When embarking upon material replacement initiatives in the name of sustainability and corporate social responsibility, a key factor in the decision making process - although we may not want to admit it - is cost. Ultimately, a solution that may check all of the boxes on other requirements becomes a non-starter if it results in a significant increase in raw material cost or requires a complete overhaul or replacement of existing systems and processes.
From yield, to output & capacity, to CAPEX, when evaluating options for rollstock supply into form fill seal processes, the ultimate cost goes well beyond the cost per pound. Continue reading to learn about 3 factors related to polymer selection that can impact the overall cost of your material replacement projects:
Yield
When evaluating yield for thermoforming and form-fill-seal processes, the density and weight of the chosen polymer plays a significant part in overall cost. Polypropylene has the lowest density & weight of all the polymers offering a ~30% decrease in density from PET and a ~13% density reduction from HIPS. For thermoforming and form-fill-seal processes, this is significant because material density directly correlates to the linear feet of extruded rollstock material for a given weight, thus impacting part yield.
Take the following example:
| Material | Density | Gauge | Width | Quantity (lbs) | Scrap | Linear Feet |
| PET | 1.33 | 0.020" | 30" | 1,000,000 | 15% | 2,777,780 |
| PS | 1.04 | 0.020" | 30" | 1,000,000 | 15% | 3,753,755 |
| XPP | 0.91 | 0.020" | 30" | 1,000,000 | 15% | 4,208,755 |
The above example shows that holding the variables of gauge, width and quantity (lbs) equal, there is an inverse relationship between material density and linear feet, in that a lower material density results in an increase in linear feet and vice versa. Because rollstock is purchased by the pound, put simply, lower density materials like PP give you more bang for your buck than higher density alternatives such as PS and PET. For thermoforming and form fill seal processes, this increase or decrease in linear feet directly impacts another component of the cost equation - part yield.
Output & Capacity
Similar to the inverse relationship that exists between material density and linear feet, an inverse relationship also exists between material density and part yield in thermoforming and form-fill-seal. Once again, holding all other variables constant such as gauge, width and quantity (lbs), a decrease in material density correlates to an increase in output, or part yield, and vice versa.
Take the following example which details the difference in output between the same quantity of three common materials used in thermoformed and form-fill-seal food packaging for various packaging formats:
|
Material |
Quantity (lbs) |
Estimated Application Part Yield | ||||
| Single-Serve Creamer Cups | Multi-Pack Yogurt Cups | Barrier Pudding Cups | Shelf-Stable Juice Cups | PC Condiment Cups | ||
| PET | 1,000,000 | 295,620,000 | 19,734,000 | 64,584,000 | 70,980,000 | 236,340,000 |
| PS | 1,000,000 | 379,000,000 | 25,300,000 | 82,800,000 | 91,000,000 | 303,000,000 |
| XPP | 1,000,000 | 424,480,000 | 28,336,000 | 92,736,000 | 101,920,000 | 339,360,000 |
Outside of the opportunity cost associated with the lower part yield for higher density materials such as PET and PS, this also presents a sustainability issue, as more raw materials must now be used to maintain the same level of output when, for example, switching from PS to PET. The opposite, however, can be said when switching to PP, as the decrease in density results in improved efficiencies vs PS.
Process Compatibility & CAPEX
This brings us to the third, and perhaps most costly, variable when it comes to evaluating options for material replacement - process compatibility. Compatibility with existing thermoforming and form-fill-seal equipment and tooling is possibly one of the most daunting challenges converters and brand owners face when tackling PS replacement whether it be for achieving sustainability goals or satisfying Proposition 65 concerns.
Ultimately, a solution that may check all of the boxes on other requirements becomes a non-starter if it requires the replacement of billions of dollars of processor owned systems and platforms. Even if equipment does not have to be replaced entirely, modifications to existing equipment represent a significant capital expenditure to the tune of $500,000 - $1,000,000+ per FFS line to achieve successful processing of alternative materials such as PET.
To help overcome this, XPP was designed to offer enhancements to key properties including improved stiffness and controlled shrinkage, to maintain that "snap" characteristic of certain FFS applications, in order to offer simple replacement of PS in thermoforming & FFS processes.
Initial XPP trials on production-scale form-fill-seal equipment typically used to process PS have resulted in:
- Excellent formability
- No trimming issues
- Compatibility with existing tooling
- No reduction in cycle times
- Maintain through-put
- Minimal setting adjustments
Thus, while alternatives often require significant capital expenditure in order to achieve successful processing, XPP solutions require minimal equipment modifications or CAPEX for equipment replacement, thus avoiding additional cost that would have otherwise been spent on unnecessary CAPEX, all while improving efficiencies, ultimately adding cost savings to the bottom line.
To learn more about how XPP compares to alternatives when it comes to the replacement of PS in form-fill-seal, download our Property Comparison Cheat Sheet today!
