A team of top experts embarked on an intensive five-year collaboration to realize the complex and groundbreaking design of the incubator, resulting in new applications and technologies. “The development team consisting of MMID, VDL and Dräger continuously encouraged each other to do their best work,” said Chris Mulder and Wouter Arents of VDL Wientjes. The incubator has several innovations that could only arise because of the synergy between the various specialists.
The triangle of client, supplier, and MMID turned out to be a potent combination. “We created a work process that ensured the sum of our parts was greater than what each separate partner would have achieved by themselves,” explains Danker Kemper, designer Producibility at MMID. Chris Mulder, CEO of VDL Wientjes confirms: “Each development partner was challenged to push boundaries and to deliver truly innovative solutions. We didn’t always choose the easy way. But every step of the way, we had each other’s expertise to rely on.”
Comfort and safety
The design team, consisting of employees from Dräger, MMID, VDL Apparatenbouw, VDL Parree and VDL Wientjes Roden, faced many challenges in the development of the hybrid incubator, which combines open and closed care for premature babies. Drägers’ goal was to develop the best possible user-friendly design for all stakeholders. First of all for the baby, but also for care staff, the parents, and cleaners. Safety, comfort, and functionality were paramount. Every part of the device had to seamlessly fit onto the next, to secure the perfect climate for the baby. The developers had to keep in mind mechanics, thermodynamics, and overall tolerances. All these aspects made the development extraordinarily complex.
Crystal clear 3D hood
MMID and VDL Wientjes are old acquaintances. The relationship goes all the way back to 1992 when MMID contracted VDL during the development of a sunbed for Alisun. When Dräger was looking for a plastics specialist, the name of the company from Roden soon popped up. The new incubator consists mainly of transparent, crystal clear, flat surfaces. The previous version of the incubator was made entirely of polycarbonate, but due to the possible health risks, posed by the presence of Bisphenol A (BPA), this material was no longer suitable. The design team had to hunt for an alternative material that was both transparent and easily shapeable. After extensive research into various plastics, the team selected acrylate; a new material and technology for Dräger. The hood and sides of the previous version of the incubator had been injection molded, but this resulted in various problems. The mold had to be re-adjusted numerous times, and there was a high rejection rate.
Choosing the material was only one of the first steps for the team. A transparent sheet tends to form dents and bumps where it gets into contact with the mold, while the specification for the hood and sides was that they had to be crystal clear. VDL Wientjes developed an entirely new technology to achieve this. “We made sure the material only touches the mold at the edges,” explains Mulder. “The fact that the front of the hood is also 3D, curved over two surfaces, made things extra difficult. This usually can’t be achieved, but we found a way to support the material without it touching the mold, which allowed us to mold a 3D shape.”
Strictly speaking, that isn’t vacuum molding, explains Wouter Arents, head of R&D at VDL Wientjes, but thermoforming, an umbrella term for thermal shaping: “We combined two technologies.” This combination required a few adjustments. Arents explains: “We had to convert an existing machine. We also used a steel vacuum molding matrix, instead of aluminum, which has the same thermal regulation as injection molding matrix, with several tempering channels and enables you to give different zones, different temperatures. Behind the mold, there were several tempering devices with valves allowing us to assign different temperatures to the various parts of the mold.”
It was alright for the back wall of the incubator to be opaque. For this, the advice of VDL Parree, a specialist in injection molding and part of the VDL Groep was obtained. They chose injection molding with ABS, a form retaining thermoplastic with little shrinkage. This choice held another technical challenge because Dräger wanted a very thick back wall as that will provide strength. “Usually injection molding ends at around 4 mm. Go to 8 mm thickness, and problems arise,” says Mulder. The achieve the required wall thickness, the design team chose another new technique: MuCELL, which involves the controlled use of gas in its supercritical state to create a foamed part and which prevents sink marks caused by shrinkage when creating thick walls. “With this technique and thick walls, it’s better to use injection molding. MuCell isn’t a very new technology, but it had never been used for this kind of product.”
The arm, the connection between the hood and the bed section, and the backbone of the machine was in part developed and produced by VDL Apparatenbouw. The complexity was partly in the movement of the arm. Mulder explains: “The arm moving away from the device wasn’t possible, due to the silicone sealings between the hood and the rest of the construction. Therefore it had to be more of a dimensional movement, with a delay before closure, to prevent excessive build up in pressure in the incubator and to prevent too much noise.” He continues: “During rough handling, for example during transport, the hood needed to stay closed, but in the case of an emergency, it has to open with one push. There were many contradictions, but in the end, we realized them all,” says Mulder. Another challenge was the fixation of the moving parts.
Nearly every Friday, the VDL team traveled to the MMID office in Delft, and in turn, a delegation of MMID employees visited VDL locations on a regular basis to build models. “After which, we all went to Dräger to deliver or to do some testing. Working this way helped us get to get to production solutions derived from a concept quickly. You can directly test producibility,” says Arents, “That was the strength of our collaboration; close collaboration allows you to make decisions quickly. That was important to Dräger as well. They specifically chose to go for a triangular relationship with makers and developers because this allows you to take bigger steps in your development process then when you first go to a developer and after that to somebody that can produce your design. With this linear approach you run the risk that at the end of the development process, the producing party shoots down the plan because it turns out not to be producible. This project was a continuous solid collaboration, and the result is a real product of a collaborative effort.”