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So I ran across this interesting video comparing plunge cutting vs gouge cutting with a grinding disc.
From this simple test it looks like you get 10 times the life out of discs using a grinding cut technique. Now I don't do a lot of this work, but it is very interesting how they way you use your grinder can make a huge difference.
Makes sense from the standpoint that with the "gouge" technique the sides of the disk are not being worn down while making the cut. That said...for the task at hand he is using the wrong tool. A circular saw with a metal cutting blade will make short work of that sheet metal and will last a very long time. The metal cutting circular saw blade also generates less heat since it is not using friction to cut the metal. I don't normally cut that type of metal but in the gauge that I cut the circular saw blade makes a cleaner cut as well.
I've noticed those same results, but never had the benefit of a high speed camera to see what was going on at the cut level.
Interesting.
For the record, I buy the cheapo discs from Harbor Freight....LOL
ever since I found metabo 6" grinder and .045 cutting disc, my portaband saw has been collecting dist...if fact I sold it last year. I've tried and tried to tell the ironworkers and pipefitters i work with that the gouge approach works better and the blades last longer but sadly their heads are
harder than what they are cutting. They will bear down on a disc like a 7" grinding rock and complain that they don't last. if they would just let the disc do it's own job they would have better results.
I cut 14 and 12 gauge metal on average once a week. My main concern when cutting this metal is maintaining the surface paint. I use a jig saw with a fine tooth metal blade. I am also concerned about time and accuracy, in business time is money and the holes I cut hold electronic components that need a tight tolerance hole.. I find the jig saw will cut just as fast as the grinding disk, I have more control and the blades are relatively cheap. I also cut stainless steel enclosures for food controls. Stainless will eat up saw blades so I use my plasma cutter.
For thicker metal I use a variety of tools. I use my metal band saw, cut off saw, plasma cutter or torch. Whatever I feel will meet my need for speed, accuracy and cost. I do like using the circular saw metal blade for angle iron, the blades seem to last a fairly long time.
