Knife Marks Per Inch

摘要

Large volumes of hardwoods and softwoods are machined, generally, along the grain for furniture, windows and moulding. Because lumber or wood parts cannot always be machined with the grain, chipped or torn grain frequently occurs. As discussed in FDM January 2006, "How to reduce chipped grain" chipped or torn grain occurs when wood splits ahead of the knife below the surface and then fails as a cantilever beam. Chipped grain is associated with sloped grain. The split follows the grain ahead of the knife and below the surface. Chipped grain is accentuated by knife cutting against the grain with high rake angles, large depth of cut, machining overly dried or wet wood, and too few knife marks per inch.