Moldex3D – How We Take Responsibility for Plastics
At Westminster Tool, we take pride in our hands-on, proactive approach to problem-solving. Part of our promise to our customers is understanding their challenges and providing unique solutions. As a company driven by continuous improvement, we believed there was a better way to fully understand our customers’ needs by considering every part of the mold. To accomplish this, we not only had to build a quality mold, but we had to understand the quality of the part that mold would eventually produce.
Because of this, in 2017, our team added moldflow analysis to our design for manufacturing (DFM) process. This analysis created a shift in focus, allowing our team to identify risks that, with a concentration centered on only the mold, would previously have been overlooked. Through this, we have developed a more comprehensive understanding of our customers’ needs.
Flow Analysis – Saving our Customers Time & Money
For our team, being proactive means developing solutions to challenges before they become problems. To accomplish this, Westminster Tool put a thorough design for manufacturing process in place. Throughout this process, our team looks to expose hurdles that may arise during the project at its inception, creating a mold that will exceed expectations. To deliver this promise, Westminster Tool uses Moldex3D, a flow analysis software, to identify these potential risks. Moldex3D is a simulation tool used to study the characteristics of how a plastic part will fill, pack, cool and warp once it is molded. This offers a baseline understanding of what is going to happen in the molding machine before you build anything. For us to be successful in any project, we remove assumptions by performing a flow analysis on every injection mold that we build.
The Moldex3D analysis provides our team the ability to predict material behavior, venting requirements and other potential challenges that might arise during mold trials, mitigating risks that could cost additional time and money at the back end. The software can also be used to brainstorm solutions to molds already built by recreating the current conditions to understand what is influencing that current condition, helping our customers avoid costly troubleshooting, which wastes time and materials.
Why Westminster Tool Uses Moldex3D
Using a mold analysis is not standard practice for mold builders, as it typically lies within the responsibilities of plastics part design, but our team found that we missed opportunities to save our customers from having issues down the road.
Example 1: Using Moldex3D as a tool to troubleshoot a processing challenge.
Recently, Westminster Tool had a new mold to build for a customer. The task was an overmold material onto a case-shaped substrate designed with two gates, but performing a flow analysis was not within the budget for the project. Our team moved forward with the project at risk.
During the first off tool (FOT) trials, the overmold material would not flow to the end of fill, ending up in a short shot. Nothing could be done to process around this issue at the customer’s facility. At this point, Westminster got curious and tried to recreate the problem in Moldex3D. The current condition of non-fill was seen through the analysis, with the main cause of the problem being too long of a flow path for the thickness of overmold material.
The results of the flow analysis led us to concurrent design, where we analyzed the effects of adding more injection locations to reduce the flow length of each to a reasonable amount based on the pressures seen in the existing mold. From the evidence gathered from Moldex3D, more gates were added to the part with an extended lead time and cost after the first FOT (first off tool) trial. During the second round of FOT trials, the overmold was able to fill the necessary volume, leading to a successful part. This example shows the importance of running a basic analysis at the DFM phase of a project. Running this analysis can mitigate risks that may not manifest until components are built and the part is molded.
Example 2: Using Moldex3D to predict material behavior during DFM.
In another example, we used the capabilities of Moldex3D during the start of a new threaded cap project, in which our team identified two challenges. The challenges found were an unknown part shrinkage and a flatness tolerance on the top face. Moldex3D was used to determine optimal process conditions and realistic shrinkage and warpage results using different pack pressures/times, cooling times, as well as gate designs.
The results of the analysis showed us that the original hot tip design would result in higher warpage at the top face, due to the amount of hot material in the part. The decision was made to utilize a valve gate, as the molten core of the part would be smaller, leading to less warpage on the critical top face. In this stage, we compared the part to the original CAD model, with a realistic shrinkage value and a steel safe plan put in place in case of failing flatness.
During molding trials, the warpage seen aligned with the warped model from Moldex3D and was within an acceptable tolerance. This is an example of how the risk of molding an unacceptable part can be mitigated by understanding how the plastic part will behave during the DFM stage of a project, where a plan can be put in place to mitigate that risk.
The images above show the warpage of the top plane of the part in the hot tip (left) and valve gate (right) scenarios, which was critical to part function. The color scale shows a maximum of ~0.030” with the hot tip, and ~0.015” warpage inward toward the threads of the part. This difference drove the decision towards the valve gate.
Moldex3D Analysis – A Crucial Step in the DFM Process
Moldex3D is a crucial part of our DFM process. With this simulation software, our design team can see the big picture overview of how the plastic will perform, as well as details that could cause defects. This information helps us to understand how the complete molding cycle will look and how the part is going to cool and warp.
Through everything we do, our motivation is centered on helping us accomplish our goal of creating quality solutions and lasting partnerships with our customers. Moldex3D provides another example of how our team found an opportunity for continued innovation to better meet the needs of our customers.
