Can heat crack a tube?

[SWMS]

I know that tubes can get thermal shock from the coolant being too cold compared to the tube, but can they crack due to too much heat?

Can anyone offer advice?

[laserdude]

I'm not sure how you would get hot coolant, but definitely yes! Always start with the tube and the coolant at the same temperature.

[seeigecannon]

I know that tubes can get thermal shock from the coolant being too cold compared to the tube, but can they crack due to too much heat?

Can anyone offer advice?

If the coolant isn't running then the tube will crack in a hurry. This is why flow switches are important.

[SWMS]

I think whats happened is a combination of things... The guy I bought the 60 Watt laser from lives in Scotland and uses 5 litres 1 litre anti freeze 4 litres water. I assume it was only being used for light use and never run particularly hard as he never had a problem, the ambient temp in the room in Scotland would have been a little cooler generally too. So, when I bought it, I thought, ok 5 litres is fine. However, 5 litres is not enough if you are cutting a large piece of mdf for a few hours. The the tube went crack, I checked the water and the flow and it was all ok. However, although the cutter is in an unheated workshop the water was hot, really hot, like above 35 degrees C.

It could also be because of not enough water being in the reservoir as evaporation due to heat would reduce the water levels. So, possibly I had some cavitation in the pump and a large air bubble formed that I didn't notice.

Either way, heat did it!

So, lesson learned, I now need a 25 litre ( 5 gallon ) drum and need to keep an eye on the water temp in the winter ( thermal shock ) and to a lesser extent in the UK summers heat.

I decided to not go down the fan and radiator route because in the winter if you use a rust resistant metal drum the cooling effect in the UK should be enough to keep the temperatures down and a fan and rad only cool to ambient temperature which would be useless in the summer, well maybe for a few days of the summer. I am also a bit anxious about relying on radiator and fan with 5 litres of coolant, there is no room for error.

An expensive lesson learned.

[laserdude]

Unfortunately, you are heading in the wrong direction! Please get a refrigerated chiller or you may get another expensive lesson. More is not better.

[SWMS]

Yeah, I know that but that's expensive. For the moment more water will do. As far as I am aware all the lower end chillers do is blow cold air over a heat sink that the coolant flows through. It's not actually chilling and can only cool it to the ambient room temperature.

[laserdude]

For the price of one tube . . .

http://www.lightobject.com/Lightobject- ... -P999.aspx

[SWMS]

Yeah, its 110V I need 230v for the UK. Whichever way I look at it, ordering from China, the UK, the USA its going to cost £300-£500. I could get an aquarium chiller but this is much the same cost. However, I have just learned that some aquarium chillers also have heater kits, which could be handy in the uk.

[Myke]

I'd like to know the coolant temperature must be approx. 20°Celsius only when the laser machine is operating? I put my machine to a wood house in the garden where the ambient temperature is hot in summer, so there will be 30°C or more. With other words, is it a problem if the coolant in the tube is 30-35°C when the machine is off?

When the machine is operating it will never exceed 25°C.

[SWMS]

I'd like to know the coolant temperature must be approx. 20°Celsius only when the laser machine is operating? I put my machine to a wood house in the garden where the ambient temperature is hot in summer, so there will be 30°C or more. With other words, is it a problem if the coolant in the tube is 30-35°C when the machine is off?

When the machine is operating it will never exceed 25°C.

It should be fine. I'd just run the pump and the cooler before you fire the laser so it gets to the right temp

I'm in the opposite position. In the winter the coolant will be too cold so I've got a pond water chiller with an integrated heater. No nasty thermal shock for me thanks!