One of the best ways to save time and money is conducting a moldflow analysis of your project before you build the mold—especially if it involves complex, tight-tolerance products. Some manufacturers opt for a lower-cost analysis (or even no analysis) to save money, but this is often a mistake that leads to higher costs. A thorough moldflow analysis will carefully evaluate dozens of key parameters that impact your design project, before the mold is built. This saves on prototyping and molding costs, improves quality, and reduces overall operational costs.
Moldflow analysis is a frequently used term in the injection molding industry but is often poorly misunderstood. The process utilizes sophisticated simulation tools to predict the flow of plastic during all phases of the injection molding process, including flow, pack, and cooling—thereby identifying and eliminating potential problems that could arise during mold design or production.
Various levels of moldflow analysis software are available; selecting the right one for your project (and interpreting it correctly) is critical for success.
The most basic level simulates the fill and packing phases. This helps optimize gate location, gate sizes, balance runners, and process conditions that impact manufacturability for thermoset and thermoplastic materials. Injection pressure and temperature, heat transfer effects, and clamp force requirements can also be determined. For thick-walled parts, moldflow analysis helps identify ideal gate and weld line locations, as well as where air traps are likely to form. Other key parameters that can be evaluated are processing conditions, flow-induced shear stress, bore diameter sizing, sequential valve gauging, cavity/part temperature differential, coolant temperature, and coolant flow rate.
Moldflow analysis is also effective for predicting the orientation of both short and long glass fibers that are added to enhance certain characteristics; misaligned fibers can impact strength, flexibility, dimension, and other performance specifications for the product.
Advanced moldflow applications provide critical information regarding more complex processes, such as mold cooling, shrinkage, and warpage. Shrink is unavoidable in plastic and is typically a result of material structure (for example, semi-crystalline or amorphous), packing pressure, and wall thickness. Engineers must be able to accurately estimate shrinkage to properly size the mold. Warp is a result of shrink and can come from three sources: unbalanced mold cooling, fiber orientation, and non-uniform shrinkage. Warpage analysis can identify the causes of warpage and where warpage will occur before the mold is built, allowing engineers the opportunity to optimize design, material selection, and processing parameters to minimize deformation, before production starts. (Source: Scientific Molding by Kaysun)
For most projects, especially those with complex, high-tolerance parts that require precise dimensional stability, moldflow analysis is essential for designing the most efficient, highest-quality injection molding process for the product. This optimizes cycle times and tooling trials—thereby reducing risk, improving quality, and reducing overall production costs.