Software updates slash carbon-fiber cure times

Behind the glory of being an innovator is the arduous process of being the first to figure out how to deliver something new. Michigan-based Plasan Carbon Composites knows this firsthand as a supplier of carbon-fiber components for the automotive industry.

Carbon fiber has been around for decades in expensive supercars and airplanes, but it’s still relatively new to mass automotive production. The composite material uses a base of plastics that are mixed, spun into fibers, and carbonized through a heating process that can exceed 5,000°F.

Carbon fiber’s lightweight and high-strength characteristics create higher-performing wind-turbine blades and commercial aircraft that are 20% lighter than aluminum-based designs. Applied to automotive vehicles, carbon fiber lowers vehicle mass, improving gas mileage.

Limiting its appeal to mass-market producers has been a series of technical manufacturing challenges:

• Expensive raw materials
• Time-consuming curing process
• Environmental conditions requiring careful monitoring, management
• Scrap often not reusable, recyclable

Improving processes

Plasan is helping push automakers toward higher adoption. The company already produces carbon-fiber components such as hoods, roofs, and side panels for popular performance vehicles such as the Chevrolet Corvette, Dodge Viper, and Ford Mustang. The company is mixing research and development, proactive development of engineered solutions, and automated manufacturing processes to pioneer carbon fiber mass production.

Traditionally, large pressure vessels known as autoclaves have been used for curing carbon fiber. But cycle times can be as long as 90 minutes, making them too inefficient to meet production targets for vehicles such as the Corvette Stingray.

The solution – first-of-their-kind pressure presses at a new 200,000ft² production facility outside Grand Rapids, Michigan. The high-speed presses abandon the autoclaves’ convection mass-heating process and use proprietary technology to directly heat the tool mold surface for faster heat transfer to the carbon fiber.

The presses reduced curing time from 90 minutes to less than 20 minutes, among the fastest curing times in the world for the production of Class A, carbon-fiber vehicle components.

Scrap problems

While cure times improved dramatically, pressure presses introduced new, complex process variables not experienced with autoclaves. The presses had no means of capturing and logging process data, so production personnel had no means of doing historical analysis of press cycles or identifying product issues with process data.

“The press process was highly variable, and we needed to straighten it out,” says Danny McKinnon, controls engineer for Plasan Carbon Composites. “My biggest challenge was being blind to what was happening on the off shifts. I couldn’t see what happened, and that limited my ability to troubleshoot and resolve issues.”

Variability in the presses led to higher-than-expected scrap and quality defects within the parts. This slowed production and created significant production losses, with scrap carbon-fiber components costing the company capacity and causing delivery issues.

Plasan turned to Rockwell Automation to help troubleshoot the problems. The goal was to implement software that could serialize and track each vehicle part going through the presses, and record and report process parameters within the equipment. The target – drive scrap to less than 4%, down from autoclaves’ historical 10% rate.

Plant managers implemented Rockwell Automation’s FactoryTalk Historian Site Edition (SE) and FactoryTalk VantagePoint EMI (enterprise manufacturing intelligence) software. FactoryTalk Historian SE captures process variables as each product goes through any of the facility’s seven presses. A serial number for each product, created by Plasan’s manufacturing execution system (MES), allows the Historian to associate process data to each part. VantagePoint EMI software uses this information to deliver real-time quality and performance dashboards and Microsoft Excel-based production reports.

With his process and quality teams, McKinnon can use the software to monitor products and 15 press process settings. If quality issues arise, managers can review process settings to investigate and remedy potential issues. Additionally, operations personnel can use daily production reports for each press to review key metrics, such as average cycle times and overall equipment effectiveness (OEE).

Results

With the ability to track parts and processes, scrap rates at Plasan fell more than 50%.

“There are so many variables to our process that it had seemed almost impossible to figure out,” McKinnon says. “The Historian software helped our team track each variable to finally see a pattern as to why we were getting scrap parts. It’s greatly reduced our scrap in the press room and is setting a new standard for quality in our plant.”

Operators also use the software to better coordinate production by reviewing cycle times to understand exactly how long parts should be in the presses, then use that information to set up schedules and staffing.

More than 70,000 carbon-fiber vehicle parts have been serialized and stored since implementing the software, helping the plant produce more than 400 carbon-fiber components per day.

The company is also extending Historian software use to other areas of production. The software tracks temperature and humidity in the plant because raw material must be kept cool and within specific temperature and moisture ranges. Otherwise, the material can dry out and become unmanufacturable.

“Temperature changes can create dry lines of the individual carbon fibers, which greatly affects part quality,” McKinnon says. “We then have to address imperfections in our finishing area by Dremeling out the dry lines and filling them back in, which is a long and tedious process. This is just another area where the Historian software can help us refine our processes and drive up quality.”

For McKinnon, additional uses for the software have been a bonus.

“I initially wanted a Historian solely so I could look at last night’s cycles to see what happened,” he says. “I wasn’t even thinking about what else historical analysis could do for us. But getting our hands on it and exploring its different uses has opened my eyes to what we can really do.”

www.plasancarbon.com

www.rockwellautomation.com