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| [Recommendations]How much power do I need to laser cut copper |
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| LaserSteve:
One, you could just send it out to the local laser job shop. Two, Your looking at Q-Switched YAG or a Q-switched Fiber Laser. Co2 can be used to cut copper, but the power required is immense. Copper is cut by ablation or sublimation cutting. The goal is to focus just above the copper and start a micro plasma. Assist gas is needed to clear the kerf left by the laser. Pulsed Green light from a frequency doubled laser excels at cutting thin copper, silver, and gold films. In fact LCD plants, ceramic module makers, wafer repair, and resistor trimmers used to use the pulsed green light from a Xenon Ion laser before doubled YAG became popular. I used to work on industrial and scientific pulsed YAG lasers at rep rates from 0.5 HZ to tens of Kilohertz, with pulse widths from macro to picosecond. Those drove a variety of wavelength conversion means, so I've worked from 230 in the UV to 15 microns in the far IR. I've also used a fair amount of Co2 systems to a Kilowatt. My personal record is 52 Joules 1064 and 32 Joules green in a single pulse, unless you want to count servicing 129 flashlamp power supplies for a Terrawatt system. I've been at this laser game for 20+ years. Pulsed UV is difficult to generate. The 355 nm CW UV is even more difficult to generate, as its done using sum frequency mixing from 1064 and 532. If you buy a cheap UV YAG, You'll spend more time adjusting doubling and tripling crystals then you will cutting metal, unless you have a decent budget. Stay away from 266 nm lasers, trust me... They are awesome for what you want to do, but the operational cost is brutal. I doubt you could ever achieve a decent cut on thin metal using a diode laser array that is less one hundred to two hundred watts. The problem then becomes the spot size from the diode array's fiber, which will be huge. . At Co2 your looking at ~ 100-200 watts or more for a thin kerf in a few mills of copper. A 400 watt Firestar CO2 I played with could barely do a clean cut on a Coke can or thin stainless sheet. In fact we painted aluminum sheet with a thin layer of spray enamel just to get the cut started cleanly. (carbon based black engine paint) Yet a few tens of watts of average power from a 532 nM doubled yag went thru the coke can at any gantry speed desired. I have a 60 watt,7-10 nanosecond, 7 KHz Green system installed near here for perforating brass and stainless steel sheets for limited production runs of lithium batteries. It works so well that I get a free lunch every time I drive by that shop. They run it at 25-35 watts, typically. It also has really good up-collimation and spatial filtering optics followed by a lens that insures a tiny spot size. Ablation or sublimation cutting is dependent on peak power. You need a pulsed laser. Think of a pulsed laser more as a very fast discharging capacitor then a tiny cutting torch. Steve |
| Fungus:
--- Quote from: blueskull on February 10, 2016, 03:18:06 am ---It has to be mounted on a robotic arm, so bulky solutions (cylindrical lens+diode bar) are not preferred, unless packaged in a sturdy, neat package. --- End quote --- ...or fix the laser to the floor and have the robot hold the copper up to the beam. ( Wouldn't that be way cooler to watch than the other way around? :popcorn: ) --- Quote from: LaserSteve on February 10, 2016, 03:20:13 pm ---One, you could just send it out to the local laser job shop. --- End quote --- If it's not an ongoing thing then this option makes a lot of sense. Cutting highly conductive metals needs serious laser power (=expensive). |
| LaserSteve:
Of Course if your doing this industrially and have budget, SP, Coherent, and Ekspla have some nice green and UV solutions... Example: http://www.spectra-physics.com/applications/pcb-manufacturing#resources http://www.spectra-physics.com/documents/ShortPulseWidth.pdf Steve |
| LaserSteve:
I see your user flag indicates China.. If you build or rebuild it, yes... Given what Chinese DPSS laser parts sell for in America, probably yes, with some judicious Ebay/AliBaba searching. China has been producing lamp pumped ND:YAG as well as importing it since the 1970s... There are a couple of Chinese Ebay sellers that make new parts for common lamp pumped systems. I'l give you an example. 1000 meters from me, in a warehouse, are two 100 watt Lee Laser lamp pumped, Q-Switched lasers removed from service in working order. They even have the fiber couplers and original crates. My employer's surplus disposal office offered them to me for 1000$ for the pair.. I turned them down, for lack of storage space. Why? No one on campus wants reuse them, because of the three phase power and lack of hardware skills. That and the fact that each system, complete with chiller, weights 340 LBS/154 KG. On a campus of 24,000 people, right now, three of us have the skills to get them running without help and there are perhaps another 20 who could be trained. So the hardware is out there, but the trained people move on. When they do, the lasers are nearly always disposed of. Which is sad, because for an EE or EE student, such a laser is just an exotic oscillator that is very easy to repair and get going on a modest budget. I mean what EE hobbyist would pass up a 7 kilowatt arc lamp that runs submerged with bare terminals in deionized water? (Edit, Most people should, unless they have some safety training, these are not toys! :palm:) So my bet is that if you do some digging, a crusty old but repairable Lamp Pumped system is available near by, either a medical unit or industrial. If you buy a lamp pumped laser, open the pump cavity and make sure the gold plating is intact and not corroded. DPSS lasers tend to be disposed of when the pump diodes degrade, and often those are a custom item. I'll give you another example, I have a 800 mW, Q-Switched Green laser head on my desk that I paid 300$ for. It needs a 8 amp constant current power supply with NO voltage or current overshoot to run the pump diode. It needs two TE coolers held to within ~ 1.25' C, which is easy. It needs 4 watts of 80 Mhz RF to drive the Q-switch and probably produces 100-200 kW peak pulses at few kilohertz. or so. Its someone's prototype. Its milled from a monolithic aluminum block, and the design is very simple. I'm half way thru reverse engineering it. Other then some very good mechanical engineering, the design is trivial and published. Other then the fact that none of the supporting electronics was included, its working just fine on my bench. I'll see if I can post a picture of the insides by tomorrow, This is do-able if you have time to find the surplus parts. There is a hobbyist laser conference every year in the US, focused on laser shows. Every year I train 5-10 people at the conference to align laser oscillator mirrors. Most people get the technique within one to two hours. EE students/good technicians who understand simple rate equations and basic geometry usually can lean to adjust the laser to peak performance in another hour or two. Its not difficult. Figure 100-200$ for a good pair of safety goggles. You'll also need 100% beam containment. These are not toys, and the safety procedures is where much of the expense in lab use comes from. Steve |
| LaserSteve:
Oh, if your in the States, getting you a used ND:YAG laser is EASY! Steve |
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