Laser tubes

[Bob Davis]

Can anybody enlighten me as to why there appears to be such a large variation in the life expectancy of laser tubes?
I have a 25 watt Epilog that is over 10 years old (1998), has been solidly used and which still appears to give the same output as when I got it in 1999. I also have a 3 year old GCC 25 watt that is still using the same settings as when new. However, I often read on this forum of tubes only lasting a year or two (or less).
What factors affect tube life? Mine are often run at 100% power for hours on end with no apparent detriment. Is ambient temp a factor in longevity? - heat doesn't seem to be a large factor with mine as they have often been run continuously in temps of 35C+. Is it "clean" power? My GCC has lots of regulation but the Epilog has always been straight off the switch.

Does anybody know?

[Dan Hintz]

Bob,

I think you'll find that most of the tubes failing after a year or two are cheap glass tubes from Asia. The higher quality RF units do still fail from time to time, but that's usually due to a failed RF board (also often easily repaired by someone skilled with a soldering iron).

[Andy Wingfield]

Hi Bob,
Here is my non technical sales rep explanation and I will get further clarification from laser engineers.
From a technical standpoint, keeping a laser tube in constant use actually helps extent the life to some level. There are 2-types of excitation methods for the sealed tube CO2's. RF excited and DC excited.
[LEFT]
DC is very old, glass tube technology that does not have a life longer than about 700 hrs max. They are cheap but the quality is not very good typically, if you want to process at any fast rate of speed. The fill in the space lasers in the market now mostly use this type of laser, which is why the prices of the machines are so low.

RF excited tubes are the more recent (though it is at least 15 years on the market). These would be the Synrad, Coherent, ULS types. Much better quality, much more reliable and of course more expensive to manufacturer. Hene the machine price is higher also.

The input voltage is not really the issue as much as the efficiency of the power transfer (within the tube). Synrad was the developer of these "free space" types of sealed laser sources and hold many design patents. Coherent (and now also Synrad) makes a "wave guide" type which has optics within the tube for power amplification. There are different trains of though as to which is the best for marking and engraving. Both have their merits but generally speaking the beam quality is excellent.

All that being said, CO2 tubes are still subject to manufacturing standards. You can get one that will last for 5-years and the next one will last for 3-years. The wattage ranges can vary 20% even is both tubes were say 60watts. Little bit of a "black magic" involved.

I have also noticed that lower wattage tubes on average at least of the sealed RF sealed variety tend to last longer then higher wattages so a 240 watt.

Regards,

[Rodne Gold]

There was a time when Coherent had a QC problem , we went thru 6 coherent tubes in my Explorers over a 1 yr period. I have had better results with Synrads .....
We find the tubes themselves do not go , it is generally the RF boards that blow , Synrad will give you exact instructions how to repair em , costs pennies....Problem is not the repair , its the tuning of the Rf boards which requires equipment most of dont have ( fancy Oscilloscopes + stand alone controller)
Thing is these tubes are OUTRAGEOUSLY expensive for what they are.....a few mirrors , RF boards and a metal tube filled with gas.....

[Dave Johnson29]

Thing is these tubes are OUTRAGEOUSLY expensive for what they are.....a few mirrors , RF boards and a metal tube filled with gas.....


Hi Rodne,

What you are paying a lot for is the development costs of the tube. For instance, as Andy mentioned, Synrad hold many Patents and they do not come cheap, usually $20K is a start price for a Patent. Developing the tube to the point of readiness to Patent is many many thousands of hours of high dollar work.

It is true the cost of the materials inside the laser may not amount to much, but putting the parts in the right spot to make thing work efficiently requires some precise machining and engineering.

The "gas" is not just CO2. It is highly purified CO2 and a mixture of 3 or more other gases in small percentages. All have to be equally as pure as the CO2 and in very exact amounts for a specific task.

I have a Synrad tube built in 1992 and I have no idea of how many hours it has worked, but Synrad rate their tubes for 45,000 hours. That sort of technology does not come cheap. This 25W tube still tips the scale at 27W.

