Talk:Laser cutting

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The article 'does not cite any references or sources'. For 'fastest class of machine', where? Fabricator article/survey? The section on pulsing isn't very satisfying yet. Jmaechtlen 01:39, 11 November 2007 (UTC)[reply]

Hi - I have written a couple of books on laser cutting which you may find useful;

1. The LIA guide to laser cutting (2nd edition)- published by the Laser institute of America. The 2nd edition (which is an expaded, improved version of the 1st) should be available in march/april 2008.

2. CO2 Laser Cutting - published by springer verlag - now out of print - but i can supply a CD of a scanned version of it. This book is considerably longer (248 pages) and more detailed than the LIA guide. If you are interested just email me; jpowell@laserexp.co.uk

Dr. John Powell —Preceding unsigned comment added by 81.178.40.38 (talk) 17:04, 6 February 2008 (UTC)[reply]

Where is reference #1 from? Mendoza.755 (talk) 03:43, 15 April 2019 (UTC)[reply]

I have a few edits for this article, nothing major just a couple extensions regarding assist gases and so on. I am, however a newbie here so before I change anything, any objections or concerns from more seasoned folks? Protolam 21:22, 7 July 2006 (UTC)[reply]

I have a dissagreement with the statement "There is also a reduced chance of warping the material that is being cut as laser systems have a small heat affected zone."

a laser effectivly cuts by superheating and therefore melting/vaporising its target, whereas more traditional cutting methods use abrasives which may cause localised heating but this is a side-effect of the cutting process rarther then beign the cutting process, as is the case with lasers. Also in mechanical cutting the cutting head conducts a significant amount of the heat generated by the cutting process. drills & saws can be designed to dissapate heat, while laser cutters clearly cant.

from my experience as an engineer i feel that perhaps the biggest dissadvantage of the laser is the heat issue and i would suggest this be a candidate for ammendment to the article.

I would welcome other peoples suggestions on this matter. —The preceding unsigned comment was added by 193.63.48.253 (talk) 12:07, 10 March 2007 (UTC).[reply]

I've never handled a warped piece from a laser cut, nor heard anyone in a laser shop whine about the laser's HAZ. Are you a manufacturing engineer with specific, hands-on experience programming or designing a process that would cause you to evaluate it in such a way? - Toastydeath 19:10, 10 March 2007 (UTC)[reply]

Actually, When I was with Amada, we went through some hoops with and for an aerospace customer so they could buy our 5 axis machine (Prima's Optimo, which Amada sold for a few years). For aircraft parts, they were really obsessed with HAZ and recast layer. I don't know if this is still as big an issue for them. Maybe it isn't as important as they thought it was. Cheers Jmaechtlen 05:19, 11 November 2007 (UTC)[reply]

Hi - If we are looking at Carbon dioxide laser cutting of metals the temperatures reached by the melt are way below the boiling point - in fact boiling is a trivial contributor to the material removal process (if the laser boiled the metal the process would be very slow) - what we have got is a situation where the the laser melts the metal and we blow a high pressure gas jet (generally nitrogen) onto the melt to remove it from the cut zone. This melt removal process also transports the vast majority of the heat out of the cut zone (the laser heat stays in the ejected melt) - only a small amount of heat is conducted sideways into the workpiece - which is why, for example, you can often pick up a laser cut part directly after it has been cut. The amount of heat absorbed by the part increases if any of the following increase; 1. Material conductivity (so copper cut parts get hotter than steel ones) 2. Material thickness (the laser has to travel slower and this gives more time for heat to escape from the cut zone) 4 the amount of detail being cut (all those changes of direction slow the laser down and cutting repeatedly in the same area means the laser is in that area is exposed to the laser beam for longer). In general though, it is true that heat affected zones for laser cut parts are small (approx 25% of the material thickness) and that thermal distortion is rarely a problem. ---- —Preceding unsigned comment added by Dr. john powell (talk • contribs) and edited by 86.139.66.115 (talk) The thicker material also has a broader section to transmit heat across the material blank/part.

