".

[AEP]

I was in that position at a former employer. In the winter they would turn down the heat at night, I wrote "warm up" programs to work all the Axis's and the spindle for 10 mins every morning before the operators began running production. it did seem to help.. But like everyone says, Unless your splitting 10ths your not going to see much..

[THEE THAINZ™]

Thanks for the info, hopefully when the next move comes it will all work out. As for now it is what it is and even with some tight tolerences I have not seen any problems to date. Just wanted to make sure that all the ducks are in a row before the machines are moved.

[mx247]

Not quite the same thing, but in our old building our wire EDM was set up in the front of the shop exposed to large windows. In the spring and fall I would notice changes in the late afternoon when the sun would shine in directly on the machine. Granted it was a wire edm so we were talking having to make offset changes in the .0002 or so range. Solved the problem by taping cardboard over the windows.

[GoetzInd]

We used to have a mill turn near a bay door and would see diam change of almost .001 if the door was opened for even 10min or so. Granted this is winter in Chicago and that was on dia.

 

Mike

[mx247]

Now that I'm thinking about this we also had a problem with a Haas mill that was located under the heater in our shop. We were cutting mold cavities and you could see witness lines when the heater had kicked on. You would think it would have been a gradual change but it definately had a distinct step probably only a few tenths and luckily they were aluminum molds so it was easy enough to polish out.

[RaiderX]

+1000 to haas thermal movement is very prevalent. What brand configuration of machine will make a difference to some extent, also are you an as9100 shop?

 

Doug

[THEE THAINZ™]

1 HAAS VF3 and a Fanuc 18i 4020 FADAL, and yes AS9100. Ambient sustained room temp last winter was down to 54 deg once last winter.