The Importance of Lot-to-Lot Consistency and How to Achieve it

The Importance of Lot-to-Lot Consistency and How to Achieve it

By Shell Polymers on Dec 23, 2021

The Importance of Lot-to-Lot Consistency and How to Achieve it

We've discussed the importance of resin quality but another vital consideration for converters is resin consistency. Not only does it make their operations run more smoothly, but it can also affect their bottom line. Inconsistent resin can lead to a host of problems that slow down lines and increase variations. A polymer supplier must use state-of-the-art machinery, procedures, and testing to enforce the highest product quality measures to achieve that consistency.

Why Does Consistency Matter to Converters?

Lot-to-lot consistency is a must for resin shipments because high amounts of variations can cause problems in production and the end products. For example, extruded films can have increased tearing if their resin is inconsistent. And no matter the process being used, converters will likely need to slow down operations to account for a resin that is different from their typical batch. After all, it's easier to work with resin that is consistently within specification versus something that shifts around within a range of specifications.

Of course, there are ways to minimize these issues on both the converter and supplier sides. For example, by testing and analyzing resin before it is shipped out. However, that kind of info has not always been comprehensive or openly shared. Plus, it can be difficult and costly to have the labs and employees needed for that level of analysis on site if you're not getting that information from a supplier.

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It can also be difficult to select a new supplier because of these very issues. How can you be sure a new supplier will provide the resin that your business needs? What kind of equipment do they use, and what processes are in place to ensure consistency? Let's dive deeper into what a supplier can do for converters when it comes to product consistency.

How Suppliers Can Ensure Consistency for Converters

How Suppliers Can Ensure Consistency for Converters

Converters should be able to expect similar resin shipments each time they place an order with a supplier. It is then the supplier's job to test the resin that is being shipped. That includes testing the additive levels, pellet size, color, dust concentration, presence of fines, melt index, and density. Analyzing the pellets in this way will help suppliers make sure they're sending the correct resin to their customers. It will also remove any guesswork from converters who have to test and analyze the resin when it gets to them.

Suppliers must test resins at a high frequency to keep lots consistent and to address quality issues. However, that is not always the case. Some in the industry test resin every four hours and adjust processes based on those test results. This kind of testing provides less real-time understanding of product quality and can become an issue for converters in the future.

As our industry continues to introduce more Industry 4.0 technology and technical analysis, the use of real-time measuring becomes a must-have rather than a nice-to-have. Imagine being able to measure several resin properties in real time and adjust processes alongside those results. A supplier with that ability will be able to ensure they're on-spec and adjust products if needed. For converters, this all leads to more consistent lots of resin as suppliers make real-time adjustments as needed.

This isn't some dream of the future; it's the here and now. It's part of the high-end equipment Shell Polymers uses in its plant to ensure lot-to-lot consistency. Why don't we take a look at what else our new plant has to offer converters?

Analysis Breeds Consistency

Analysis Breeds Consistency

From start to finish, we take steps throughout our production process to ensure consistency in our resin. This is particularly important in the finishing process. This is when we introduce additives to the resin and mix them into a homogenized material in our state-of-the-art blend silos. That resin is forced through dye plates and turned into pellets, and those pellets are sorted so that the right-sized pellets make it to customers.

To hit a high level of product consistency, we rely on our labs to analyze resin at three stages. Those stages include the properties of the ingredients that go into a product, the product streams mid-production, and the final resin.

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In our polymer science labs, we will provide a high level of transparency through detailed info about a product's mechanical properties. That data will be shared at the macro and molecular level with converters, so they fully understand what they are getting from us. After all, it's their resin, and converters should know what goes into it.

Finally, our qualification criteria are put in place to make sure we are giving a similar product to customers each time. This standard helps ensure things like density and melt index are the same as the previous batch. But the journey to quality doesn't end at analysis.

The Right Equipment Makes a Difference

The Right Equipment Makes a Difference

The best-in-class equipment we use at our plant ensures that resin is properly dosed with additives. Likewise, our blend silos play a critical role in homogenizing the pellets into an average product when it comes to specifications. From a supplier selection standpoint, it's important to realize that not all suppliers have blend silos, and this can lead to batches of resin with unusually high or low amounts of additives, among other issues.

To meet converter expectations and reduce any fear of new supplies, the pellets we create will be of the quality and grade they expect. To make that happen, we'll be using a state-of-the-art quality analyzer to get real-time measurements of the resin. This will enable our teams to quickly adjust as needed to create the right pellets and will reduce the reliance on slower methods such as sampling.

Our plant isn't the only location with these important solutions and processes. Resin batches can be contaminated during shipping, and that can lead to production slowdowns as supply issues get ironed out. To mitigate potential contamination, we are implementing direct-to-truck loading, required wash certificates, and a rigorous inspection program at our SIT yard. This will minimize how often the product is handled, making it less susceptible to damage or contamination.

When all of these processes are put together, it creates a well-oiled machine that focuses on product quality and consistency. We've built a plant that addresses the specific needs converters have told us about with regards to product consistency and quality.

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