Jmaechtlen 05:28, 11 November 2007 (UTC)[reply]

Just to throw my two of some currency in here - I've never seen anything permantly warp from laser cutting, What it comes down to is - yes the item gets hot - but never hot enough to permanently warp the item to any great degree. Thick items do get fairly warm - but only to the point where it's around the point of too hot to handle. The issues come not in permanent damage but heat expansion. Basically when you start with a cold sheet, then start cutting, after a period of time the whole sheet expands so now your sheet is bigger due to heat expansion - now anything new you cut is going to be smaller by the time it cools down. That being said because you've now cut pieces out you get a bit of a heatsink effect whereby your sheet of metal allows air too pass over a larger surface area and cool down quicker. It's all things you have to think about when you operate such a machine, and if it's a serious problem it's easy to add a pause between cutting each item - or if your machine bed is large enough like with many CO2 lasers it's also plausable to have multiple sheets and stagger cutting between each one. Now where I have seen permanent warrping is in laser marking this is because you're often permanently changing the properties on one side of the item. This is very common if you laser mark very thin metals, again it's something the operator needs to (will) know. --Streaky (talk) 19:50, 23 June 2008 (UTC)[reply]

that may be the beginnings of a new article. —Preceding unsigned comment added by Jmaechtlen (talk • contribs)

We have 3500Watt Cincinnati CO2 Laser. We cut Stainless exclusively. The heat distortion is non exsitance with laser compare to abbrasive disk cut. Reason is, beam moves 600 inches per minutes on 18 ga, and always use "assist gas" to blow away the kirf ( 0.007" wide) so it cools down before transfer heat to other area. When compressed air or gas blow out from nozzle, it cools it self by nature. —Preceding unsigned comment added by 24.83.160.233 (talk) 21:14, 11 September 2009 (UTC)[reply]

Can laser cutting be employed for sharpening Bisalloy wood-chipping teeth, Brinell hardness around 300? Would the amount of heat generated affect the cutting edge? Rumiton (talk) 15:28, 6 August 2008 (UTC)[reply]

I tweaked the machine descriptions, and beam delivery stuff. I ripped out the mention of 'pivot beam' for now. I'm not opposed to mentioning it, we just need to do it a bit differently. As I understand it, pivot beam is one mfg's way to keep a constant beam path length. Is that correct? We should draw a distinction between the changing distance/location of the cutting head, and the issue of compensating for any change in beam path length. The pivot beam keeps a constant path length, avoiding the need for active optics and simplifying collimation. Right?—Preceding unsigned comment added by Jmaechtlen (talk • contribs)

Looks like the text of this section is ripped wholesale from this whitepaper: http://www.spilasers.com/whitepapers/laser-systems/ How should attribution be handled here? Paulw1128 (talk) 20:08, 13 October 2016 (UTC)[reply]

not physics—Preceding unsigned comment added by Jmaechtlen (talk • contribs)

Agree, I changed it. Wizard191 (talk) 00:28, 10 February 2009 (UTC)[reply]

The following sequence of sentences confuses me.

"The neodymium (Nd) and neodymium yttrium-aluminum-garnet (Nd-YAG) lasers are identical in style and differ only in application. Nd is used for boring and where high energy but low repetition are required. the Nd-YAG laser is used where very high power is needed and for boring and engraving."

I cannot grasp the similarities and differences from this. What I come up with is that while both are used for boring, Nd-Yag is used for engraving and repeatability. I do not understand the difference between the high power and the high energy. Further, if you are going to say that they differ only in application, you should not follow up by listing the same application for both. It is confusing to a novice reader. —Preceding unsigned comment added by 12.2.81.84 (talk) 18:17, 5 February 2009 (UTC)[reply]

Hi .. That sentence baffles me too .. and i have written two books on the subject.

Nd ions do undergo a lasing reaction if you shine a lot of light at them - ie if you expose Nd ions to lots of disorganised light the Nd ions will repackage a some of that light into an organised beam (one wavelength, one direction) of laser light. However - to expose the Nd ions to lots of light you need to hold them inside a rod of a very clear material like glass. Thats where the YAG (Yttrium-Aluminium-Garnet) comes in - YAG is basically a very clear glass. To make an Nd:YAG laser you get molten YAG and sprinkle some Nd into it then let it set in a rod shaped mould. You then machine/polish the rod so light can get to the Nd ions - and put the rod inside a mirrored box with a bright light source (eg a flash lamp). When the bright light source illuminates the rod, the neodynium grabs some of that light and transforms it into a laser beam.

So - as far as i know, there are no pure Nd lasers - but there are Nd:YAG lasers. So i think all the applications mentioned refer to Nd:YAG lasers.

