Tom Walz
04-12-2010, 7:31 PM
Tip breakage on panel saw blades
There is currently a problem with tip breakage on some panel saw blades. I have done two analyses already this month with another one reported.
Some companies are using really hard tips on panel saws trying for long life. The customers are running these saws hard and getting them hot enough to heat check the carbide.
Various studies have tried to measure the temperature of saw tips in the cut. Some have come up with figures well over 1,000 degrees F. I believe Sandy Stewart once came up with 1500 F. Saw tips are somewhat thermally conductive because of the cobalt in them. However a very hard tip has very little Cobalt so it is a very poor thermal conductor. This means that the outside gets much, much hotter than the inside which is a pretty good way to crack the outside.
Once the carbide is cracked or heat checked it takes very little to break it. This has been described as the tips “popping” apart.
This may occur during use. It can occur during handling when a saw blade is laid down on a wooden or similar surface and the tip breaks. (Modern carbide should be pretty tough. I did a demo where I shot a tip out of a .410 against a concrete block wall with no damage to the carbide saw tip.) It is definitely showing up in sharpening shops where the tips break during the grinding.
There is currently a problem with tip breakage on some panel saw blades. I have done two analyses already this month with another one reported.
Some companies are using really hard tips on panel saws trying for long life. The customers are running these saws hard and getting them hot enough to heat check the carbide.
Various studies have tried to measure the temperature of saw tips in the cut. Some have come up with figures well over 1,000 degrees F. I believe Sandy Stewart once came up with 1500 F. Saw tips are somewhat thermally conductive because of the cobalt in them. However a very hard tip has very little Cobalt so it is a very poor thermal conductor. This means that the outside gets much, much hotter than the inside which is a pretty good way to crack the outside.
Once the carbide is cracked or heat checked it takes very little to break it. This has been described as the tips “popping” apart.
This may occur during use. It can occur during handling when a saw blade is laid down on a wooden or similar surface and the tip breaks. (Modern carbide should be pretty tough. I did a demo where I shot a tip out of a .410 against a concrete block wall with no damage to the carbide saw tip.) It is definitely showing up in sharpening shops where the tips break during the grinding.