TK Precision Plastics (Shenzhen) Ltd. Yu Ling
Introduction:
Moldflow software is used to analyze the average volume shrinkage rate of products and simulate the injection molding process for the appearance parts of 3C products. By analyzing the flow of the injection molding process, the optimal gate position for the part is identified, and potential defects such as air traps and weld lines are predicted and displayed. In addition, by examining changes in injection pressure, clamping force, the filling process, temperature variations, and product quality during molding, the analysis helps process engineers identify defect causes before mold trials. This, in turn, allows for improvements in both the mold structure and product design, enhancing the success rate of mold trials.
Case Description:
As shown in Figure 1, the product is a speaker component, molded in a single color, and made from PC material.
The left image displays the 3D CAD file, while the right image highlights the shrinkage issue identified through Moldflow analysis.
This shrinkage occurs on the appearance surface, leading to significant aesthetic defects!
In this case, the severity of the shrinkage was an unforeseen defect that could not be predicted based on experience. If adjustments to the gate position and solution were made after the mold trial, it would result in increased mold development costs.
Reason for Product Structural Constraints?
The product’s structural design has already been finalized by the client, and changes to the appearance ID are not possible.
Analysis of Shrinkage Causes:
We analyzed several gate configurations, but none were able to mitigate the product’s shrinkage issue.
1. Improvement Solution:
The final proposal was to change the existing single-color product to a two-color molding process, without altering the client’s appearance ID.
Through Moldflow verification and comparison, the issue was resolved at an early stage, effectively preventing further complications.
The final product met the client's requirements.
Case Description:
Product Introduction: game console cover, molded in a single color, made from PC material.
The left image shows the 3D CAD file, while the right image highlights the shrinkage issue identified through Moldflow analysis.
Shrinkage and stress marks appear on the appearance surface, leading to significant aesthetic defects!
In this case, Moldflow analysis was used to predict and address the shrinkage issue before modifying the product. Stress marks were verified in advance, which shortened the mold modification cycle and reduced the number of mold trials.
Reason for Product Structural Constraints?
The product’s structure has already been finalized by the client, and changes to the appearance requirements are not possible.
Analysis of Shrinkage Causes:
The current product has a main wall thickness of 3.2mm, but some areas have a wall thickness of only 1.2mm. Visually, this indicates a high risk of stress marks on the surface.
The final proposal was to convert the existing single-color product to a two-color molding process, without altering the client’s appearance ID, followed by Moldflow verification.
2. Improvement Solution:
Verification 1: The shrinkage issue was improved with the two-color molding process, but the analysis still indicated the presence of stress marks, which were also observed on the actual product.
Verification 2: Since the issue had been predicted in advance, we promptly communicated with the client and added additional material to the local area of the injection. This approach aligned with the Moldflow analysis results and successfully resolved the aesthetic issue.
These products played a critical role in the project. Through early Moldflow analysis, we were able to control costs to a minimum.
By predicting product defects in advance, an average of RMB 100,000 in mold modification costs is saved per mold set.
By predicting product defects early, 3 mold trials are saved, reducing costs by approximately RMB 20,000.
For 20 similar products over the course of the year, the total benefit is 20 × (100,000 + 20,000) = RMB 2.4 million.
Using Moldflow
Moldflow allows for shrinkage rate analysis before mold production, enabling improvements to be made prior to mold opening.
Improvement Costs: RMB 0 to several tens of thousands (including quality adjustments).
Improvement Time: 0 to several days (as above).
Quality Improvement
Conclusion:
Through the two cases discussed, we’ve concluded that shrinkage and stress marks can be analyzed by average volume shrinkage. If the result is less than 2%, the product should not exhibit any significant issues.
From these two cases, we also emphasize the importance of considering the specific product and leveraging analysis data from Moldflow to provide professional advice. This allows us to predict shrinkage and appearance-related stress risks in advance.
Case 2: The product was changed from a single color to a two-color design. This resolved the shrinkage issue; however, despite the shallow grooves of the two-color design, stress marks were still present. The mold trial showed that the product still had stress marks. Through additional injection molding verification, it was confirmed that for two-color products, the second injection must be completely free of recessed areas to prevent stress marks.
Customer Feedback
All products are required to be lightweight, as lightweight design benefits both the environment and helps our customers reduce costs. However, this must be achieved without compromising quality, which presents a challenge for the industry. The goal we have always pursued is to find ways to minimize weight while ensuring product quality. In this process, Moldflow software will play a key role.
Business Scope
Component Solutions
