Bending stretches wood along the outer side of the bend, and compresses it along the inner side, producing stress that wants to bring the bent piece back to its original shape, a tendency called “springback.” Steaming softens the lignin to release this stress. Have you encountered challenges with Grain Direction in sheet metal? Pith introduces similar lines of weaknesses. Since commercial sheet metal bending can be done with less concern for stresses caused during forming operation, the radius can be near zero for thin sheet metal. Scratches and sharp/burred edges contribute to crack initiation when bending … Why is Grain Direction So Important? If you have wrong paper grain direction, there is a higher chance of fractures or tears. A metal’s strength is directly related to its grain size; reducing grain size is a common way to improve material strength which often has little to no effect on the material’s toughness. The result is a smooth surface. When bent transverse to the grain, long edges of grain boundaries are exposed to high strain with high potential for crack initiation. To predict the material’s behaviour accurately during bending you need to accommodate for grain direction, especially at the press brake. We can manually control the grain direction of the metal in the flat pattern, and subsequently how the bounding box is oriented to address these concerns. Surface checks, which are … The pieces should be end-coated to prevent excessive end-grain absorption. Grain Direction “Going against the grain” is a familiar phrase. Texture or grain direction must be taken into account for accurate predictions of material behavior and characteristics when forming/bending. It means doing something the wrong way.When you’re talking about wood, you always want to go with the grain—cutting or planing a board in a way that follows the natural structure of the tree (Photo 1). Grain Direction is formed in metal in the direction in which the sheet was rolled at the steel mill. However, wrong grain direction makes book less usable and even leads to structural damage and early deterioration: When you turn the pages, they tend to bend a bit. 8.24 Generally, the die opening is straight up to a certain length and tapered thereafter. In cold-rolled steel, the inside bend radius can change depending on whether you’re bending with or against the grain. Explain the Shakes, which are longitudinal separations parallel to the annual rings, are responsible for failures in shear during the bending operation. Forming or bending “with the grain” requires less force because the materials ductility is already stretched. The grains run parallel to the rolling direction. A steel plate’s grain direction comes from the mill’s rolling process, which stretches the metallurgical structure of the material. First, the grain of the wood should be parallel to the sides of the piece being bent and not at an angle. 8.23 How does the grain direction in sheet metal affect the design of: (a) Bending dies (b) Blanking dies. Pages may also resist turning if the grain direction is wrong. NOTE: grain is the rolling direction which elongates grains in the same direction. One way to do this is to draw faint lines in the direction of the grain on the backside of the material. A project can be done a lot faster when the grain direction is already marked on the materials. If that is not an option, you can jot the grain direction … Mark or take note of the direction grain. In the example above, perhaps were using a certain type of steel and specific bend radius whereby we need to be careful to ensure the sheet metal does not crack due to bending. by distorted grain and also because they resist compression. Explain the reason. 8.25 In die shearing operations, die size is the hole size and punch size is the blank size. Even a small grain angle of 20 degrees can cut the wood's basic strength in half. for such a shape. Grain direction also impacts the amount of spring-back you can expect.