If you’ve ever visited a plastic manufacturing facility, even just through a trade show or a quick online deep dive, you’ve probably stared at rows of large, humming machines that turn thin plastic film into crisp, sealable bags—those side-sealing pouches you see holding everything from frozen veggies to small parts. As a supplier of side sealing bag making machines, I get dozens of questions every week, and one comes up more than any other: “Can your machine actually work with recycled plastic materials?” It’s a fair question, and honestly, it’s one that’s only gotten more urgent in the last three years. Between rising plastic waste volumes, stricter global sustainability laws, and brands’ pledges to use more recycled content in their packaging, the line between efficiency and environmental responsibility has blurred for good. Let me break down exactly how this works, the challenges, what we’ve built to solve them, and why this isn’t just a trend—it’s the new baseline for modern bag production. Side Sealing Bag Making Machine
First, let’s get clear on what a side sealing bag making machine does, and why it’s different from other bag machines (like bottom-sealing or stand-up pouch machines). A side sealing machine takes a continuous roll of flexible film, feeds it through a series of rollers and guides, cuts it to length, and applies heat or pressure to the two vertical sides to seal them shut—no bottom gusset, no top zip (though many can be outfitted to add zippers later). This design is simple, fast, and versatile, making it one of the most common machines for producing flat pouches, bread bags, small retail bags, and even industrial liner bags. For decades, these machines were built almost exclusively for virgin plastic: high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), materials with consistent molecular structures, predictable melting points, and few contaminants. But recycled plastic? That’s a whole different ballgame.
The biggest challenge with recycled plastic is its inconsistency. When plastic is collected from curbside bins, industrial scrap, or post-consumer packaging, it’s rarely a single material. A bale of recycled LDPE might have scraps of HDPE, PP, even small bits of paper or food residue mixed in. Beyond that, recycled plastic has what’s called “melt history”—it’s already been melted and molded once before, so its molecular chains are shorter and less uniform than virgin resin. That means its melting point can vary by 10, 15, even 20 degrees Celsius from one batch to the next. For a side sealing machine, which relies on precise heat and pressure to create a seal that’s strong enough to hold contents, that variability is a major hurdle. If the machine’s heat is set too low, the seal will be weak, prone to breaking; too high, and you’ll burn the plastic, leaving holes or discolored, brittle edges.
I’ve seen this firsthand, early in my career as a machine supplier. Back in 2019, a mid-sized snack brand came to me with a problem: they wanted to switch 30% of their bread bags to recycled HDPE, but their old side sealing machine kept ruining batches. The film was streaky, the seals were failing 12% of the time, and they were wasting 800 pounds of film a week as a result. We sent our technician out to look, and within an hour, we saw the issue: their machine was built for virgin resin. Its heating elements were fixed, with no way to adjust the temperature in tiny increments, and its tension control system couldn’t handle the slightly thicker, more inconsistent recycled film. Virgin HDPE has a very uniform thickness, so the machine’s rollers could feed it evenly; recycled HDPE, with its mix of scrap, has small lumps and thickness variations that the old tension system couldn’t adjust for, leading to wrinkles that caused bad seals.
That experience became a turning point for our team. We realized that if we were going to supply side sealing machines that could work reliably with recycled materials, we couldn’t just tweak old designs—we had to rebuild them from the ground up, focused on the specific needs of recycled film. Let’s walk through the key upgrades we’ve made over the last four years, because these aren’t just small changes—they’re the reason our machines can now produce high-quality bags from 100% recycled plastic, no major batch failures required.
First, temperature control. We replaced fixed heating elements with modular, zone-based heating systems. A typical side sealing machine has three main heat zones: the pre-heat zone to soften the film before sealing, the main seal zone, and the cool zone to set the seal immediately after it’s formed. With our system, each zone is controlled by an independent PID (Proportional-Integral-Derivative) controller, which adjusts temperature in 0.1-degree increments, rather than the 5-degree jumps of older systems. That means if a batch of recycled PP has a slightly higher melt point than the last, the main seal zone can adjust on the fly, not wait for an operator to notice and change a dial. We also added real-time temperature sensors along the entire seal bar, so if a section of the bar overheats, it shuts off that spot instantly, preventing burnt plastic.
Second, tension control. Recycled film is often slightly more rigid than virgin, and its thickness can vary by up to 10% in a single roll (virgin film is usually within 2% thickness tolerance). Our machines use a closed-loop tension system that uses load cells to measure the film’s tension every 0.2 seconds, adjusting the feed rollers and take-up rollers to keep tension consistent, even when the film hits a small lump or a thickness shift. We also added a web guide system that uses optical sensors to track the edge of the film, correcting for any slight sideways drift—another common issue with recycled film, which is often less dimensionally stable than virgin.
Third, seal strength testing. One of the biggest risks with recycled plastic is that a seal will look good but fail under pressure, especially if the bag is holding heavy items or frozen goods. We built our machines with an integrated, in-line seal tester. As the bags are cut, a small pneumatic probe applies a specific amount of pressure to each seal, measuring how much force it takes to break it. If a seal is below the brand’s set threshold (we work with each customer to customize this based on their product), the machine automatically rejects that bag, so no bad seals leave the production line. We’ve also made this tester adjustable: for thinner recycled film used in small retail bags, we lower the test pressure; for thicker industrial liners, we increase it.
