Mold Flow Analysis

Before the first cut of material to create a plastic injection molding die is started, a mold flow analysis should be completed.  Not every application requires mold flow analysis. Depending on the product geometry and tolerance requirements SEA-LECT Plastics engineers will make recommendations for including mold flow analysis in the production budget.  Here’s why we recommend a complete analysis in the first steps of the process when necessary.

A trained and experienced tool maker will perform an analysis of the injection molding mold before the first cut is made of the mold material.  This will predict how to create the lightest, strongest, and most consistent parts from each cavity in the mold.  You can select the resin for your parts, and the software will show an accurate prediction of the resin flowing into each cavity in the injection molding tool.  This can also offer opportunity to optimize melt temperature, molding pressures, fill cycle times, plus other variables before the first art is produced.

The main reason to complete a mold flow analysis is the ability to predict where the current mold will have complications and offer a visual representation of where to focus resources to create fast, efficient, and consistent injection molded parts.

These are results that you can expect after an analysis identifies all areas needed for improvement:

• Faster cycle times – You can expect your mold to run faster as it will be able to fill the parts quicker and more consistently after an anlysis that optimizes the injection molding process.
• Reduce clamp tonnage – An optimized mold will reduce all restrictions and require only a miminum clamp load to secure the mold closed during the injection process.
• Produce better quality parts – Your mold will offer consistency from part to part, whether that runs in the hundreds or millions. A properly designed mold will yield very minimal variance.
• Speed up overall project progress – A mold flow analysis takes the guess work out of optimization and offers your tooling maker the resulting design that requires little to no modification to make optimized parts. Development time it minimized, which will also save you investment cost.
• Reduce the number of mold test cycles – In early years of injection molding, development could take months to find the optimum design through trial and error. A computerized analysis removes most or all of the trial time, and allows the first use of the tool to produce optimized parts.
• Reduce your delivery time on parts – An optimized mold will be ready to produce production parts sooner than ever before. As analysis modeling and software continually become better at creating accurate models, molds require less design and tooling changes before production can begin.

Analysis offers results that require minimal validation before production trials can begin.  These are the results you can expect from the analysis, and how they will optimize your mold:

The filling and packing analysis allows the designer and toolmaker to see how the chosen resin will behave as it flows through the mold creating your parts.  In order to optimize the fill / pack for an injection molding tool, these will need to be improved:

• The gate and runner size will be perfected to flow resin well.
• The tool will be sized correctly for tonnage and machine use.
• You will have the ability to choose welding / knit line placement between the cavity halves.
• The sink marks will be identified and countered, if required
• Gate positions in the mold can be adjusted or moved
• Molding variables, such as pressure, can be varied and validated
• The chosen resin can be verified as the best choice

Cooling time in injection molding can determine the difference between a good and bad part that meets dimensional criteria, and can also vary cycle time that causes downtime and lost revenue.  Optimizing the cooling phase of the injection molding cycle gives you these benefits:

• Reduced and predictable warpage that ensures the parts created meet your specifications every time they are produced
• Optimized coolant paths through the injection molding tool
• Optimized coolant tube sizes and flow rates to minimize cycle time while producing excellent quality
• Verification of baffles and bubblers to choose the best for your molding conditions

Many factors can affect dimensional tolerance part after part, and analyzing the conditions inducing warpage will reduce scrap and increase productivity.

• One major benefit of injection molding is producing parts repetitively and consistently. A warp analysis will identify variable and parameter limits to ensure each part produced will be within production design tolerance.
• Factors that contribute to part warpage include: part design, final resin selection, fiber orientation, the molding process itself, and the mold cooling system design.
• The Warp Analysis can also define the variables that need constant monitoring in production to reduce variation, scrap mitigation, and efficient molding conditions.

One last benefit from a mold analysis it to predict the strength and structure for each part cavity.  This prediction will allow the designer to adjust the part design, mold design, or molding conditions to ensure the parts produced meet your design structure needs.  The FEA analysis predicts the weak points (as well as the strongest points), which can be further enhanced for break points, fracture points, and durability over the lifecycle.  From there material / resin selection, part designs, molding processes, and assembly processes can be refined to offer a part at a reduced cost with maximum functionality.

SEA-LECT Plastics has an elite team of designers, toolmakers, and engineers that have the expertise to design and optimize world-class injection molding operations.  When you need a partner to design or optimize your next injection molding project, call us (425) 339-0288 or email us at mattp@sealectplastics.com.  We can offer you advice on the best technology to use, the best materials to meet your product demands, and how to navigate through each development stage with ease.