MaintenanceGuy Posted July 7, 2017 Share Posted July 7, 2017 Hello all! Im new to the board here and need some help with questions about the small forging furnace we have here at work. It was built by a previous maintenance supervisor and it works decent but I think I can make it much more efficient and effective. A few months ago I did some work to fix it up a bit and didn't know a darned thing about forges so I made some mistakes. After reading through some threads here you seem like a quite knowledgeable group. Our forge is fed by 4- 100 gallon propane tanks and a blower that I don't know the CFM on. we have 3/4" pipe running 10psi of gas into 1" pipe at the forge. I haven't been able to obtain a true temperature reading as I don't have an instrument capable of reading high enough temps, but we are making 1.25" round A36 bar hot enough to flatten, punch, and bend a tight 180* radius. Here's a couple pictures of what our machine looks like. Thank you in advance for any help!! Quote Link to comment Share on other sites More sharing options...
Latticino Posted July 7, 2017 Share Posted July 7, 2017 As I've stated before, efficiency of a forge means different things to different folks, particularly in a production facility. For example the cost of time wasted waiting for stock to heat up may be vastly more important than the nominal savings in fuel you may get by reducing interior lining thermal mass (not to mention the potential for overall down time if you reduce the durability of the thermal lining and it needs to be replaced). You don't give us information regarding your process throughput (how many of these 1.25" rods you expect to forge in a certain period of time and overall for a shift) or what you see as the downside to your current forge operation. You might want to calculate what the percentage cost of running the forge is per part fabricated and see if a 20% or so improvement in efficiency is going to be significant. My instinct is that the energy use of the forge is an overall small cost compared to that for labor and materials, so an efficiency upgrade may not be worth contemplating, but a lot depends on your process. That being said I can offer a couple of comments based on the information you have provided: It appears that you have a high pressure blower system installed, with a lot of short radius elbows and fittings, including a reducer or two where an air valve is used, presumably for metering. You can likely reduce the fan energy losses by upgrading this system (larger diameter pipe, butterfly valves or VFD, long radius elbows...), but that will only net you a nominal savings in electrical energy IMHO. How is your forge insulation performing (what is the outer skin temperature of the forge)? If more than 5 deg. above ambient it can be improved by adding additional insulation. Of course this will require relining the forge, and whether the downtime and cost of new lining materials is acceptable, or worth the eventual savings in gas is a good question. A 3/4" propane line at 10 PSI without a reducing orifice could put a tremendous amount of fuel into the forge. I expect some kind of metering orifice is included somewhere. That being said, from an efficiency standpoint the goal is to reduce thermal loss exiting the forge interior (other than that used directly for heating the stock). The three major mechanisms for that are conductive losses through the forge skin (as discussed above), radiant losses through the forge door and convective losses with the combustion byproducts exiting the door. Radiant losses can be dealt with by improved door design, though the current long throat of the forge opening appears to be doing fairly well already. Convective losses are more related to the flame speed for your burner system, and that is where I think you have the best opportunity for improvement. To achieve the same BTUH output with a slower speed flame you need to do one or more of the following: increase the burner outlet area, provide optimal mixing of the fuel/air, design the burner outlet to have exit conditions with closer to ideal velocities across the burner jet, and design your burner system to allow precise metering of both air and gas. From your piping configuration I think you should have adequate mixing. The burner outlet design might be improved using a multi port outlet burner (see Joppa Glassworks), or flame retention nozzle. Proper metering can be accomplished by using a variety of commercial products. Your process is really the critical issue as regards everything from upgraded burner design to door mechanisms and overall forge size. If the forge only runs for an hour after all the rod ends are heated and a huge team of workers descend on the heated stock processing them all simultaneously, an optimal production forge is different than if they are all setup like you show, and one worker processes each rod individually. In the former case the forge thermal mass could be reduced to increase effectiveness, in the latter the overall size of the forge could be reduced significantly. If the forge is used for other operations that require that large an opening it may not be practical to make changes in the door design or forge size. I don't see any safety systems installed for the gas train or forge. In a commercial or industrial environment this is more likely than not a code violation that could get you shut down if inspected. If there is an accident OSHA will have a field day. If you want to see what a more typical commercial burner assembly looks like, please see the following: http://www.buckpitt.com/content/file/JA.pdf Quote Link to comment Share on other sites More sharing options...
