Injection Molding Design & Process Optimization

Posted by Al Elger on Mar 26, 2013 11:30:00 AM

blank.pngScientific molding is the best way to deliver complex, high-performance parts. It is a highly precise, data-driven process that eliminates any guesswork and maximizes quality and manufacturability. Scientific molding is especially valuable when it comes to decisions about process optimization,molding and tooling design validation, and product quality control. This approach is superior to standard molding procedures because of the high level of scientific control utilized through upfront design of experiments, flow analysis, process monitoring, and quality control that can correct any process variations with-in seconds.

One of the most important steps in developing a robust injection-molding process is utilizing a design of experiments (DOE) on the mold.

The DOE process is a critical aspect of the scientific molding process. After considerable preparation and engineering regarding product design and process parameter selection, the DOE process is established—a big step toward optimizing the process.

However, to ensure consistent and repeatable production of flawless molded parts, the process extremes must be completely investigated and the injection mold evaluated before it’s called into action. This is how tooling weaknesses are identified and corrected. This is one of the most important jobs of the process engineer.

Both the tool engineer and process engineer thoroughly examine every aspect of the mold’s mechanical functionality to make sure everything works as designed, using the material settings provided by the supplier of the material to be molded. They then conduct short-shot testing to assess the dynamic pressure loss and, in a multiple-cavity mold, to check for any imbalance among the cavities. This step is also the stage for a crucial objective: establishing the rheology curve (or viscosity curve) to indicate the best fill rate and pattern.

After this, gate seal studies are performed from both the pressure curve and the weight of the sample parts to see if the gates seal fully, and at what point, on the mold cavity (or multiple cavities). Engineers examine the test parts from the processing extremes for any defects and record their findings along with recommendations for any adjustments in the process or the tool in order to correct the defects. They also record data on the melt temperature, fill time, mold temperature, coolant flow, cycle time, and pressure curves.

The parts then go to quality control for examination of their measurements, shot-to-shot consistencies, and overall quality. That information is used for any necessary adjustments to the tool, before new samples are made. The new samples then undergo the same quality testing, with necessary adjustments made again as needed. Once all the process parameters meet their performance ranges, the mold is ready for action and production process has been optimized.

Mold design and process optimization is vital for creating a highly efficient and low-cost production process by eliminating any problems or quirks before production starts—ensuring top quality and repeatability.

By understanding each phase of product development—especially mold design and process optimization—scientific molding engineers can build the most efficient and robust process possible for your product, saving money on upfront quality and speeding up throughput.

Topics: Injection Molding