- Improved high-speed handling due to unique one-piece fog-lamp bezel
- Integrated aero feature improves fuel economy
- Parts consolidation saves weight and reduces assembly time
A unique one-piece fog-lamp bezel with integrated wheel aero curtains saves nearly 1 lb/0.45 kg of weight and improves aerodynamics on the 2015 model year (MY) Ford Mustang. The component is injection molded by Flex-N-Gate Corp. using Luran S, an acrylonitrile styrene acrylate (ASA) resin from Styrolution. It is mounted below the bumper fascia on the front of the vehicle and helps improve fuel economy as well as handling while retaining the vehicle’s distinctive front end. The new part has been so successful that it already is being implemented on other Ford vehicles.
Integrated aero feature improves fuel economy
The part features vertical slots in front corners by left- and right-side fog lamps that function as dedicated air channels, capturing and directing incoming air to vents in the front wheel wells. As the high-speed curtain of air flows across the wheels, it reduces turbulence caused by wheel rotation, which aids fuel efficiency, increases downforce, and improves road handling and stability at higher speeds.
Parts consolidation saves weight and reduces assembly time
Traditional fog-lamp bezels have been multi-piece assemblies with 3-4 brackets and separate air ducts that had to be sonically welded to the bezel during a post-mold finishing step. However, by integrating the duct into the fog lamp bezel and the B-side of the fog-lamp bracket along with the park/turn lamp assembly, all functional benefits are maintained or improved while lowering mass 20 percent and reducing part complexity. In turn, this has helped Ford save 30-seconds assembly time at the company’s assembly plant due to elimination of the separate brackets. The idea for the integrated design came from Vince Carnes, release engineer at Ford who recalls he was benchmarking different vehicles to determine how many pieces made up various assemblies and thought that the fog-lamp bezel assembly could benefit from parts consolidation.
Demanding performance and aesthetic requirements
The part had to meet demanding performance specifications including both 49CFR Part 581/ECE R42 Low Speed Impact as well as GTR-9 Pedestrian Lower Leg (TRL) requirements. It also required dimensional stability over a broad temperature range and the strength to hold fog lamps without juddering during driving while also meeting noise/vibration/harshness (NVH) targets. Another important property was stiffness to prevent sagging across the 500mm/19.7-inch long, 450mm/17.7-inch tall, 240mm/9.45-inch deep part with 3.0mm/0.118 inch nominal wall. Further, the part needed good heat-aging properties, resistance to automotive chemicals and road salts, and resistance to ultraviolet (UV) radiation from sunlight, which is very important as this is an unpainted exterior part. During the two-year development period, all design and computer-aided simulation work, as well as physical testing, including wind-tunnel evaluation, was done in-house at the automaker achieving good correlation between predicted and measured properties.
Unreinforced, easy-flow, injection-molding ASA grade
Styrolution worked with both Flex-N-Gate and Ford to help identify the right material to meet design as well as manufacturing targets for the application. The grade chosen was Luran S 777K in black. This unreinforced, easy-flow, injection-molding grade provided very good physical and mechanical properties to meet the application’s requirements as well as cost targets. In addition it offers very good heat-aging properties, which protect against loss of mechanical and aesthetic properties caused by prolonged exposure to temperature fluctuations. It also features a special UV-stabilization package for enhanced weatherability to preserve part aesthetics even under heavy exposure to sun, wind, rain, ice, and snow. Due to its dimensional stability and minimal warpage, parts produced with this material also are able to meet Ford’s stringent gap requirements.
Final part weight for models with fog lamps was 0.890 pounds/0.404 kilograms and for models without fog lamps was 0.935 pounds/0.424 kg.
