Submitted ByEdit Dates
Date Uploaded: November 15, 2003, 2:47 am Last Edited: December 12, 2012, 12:33 pm |
 Add toSite Favourites Print this Article |
Why Power-Winding Is Not Worth It
Article © MAIL User: Blaise
This article is a simple mathematical demonstration of why power-winding coils for maille doesn't make sense, from a standpoint of time and efficiency. It will compare the total time improvement in a weaving process where the only change is in the specific method of winding coils, i.e. hand vs power winding.
We must begin by looking at the time per ring needed to hand-wind coils, since hand-winding is the only other widely accessible option available to a mailer. In terms of ring-making speed, each revolution of the mandrel around which a coil is being wound produces 1 ring. In a basic "U" shaped winding jig, with the mandrel-end bent into an "S" shape and inserted through the ends of the "U", a fast coiler can manage 3 turns per second. Just to be conservative, let's assume rather that one can only manage 2 turns per second over the long term. Therefore, the hand-winder produces 2 rings per second, or 120 rings per minute.
Next, we look at production rate for power-wound rings. A power drill, the most common drive mechanism used to power-wind, is capable of revolution speeds far in excess of human reaction times, so the limiting factor will normally be the user and wire guiding method, rather than the unit itself. For the sake of conservative argument however, we assume that all power-winders will make a wire guiding jig of some kind to eliminate wrap-backs and safety issues, and can use their power-winding unit at full speed. This ideal system could conceivably run continuously at 1800 rpm, or 30 rings per second.
These estimates give us ring production times of 0.500 seconds per ring for hand-winding and 0.033 seconds per ring for power winding. In relative terms, this means that power-winding is 15 times as fast as hand winding. Assuming no differences in the production process (wire-feeding, wire anchoring method, cutting, etc...), we see a time difference between the two methods of 0.500 - 0.033 = 0.467 seconds per ring. On the face of it, this is a huge increase in ring production speed, at 1500%.
Now we must look at the real time saved in the course of actually mailling. A full hauberk can take 20,000 rings to complete. Let us assume that a truly prodigous mailler will make 10 of these a year for a total of 200,000 rings, along with an additional 50,000 rings in other, smaller projects. This gives us a total number of consumed rings per year at 250,000.
At a savings of 0.467 seconds per ring, power-winding will save this hypothetical mailler 116,750 seconds, or 32.4 hours per year.
However, now we have to look at how much time our super-mailer puts into weaving on the whole. Under normal conditions, most hand-winding maillers can manage approximately 30 seconds total per ring, from raw wire to assembled weave, not counting time for weaving-related activities like tailoring and fitting. We will again be conservative, and say that our super-mailer is very fast, and not too concerned about closures, and can manage 20 seconds per ring, wire to weave.
This gives us a total weaving time per year of 20 * 250,000 = 5,000,000 seconds, or 1,389 hours.
As we saw above, if our hypothetical weaver power-winds, he will save 32.4 hours out of that, leaving us with 1356.6 hours. He has saved 2.3% of his total mailling time!
2.3% is an incredibly small time savings, but it gets worse.
If we go back to our overly conservative conditions, and re-analyze them with more realistic numbers, our power-winder makes more like 15 rings per second, bringing our per-ring time savings to 0.433. Additionally, if our mailler is a bit less super, he only weaves one ring per 25 seconds. Now his total weaving time per year is 6,250,000 seconds, or 1736 hours, of which he only saves 0.433 * 250000 = 108,250 seconds, or 30 hours, i.e 1.7% of total mailling time saved.
So now, we're at 1.7% improvement, in an estimate which looks more realistic, but wait, there's more. If our mailler now learns to hand coil a little faster, at 3 rings per second, our time saved per ring drops to 0.264 seconds per ring, so the actual yearly time savings is only 0.264 * 250000 = 66000 seconds, or 18 hours, giving us a grand total of 1% of total mailling time saved.
