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.
