GMT, a granddaddy of thermoplastic composites, has had slow market penetration since its commercial roll-out by PPG Industries and GE in the 1970s and 1980s. There was some penetration in automotive bumpers and load beams, but PPG and SABIC (which had bought GE Plastics) sold the business in 2007.
Now comes news of a major automotive interior application, portending, wider use because of its potential to replace steel assemblies in structural applications.
Ford is using compression molded GMT to replace a five-piece steel structural assembly in the second row seatback of the 2015 Mustang. The one-piece plastic assembly reduces weight and costs while meeting “extremely challenging” luggage retention requirements.
Ford says that the thickness of the structure is also reduced by 8 mm, allowing more foam that increases the comfort level for passengers.
The GMT (glass-mat thermoplastic), uses 45 percent glass-reinforcement. There are no steel reinforcements, as there were in a previous structural GMT by Audi in a different application.
The parts are molded in Conneaut, Ohio by Continental Structural Products in a fully automated line with precision charge placement utilizing laser locators for the positioning of GMT sheets. Two 462 x 457 mm sheets are stacked with glass fibers aligned perpendicular to each other. Total cycle time is 98 seconds; actual molding time is 56 seconds.
The savings in tool costs are estimated at $400,000. Weight reduction is 3.1 kg per vehicle. Other benefits include:
- Elimination of welding and related inspection requirements,
- Elimination of sharp edges,
- No rust potential,
- Easier installation,
- Material is recyclable, and
- Supply chain transportation costs are reduced.
The material supplier is Hanwha L&C, a South Korean company that bought Azdel in 2007 and further developed IXIS, a plastic it describes as stronger than iron. The plastic matrix is polypropylene. Azdel was a JV of PPG and GE before its sale to SABIC and then Hanwha, which operates a recently expanded GMT plant in Virginia.
Continental Structural Plastics earlier this month completed the acquisition of Magna’s automotive composites business as it grows its role in the composites business. CSP says it is now the world’s largest SMC compounder and manufacturer. SMC is a thermoset composite that competes with GMT. Compression molding machines included in the Magna deal range in size from 175 tons of clamping force to 4,000 tons. GMT can be molded on SMC machines, although the processes are different.
CSP is headquartered in Auburn, Michigan and is a major automotive Tier II.