I also have an RF excited 50W CO2 glass tube that was built in 1996 or 1997 and is still going strong. It was built in the US, possibly by Coherent (I can't recall) and cost around $15K for the tube when new. I bought it surplus in about 1998. It was designed for medical use and can pulse incredibly fast and accurately (pulse duration). Again technology like that does not come cheap. The last time I measured it, this laser output 62W and it was about 10 years old at the time.

I am not trying to justify huge prices, but rather explain why lower cost ones last a shorter time than higher priced ones.

[Dan Hintz]

Dave,

I'm not sure I agree with you on every point. Patents do not start at $20k... in fact, the actual design patent fee is a mere $220 for companies ($110 for individuals), $100 for a search, and $140 for the examination. You may jack up the cost by having a patent reviewed by a patent lawyer, but that should be no more than a few grand if he's worth his salt. I would say $3-$4k is a more reasonable figure.

I'll agree with you on the R&D for max output and precision assembly work.

While the gases may be ultra-pure, their cost is ultra-cheap, too (all things considered). A few tanks of lab-quality gas will set them back a couple of grand, but they can fill hundreds of tubes with that.

As far as lifetimes go, the cheaper (Asian) glass tubes typically have significantly shorter lifetimes due to a lack of quality control. The tubes are rarely sealed properly, and once the gas mixture changes, the lasing action decreases quickly. US-made tubes have a higher level og quality control... if they didn't, you'd see them fail more often.

[Dave Johnson29]

I'm not sure I agree with you on every point. Patents do not start at $20k... in fact, the actual design patent fee is a mere $220 for companies ($110 for individuals), $100 for a search, and $140 for the examination. You may jack up the cost by having a patent reviewed by a patent lawyer, but that should be no more than a few grand if he's worth his salt. I would say $3-$4k is a more reasonable figure.


Hi Dan,

Yup, you may be correct if you do it yourself but with this kind of technology and the money-stakes involved I really cannot imagine Synrad would give the project to an office junior to do a Patent search. :)

I would bet good money and lots of it that Synrad used a Law Firm at the top of the field for US and International Patents. That's the $20K I was talking about. How do I know? Been there done that many times on a team lodging a Patent. Also I know of no Patent that was ever accepted the first time. The money mounts up like snow against a fence line.

Doing the search is not just finding others like it, it is imperative that you are significantly different to the Prior Art otherwise the Patent examiner will toss it out. That means when you do the search you have to review the contents of everything that turns up ands make sure your stuff is unique. Nope. I stick by my $20K and up and probably conservative at that.

Here's the degree of difficulty for just one of their Patents and there are many others they hold.

Assignee: Universal Laser Systems, Inc. (Scottsdale, AZ)
Appl. No.: 09/198,910
Filed: November 24, 1998

Current U.S. Class: 372/38.1
Current International Class: H01S 3/0975 (20060101); H01S 003/00 ()
Field of Search: 372/38
References Cited [Referenced By]
U.S. Patent Documents

2531103 November 1950 Beckwith
3593189 July 1971 Buhrer
3626330 December 1971 Zalonis
3729688 April 1973 Cerny
3790852 February 1974 Bolin
3965440 June 1976 Graves
4169251 September 1979 Laakmann
4363126 December 1982 Chenausky
4373202 February 1983 Laakmann
4383203 May 1983 Stanley
4451766 May 1984 Angle
4455658 June 1984 Sutter
4748634 May 1988 Hesterman
4809284 February 1989 Chenausky
4833681 May 1989 Akiyama
4837772 June 1989 Laakmann
4856010 August 1989 Wissman
4891819 January 1990 Sutter
4893353 January 1990 Iwaoka
5008894 April 1991 Laakmann
5135604 August 1992 Kumar
5150372 September 1992 Nourrcier
5475703 December 1995 Scalise
5479428 December 1995 Kuzumoto
5528613 June 1996 Macken
5549795 August 1996 Gregoire

[Andy Wingfield]

Hi Bob,
Here is a response I received from Orlan Hayes of Trotec in reference to C02 laser tubes.

Andy,

The price of technology will always be maintenance.

