Mold layout method
The die layout method is a core step in stamping process design that determines material utilization and production efficiency. It refers to the method of rationally arranging stamping parts on strips or sheets. Scientific layout not only reduces material waste but also ensures the stability of the stamping process, reduces die wear, and extends die life. The selection of a layout method requires comprehensive consideration of factors such as part shape, size, precision requirements, production batch, and material properties. Common layout methods include straight layout, oblique layout, opposite layout, mixed layout, and waste-free layout. Each method has its own applicable scenarios and technical characteristics.
The most basic nesting method is the straight-line method, where parts are arranged in the same direction along the length of the strip, in an orderly and neat manner, making the feeding process simple and stable. This method is suitable for parts with regular and symmetrical shapes, such as circles, rectangles, and squares, and is particularly well-suited for automated feeding production lines. The advantages of the straight-line method lie in its ease of operation, simple mold structure, and high production efficiency. However, irregular part shapes can result in significant material waste. For example, when a 20mm diameter circular gasket is produced using the straight-line method, the part center distance is 25mm and the material width is 26mm (including a 3mm edge overlap). Although the material utilization rate is approximately 78%, its stable feeding rhythm still makes it advantageous in mass production.
The oblique arrangement method arranges parts at a certain angle to the length of the strip, reducing the gap between parts by tilting the arrangement, thereby improving material utilization. This method is particularly suitable for parts with sharp corners, grooves, or asymmetrical shapes, such as triangles, trapezoids, and L-shapes. By adjusting the angle, the protruding parts of adjacent parts can be staggered with the recessed parts of other parts to avoid wasted space. The oblique arrangement angle is usually between 15° and 45°. The specific angle needs to be calculated and determined based on the part shape to ensure that there is no interference between parts. For example, after an L-shaped stamping part (long side 30mm, short side 20mm) was arranged at a 30° oblique angle, the lateral gap between parts was reduced from 5mm in straight arrangement to 2mm, and the material utilization rate was increased from 65% to 82%. At the same time, the problem of material accumulation at sharp corners in straight arrangement was avoided.
The symmetrical arrangement method (also known as staggered arrangement) arranges two adjacent rows of parts at 180° angles in opposite directions, aligning the protruding portions of one part with the recessed portions of the other row, achieving efficient space utilization. This method is suitable for parts with symmetrical structures or complementary shapes, such as U-shaped parts, Z-shaped parts, and parts with flanges. It can significantly reduce the gap between the rows and improve material utilization. The key to the symmetrical arrangement method is to ensure the symmetry of the parts; otherwise, it may lead to complex mold structures or difficult feeding. For example, when a U-shaped part (opening width 15mm, height 20mm) was arranged using the symmetrical arrangement method, the openings of the two rows of parts faced each other, and the center overlap was reduced from 4mm in straight arrangement to 2mm, improving material utilization by approximately 15%. Furthermore, due to the symmetrical force distribution, mold wear is more even.
The mixed arrangement method arranges a variety of different parts on the same die strip, achieving the goal of “one die for multiple products.” This method is particularly suitable for high-variety, small-batch production or the production of supporting products. This method fully utilizes material scraps, improving overall material utilization while reducing the number of molds and production changeover time. The mixed arrangement method is relatively difficult to design, as it requires ensuring that the stamping process parameters of each part (such as blanking force and forming sequence) match to avoid mutual interference. For example, when producing washing machine parts, circular gaskets and rectangular brackets can be mixed on the same sheet of material, and small rectangular parts can be arranged in the gaps between the circular parts. This increases material utilization from 70% when producing a single part to 85%, significantly reducing overall production costs.
Wasteless stacking is an ultimate method for optimizing material utilization. Through precise design of part shape and arrangement, there is virtually no overlap between parts or between parts and strip edges, achieving material utilization rates exceeding 90%. This method is suitable for thin parts with regular shapes and low dimensional accuracy requirements, such as gaskets and washers. It typically requires a precise feeding mechanism and high-precision molds to ensure a stable stamping process. Wasteless stacking places extremely high demands on part shape symmetry, and the mold’s cutting edge strength must be particularly enhanced to prevent rapid wear due to insufficient overlap. For example, using wasteless stacking on an electronic gasket (0.3mm thick, 10mm diameter) resulted in a process gap of only 0.5mm between parts, increasing material utilization from 75% with traditional stacking to 92%. However, this method places higher demands on mold guidance accuracy and feeding error control (feeding accuracy must be ≤± 0.05mm).
When selecting a mold layout method, a comprehensive technical and economic analysis is necessary. Don’t simply pursue material utilization while ignoring production efficiency and mold costs. For example, while waste-free layout offers high material utilization, it’s difficult to manufacture and results in a short mold lifespan, making it suitable for parts made from precious materials or thin materials. On the other hand, while the straight layout method offers slightly lower utilization, it offers low mold maintenance costs and stable production, making it suitable for high-volume production of conventional parts. In practice, simulation optimization using computer-aided layout software (such as AutoNEST and Sigmanest) is often required, combined with test punching verification, to ultimately determine the optimal layout solution, achieving a balance between material utilization, production efficiency, and mold lifespan.
