Many different cosmetic defects can make plastic parts unsuitable for use. Weld lines, small scuff marks, and other issues may not detract from part performance, but consumers won’t want to purchase a product that has visible imperfections.Overcoming these cosmetic defects, then, is just as important as dealing with other issues.
Dealing with cosmetic defects once meant physically inspecting every part. The downside to this is that it unnecessarily inflated labor costs related to production. Today, however, computer simulations make it much easier to determine what cosmetic defects may appear, where they are likely to be found, and what the cause might be. The simulations decrease the amount of prototyping and quality checks required and reduce total cost of ownership. Scientific Injection Molding also allows tight management of manufacturing tolerances, and when implemented effectively, greatly reduces the chance of cosmetic defects.
The Challenges of Eliminating Cosmetic Defects
There are a variety of different challenges you may face when trying to eliminate cosmetic defects. Material selection may lead to inherent cosmetic risks, creative design features may increase the risk of defects, packaging choice may lead to damage during shipping, and defects may develop over time as the mold wears.
Then there is the fact that cosmetic defects are often not easy to quantify. They may appear inconsistently, and it may seem nearly impossible to reproduce them on purpose. The data involved is very inconsistent, making it difficult to characterize the defects and determine their cause.
Because of these factors, even advanced computer simulations aren’t always able to determine what types of cosmetic defects you may face. Technology is advancing, however, and these simulations are getting much better. Today, you’ll find that you can eliminate many defects using simulations rather than prototypes, saving time and other resources.
The Four Crucial Aspects to Explore
There are four main aspects of a part’s cosmetic look that need to be addressed to eliminate as many cosmetic defects as possible.
The Process. Different processes may lead to the creation of the same part, but these processes are not necessarily equal when it comes to cosmetics. Some methods may result in jetting, for example, leaving blemishes in the final product, while using an alternative process may not. Simulating various processes can give you an idea of the pros and cons of each and alert you to potential defects.
The Material. The material used to create the part also plays a significant role in the final cosmetic look. Some materials are more apt to show defects than others. The fillers used in some plastics also have an impact on defects and the final appearance of the piece. Simulations can be done to determine how likely one material is to show certain defects and to look at things such as weld lines. Engineers can run “what if” scenarios that look at different pressures, temperatures, and materials to determine the best combination for the part.
Part Geometry. By running numerous simulations on the part size, shape, thickness, and other variables, it’s possible to determine the best part geometry for both function and appearance. These simulations can be used to identify factors such as the perfect mold fill and the fill rate. Uniformly filling a cavity with the optimal amount of plastic can impact the final cosmetic look in a variety ways.
The Design of the Mold. Mold design is the fourth factor related to cosmetic design. The gate thickness and area and shear rate can be adjusted to help reduce possible errors. Engineers can run simulations to determine which option reduces the chance of defects the most.
Overcoming Cosmetic Defects with Simulations Reduces Time and Resources
Using computer simulations allows you to significantly reduce the time and the work involved in creating parts with no cosmetic defects. Highly cosmetic parts come with many challenges related to color and finish. You have to work out the perfect approach and look at a variety of factors to determine the best combination for optimum surface quality. Any change in the material or other variables can result in running a new series of simulations.
By focusing on the four critical factors related to cosmetic defects – the process, the material, the part geometry, and the design of the mold – it is possible to reduce or nearly eliminate cosmetic defects.
If you’re in need of high quality cosmetic components, New Berlin Plastics can help. We partner with many companies to provide custom injection molding that is both functional and aesthetically pleasing. Our simulations help us determine the best combination of materials, mold, and process to deliver the parts you need.