Grinding Carbide 101
Knife grinding basics for carbide cutterheads. February 14, 2007
This article was reprinted with permission from Wood Tech Tooling, www.woodtechtooling.com.
Grinding of Carbide Knives, BAK-PAKŪ Knives & Double Back Knives
Description:
Carbide inlay consists of a tool steel body with a brazed carbide face. BAK-PAKŪ is a two piece sandwich system with separate solid carbide knife and steel backer. These two pieces are then fit together and clamped in the cutterhead knife slot as a unit. This system allows the use of a higher grade carbide to offer increased life expectancy and give improved finish quality.
Profile Grinder Recommendations:
Run the grinding wheel at maximum wheel speed of not more than 3,000 RPMs. As carbide is a much harder material than standard HSS, a faster wheel speed will allow more efficient grinding. Allow the grinding wheel to do the work, as forcing the wheel will create unnecessary heat buildup. Heat buildup can cause the carbide to crack or delaminate.
Wheel Recommendations:
We highly recommend using a specialized diamond wheel for this application. A standard diamond wheel will create unnecessary heat buildup when coming into contact with the steel body or backer. Our CDX diamond wheel is designed to greatly reduce this heat buildup, while allowing grinding of both carbide and backer simultaneously. Grit size recommendations on CDX wheels are as follows: 80 grit for heavy stock removal; 150 or 180 grit for standard stock removal and good finish; 220 or 400 grit for extremely fine finish situations, such as profile wrapping. In extreme hogging situations, a black silicon carbide wheel can provide very rough material removal. However, the trade off is a very short wheel life and extremely limited finish capabilities.
Clearance Angle Recommendations:
Back clearance: 12° to 15°. More than 15° does not allow enough backing material to provide adequate knife strength.
Side clearance: Never exceed 5°. Use only when necessary.
Finish Expectations:
Carbide knives generally produce a less acceptable finish than HSS knives. Improvements in carbide manufacturing; and in particular BAK-PAKŪ knives, offer better finish results than standard brazed carbide tipped knives. As carbide is recommended to machine MDF and other man-made materials (in addition to most exotic hardwoods), the use of BAK-PAKŪ knives to achieve good knife life and very acceptable finish quality is advised. Call us with your particular application for best recommendations.
This article was reprinted with permission from Wood Tech Tooling, www.woodtechtooling.com.
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