Also, spaces between pierced holes and bends should accommodate the bend radius ( H) and be far enough from the bend.
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In cases where holes must be near the edge, the minimum space between the edge and holes should be at least the sheet thickness ( T). Distance between holes ensures strength of the metal and prevents holes from deforming during the bending or forming processes. It should be at least two times the sheet thickness (2 T), if not more. It also leads to slug-pulling when withdrawing the punch, which ultimately affects the life of both punch and metal sheet. Hole diameters less than the sheet thickness result in higher punch loading, longer burnish in the holes, and excessive burr. It is always better to specify hole diameters that are greater than the sheet’s thickness ( T). In a sheet-metal design, specifying hole sizes, locations, and their alignment is critical. DFM also provides insights on developing designs that are easier to manufacture. It suggests standardizing parts so they can be used over and over in different applications. A DFM strategy focuses on simplifying designs and reducing the parts counts. This reduces the possibility of errors and ECOs, and fills the void between ideal and real world. With DFM, designers can consider important manufacturability factors while developing sheet-metal designs. Fortunately, it’s possible if companies and engineers adopt a Design for Manufacturability (DFM) strategy. Ideal World leads to Real WorldĬlosing this gap is critical. The overflowing engineering change orders (ECOs), fixing the design errors, and sending revisions back to the shop floor turns into a vicious cycle, one that is often difficult to break. This gap between the ideal and real-world sheet-metal design usually proves costly.
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But the truth is, numerous factors including chamfers at the edges, collars near hole, and spaces between drilled holes matter in the sheet metal world. Tolerances and allowances are exact, and there’s no need to add any feature or change the design to accommodate the shop floor or real-world material behavior. In the ideal world, everything is perfect. Many engineers developing 3D models for sheet-metal products are unaware of the fabrication tools used to form the part or product, and instead design models for an “ideal” world. The reason behind these preventable engineering errors is usually the wide gap between how sheet-metal parts are designed in CAD systems and how they are actually fabricated on the shop floor. In fact, research suggests that manufacturers spend 30% to 50% of their time fixing errors and almost 24% of those errors are related to manufacturability. Engineers designing sheet-metal enclosures and assemblies often end up redesigning them so they can be manufactured.