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Looking for advice from someone familiar with the real-life effect that Plasma Cutters have on the hardness/temper of steel.Here's the situation: 1) I have a small business that sells digging tools like the Grub Hoe, Grape Hoe, Mattock, and others. See at http://www.easydigging.com/2) I keep getting getting requests for custom variations of the tools, which I would REALLY like to be able to supply. Things like trimming a 6" hoe down to 3", or cutting triangular teeth in the edge.3) I have a friend with a plasma cutter who uses it for artwork and sculptures. He is willing to cut any shape I can sketch on my stock tools.4) I know from my supplier that the tools are forged SAE1045 steel and that the cutting edge is tempered to stay sharp.But the BIG question is -- Will the heat from the plasma cutter noticeably alter the temper of the cutting edge?Any experiences or advice is welcome. Thanks guys!
Reply:Originally Posted by Greg BakaBut the BIG question is -- Will the heat from the plasma cutter noticeably alter the temper of the cutting edge?Any experiences or advice is welcome. Thanks guys!
Reply:If every single one of those tools is tempered steel then as soon as there is significant wear or sharpening then the tempered portion is removed anyway, at least the leading edge. If any are cast then those are a different story. Inform them of the results and proceed as per their instructions. I'd think re-tempering would add layers of cost that most users of hand tools aren't gonna want to shell out for.
Reply:I have cut, trimmed, modified various digging tools for years, it's generally not a problem. Either with a cutting torch or with a plasma cutter, properly operated (don't get the material super hot).Most shovels and hoes are thin enough, you can cut fast enough, the heat affected area is very small. Say you cut something down to 3", you might wear fast to 2 15/16", then wear will revert to normal for that tool and material.Best thing to do, is experiment ... pick a customer, modify a few tools for him, stay in touch with him, see how things are working out.Then, report back here, so we can all find out, real-world experience.
Reply:One of the big benefits of plasma is the small zone that is heat effected. As said, in that small zone you may notice some additional wear, loss of sharp corners etc, but the rest should stay normal..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Its actually an interesting question.....with different answers depending on the content of the steel. If it truly is a heat tempered steel.....then the plasma will have a minimal effect on it as long as you let it cool naturally....do not immerse it in water or cool it with an air gun after cutting. In fact, with air plasma, you will have a case hardened nitrided edge (about .005" deep) that will be harder than the original steel.There are some grades of steel that will harden from the heat effect of plasma cutting.... but only in a limited area where the heat is above a certain temp......there are some grades of steel (hardox is one) where the material will soften near the plasma cut edge. You almost need the advise of a metalurgist.Jim
Reply:one thing that would be fairly certain though:alteration of the tools would void any warranty from the manufacturer so if there is a problem with the tool and it has been altered, it is all on you. About the only way to limit your liability would be to include notification that the alterations void the manufacturers warranty and unless you want to impose your own warranty, there will be no warranty on the tool.
Reply:Greg, Jim's probably the most knowledgeable person here on plasma cutters ( since he works for Hypertherm ). Your probably not going to get anyone else who can better answer your question..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Unless a customer is digging rocky ground, I think the effect on the edge will be minimal. MikeOl' Stonebreaker "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Thank you everybody for sharing your knowledge!It sounds like it is worth a try. Here's what I was thinking as a first stab at it:1) cut one right to the final shape2) cut a second one so the cut at the tempered edge is a little above the line, then grind back to the final line.3) come up with some way to evaluate the hardness (hopefully)Anybody know a way to determine if a steel is hard or soft? Seems like I remember something about trying to see if a certain type of file will cut it or not....I'll report back as soon as I get to try it
Reply:The edges I have cut on heavy equipment farm blades & construction equipment actually seemed to be harder than original because of the fast high heat of the plasma doing what use to be called flame hardening such as saw blades. But since the cuts occur so fast as Jim said the harden edge is not that deep only 5 thousandths of and inch! In the case of dozer backhoe or certain cutting tools that work against stone that case hardness will not last long. I flame harden the edge on my Ford New Holland Extend A Hoe Backhoe rock buckets (despite them being forge hardened) because I do alot of digging in heavy laden rock fields or home foundations.Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.& 2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:There is a trick in regards to the color of the sparks that come off a grinding wheel....an old machinist told me that once.....but I'm not sure if I actually believed him....I was wet behind the ears in my early 20's!Jim
Reply:Jim there is a method to testing the metal with a grinder as well as several other methods out there. A company called Goodwin Research & Development has a paper called Metallurgy Made Simple that does an excellent job of explaining and showing visually.Goodwin's Internet site is http://goodwinrandd.com/CD%20Series%...20Ready%20.pdfThe above http will bring you right to their pdf document.The grinding method is very hard to explain without visuals. Its one of those you learn by seeing and the site is the next best thing to actually looking over the shoulder of an old timer performing the test.Hope that helps,Tom aka old timer(wow I really am dating my age here)Co-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.& 2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:I think your over thinking things, I have plenty of garden tools that I know are not hardened and they work just fine. It has been established that the HAZ will be minimal, so most of the surface will find good as new, the others might be slightly less off but still....Have we all gone mad?
