SHOP: Blades are made from a variety of materials. When is a bimetal blade the best option?
CHIBE: It depends on material and cutting ability needed. Bimetal blades tend to be more cost-effective for customers compared to carbide tipped blades. In some instances, it’s not worth it for a shop to purchase a carbide blade. If your’re cutting mild steels and you’re cutting in the back of a fab shop, or you’re cutting in a maintenance area of a plant, are you really going to need carbide tipped blades? That’s where a bimetal blade really earns its keep. Bimetal can do quite a few things using proper feeds and speeds. This will allow you to prolong your blade life and cut more efficiently.
SHOP: What’s the upper limit on how hard a material a bimetal blade can cut?
CHIBE: I’ve seen it cut 40/45 Rockwell C. It has to do with the type of bimetal blade you’re using too, because you can have different edge materials even on bimetal. You can go to an M51 and that’s going to last a long time and do a good job and you can probably cut above 40/45 Rockwell C with that. The tooth tips on a bimetal blade are about 67/69 Rockwell C hardness so obviously once you get to material of that hardness you’re not going to be able to cut through that. The premium bimetal blades on the market today they will do a good job for you. People think they have to go to carbide for harder materials and that’s not necessarily true. I’ve cut a lot of hard material with bimetal blades. They’re probably not going to last as long as a carbide blade and maybe won’t cut at the rates of a carbide blade but that doesn’t mean you can’t cut hard material with it.
SHOP: When should carbide-tipped blades be considered as the best option? What advantages does they provide?
CHIBE: The advantages are that they’re going to cut faster and they’re also going to last longer than a bimetal blade. In many cases, carbide blades are preferred when cutting non-ferrous material. One thing to consider when using carbide blades, you have to make up for the extra cost of the blade. If it lasts just as long as the bimetal blade, why should you switch, unless a higher level of performance is necessary. For some people, it is. They need to cut fast.
SHOP: What’s the upper limit of how hard a material a carbide tipped blade can cut?
CHIBE: You’re looking at 60-65. Rockwell C. You can cut some pretty tough material.
SHOP: What about the cut finish? With a carbide tipped blade do you see an improvement in cut finish over the bimetal blades?
CHIBE: Yes. You have a couple of different designs of carbide tipped blades. You have a triple-chip carbide, which has many facets ground into the carbide teeth, and it will give you a really nice finish. With triple chip carbide, you tend to get a nicer finish as well as fast cut times. I’ve seen some mirror finishes. When you get into a set style carbide, that’s not going to produce the same finish as a triple chip carbide but will still produce a good finish. When you’re cutting with a bimetal blade, you’re going to see more of the striations through it. If finish is important to you, triple chip carbide will achieve the best finish.
Russell J. Chibe is a regional sales manager with Cosen Saws, North America.