Zahnrad Kopf
Diamond
- Joined
- Apr 5, 2010
- Location
- Tropic of Milwaukee
So, we have been making some cutting tools made of HSS, lately. Up to now, I have tried some pre hardened HSS as well as using some "donor" tools that were already working tools. Both choices result with using WEDM to cut the tool I want, from the "blank".
All examples were tested before AND after WEDMing. They were even tested after sharpening. Bottom line is that they are all verified to Rockwell C scale 61 - 65.
The issue I am experiencing is that the cutters are not showing any life. AT ALL. I can get about 1 - 2 passes or uses from them and then they need resharpening. Teeth appear to be crumbling. When they do not crumble, they round over. Much like one would expect to see from typical, normal alloy steels running against something harder. Except, that the situation is decidedly reverse. The work piece is in the low Thirties to high Twenties in Rockwell C scale hardness, and the cutters ( as previously mentioned ) are in the 60's. They come from several sources, so it isn't the origin of the material.
Frankly, it is acting almost exactly how we used to expect Carbide to act after WEDMing. This only makes it more confounding and frustrating. Interestingly, once they are re-sharpened to a point much deeper, they perform more adequately but still dull fairly rapidly, considering. We're getting only about 7 - 10 applications before needing more extensive re-sharpening. ( They should last at least twice as long, and need 1/4 or less sharpening. )
So, I am wondering if there is something I am ignorant of with regard to WEDMing hardened HSS, whether it be process related, or metallurgical, or simply some manner of black magic. It just isn't making sense.
Ironically, the carbide ones are performing wonderfully!
All examples were tested before AND after WEDMing. They were even tested after sharpening. Bottom line is that they are all verified to Rockwell C scale 61 - 65.
The issue I am experiencing is that the cutters are not showing any life. AT ALL. I can get about 1 - 2 passes or uses from them and then they need resharpening. Teeth appear to be crumbling. When they do not crumble, they round over. Much like one would expect to see from typical, normal alloy steels running against something harder. Except, that the situation is decidedly reverse. The work piece is in the low Thirties to high Twenties in Rockwell C scale hardness, and the cutters ( as previously mentioned ) are in the 60's. They come from several sources, so it isn't the origin of the material.
Frankly, it is acting almost exactly how we used to expect Carbide to act after WEDMing. This only makes it more confounding and frustrating. Interestingly, once they are re-sharpened to a point much deeper, they perform more adequately but still dull fairly rapidly, considering. We're getting only about 7 - 10 applications before needing more extensive re-sharpening. ( They should last at least twice as long, and need 1/4 or less sharpening. )
So, I am wondering if there is something I am ignorant of with regard to WEDMing hardened HSS, whether it be process related, or metallurgical, or simply some manner of black magic. It just isn't making sense.
Ironically, the carbide ones are performing wonderfully!