I have my theories but will call Synrad technical support 425.349.3500 for their determination..

Electronic failure of the RF driver or power supplies or the control circuits are the most common cause.

Basic variations in electrical components, variations in assembly along with the local environmental, electrical service and usage all are factors. The contributing factors to failure include heat, thermal shock, vibration and incoming electrical.

Generally the longest life occurs with any laser if they can be used 24/7 in a controlled environment.

[Andy Wingfield]

Hi Bob,

Here is some additional information from Gary Sheriff of SherTec.

Any of my Trotec customers on the forum know that Gary is my go to guy.

SherTec, Inc.
2621 Green River Road #105
Corona, CA 92882

Tel (909) 518-6000
Fax (909) 494-4463
Andy,
well designed and manufactured laser tube is difficult to achieve. A testament to that is the (generally speaking) small number of competitors in the low power, sealed laser tubes ranging from 10 watts to 200 watts. The gas in a CO2 laser tube is made up of many gases. The most abundant gas, believe it or not, is helium which is used mostly for heat transfer (cooling). Helium is very difficult to seal making the tube susceptible to temperature fluctuations. The gas can leak out because different materials (used to seal the tube) will expand and contract at different ratios. This is why it is important to put the laser system in a controlled temperature environment. In addition, it is probable that you will see a power loss if your ambient temperature is allowed to climb over 72 degrees. The power loss will increase and tube lifetime will decrease if running in temperatures over 100 degrees. That is why you should consider water cooling if you are running in a “hot” environment.

With that said, most of the time when a tube fails, it is usually electronic in nature such as drivers, amplifiers, etc. Incoming power from the wall should be clean. One, cheap and easy method is using a surge arrestor such as found at a typical hardware or electronic store. Make sure the clipping voltage is low. If there is lighting outside, electricity is more susceptible to energy spikes and you want those spikes to be clipped. This is true for any electronic such as a TV.

The tube generally has a lifetime of 3-5 years, whether it is in use or not. Consider yourself lucky if you get over 5 years, which I found is not unusual.


Regards,

Andy Wingfield
913-486-6341
wanlaser

[Richard Rumancik]

Just a comment regarding the ">45,000 hours" for Synrad tubes - although I think the Synrad tubes are good products and I respect the company, this number is from marketing, not engineering. Synrad does not guarantee anything near this; they are basically reporting that "some customers" have claimed that kind of lifetime. You can be sure if the sample is large (100,000 lasers) you will get some that seem to run forever, but it might not be anywhere near the norm or median lifetime.

I don't see anything in the Synrad manuals indication MTBF (mean time between failure) or anything like that. Also, I couldn't figure out why they only give a 1 year warranty if the laser is good for 45,000 hours (1 year is 8000 hours if ran 24/7, which is very unlikely for laser engravers). So even though the products are good, don't read too much into that number.

[Andy Wingfield]

Hi Bob,
I wanted to make sure that if you were considering a new Trotec Speedy 300, that is was clear that the Synrad tube is covered 100% for three years for wattages up to 50 watts and two years from 60-120 watts. this pertains to the US

In regards to a new Speedy 100A the Synrad tube is covered for two years on all available wattages on the 100A. This pertains to the US.
Here is some information I received from Iyvind Hansen.
There is no simple answer to your question - but I will try to briefly answer.

There are 3 primary components to a laser (really 2, with one broken down into two sub components): The electronics, the tube/resonator and the optics.

The tube contains the CO2 gas mix (several other gasses in the mix). The exact gas mix is the critical part of "gas life". As the mix changes, the performance changes. The key to Synrad's long gas life is our manufacturing process and tube design. The seals are designed and tested to have incredibly low leak rates. We have developed (over 3 decades of experience) manufacturing processes that prevent gas contamination. There are several proprietary methods used that make this happen.

The optics and electronics are obviously going to be effected by external factors such as heat, dirt and moisture. It is always hard to say just how significant any factor is until it has damaged things. Running in 35C+ ambient is fine - but you may decrease the life vs.. running at 20C (but you have not had a failure).

