thats why parts warp. Be careful not to confuse this with surface finishes produced by grinding of other finishing operations. Rolling metal into sheet form at the mill elongates the metal crystals and gives it a grain. 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. As a general rule, the grain line must run perpendicular to the bend to avoid the potential for cracking or fracture. By continuing to use this site you are giving us your consent to use cookies in accordance with our privacy policy. Wash the oxidizing solution away, and when the piece is dried, the grain flow is revealed clearly. He has contributed to nationally published books and he leads the Word Weavers of West Michigan writers' group. Knowing why grain direction is important will be helpful as well. Although not as visible, grains in a piece of steel are like the wood grain in a piece of lumber. e) micrograph of acid etched metal highlighting grain boundaries A crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials. Because of the ex… The word (Grain) addresses the size and direction of the grains with relation to the block of aluminum. Randomly oriented, the grains contact each other at surfaces called grain boundaries. Setup of that production line and the methods used to bend sheet metal are important to sheet metal design. Examine both folds, and it can be seen that one fold is decisively cleaner and smoother than the other. To begin, let us provide a definition of grain flow in forgings. Since 2003, Timothy Burns' writing has appeared in magazines, management and leadership papers. Most grain boundaries are preferred sites for the onset of corrosion and for the precipitation of new phases from the solid. Flood the face of the steel with acid, and as soon as the surface begins to etch, wash the acid off with pure water. There are few things worse than experiencing an avoidable problem. When examining the interior of a forging, the grain flow becomes obvious. As paper is made, all the fibers within the pulp stew begin to line up in the direction in which the paper machine is moving. Most metals are crystalline in nature and contain internal boundaries, commonly known as “grain boundaries.” When a metal or alloy is processed, the atoms within each growing grain are lined up in a specific pattern, depending on the crystal structure of sample. Paper fibers expand and contract as much as 400 percent more across the grain direction of the paper fiber than with the grain direction. These groupings of molecules manifest as irregularly shaped crystals or crystal-grains. This can result in very unpleasant consequences, including gusseting of the spine of the finished piece. The grain is on both sides of the sheet, and run the same direction, but there is only protective film on one side. Individual grains are elongated in the direction of the metal flow or plastic deformation. The easiest and best way to determine the grain direction of paper is to order it in the direction required, whether grain short or grain long. The end result is that many more fibers than not are pointed in the same direction along a sheet of paper, forming a “grain direction.”. One of the most important properties to understand about paper fiber is grain direction – the direction in which the fibers align on a specific sheet of paper. When bending metal along this grain there’s an increased risk of cracking, especially when putting-in a tight radius. When Sheetmetal is bend perpendicular to rolling direction grain rearranges. Grain direction is a term used to describe the rolling direction of metal after being manufactured into sheet, plate or coil. Work-hardening. But in carefully engineered parts, when the surface is polished, and the surface imperfections removed, the grain flow is slightly visible in the mirror like surface with a magnifying glass, or under a low power microscope. Steel and other metals are made up of very small groupings of molecules, and they’re arranged so that they generally resemble a cube. More importantly, non-metallic inclusions, particles and other impurities inherited during the casting process are elongated in the direction of grain flow. Whereas bending parallel to rolling direction can lead to cracks because of destruction in grain structure. The fingertips of the right hand represent paper fibers bound perpendicular to the spine of the book, which is represented by the left palm. The structure and size of the grains determine important physical properties of the solid metal. Fold across the parallel direction of the pencils, and the pencils will all snap in two. Sometimes the side of the sheet with the grain direction is bolded, so 11x17-inch would be grain long or 11x17-inch would be grain short. As applied to cloth, the term refers to the way the fibers are woven. That is the question. Grain Direction is not to be confused with surface finishes made by sanding or other finishing operations. It’s always best to bend across the grain. Thousands of brand-name papers, envelopes, card stocks, swatch books, samples and other products are available with an array of custom services including paper cutting, perforating, scoring, drilling, envelope printing and custom watermarking. This can easily be demonstrated by taking a light cover stock, perhaps a 65 lb. Grain direction is noted on most paper packaging, swatch books and paper mill stock sheets in one of a few different formats. How well the metal deals with the expansion and compression (among other factors) determines the amount of unexpected deformation (see Figure 2). These option will be the default on, but the user has the availability to … Often there will be multiple indications of the grain direction on the label of a ream of paper. There is almost no way to repair a gusseted book once it is bound, but this issue can be avoided by using proper binding techniques. Just be sure and specify which direction you want the grain to go. Applying this to metal bending, be it plate bending, press braking or any other type of metal forming, consideration must be given to the grain direction before any process is carried out. This manufacturing method is where hot metal is compressed through rollers and forced into shape, elongating the crystals in the process. The orientation of crystallites can be random with no preferred direction, called random texture, or directed, possibly due to growth and processing conditions. It is a matter of how paper fibers expand and contract in the open air. Eight main factors affect deformation during sheet metal forming, and many relate to material grain. Figure 1 shows the grain flow in a forged and machined component. Even under a magnifying glass, the rough steel surface makes it impossible to evaluate the grain flow without some kind of test. The Official Publication of the Foil & Specialty Effects Association, Grain Direction – The Long and Short of It. Grain direction is very important and makes a huge difference as to how the paper will react when attempting to fold, score and bind it. In contrast, if the sheet was cut “grain short,” then most of the fibers would be pointing across the short side of the sheet in the 8.5-inch direction, or what is called the “grain short” direction. When trying to visualize what happens in gusseting, imagine a pair of hands making a “time-out” sign – the fingertips of the right hand pressing into the palm of the left hand. Grains of a metal ingot can be elongated and locked together by rolling to improve the mechanical properties in the direction of grain … With growth, each grain will eventually impact others and form an interface where the atomic orientation… During sheet metal processing ( rolling operation), material grains are arranged in the direction of rolling. 