5 Tips To Optimize The Injection Molding Process

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What does it mean to “optimize” your injection molding process? In a big-picture sense (and by nature, oversimplified), it means examining your process critically to create the most efficient, value-driven process possible. We’ll get more in-depth into the concept of injection molding optimization below.
It’s not that far a leap from other aspects of the molding process where you’ve likely heard “optimization” discussed before, such as with product design. An optimized design process takes relevant best practices into account. It then considers the physical engineering aspect of the overall production process, and, from there, pursues a better way of designing a product for maximum efficiency and bottom-line effectiveness.

It’s helpful to think of effective injection molding process optimization as a scientific procedure above all, totally driven by data and observation. A caveat here: This means that findings can potentially fly in the face of conventional wisdom or “accepted” ways of doing tasks — which is exactly why process optimization is critically important. If a set of rules or conventions could simply be applied to the process, and the process would work as well as possible, optimization wouldn’t be necessary. Unfortunately, it doesn’t always work that way. Fortunately, though, optimization is a well-regarded and researched practice.

Now that we have a baseline understanding of injection molding process optimization, let’s look at five tips for doing so.

1. Quality control via sample creation.

While quality control is, of course, a critical part of the overall molding production process, which usually occurs post-production, quality control for sample parts operates a bit differently. In pursuit of injection molding process optimization, sample parts can play a key role. They take the risk away from conducting testing and optimization by way of a full production run (where problems are only identified after the fact). Further, they allow you to get a better sense of your process and how your machinery is operating upfront, in a more controlled environment.

By evaluating a sample production process of a limited part run, you can get a firsthand look at how your full process will go, evaluating part quality, shot size, melt temperature of the actual batch of resin you have on hand (as opposed to what the resin is “rated” for) and more. The insights that you can gain from a sample run and a robust round of quality control review will often more than make up for the time and money you invest.

2. Mold testing and evaluation.

Examining the functionality of your mold as it works using your intended material can also yield major benefits in optimizing a molding process. The broad range of resin materials and formulations available means that slight differences in viscosity, melt temperature, mold temperature and more, can add up to cumulative fluctuations and variations in the molding process that can lead to rejected parts, an inefficient process and, overall, an unoptimized production run (meaning that somewhere, money is being left on the table). Some key aspects of mold testing are short shot testing, fill rate and pattern, and pressure curve assessments.

3. Tool testing and adjustments.

Once you have a usable sample size of information from your mold testing and sample part quality control, you’re then able to do the fine-tuning that can lead to big gains in process optimization and efficiency. For instance, if you encountered short shot issues or inconsistent fill times, you may be able to tweak the design and layout of the tool to optimize for these problems. If the mold temperature was inconsistent or out of an acceptable range, you can adjust for more optimal heating and cooling times. After putting in the work of sample creation and testing, this stage is where you can make the adjustments that lead to tangible results — in other words, the fun part.

4. Process parameter and performance ranges.

Every part of an injection molding process has acceptable performance ranges — from the machinery to the tool to the resin — and more. An unoptimized process is one that operates outside of these ranges, or even at the outer bounds of them. That’s right: Even if the components of your process are technically operating within range, your process may still not be truly “optimized” if you haven’t done the testing and fine-tuning to see if improvements are possible.

As you go through the above steps and use the tangible results of your testing to make incremental (or major) adjustments in process components, the results can start to add up until you’re seeing a real impact on your bottom line, your results and the value you’re able to offer customers.

5. Create or follow a given design of experiments (DOE) process.

Repeatability is one of the biggest factors in value and efficiency in the injection molding process — a repeatable process will yield reliable, acceptable part rates, can easily undergo troubleshooting, and allows the operator to be as aware as possible of how the process is working. As you conduct testing to optimize your injection molding process, repeatability is a critical factor to keep in mind there as well, and “design of experiments” is the “official” term for doing so.

“Design of experiments” essentially means that you’re executing your testing in a planned, structured and documented way. This means, any irregularities or other issues that are identified can easily be traced to their specific source. All too often, testing is done with a number of variables in an unreliable way (for example, at two extremes, rather than on a mathematically derived curve), which leads to guesswork as to the cause of any identified issues. In short, if you’re guessing at the cause of a problem that your testing identified, you’re not getting the full value of your testing efforts (and in fact, might not be getting any of the value). Design your testing experiments with as much rigor as you’d design a part, and you’ll be primed to reap the benefits.

Experience in injection molding design and process is one of the greatest tools at your disposal for an efficient and successful production experience. For more information about how you can optimize design and process for your product, contact RevPart today.

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