MaintenanceGuy Posted July 7, 2017 Author Share Posted July 7, 2017 To start off let me say that this forge was built in house about 30 years ago by a maintenance guy who was no engineer. He did a great job with what he had to go on. All of the points you made above are exactly what I was hoping to see you address. I have already ordered a control system for the forge that will allow me to consistently and accurately monitor and control temperatures inside as well as add in some much needed safety features. When I rebuilt the forge about 6 months ago I was told the department where it is used was being shut down in 3 months, so I did the work with that in mind. Now they want this to remain a part of the business indefinitely. That being said, I simply lined the inside with fire brick the same way it was done originally, having no knowledge about the proper construction of a forge I used the wrong brick and also severely under- insulated the whole thing. There is no doubt a HUGE amount of conductive heat loss as well as a massive amount of heat and flame visibly exiting the openings of the unit. There is no question in my mind that I need to reline the interior to upgrade the insulation, I guess what I am wondering is, are the products Im seeing mentioned on here durable enough to hold up to a forge regularly run 10hours a day 5 days a week? Typically the number of bars put into the forge to be heated run from 26-60 pcs and we are only trying to heat about 8" of the end of the rod. One guy runs the whole operation and he takes each piece out and runs them through one by one once they are hot. Heat up time is definitely an issue however I don't feel that it takes that long contrary to the operators opinion. I would like to redesign the door however there are times when it is filled almost to capacity of the current opening. Cost is the single biggest determining factor in how I proceed in any modifications to this machine. I really need to figure out a way to use what I already have to increase the throughput of material on this thing and also add in safety features to protect the operator and myself when I'm working on it. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 7, 2017 Share Posted July 7, 2017 This is a case where the interior does need to be lined with hard high temp firebrick for durability and heat transfer. However those bricks need to then be insulated on their outside. Also can you rework the door so the bars are on a slant; you pull a bar at the bottom and add in a bar at the top allowing for heating as they work their way down to the bottom. Continuous rather than batch loading.I'd have a reflector surface on the inside of the door with the slot on it and offset slightly so the exhaust goes up rather than out no big openings directed at the user! Real easy to sketch, hard for me to describe. Bar holders on a slant so they auto feed down, but not put too much pressure on the bottom bar---you need to pull it after all Bars go into the furnace through a door with a slot cut in it matching the slant of the bar holder. Door is lined with IR reflective insulation and with a gap allowing exhaust to exit at the top and not towards the user. You want to adjust the furnace so the bars are at working temp when they get to the bottom of the slant. No reason to have them at working temp earlier. Quote Link to comment Share on other sites More sharing options...
Kozzy Posted July 7, 2017 Share Posted July 7, 2017 Look up furnace curtains. The operator will thank you and efficiency will go up enough to definitely pay for it (but not remarkably) Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 7, 2017 Share Posted July 7, 2017 Welcome aboard, glad to have you. If you'll put your general location in the header you might be surprised how many of the Iforge gang live within visiting distance. Truth is if your guy is processing say fewer than 60 pieces an hour I'd recommend buying an induction forge. There really isn't a good reason to have all that steel heating at the same time if there's a better tool. An industrial strength induction heater will bring 8" of one of those bars up to welding temp in maybe 30 seconds or less. It won't make the area near it really HOT with waste heat. It isn't a CO hazard. doesn't use more electricity than necessary to keep the circuitry warm and cooling water flowing when not actively heating steel. If an induction forge isn't in the works then use high temp hard fire brick for the flame face and back it with several inches of an insulating refractory be it light fire brick or ceramic wool blanket. I'd start by thinking 5"-6" more if you're keeping this thing hot 24/7. Sloping the floor so the stock self feeds is a given improvement. Closing the opening till there's only a little gap above the stock and a thermal baffle to shield the room and reflect the heat back into the forge. I think are basic upgrades the original builder didn't know about. Our guys from Upstate NY and NM have said about what I have to say other than losing the furnace and switching to an induction heater. The heating coils on an induction forge don't need to surround the stock, you could have the stock roll down sloping rails and into the induction coils to be drawn out and forged. That's my vote on upgrading your forging heat source. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Kozzy Posted July 7, 2017 Share Posted July 7, 2017 Listen to Frosty on the induction heater thing---if you can sell the idea. It'd definitely pay for itself in short order. It'd also be easier to reduce scaling if that's been any problem. Might be a hard sell with the inertia of "we've been doing it this way for 50 years" thing but it'd be well worth the battle. Quote Link to comment Share on other sites More sharing options...
wpearson Posted July 8, 2017 Share Posted July 8, 2017 Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 8, 2017 Share Posted July 8, 2017 Shows what you can do with a few old industrial tools---and an induction forge! Once he's got the setup dialed in I bet he can make a decent shop rate pretty easily! Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted July 9, 2017 Share Posted July 9, 2017 Both standard flan-blown, and wasp waist (ex. Ransom brand) burners are available with Giberson ceramic heads (multi-port flame nozzles), so that people who are looking for something similar to a ribbon burner's performance in a more familiar package. s can use them on both standard styles of burner http://www.joppaglass.com/homepg/joppa cat_web.vers.pdf Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 10, 2017 Share Posted July 10, 2017 On 7/8/2017 at 7:32 AM, ThomasPowers said: Shows what you can do with a few old industrial tools---and an induction forge! Once he's got the setup dialed in I bet he can make a decent shop rate pretty easily! I'll bet you're right Thomas! Naked Anvil used to be a regular poster here, AKA Grant Sarver the founder and then owner of Off Center, Products. The company lives on even though Grant passed a few years ago. That's the small scale induction forge he designed and marketed for home shop to small industrial operations, a friend of mine is handling the units now. I'd LOVE to be able to afford one. This is the first I've seen his videos though, thanks for posting the link WPearson. I really should get out more. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
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