Quick Tip / Reduce Power Use & Prolong Tube Life

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Spooky
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Quick Tip / Reduce Power Use & Prolong Tube Life

Post by Spooky »

Just a quick one,

Ever noticed that ramping up power and speed doesn't always get results??

Have a look at the numbers:

20 Speed
50 Power

40 Speed
100 Power

10 Speed
25 Power

In theory they should within material limitations all work the same, if you double the speed you should double the power.
Not so, the inverse square law applies for more than just one reason. Without bothering with the physics what often does happen at the "hot end" is carburisation, As the beam vapourises the wood (or acrylic) carbon is formed (due to the nature of laser radiation that carbon is very pure) sadly that nice black mess in the bottom of the cut prevents beam penetration from going right through. The same thing can apply when you run a cut twice (most often it notices in wood) as not only is the laser trying to *burn* the substrate (the material) it's also having to cope with a layer of carbon.

Often this will result in sub standard cuts or no penetration on the sheet.

Solution:

Lower your speed AND lower the power. If your getting problems running at say 20 speed and 100 power try dropping to 15 speed and around 65 power. As a rule of thumb reductions of 25% of your speed *can* allow a reduction in power of 40%.
This will allow the beam to cut substrate in it's virgin form without having to cope with a layer of carbon.

Materials do vary of course but in general running at 100% power all the time is going to heat up your coolant, reduce tube life, cost more in electricity and produce more smoke / fumes.

If your somebody that likes to run flat out all the time then remember double the speed requires FOUR times the power!! (and deep pockets to keep you in new tubes)

best wishes

Dave
Please note I am not employed by HPC, any advice or recomendations I give are based on my own experience and are not necessarily the same as HPC's. First point of contact on any hardware issues should be with HPC
Dave@OpticalPower.co.uk
Mike
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Re: Quick Tip / Reduce Power Use & Prolong Tube Life

Post by Mike »

This is good advice Dave, Thanks

The hard part though on a commercial side is time costs money, so if I can engrave 5 panels in an hour as apposed to 2 panels in an hour that’s better for me in the short term and allot less stressful! But then having a laser tube needing replaced is allot more stressful.

I am mostly engraving control panels, so the other the figure I play with to improve time is the scan gap, the bigger the scan gap the less defined the engraving but the quicker it is, finding the median over quality and time is the key for me.

Mike
Spooky
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Re: Quick Tip / Reduce Power Use & Prolong Tube Life

Post by Spooky »

I hear you there Mike,
I'm going to be looking at the same thing after Christmas as I have a LOT of actual cutting work to do and have to stay within resonable lead times :( It's worse with the bigger machine I'm buying as RF tubes cost £1500 to £3000 to get refilled when they go down, a second tube for a quick swap out isn't really very practical at £7000+ each either :(

Getting that finite balance is hard but the savings available if we do are well worth looking for.

At the minute I tend to opt for 85% power max and keep a spare tube in stock.

best wishes

Dave
Please note I am not employed by HPC, any advice or recomendations I give are based on my own experience and are not necessarily the same as HPC's. First point of contact on any hardware issues should be with HPC
Dave@OpticalPower.co.uk
SimonMallas
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Re: Quick Tip / Reduce Power Use & Prolong Tube Life

Post by SimonMallas »

Hi Dave,
Ya it all sounds really good, less power less speed and longer tube life. However in practice it doesn't make any noticable differance. I can't really explain the how's and why's ( sure a good google may turn up a fancy explanation ), I only go on experiance out in the field, feedback from customers and who's ordering tubes and when. Maybe the tube manufacturers are starting to use some of the some exotic co2 repairing gases used in the RF's. All I know is they are constainly surprising me with there life span!!
Cheers Simon
Spooky
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Re: Quick Tip / Reduce Power Use & Prolong Tube Life

Post by Spooky »

I tend to agree Si, it's a juggle between working faster for a shorter time or slower for a longer time.
Electrode errosion, gas permiation,gas contamination,gas leakage,voltage fluctuation....so many things that can kill a tube (or cause it to wear out) that I guess it's flip a coin to decide wether its better to run at 90% for a year or 75% for 2 years. If a tube is going to die through gas permiation after a year then running it at the high end for that year is going to be better but if it's electrode errosion then running it at a lower power is going to be more efficient.

I guess it all comes down to what the needs of the end user are, if they need to save the cost of new tubes then low power, if tubes are considered disposable after XX time then run it flat out.

best wishes

Dave
Please note I am not employed by HPC, any advice or recomendations I give are based on my own experience and are not necessarily the same as HPC's. First point of contact on any hardware issues should be with HPC
Dave@OpticalPower.co.uk
SimonMallas
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Re: Quick Tip / Reduce Power Use & Prolong Tube Life

Post by SimonMallas »

Hi Dave,
Think we'll have to agree to disagree on this one, as changing the power by 15% isnt going to double the life of a tube, even dropping it by 45% isnt going to show much in prolonged life. As for electrode errosion, gas permiation, gas contamination, gas leakage these arent an issue at all ( unless you ve got a flow gas laser that is) The electode on a sealed glass laser will far out last the life expectancy of the gas.Its 6 of one, half a dozen of another on this topic. So on reflection the savings arent that significant.
Cheers Simon
PhillyDee
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Re: Quick Tip / Reduce Power Use & Prolong Tube Life

Post by PhillyDee »

Of course, the tube is not the only variable here. The PSU is also a factor in tubes, whether or not its a fluctuating voltages outside the tolerances of the tube etc.
http://www.tmbelectronics.com - Electronics, tools, hobby tools, power tools, and much more!

An ex LS3020 user now playing with an LS6840PRO (60W) and an LS1290PRO (80W)
SimonMallas
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Re: Quick Tip / Reduce Power Use & Prolong Tube Life

Post by SimonMallas »

Morning Phil,
I would be interested to know where your getting your info? Over the years we have pretty much tested everything on the machines to destruction : ) adding the fact that we have so many machines out there and for so long. Sorry ranting! PSU are not an issue, there very reliable and dont cause use any problems. Theres a 20 to 30% chance of take them out if you blow your tube through freezing or the bubble of death, but other than that there good. I am talking from a HPC pospective, can't vouch for all PSU's
Cheers Simon
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