The bottom line is that a quality laser will typically run for years in a system, but even the best of lasers can be damaged quickly with a electrical surge, corrosion or contamination of optics.

[Richard Rumancik]

I should have mentioned that a laser manufacturer that is buying Synrad tubes can extend the Synrad warranty beyond the Synrad warranty period to anything they want. But if Synrad is confident in their products I still don't understand why an off-the-shelf tube only has a one year warranty.

The laser system manufacturers are probably not taking a huge risk as they know laser systems might see only 2000 hours a year on it if operated 8 hours/day 250 days/year. Many systems much less, especially in the first year. I understand that there is some loss of lifetime whether the tube is operational or not, but I don't think Synrad should be reporting anomalies of performance and leaving the impression that this is the norm:

"Synrad lasers have operated in excess of 45,000 hours and are still going strong." (Synrad website)

Synrad may unfairly take the hit if someone does not have proper surge suppressors etc on the input. If they are lucky, the power supply will smoke before the laser tube takes the spike. But power supplies are rather expensive as well. I would not recommend that users operate a laser without at least a minimal amount of surge suppression. You can get a 3000 joule surge suppressor for $50. If you have a bit more to spend there are better options; contact your power company or an electrician.

[Ed Mihalack]

I think you'll find that most of the tubes failing after a year or two are cheap glass tubes from Asia. The higher quality RF units do still fail from time to time, but that's usually due to a failed RF board (also often easily repaired by someone skilled with a soldering iron).


Dan,
My Universal VersaLaser stopped firing abruptly. This after it started striping rather abruptly 4 days ago. Thank you for responding to that post. I am skilled with a soldering iron (retired shop teacher) Universal Tech Support doesn't open till Monday. Any way I can check the RF board while I am waiting.
Ed

[AL Ursich]

Excellent Discussion....

I worked at the Sony Picture Tube plant in San Diego for 4 years starting in 95. It is now a dusty parking lot....

It took about 12 hours to make a CRT on the 17 inch Monitor line that I worked on. CRT's came at me at about 240 an hour and I got them just after they were evacuated and sealed. I did Electron Gun Baking, Fired off a Getter Flash inside to improve the vacuum, had a robot paint on the carbon, added the metal band to the front of the CRT area and added the base cap.

Lots of critical things that in my opinion had a longevity impact on the CRT. We did things by the book but lots could go wrong and you wouldn't know for 2 years....

SO I imagine the feat of producing a Laser Tube and all the sealing requirements leave open the door for slight variations on things that could effect the longevity of the Tube.

I have seen many posts between the forums I visit around the RF and Power Supply part of the Laser being a problem.

I also spent 4 years at a Sony Service Center in Philly fixing everything from Phones, DVD, and Play Stations. Saw many component failures and learned to watch trends. Lightning Damage was a common phone problem.

SO it comes down to a little LUCK getting a good tube with great longevity, then it's our part to keep the power clean and a stable temperature. The little power cubes that help prevent a power surge activate and self destruct to shunt the surge to ground. So they are a one time deal..... Some have lights on them telling you they are still good.

Good Luck,

AL:D

[Scott Shepherd]

I went to an advanced training class that ULS put on several months ago and part of the class explained how the tubes were made and how they worked and also, their life span, failure rates, etc.

The biggest problem that was mentioned was that the molecules of the gasses that are in the tube that get excited by powering it on are floating in there as used. However, when they are allowed to sit, the molecules tend to fall to the bottom, and if memory serves me correctly, they may actually stick together (I could be wrong on that). If they don't stick together, then it's just that they don't get excited enough to bring them into action. So next time it's powered on, they don't excite at the same rate/level they did before. I gathered that one of the worst things you can do is to not use your laser fairly regularly.

I have the graph in my paper work from the class somewhere around here that shows the average lifespan. It shows 4-6 years, but it also showed the failure method, for lack of a better word, but at the failure point, it doesn't slowly die, it just loses power almost to nothing. So it's not a long, slow, gradual lessening of the power, but rather a "It worked fine today, it doesn't work tomorrow" type of failure, as an average.