We take sustainability very seriously.
At this stage of the game, it's crucial that we all take seriously the need for sustainable product packaging solutions for all of our customers in packaged goods verticals. As the global leader in polymer thermoforming and automation, BMG has been hard at work helping our partners with sustainable solutions for their customers’ needs. We have been discovering and vetting new ways to be green without sacrificing function in response to the growing demand for recyclable, eco-friendly product packaging.
As a viable material solution, polypropylene has been a highly sought-after material for thermoforming processes. Many manufacturers are switching to this cost-effective, highly recyclable material, especially in food packaging. Polypropylene has long been approved for food contact by the FDA, offers incredible design flexibility, and is known worldwide for its durability and lasting performance. All of these factors have led manufacturers to migrate to this material to be part of a more carbon-neutral future that has had a lasting positive impact on their ROI.
Many manufacturers are forever lost in the switching matrix, trying to weigh the cost of migrating to Polypropylene and how it will affect the bottom line. The pros and cons are self-evident. Let's look at what it takes to transition to a Polypropylene environment. Listed below are the top ten items one needs to consider when switching over to Polypropylene as a manufacturing substrate:
1. Polypropylene has higher expansion and shrink rates.
2. Know your material filler and how much to use.
3. Increase blow form.
4. Increase thermoformer oven stops.
5. Roll-fed thermoformers require material preheating.
6. Superior material heating from inline extrusion.
7. Decrease trim mold die clearances.
8. Heat trim knives.
9. Increase mold cooling.
10. Review product design.
Now that we have noted the different variables that you need to consider in the transition process as they relate to polypropylene, we can dive deeper into what that means and what you need to consider in your decision to make the leap.
Shrink Rates: Polypropylene has a typical shrink rate of up to .015 per inch. This is higher than what you would traditionally experience with HIPS (High Impact Polystyrene) or PET (Polyethylene terephthalate). This makes it necessary for you to review your product and mold design to ensure that the different expansion and shrink rates are accounted for. As in any of these processes, a qualified BMG expert can assist you in this evaluation and get you the data on acceptable ranges of tolerances.
Material Filler: Talc is the common filler for Polypropylene material, but it is important to know how much talc has been added to your material. Talc filler at 10% or less generally does not incur excessive wear on your tooling or extrusion equipment. However, a filler rate of greater than 10% can cause premature wear and be an issue. Replacing worn components in tools and extruders can be costly in the long run, but simple material monitoring can reduce exposure to this.
Blow Form PSI: The molecular orientation of Polypropylene material during the thermoforming process can vary. Polypropylene may require more stretching and orientation within the tool, necessitating higher psi for finer product detail. The minimum blow form required is 100 psi.
Maximum Oven Stops: Polypropylene has a lower coefficient of thermal expansion than polystyrene, which means that it may not expand as much during the heating phase. Using additional oven stops in the thermoforming machine extends the plastic material's heating or curing time. Recommended oven stops are 5 stops for post trim and 4 stops for Form/Cut/Stack applications.
Preheating Polypropylene: As stated above, Polypropylene’s molecular orientation can vary. It is easy to have distortion in the heating, causing hot spots, uneven thickness across the sheet, and even material degradation. If the material is not fully cured or heated, the expansion of the molecules will affect your finished product. If your thermoforming machine’s oven is too short to heat your roll of material thoroughly and evenly, a preheater can extend the heating process of the sheet.
Inline Extrusion: Inline extrusion is the suggested or preferred method of introducing Polypropylene material into the thermoformer. This is when the extruder melts the plastic pellets into sheets, and the heated material is fed directly into the thermoforming machine's infeed. The extruder has heated the sheet to the ideal temperature, and the molecules are fully expanded. This is an expensive method and is dependent on product volume and mix.
Decrease Punch and Die Clearance: The expansion and shrink rates of heated Polypropylene affect your trim tools. Match metal (post-trim) applications require a die clearance from .005” to .0025”. The most common clearance used for dies is .0025”.
Heated Knives: Form/Cut/Stack trim molds use steel rule or forged knives. Since Polypropylene is more flexible and durable, trimming products is more complicated. Heating the knives provides a superior trim.
Mold Cooling: As discussed above, polypropylene requires more heating to cure the material properly. Because the material is coming into the mold hotter, the mold requires additional cooling to form and cool the product. Molds should be designed to remove 25% to 50% more BTUs per hour than a traditional HIPS tool.
Product Design: As previously mentioned, polypropylene is a different material to heat and cool. It is more flexible, and durable, and has different expansion and shrink rates than similar materials. The trim tool die clearance, blow form psi, and mold cooling require review. Be confident that you have thoroughly reviewed your tool to form the best product possible.
Switching thermoformed materials can be daunting and involve many complex challenges. BMG prides itself on its ability to partner with clients and assist them through the entire process. We highly recommend that our clients contact one of our process engineers so they can provide a road map for getting their machine running at peak efficiency and producing the best products possible in the market.
BMG has found that one of the critical aspects of developing a viable solution for transitioning to a more sustainable packaging and the engineering to manufacture it is to develop all solutions concurrently with our partners. This linear development facilitates cross-departmental collaboration by allowing the processes of design, engineering, execution, and artwork development, simulation, and validation to run concurrently. It also ensures that quality, regulatory compliance, and package performance are maintained in the development stages. This is why BMG works from the vantage point of providing its customers with solutions from a holistic point of view. It’s better to have an understanding of the entire process so that you don’t inadvertently compromise the gains you make in pursuing a sustainable solution.
Sustainability, mainly focused on the regulatory and public concerns around single-use packaging waste, combines with other influential trends to drive significant changes in consumer packaging. Regulators are actively moving on this issue, and fast-moving consumer goods (FMCG) companies and retailers are proactively making bold commitments to improve both the sustainability of their packaging and fundamentally rethink their packaging systems. Polypropylene is a step forward in the sustainable packaging paradigm.
What we do and why we do it
Material choices have the potential to dictate performance, durability, sustainability, and the impact they will have on the environment and the ever-evolving consumer preferences model. In the end, Polypropylene is a good choice for the planet. BMG’s engineering of a symbiotic relationship between innovation and sustainability is essentially the attention given to selecting materials that aid in creating unique pathways towards an enduring process with less environmental impact. A process where excellence in design converges with a conscientious commitment to the environment and, ultimately, consumer satisfaction.
Think green
Be reassured that we are all about the success of our clients, but not at the expense of the planet. We carry our concerns everywhere we go, and this thought impacts everything we do. In the future, we will be developing better ways to power everything we do in thermoformed packaging so that we can all be proud of the changes we are making for the good of the planet. We are constantly striving towards minimizing our exposure to the detriment of our world, developing technology that uses environmentally friendly energy materials, and striving to create technology that lessens our and our customers' carbon footprint. The consumer has been calling for it, the government is busy regulating
it, and manufacturing needs to pull the band off and prepare for the wholesale changes just around the corner. We live on this block and around the corner. We know what's coming, and our incredible new product line is the future.