Why Saw Tips Come off Saws
Carbide Surface Prepartion is Critical
I have been working on this issue about thirty years and, in my experience, the number one reason saw tips come off saws is bad surface preparation of the steel or the carbide.
Laser cut steel makes flat, high quality saw plate but the heat affected zone needs to be ground back on the areas to be brazed. In my research it looked like 0.005” to 0.007” stock removal was enough. The current, common manufacturing standard seems to be about 0.010” which is a nice, safe figure. Then the steel needs to be free of oils and greases preferably by cleaning with a caustic product resulting in saponification. (The caustic reacts with the grease to make soap which is easily rinsed off.)
The carbide typically needs to be tested for wetting.
Above is a picture of sample tips. They were sent to me by someone who wants to be a new supplier to me. The top row shows that the braze alloy (golden color) flowed evenly and completely cross the tops of the tips. This is good “wetting”. The bottom row shows that the braze alloy balled up and had minimal flow. This is a relatively “non-wetting” surface. In other words, braze alloy sticks well to a wettable surface and not at all to a non-wetting surface with a whole range of surfaces between the two conditions.
If the braze alloy does not stick to the carbide then the carbide will not stay on the saws.
If the carbide comes off clean (comes off without breaking) then the most likely cause is poor surface preparation.
No matter how well the part is brazed it is still possible to break a tip.
Leave a Reply