The real time savings probably falls between 1 and 2 percent for most maillers, which, in my humble opinion, just isn't worth the trouble, given the apparatus you have to build and the price of the drive mechanism. Plus, remember that our example here involves a completely safe power-winding method, which most power-winding maillers do not use!
Is 1% of your mailling time worth a finger or a pint of blood?
We must begin by looking at the time per ring needed to hand-wind coils, since hand-winding is the only other widely accessible option available to a mailer. In terms of ring-making speed, each revolution of the mandrel around which a coil is being wound produces 1 ring. In a basic "U" shaped winding jig, with the mandrel-end bent into an "S" shape and inserted through the ends of the "U", a fast coiler can manage 3 turns per second. Just to be conservative, let's assume rather that one can only manage 2 turns per second over the long term. Therefore, the hand-winder produces 2 rings per second, or 120 rings per minute.
Next, we look at production rate for power-wound rings. A power drill, the most common drive mechanism used to power-wind, is capable of revolution speeds far in excess of human reaction times, so the limiting factor will normally be the user and wire guiding method, rather than the unit itself. For the sake of conservative argument however, we assume that all power-winders will make a wire guiding jig of some kind to eliminate wrap-backs and safety issues, and can use their power-winding unit at full speed. This ideal system could conceivably run continuously at 1800 rpm, or 30 rings per second.
These estimates give us ring production times of 0.500 seconds per ring for hand-winding and 0.033 seconds per ring for power winding. In relative terms, this means that power-winding is 15 times as fast as hand winding. Assuming no differences in the production process (wire-feeding, wire anchoring method, cutting, etc...), we see a time difference between the two methods of 0.500 - 0.033 = 0.467 seconds per ring. On the face of it, this is a huge increase in ring production speed, at 1500%.
Now we must look at the real time saved in the course of actually mailling. A full hauberk can take 20,000 rings to complete. Let us assume that a truly prodigous mailler will make 10 of these a year for a total of 200,000 rings, along with an additional 50,000 rings in other, smaller projects. This gives us a total number of consumed rings per year at 250,000.
At a savings of 0.467 seconds per ring, power-winding will save this hypothetical mailler 116,750 seconds, or 32.4 hours per year.
However, now we have to look at how much time our super-mailer puts into weaving on the whole. Under normal conditions, most hand-winding maillers can manage approximately 30 seconds total per ring, from raw wire to assembled weave, not counting time for weaving-related activities like tailoring and fitting. We will again be conservative, and say that our super-mailer is very fast, and not too concerned about closures, and can manage 20 seconds per ring, wire to weave.
This gives us a total weaving time per year of 20 * 250,000 = 5,000,000 seconds, or 1,389 hours.
As we saw above, if our hypothetical weaver power-winds, he will save 32.4 hours out of that, leaving us with 1356.6 hours. He has saved 2.3% of his total mailling time!
2.3% is an incredibly small time savings, but it gets worse.
If we go back to our overly conservative conditions, and re-analyze them with more realistic numbers, our power-winder makes more like 15 rings per second, bringing our per-ring time savings to 0.433. Additionally, if our mailler is a bit less super, he only weaves one ring per 25 seconds. Now his total weaving time per year is 6,250,000 seconds, or 1736 hours, of which he only saves 0.433 * 250000 = 108,250 seconds, or 30 hours, i.e 1.7% of total mailling time saved.
So now, we're at 1.7% improvement, in an estimate which looks more realistic, but wait, there's more. If our mailler now learns to hand coil a little faster, at 3 rings per second, our time saved per ring drops to 0.264 seconds per ring, so the actual yearly time savings is only 0.264 * 250000 = 66000 seconds, or 18 hours, giving us a grand total of 1% of total mailling time saved.
The real time savings probably falls between 1 and 2 percent for most maillers, which, in my humble opinion, just isn't worth the trouble, given the apparatus you have to build and the price of the drive mechanism. Plus, remember that our example here involves a completely safe power-winding method, which most power-winding maillers do not use!
Is 1% of your mailling time worth a finger or a pint of blood?
Original URL: http://www.mailleartisans.org/articles/articledisplay.php?key=205