2. Typically, when using an 8.5×11-inch sheet of paper, the grain is in the 11-inch, or the “grain long,” direction, meaning that the vast majority of fibers are aligned parallel to the 11-inch length of the paper. Will you fold, score and bind your paper, or will you crush, break and warp your paper? The engineer modeling the part needs to understand the grain structure of the metal coil that will be used. The acid will etch the surface, revealing the grain flow pattern. Grain flow is the direction of the pattern that the crystals take during plastic deformation. Adhesive binding on paper with the wrong grain direction can produce disastrous results. The grain flow in a piece of engineered or forged steel is often not visible to the naked eye. Most commonly, grain direction will be noted as the last dimension of the sheet. In grained sheet metal material we always create the model so that the extents will reflect the grain dim as being the length in the parts list. Another solution for quick grain flow examination is etching the surface with a 3 : 2 : 1 solution of water, hydrochloric acid and hydrogen peroxide. FSEA/IADD Joint Conference Announces 2018 Programming Line-Up, Four Drivers for Luxury Packaging Markets. For engineered steel pieces, manufacturers and engineers identify the direction of the grain flow to evaluating the piece's design characteristics and strength. Grain Direction is formed in metal in the direction in which the sheet was rolled at the steel mill. Grain direction can also refer to The direction in which the greater number of fibers are oriented in paper or board. So, what? Definition: Forging Flow Lines is a directional orientation of metal grains and any non-metallic inclusions that have been deformed due to forging. cover, and folding it the length of the sheet and then folding it the width of the sheet. We all have our issues, right? A few minutes spent learning about and understanding grain direction will help for years to come. It is produced by polishing the metal with a 80- 180 grit belt or wheel finish. Just be sure and handle the parts carefully after graining, as a scratch going against the grain will show up after processing. The reason that grain direction is so important to successful binding is different from when folding and scoring; it is not a matter of breaking fibers. What results, in this scenario, is severe warping of the sheets as they try to move within the bound spine. Read on Mobile Enter Reading Mode. Paper, like wood, has a grain. Yes, that pesky little grain direction issue – which is stated in so many swatch books, printing guides and all over paper mill literature – really means something and should be understood by everyone from graphic designers, printers, finishers and binders to home hobbyists. These grains vary in size and in orientation but are usually microscopic and their direction is determined by the processing conditions. Grain direction. When working with paper, it is vital to know which way the grain flows. Metals which are heat treated or machined also have grain patterns which are also predictable, and uniform. The grain direction may be underlined, 11×17-inch would be grain long, or 11×17-inch would be grain short. While it is not exactly the same in paper as with pencils, the concept does illustrate that the best way to fold and score paper is with the grain direction parallel to your fold and score. Grain Directions: We can see three different grain directions above: L Direction: This is the strongest ‘Long’ (L) direction along the dominant grain direction shown in blue in the figure above; LT Direction: This is the orthogonal ‘Long Transverse’ (LT) grain direction in the plane of the plate, shown in red above Paper fibers constantly expand and contract, mainly due to ambient conditions as well as glues and moisture associated with many binding processes. By paying attention to grain direction, it is possible to avoid some of the all too common production errors that occur due to incorrectly formatting projects with respect to paper’s grain direction. Polycrystalline materials are solids comprised of a variety of differing crystallites, which are also commonly referred to as the grain of the metal. Each is influenced by how the metal deforms, which in turn depends on the metal… Most likely, the expansion and contraction of unbound paper won’t be seen or noticed, but it is happening. The length of these groupings is smaller than one-tenth of a millionth of an inch on each side. Paper has a grain direction. Grain flow is a directional orientation of metal grains and any inclusions that have been deformed by forging. Metal working processes orient the grains in metals in predictable patterns. We suggest the following basic rules mentioned earlier and the following rules that are more specific to metal doors to determine proper grain direction: (65 RA – 30 RA) #4 Dairy or Sanitary Finish Whichever format is used, paper mills make a big effort to indicate the grain direction of every sheet of paper. There is the "Short Traverse" which would be the thickness (or "depth") of the sheet/extrusion/etc. The grain flow determines the strength of the metal piece. Binding with the grain direction is very important for all methods of binding. There are probably companies in your area that offer this service. Grain direction is a key factor in forming Not so much in milling... Sound like something is wrong with your machine/process ... cold rolled metal can have a grain and differences in metal properties from the hard skin to the softer center. When discussing the strength of forged or milled steel parts, grain flow refers to how the molecules in the metal are aligned. Metals are built-up from an orderly arrangement of crystals.
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