Cheers Dr. John Powell

I'm missing fiber laser cutting as a separate entry. This technology has been developed by IPG. —Preceding unsigned comment added by 84.197.236.198 (talk) 23:19, 9 February 2009 (UTC)[reply]

Are the power needed for stainless steel figures correct? They appear to go down with increasing thickness. I would have expected the power needed to increase with thickness. (The source data may have changed units.) Andrew Swallow (talk) 21:00, 23 April 2009 (UTC)[reply]

I took a look at the source and it lists the same info. It does seem dubious so it ought to be cross-referenced. Wizard191 (talk) 22:22, 23 April 2009 (UTC)[reply]

I am assuming that as the thickness increases the feed rate has to decrease, however power also needs ot be reduced because of thermal effects? 86.157.52.239 (talk) 08:30, 7 April 2014 (UTC)[reply]

Todd's book is a survey of processes, and not definitive for laser cutting by any means, It just provides a brief overview. And it is old. Anyway- the feedrates for Stainless were probably for a limited power system, maybe even a YAG. It also doesn't mention feedrate- those were probably very slow feedrates. In thicker materials you had to pulse, where the average power went way down. Modern CO2 machines will use lots of power and really tear through it. Of course, modern YAG machines have improved as well.

A lot of the stuff on feedrates and power were too general and only partially true. Still needs work. I don't think Todd is a good source of real application power and feedrate info.

more later. Jay —Preceding unsigned comment added by Jmaechtlen (talk • contribs) 18:34, 18 December 2009 (UTC)[reply]

You are quite right about Todd not being a very good source. Any sources or other help you can provide is much appreciated. Wizard191 (talk) 19:33, 18 December 2009 (UTC)[reply]

Please would someone knowledgeable add some information on what happens to the beam after it passes through the material ? How is the excess energy dissipated, or what happens to it ? Darkman101 (talk) 16:01, 12 June 2016 (UTC)[reply]

Consider the simplest case, that of a now fairly commonplace CO2 creative cutting laser. These route a "beam" around inside the machine, but the actual cutting is done by a focused spot, not a parallel beam. After the last mirror points the beam downwards, it passes through a plano-convex lens with a focal length of 2" (sometimes 4"). This means that 2" below the lens, on the surface of the workpiece material, the beam is focussed down to the smallest possible spot (it's not a terribly small spot, the optics are relatively simple). At this point, the laser cuts. There is a small volume of space, an hourglass a few mm high, where the intensity of the focussed beam is enough to cut with precision. Above this volume (i.e. the laser is out of focus) the beam spot will mark the material with an engraved mark, but it won't effectively cut it - this is sometimes done deliberately when engraved to mark a wider line.

Below this optimum focus, the focussed beam spreads out again. 2" below the focus it's back to an intensity less than the original beam. As it has also passed through a cloud of smoke, if it passed right through the material at all, then it's also attenuated. A few inches lower down and the beam is distributed over quite a large area, so its intensity is much reduced.

Immediately below the focus point, the workpiece supports in this laser are made of laser-proof metal - steel and aluminium honeycomb. They are simply unaffected by a paltry couple of hundred watts of CO2 light at 10.6μm. The 'crumb tray' below a laser is often full of cut chads of wood or card. When these are heated (not cut) by the out of focus beam, then they can easily be heated to their ignition temperature. It is very common for a fire to start unnoticed in uncleared chads below the laser bed. Andy Dingley (talk) 18:08, 12 June 2016 (UTC)[reply]

I have made some custom laser-cut work such as tactile 3D map for blind children from OpenStreetMap data. Would it be welcomed to add them to this article?

Can I add them straightaway? Asking as it is kind of COI - I got grant for this project and the justification for funding was that it would promote OpenStreetMap ( https://wiki.openstreetmap.org/wiki/Microgrants/Microgrants_2020/Proposal/Tactile_maps_for_blind_or_visually_impaired_children ).

I also made some custom maps as gifts (also matching "is now used by schools, small businesses, and hobbyists") and right now images are only matching industrial application, with quite wide use in hackerspaces not represented

I am planning to make a better images, but https://github.com/matkoniecz/lunar_assembler#laser-cut-3d-tactile-map is showing what kind of thing I want to use as an illustration.

Mateusz Konieczny (talk) 14:18, 28 May 2021 (UTC)[reply]