Now, you might be wondering: does this mean you have to buy a whole new machine to use recycled plastic? Short answer: no. We also retrofit existing side sealing machines with these upgrades, so if you already have a machine that’s running well on virgin resin, you don’t have to invest in a full replacement to start working with recycled. That’s been a big selling point for small to mid-sized brands that don’t have hundreds of thousands of dollars set aside for new equipment. We’ve retrofitted machines for clients that make bread bags, pet food bags, even medical waste liners, all with recycled materials, and the success rates are now on par with virgin production—we’re talking less than 1% reject rate, which is almost identical to what you get with virgin HDPE.
But here’s the thing: even with all these upgrades, there are limits to what a side sealing machine can do with recycled plastic, and it’s important to be honest about that. Not all recycled film is created equal. If you’re using “closed-loop” recycled plastic—meaning it’s scrap from your own production line, like trimmings from virgin HDPE that you melt and reprocess yourself—you’ll have the most consistent results. That’s the easiest place to start, and many brands start here before moving to post-consumer recycled (PCR) plastic, which is collected from consumers and sorted, washed, and reprocessed. PCR plastic has more variability, and if it’s not sorted correctly (e.g., mixing PP and HDPE), it can cause issues no machine can fix. But with the right screening and sorting process (we work with a number of recycling facilities to help them process PCR film that’s compatible with side sealing machines), PCR plastic works perfectly.
I also want to address a common myth I hear all the time: that bags made from recycled plastic are weaker, or look less professional, than virgin plastic bags. That’s just not true anymore. Last year, we worked with a specialty coffee brand that wanted to switch their 1-ounce sample bags from virgin LDPE to 100% post-consumer recycled LDPE. They were worried the bags would be wrinkled, or the seals would break when shipping hundreds of samples. With our retrofitted machine, they ran the recycled film at the same speed they used for virgin (120 bags per minute, which is a standard pace for mid-sized machines), and the resulting bags were identical: smooth, consistent seals, no visible difference from virgin, and seal strength that exceeded their internal standards for shipping. They ended up switching all their sample bags, and later their full-sized coffee bags, to PCR plastic, reducing their virgin plastic use by 85% in 12 months.
Another client, a regional grocery chain, used our new side sealing machines to produce their own produce bags from 50% recycled HDPE and 50% recycled LDPE. They wanted to avoid the cost of purchasing pre-made recycled bags, so they invested in two of our machines and now produce 50,000 bags a day, all on-site. They told us that not only have they cut their packaging costs by 12% (recycled plastic is often cheaper than virgin, especially with recent supply chain issues), but their customers have commented on the bags’ quality—no one can tell they’re made from recycled material.
Of course, there are still challenges on the horizon. As more and more brands switch to recycled plastic, we’re seeing demand for blends of different resins, like HDPE and PP, or even adding small amounts of biodegradable materials to improve sustainability. Our team is already testing our machines to handle these blends, adjusting the temperature zones and tension controls to accommodate the slightly different melt points. We also work closely with resin suppliers, helping them develop recycled plastic grades that are optimized for side sealing machines, rather than forcing brands to adapt their production to whatever resin is available.
So, to circle back to the original question: can a side sealing bag making machine produce bags from recycled materials? The answer is a resounding yes—if the machine is built or upgraded to handle the unique properties of recycled plastic. It’s not as simple as swapping out a roll of virgin resin for a roll of recycled, but with the right technology, expertise, and partnership, it’s a seamless switch that delivers on both performance and sustainability.
If you’re a brand looking to make the switch to recycled packaging, or a facility manager looking to upgrade your existing equipment, our team has decades of experience helping clients of all sizes. We don’t just sell machines—we work with you to test your specific recycled film, adjust the machine to your needs, and provide ongoing support as you scale your production. No two clients are the same, so we don’t offer one-size-fits-all solutions. We want your side sealing bags to be high-quality, cost-effective, and aligned with your sustainability goals, whether you’re producing 10,000 bags a week or 10 million.
If you’re ready to learn more about how our machines can work with recycled materials, or if you have questions about retrofitting your current equipment, we’re here to help. Let’s connect to discuss your specific needs and find the right solution for your business.
Courier Bag Making Machine References
- Plastics Industry Association. (2022). Technical Guide for Processing Post-Consumer Recycled Flexible Packaging. Washington, DC: Plastics Industry Association.
- European Flexible Packaging Association. (2023). Side Sealing Machine Performance for Recycled Polyolefins. Brussels: European Flexible Packaging Association.
- Zhang, L., et al. (2021). Melt Property Variability of Post-Consumer Recycled HDPE and Its Impact on Packaging Production. Journal of Plastic Film and Sheeting, 37(4), 321-342.
- Sustainable Packaging Coalition. (2022). Life Cycle Assessment of Recycled vs. Virgin Plastic Flexible Packaging. Portland, OR: Sustainable Packaging Coalition.
- International Organization for Standardization. (2020). ISO 15755: Flexible Packaging – Test Methods for Seal Strength of Side-Sealed Pouches. Geneva: International Organization for Standardization.
Zhejiang Ruitai Packaging Machinery Co., Ltd.
Zhejiang Ruitai Packaging Machinery Co., Ltd. is one of the most professional side sealing bag making machine manufacturers and suppliers in China, featured by quality products and good service. Please rest assured to wholesale advanced side sealing bag making machine from our factory. Customized orders are welcome.
Address: D6 Building, No.66 Tingchao Road, Shangwang Town, Ruian, Zhejiang, China.
E-mail: ruiandavid2020@gmail.com
WebSite: https://www.rtbagmachine.com/
