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Unilever and Serioplast save 90% on costs with 3D printed packaging molds

Leveraging 3D printing for blow molding tools has dramatic time and cost advantages

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Like many companies, Unilever—the fast-moving consumer goods company with brands like Dove, Persil and Ben & Jerry’s under its umbrella—has turned to additive manufacturing for its prototyping needs. However, rather than print prototypes of its product packaging directly, it has taken an alternative route, leveraging SLA 3D printing to produce blow molding tools. This approach, which it has taken in partnership with packaging manufacturer Serioplast and Formlabs, has dramatically cut product development cycles for new plastic bottle packaging and tooling costs.

Prior to this new prototyping method, Serioplast would 3D print packaging prototypes directly or order metal tooling for blow molding prototyping. Both these process had their limitations: directly 3D printed prototypes could not match the transparency or feel of the final product, and metal tooling for blow molding prototypes came with long lead times and high costs. As Flavio Migliarelli, R&D Design Manager at Serioplast, said: “We have to wait six to 12 weeks before we can give a client the real sample, so we’re wasting so many weeks just to try a new bottle design. Sometimes it’s demanding and frustrating because maybe you have to start again.”

By 3D printing the molds for the stretch blow molding process, however, the companies can now create realistic packaging prototypes that cut those lead times by six weeks and reduce costs by up to 90%. The blow molding process itself consists of placing a plastic preform (such as PET) into a mold and inflating it to conform to the mold’s geometry. Stretch blow molding is a specific form of this technique that is standard across the packaging industry to make anything from water bottles to dish soap containers.

Unilever Serioplast 3D printed packaging molds

While highly effective for mass production scales, blow molding has traditionally not been economically viable for low-volume or prototyping applications due to the high cost of metal tooling (ranging from $2,000 to $100,000) and the time associated with having to outsource tooling (it should be said that even in-house tooling using CNC machining can take several weeks). In an industry like fast-moving consumer goods especially, where design innovation and marketing are vital, this slow pace and inflexibility are a roadblock.

3D printing was a clear solution to this problem, however Unilever and Serioplast had to find a suitable process and a material that could withstand both the pressure and heat generated in the stretch blow molding process as well as maintain dimensional accuracy and overall stability. This led them to Formlabs, which presented its Rigid 10K Resin, a glass-filled photopolymer with an HDT of 218°C and a tensile strength of 10,000 MPa.

Using a combination of this material and Formlabs’ SLA technology, Serioplast was able to produce blow mold tooling within just two days and accelerate the time to start pilot testing (from six weeks down to two weeks). This is in combination with the ability to create highly realistic packaging prototypes made from the same material used for finished products and to pilot test multiple different designs at once. “With the 3D printed mold, we can save up to 70% time and 90% cost compared to the standard mold. In the past, [clients] had to wait up to 12 weeks just for one design, now we can make five designs,” said Migliarelli.

Unilever Serioplast 3D printed packaging molds

There are also other benefits to using 3D printing in the production of blow molding tools. For example, Serioplast can more easily validate the blow molding process and the PET preforms it uses. Migliarelli explained: “We are using the same process window as with a standard pilot mold. This is super good, because we can test the final process windows and see what happens to the bottle. We are talking about up to 30 bar pressure. It’s absolutely good and reliable on that. We are also talking about 100 °C heating for the preform, without any wearing on the cavity of the 3D printed mold.  We could produce very easily up to 100, 200 bottles every day. We can go up to 1000 with more time.”

The prototypes made using the 3D printed molds also have the benefit of allowing Unilever to test and improve elements of its production line before going into full-scale production. Thanks to the high-degree of fidelity between the prototype and the final part, the prototype bottle can be tested in terms of filling, capping, packing and more. Overall, this innovative use of 3D printing is solving challenges that direct 3D printing and traditional tooling simply couldn’t. “The big impact we have with the 3D printer is the possibility to have your dreams come true,” concluded Stefano Cademartiri, CAD & Prototyping Owner at Unilever. “Something that’s on your screen is in your hands in a couple of weeks. A real product, with a real bottle, with a real cap, and a real label.”

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Tess Boissonneault

Tess Boissonneault is a Montreal-based content writer and editor with five years of experience covering the additive manufacturing world. She has a particular interest in amplifying the voices of women working within the industry and is an avid follower of the ever-evolving AM sector. Tess holds a master's degree in Media Studies from the University of Amsterdam.

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