Reply:If you are really worried about it find a waterjet to do it, or send me one and I'll throw it on the waterjet and there wont be a HAZ to worry about.If you cannot convince them, confuse them. Harry S Truman
Reply:Had to brush up on "flame hardening". This would be fine for your purposes. Just heat the edge up (like red-hot) then dunk it. Spraying may get similar results. The quenching will induce hardness, and brittleness. Immediate re-heating to a lesser temperature (maybe 800 degrees) will temper the steel which will reduce internal stress and drawback some of the hardness and give the steel more toughness. But the tempering process can take more time than hardening. Soaking the edge in 800 degree heat for up to half an hour will relax the stresses, creating a tougher edge. Metallurgy, whodathunkit? http://www.metalsuppliersonline.com/...metals/845.asphttp://www.technologystudent.com/equip1/heat1.htmCity of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:good sites tangleCo-Own CNC shop:Miller :1251 plasma cutter, MaxStar 700 TIG/Stick, & XMT 456 Multiprocess Welder.& 2 Hypertherm HPR260's Plasma CutterSorry I had a bad stroke but now I am back.
Reply:http://www.gordonengland.co.uk/hardness/rockwell.htmSteel hardness test method.
Reply:A someone that works with steel and heat treatment all the time in knife making I may be able to shed some light on the topic.Will plasma ruin the heat treat? YESWill it do so much damage that you cannot do what you want? NOANYTHING that gets the steel hotter than the temper temperature will draw out the temper and soften the steel. In your case this heated area would be small initially but after cutting the heat would spread into the rest of the metal, drawing that temper out as well.If I were the one wanting to do this I would proceed as follows:Draw your design on the tool. Cut it as quickly as possible and then put part in water or oil to stop the spread of the heat into the tool. Now you have a tool with a small area damaged by heat. If you resharpen the tool (keep it cool by going slow and dipping in coolant often) you will grind off the damaged area and your tool will be good to go.Is there a way to test if it is hardened already? YESYou can try to file the cutting edge, if the file skates off without biting, it is hardened. Unfortunately this works only if the steel was hardened harder than the file (not likely on garden tools).You can check hardness with a grinder also. Get a piece of mild steel (angle iron or flat bar will work) and put it to the grinder and observe the sparks that fly away. Then test your tool. If the steel is hard it will put out a LOT more tiny sparks that die fast and do not fly far from the grinder like the soft steel ones will.
Reply:Every garden tool I've encountered was just made out of some sort of mild to low carbon steel. Nothing exotic or hard because hardness also generally means brittleness in steels, garden tools generally need to be tougher, not hard. I doubt it's any exotic steel or heat treatment process because it would make the garden tool more expensive then it needs to be. Before cutting it, you can do a hardness test. The grinder spark test is a good way to determine carbon content and therefore hardness, a large shower of sparks indicates high carbon, a small amount low carbon. Also a file, if it bites into it it is mild steel and a plasma will do little to soften it as mild steel doesn't take to heat treatment all that well so most manufacturers don't bother heat treating mild steel.Last edited by Fundido; 12-30-2009 at 11:35 AM.
Reply:All the garden tools that I have modified, I just cut them in my bandsaw so I figure that must be regular mild steel or very very close.Miller DVI2Lincoln Precision Tig 225Thermodynamics Cutmaster 38Everything else needed.
Reply:Originally Posted by Greg Baka.................4) I know from my supplier that the tools are forged SAE1045 steel and that the cutting edge is tempered to stay sharp.But the BIG question is -- Will the heat from the plasma cutter noticeably alter the temper of the cutting edge?Any experiences or advice is welcome. Thanks guys!
Reply:As I said many posts ago....it is not the heat induced into the material from the plasma that causes most of the hardness, rather, it is the chemical effect from an air plasma....air is roughly 20% oxygen, and 80% nitrogen.....the nitrogen content creates a nitride finish...or a case hardening on the edge of mild steel that is about .005" thick. I would guess that this is a good thing for garden tools. This hardened edge from air plasma can be a bad thing...if you are trying to drill or machine the edge...as it is extremely hard.If you use an oxygen plasma....there is no nitriding of the edge....just a very small (maybe .005") haz (heat affected zone)......which on mild steel can cause minimal hardening of the edge, and on some tempered and high carbon steel can actually cause a softening of the edge.Not all plasmas effect the edge in the same way. Plasma typically has a very small heat affected zone.I doubt that plasma would have any noticeable effect on the edge of any garden tool. Modify the tools as desired.......should be a non issue!I have worked with quite a few end users over the years that absolutely love the hardened air plasma edge....it makes their tools last longer!Jim Colt
Reply:Originally Posted by jimcoltAs I said many posts ago....it is not the heat induced into the material from the plasma that causes most of the hardness, rather, it is the chemical effect from an air plasma....air is roughly 20% oxygen, and 80% nitrogen.....the nitrogen content creates a nitride finish...or a case hardening on the edge of mild steel that is about .005" thick. I would guess that this is a good thing for garden tools. This hardened edge from air plasma can be a bad thing...if you are trying to drill or machine the edge...as it is extremely hard.If you use an oxygen plasma....there is no nitriding of the edge....just a very small (maybe .005") haz (heat affected zone)......which on mild steel can cause minimal hardening of the edge, and on some tempered and high carbon steel can actually cause a softening of the edge.Not all plasmas effect the edge in the same way. Plasma typically has a very small heat affected zone.I doubt that plasma would have any noticeable effect on the edge of any garden tool. Modify the tools as desired.......should be a non issue!I have worked with quite a few end users over the years that absolutely love the hardened air plasma edge....it makes their tools last longer!Jim Colt |
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发表于 2021-9-1 00:39:31