Manufacturing

Going with the Flow

14 Sep, 2006 By: Michelle Nicolson

Healthcare company turns around a part redesign in a matter of days instead of months, thanks to CFD software.


VIASYS Healthcare is a company that understands the value of time. The organization develops, manufactures, markets and services medical devices used in respiratory care, neurology, vascular medicine, critical care and the medical and surgical products markets. These complex and high-tech products are designed for diagnosing and treating cardiopulmonary, digestive, neurological, respiratory and vascular disorders for neonatal, pediatric and adult patients -- health issues where time is of the essence and improved products can make a difference in a patient's recovery.

The company made a challenge to its team of R&D engineers: Redesign the flow generator, a key component of the company's nasal CPAP (continuous positive airway pressure) device that fits on the patient's nose to aid breathing. The company wanted a redesigned flow generator that would fit all the products in its ventilator line. This piece of plastic is tiny -- just .04" -- but vital to the ventilation system.

VIASYS engineers have used SolidWorks for their mechanical designs for about three years, then added STAR-Works CFD (computational fluid dynamics) software from CD-adapco two years ago. STAR-Works integrates into SolidWorks, so the engineers didn't have to import or transfer any data to run the tests. The team's latest challenge seemed like a perfect opportunity to test out the CFD software's capabilities.

figure
A CPAP device from VIASYS Healthcare.

The Challenge
"Because the [CPAP flow generator] is so small and injected-molded plastic, we didn't want to spend a lot of money creating and testing multiple product prototypes," explains Steve Han, a mechanical engineer in the VIASYS engineering R&D department. Instead, the engineers decided to simulate the flow conditions of their design with the software before a physical prototype was ever made.

In just a few days, Han and the rest of the engineering team were able to run 30-40 case studies on flow simulation using the STAR-Works software. The results from those tests enabled the team to optimize their design for best performance without testing a single physical prototype.

figure
VIASYS engineers tested the airflow through the CPAP design using STAR-Works.

Quick Turnaround
Using the CFD software produced immediate benefits for the engineering team in terms of time saved. Normally, testing the flow device would require creating a physical prototype and then testing in the company's in-house laboratory. After collaborating the results, the engineers would make adjustments to the design and start the process over again, repeating it until they optimized the design. But the CFD software eliminated the need for the multiple physical prototypes and testing.

"We could do the case studies in a couple of hours instead of a couple of months for product testing," Han says. Engineers could make their design changes in response to the CFD results, then simply run another case study almost immediately. The quick turnaround also saved money, and the capital that would normally be spent on testing could now be redirected to the tools to actually manufacture the part.

The R&D team was concerned about more than just time and money savings, though: Accuracy was very important for the design of this device given such small dimensions. "We made slight tweaks, but only one design," Han comments. "Even the first samples correlated to real-life conditions."

The part is in preproduction, months ahead of schedule, and Han credits the quick turnaround to STAR-Works. VIASYS Healthcare's management staff is duly impressed with the results and the hundreds of thousands of dollars saved in the redesign process. And that time and money saved will positively affect patients of the hospitals that will purchase the updated equipment much earlier than anticipated. That could help a lot of people breathe easier.


About the Author: Michelle Nicolson


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