Thermoplastic engine cowls set molding record

July 8, 2004
Injection-molded thermoplastic engine cowls for Mercury Marine, Fond du Lac, Wis., Verado outboard engines weigh about 70% of equivalent thermoset SMC (sheet-molding-compound) parts and cost 46% less to make.

Injection-molded thermoplastic engine cowls for Mercury Marine, Fond du Lac, Wis. (www.mercurymarine.com), Verado outboard engines weigh about 70% of equivalent thermoset SMC (sheet-molding-compound) parts and cost 46% less to make.

The cowl parts of Zytel and Minlon nylon resins from DuPont Engineering Polymers, Wilmington, Del. (www.dupont.com), are finished in a threecoat system that gives first-pass acceptance yields of 95% or better at each stage, according to Mercury Marine. In contrast, SMC cowling parts used in the company's other marine engines need filler, primer, and two finish coats. Painting yields are low using this approach because each coat requires multiple passes to fix defects caused by porosity and solvent popping.

The scoop-shaped top cowl of 33% glassreinforced Zytel nylon is said to be the largest component ever injection molded from the material. The rear cowl is also molded from Zytel and the front of DuPont Minlon mineral/glass-reinforced nylon for added flatness. The lower cowling consists of two parts molded from DuPont Surlyn Reflection Series supergloss alloy and needs no paint. Bemis Manufacturing Co., Sheboygan Falls, Wis. (www.bemismfg.com), molds the six parts.

At the annual Product Design Competition sponsored by the Society of the Plastics Industry's Structural Plastics Div., the engine cowl won the Conference Award, the People's Choice Award, the IDSA/Plastics News Design Award, and was also recognized as the most innovative entry in the competition's Recreation and Leisure category.

— Lawrence Kren

Sponsored Recommendations

The entire spectrum of drive technology

June 5, 2024
Read exciting stories about all aspects of maxon drive technology in our magazine.

MONITORING RELAYS — TYPES AND APPLICATIONS

May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

Solenoid Valve Mechanics: Understanding Force Balance Equations

May 13, 2024
When evaluating a solenoid valve for a particular application, it is important to ensure that the valve can both remain in state and transition between its de-energized and fully...

Solenoid Valve Basics: What They Are, What They Do, and How They Work

May 13, 2024
A solenoid valve is an electromechanical device used to control the flow of a liquid or gas. It is comprised of two features: a solenoid and a valve. The solenoid is an electric...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!