Case Study: Liebert

Controlling Costs, Meeting Complex Specs: How Pressure Forming from Profile Plastics Led to Part Success

The highly detailed ceiling-mounted plenum is lightweight, attractive, and includes an access door for periodic filter changes.

PROJECT AT A GLANCE

End Product Air-conditioning system for computer/server room
Services Pressure forming for plastic molded air-conditioner plenum and access door; vacuum forming for nine internal components
Industry IT
What option can you take for a part when your volume needs are uncertain? Liebert Corporation’s air-conditioning plenum was a complicated part that demanded ingenuity. Meanwhile, the project budget required a highly cost-conscious approach. After investigating a number of possibilities, Liebert chose Profile Plastics to rise to the challenge.

Challenge: How can you cost-effectively manufacture a ceiling-mounted part with numerous design complexities?

Liebert (today a business of Vertiv) solves power and thermal management challenges for IT-related environments. The company needed a ceiling-mounted plenum for a precision air-conditioning system. Complicating that need, however, were the various criteria that the plenum ultimately had to meet.

First, the possibility of condensation called for a material that wouldn’t rust or degrade in other ways. Plastic seemed to be a smart option in that regard, though there were still a number of challenges that a plastic manufacturer would need to overcome:

Cost-conscious tooling. Due to initial volume uncertainty and budget constraints, Liebert needed a lower-cost tooling solution, which made injection molding and its expensive tooling process a less viable option.

Daunting draw ratio. The part’s dimensions—24” x 48” x 9”—created a draw ratio outside the range of a typical pressure-formed part, which was another possible option.

Difficult undercut requirements. The part required a ½-inch undercut along a perimeter of 360°—a demanding specification for a plastic part.

Numerous additional needs. As a ceiling-mounted component, the part had to be lightweight and aesthetically pleasing yet also rigid and durable, especially the snap-in access door used for periodic filter changes.

Liebert received multiple bids, including one for injection-molding tooling that ended up being six times the tooling cost for the process that was ultimately selected: pressure forming with Profile Plastics.

Liebert received multiple bids, including one for injection-molding tooling that ended up being six times the tooling cost for the process that was ultimately selected: pressure forming with Profile Plastics.

Solution: A pressure-forming partner able to deliver a cost-effective part using innovative strategies

Working with engineers from both Liebert and toolmaker Le Bac Plastic Mold, Profile Plastics provided insights and design for manufacturing expertise that led to solutions like the following:

Taking a unique—yet still cost-effective—tooling approach. Tooling for the pressure forming process is inherently less expensive than options such as injection molding.

But because of this part’s challenging design and dimensions, along with the higher-than-usual 75 to 90 psi required for the surface detail, Profile Plastics took an innovative approach that included:

  • EPainstakingly calculating tool strengths in the design process
  • EDeveloping a series of wooden prototype tools prior to final tooling
  • EOpting for a final machined-aluminum tool, which allowed for more design flexibility (using inserts) and helped create excellent surface texture
  • EGoing a step further with tooling by developing a custom-engineered mold that could be hydraulically operated for successful part removal

Pushing conventional draw ratio limitations. Draw ratios of 3:1, for example, are common in pressure forming. But higher draw ratios create more potential for problems. The Liebert plenum and the sharp detail of its louvers, in particular, required draw ratios of 5:1.

Thanks largely to the use of those wooden prototypes (see above), Profile Plastics identified the ideal combination of louver depth, angle, and width for the part.

    Because of this part’s challenging design and dimensions, Profile Plastics took an innovative approach.

    Results: Lower tooling costs and a high-quality part to help test market potential

    For Liebert, the ultimate outcome was a success for reasons like these:

    Complex part challenges overcome, part specifications met. The pressure-formed plenum and access door met the needed tolerances—including the ±.020 for critical areas—and achieved both the necessary strength and desired appearance.

    A streamlined process with a simplified supply chain. Along with the plenum and access door, Profile Plastics vacuum-formed nine internal components in three molds AND provided value-added assembly services, shipping the finished part to Liebert ready to be installed.

    The right option for cost-effective market testing. Thanks to the lower tooling costs of pressure forming, Liebert could test the market potential without making major tooling investments.

    Interested in a more-cost effective solution for your plastic part? Just want to talk about your future thermoforming needs?

    Set up an introductory call with Profile Plastics.