Laser/losing power during day chiller?

[John Stephens]

I'm having a problem with 2 laser engraving systems I purchased.
They are basically one of a kind units as very few were produced and the manufacturer is no longer in business. Consequently, there is no one that we can contact for assistance. The lasers are Synrad 100 Watt Evolutions. They are cooled with Remcor Liquid Cooling System Chillers. They use Galvo marking heads. They seem to lose power during the day. For the first hour or two they burn cleanly. But as the day progresses they seem to burn with much less power leaving an increasing amount of the coating(paint) on the substrate that we are attempting to burn off cleanly. In the mornings they burn crystal clear but within an hour or two the burn is no longer acceptable and gets increasingly worse.

The temperature on the chillers is always in the normal range.

Does anyone have any suggestions as to what may be causing this loss of power or ability to burn cleanly as the day wears on?

Any comments or suggestions would be greatly appreciated.

Thank you,

John

[Dan Hintz]

When was the last time you had the gas recharged/replaced?

[John Stephens]

Dan,

The lasers are about 2 years old but don't have more than 200
hours on either one. They have hardly been used.

Thank you,

John

[Gary Hair]

The lasers are about 2 years old but don't have more than 200
hours on either one. They have hardly been used.

Unfortunately, time is the enemy not usage. There is a school of thought, and one that I have seen evidence supporting, that more usage is better when you are talking about how long a tube will last. The fact that your tubes haven't been used much in 2 years could indicate that they are in need of recharging or replacement. That's a tough pill to swallow with 100 watt tubes, but it may be a reality.

Gary

[Rodne Gold]

I doubt it is the case that the tubes need recharging as power drops during use , it isn't an overall power drop right from word go. I suspect its heat related. I would check the chillers and more importantly the circulation system as this might be clogged or have some scale build up preventing proper heat transferrance. What are you using as coolant and how often do you change it?
You can mail synrad directly , they are extremely helpful and can give you answers , we thought a tube had failed and they quickly directed us elsewhere for a solution which worked.

[Jon Colley]

I would completely agree with Rodne. I don't have experience with this particular chiller but what you are describing certainly sounds like an issue of poor coolant circulation. The chillers should have a trap/filter for debris that should be cleaned. It's probably also worth changing out the coolant and cleaning the air intake while you are doing maintenance. Make sure you check into the right type of coolant for your system. It could be a water/anti-freeze mix or it could be straight distilled water.

[Mike Mackenzie]

What happens if you shut them off for an hour and then start them back up? Does the quality come back? Usually those tubes had a over temp sensor in them that would shut the tube down if it got to hot. You should be able to test the flow of your chiller pretty easily by taking out the return line and put it into a bucket then turn it on. If your water is flowing then the circulation is working. You may also feel the water coming out to see how warm it is. that might tell you if the chiller coolant is OK.

[John Stephens]

Thank you all for your thoughtful comments and suggestions.

I will try them this weekend and let you know the results.

Thanks again,

John

[Bruce Volden]

One more thing that occured to me---can you monitor the power supply voltage that feeds the tube?? Perhaps heat is an issue here also, dropping the power / volts after usage?? I know I had this type of problem years ago when the power supply was not holding at 30VDC (my system).

Bruce