Surface checks, which are … The grains run parallel to the rolling direction. 8.24 Generally, the die opening is straight up to a certain length and tapered thereafter. One way to do this is to draw faint lines in the direction of the grain on the backside of the material. If that is not an option, you can jot the grain direction … for such a shape. Scratches and sharp/burred edges contribute to crack initiation when bending … NOTE: grain is the rolling direction which elongates grains in the same direction. The result is a smooth surface. Forming or bending “with the grain” requires less force because the materials ductility is already stretched. Texture or grain direction must be taken into account for accurate predictions of material behavior and characteristics when forming/bending. 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. 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. 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). Explain the reason. 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. 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. Even a small grain angle of 20 degrees can cut the wood's basic strength in half. Why is Grain Direction So Important? Have you encountered challenges with Grain Direction in sheet metal? 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. A project can be done a lot faster when the grain direction is already marked on the materials. The pieces should be end-coated to prevent excessive end-grain absorption. Grain Direction is formed in metal in the direction in which the sheet was rolled at the steel mill. Grain Direction “Going against the grain” is a familiar phrase. Pages may also resist turning if the grain direction is wrong. In cold-rolled steel, the inside bend radius can change depending on whether you’re bending with or against the grain. If you have wrong paper grain direction, there is a higher chance of fractures or tears. 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. When bent transverse to the grain, long edges of grain boundaries are exposed to high strain with high potential for crack initiation. Mark or take note of the direction grain. Shakes, which are longitudinal separations parallel to the annual rings, are responsible for failures in shear during the bending operation. by distorted grain and also because they resist compression. Explain the To predict the material’s behaviour accurately during bending you need to accommodate for grain direction, especially at the press brake. Pith introduces similar lines of weaknesses. 8.23 How does the grain direction in sheet metal affect the design of: (a) Bending dies (b) Blanking dies. 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2020 grain direction in bending operation