Designfax weekly eMagazine

Subscribe Today!

Archives

View Archives

Partners

Manufacturing Center
Product Spotlight

Modern Applications News
Metalworking Ideas For
Today's Job Shops

Tooling and Production
Strategies for large
metalworking plants

Wheels:
Kenworth beefs up simultaneous design and manufacturing

The Class 8 Kenworth T680 sets new standards for the company in integrating simultaneous design and manufacture.

 

 

When engineers at big-truck maker Kenworth were first tinkering with the idea of how to produce their latest and greatest Class 8 truck, they started with a list – a wish list, that is – and a determination to break down the wall between design and manufacturing. The subsequent development of the Kenworth T680 represents a leap forward in building world-class, quality trucks.

Early in the design process, Kenworth engineers involved manufacturing personnel to develop standardized manufacturing processes, which led to improved efficiency and easier assembly.

"We first brought together employees from our cab trim, cab assembly, and paint areas to review customer comments and pages of data. We then developed a manufacturing book of wishes that we all wanted to see in the T680, and reviewed it with the design engineers as they created the new truck," says Robert Culwell, Kenworth's division manufacturing engineering manager in Kirkland, WA. "Based on customer wants and our professional experience, we compiled a list of components and features that the truck should have. Working together with the design engineers, we determined how manufacturing could contribute to build a world-class truck."

The new Kenworth T680 triple-seal door is 30% larger, stronger, and easier to assemble. Engineers used 3D computer imaging to design a door frame and door that closes tightly with a degree of consistency and precision. A tight-fitting cab creates a quieter, more comfortable work environment for drivers.

 

 

 

 

"Involving manufacturing personnel in the T680 design process enabled Kenworth to deliver a new truck that takes into consideration, within the assembly process, all of the little things that make the T680 so unique," says Scott Blue, plant manager at the Chillicothe, Ohio-based Kenworth assembly plant, which is a production facility for the aerodynamic T680. "And by leveraging advanced technology, we've been able to greatly enhance the T680's quality while further enhancing the efficiency of our manufacturing process."

The new Kenworth T680 door is one example of how Kenworth design and manufacturing engineers achieved a new level of manufacturing precision and quality. "We wanted a world-class door that was larger, more robust, and easier to assemble," says Culwell. "Our engineers utilized advanced three-dimensional computer imaging to design a door frame and door that closes tightly with a degree of consistency and high precision."

The T680's stamped aluminum door is 30% larger, yet lightweight and extremely stiff, making for excellent seal integrity. A pressure-relief valve equalizes interior and exterior air pressure to make the door easy to open and close with little effort. Once the door is closed, the T680's triple-seal design minimizes sound transmission. "All the contours and the shape match perfectly," Culwell says. "A tight-fitting cab creates a quieter, more comfortable work environment for drivers."

The interaction between design and manufacturing allowed the engineers from both disciplines to learn from each other. The process produced manufacturing efficiencies, not only of the T680, but for other Kenworth models. For example, engineers quickly discovered that the T680 could be made stronger and the assembly process more efficient by using the Henrob self-penetrating fastener as the standard for all joint and installation needs.

Kenworth engineers came up with a new, quick-drying adhesive urethane that makes the T680 windshield leak-free and will be used on other Kenworth vehicles from now on. The design change ulitmately helped to produce a one-piece, bonded-in panoramic windshield that offers a 27° rake angle for improved aerodynamics and thicker glass for greater rock chip resistance.

 

 

 

 

"Using this fastener enabled us to standardize our tools and assembly processes, and had some benefits for product enhancement for the T680 and all our vehicles," Culwell says. "Since the Henrob fastener is self-penetrating, it doesn't require holes. This allows us to install the stamped aluminum panels on the T680 cab, eliminating the step of pre-punching holes. We have provided customers with a cab structure that is stiff and much more resistant to water, noise, and vibration."

With the T680, Kenworth also standardized the placement of many different components, says Culwell. "To increase efficiency, we established new manufacturing standards eliminating variations in where components are placed. That makes the trucks easier to assemble and improved efficiency."

The manufacturing of the T680 also takes advantage of technology developed for building other Kenworth trucks. Take electrostatic painting, for example. With this technique, electrically charged paint particles are magnetically attracted to the truck's surface when the vehicle is grounded, Culwell says. This method creates a uniform and durable undercoat for better adhesion of the topcoat for a quality finish.

There are also techniques developed for the T680 that will benefit how other Kenworth trucks are made. Prior to the T680, waterproof urethane was applied robotically before the Kenworth truck windshield was installed, says Lex Tisdale, Kenworth - Chillicothe plant manufacturing engineering manager. This installation process made it easier for the windshield to be replaced later. The opportunity presented was to find a way to further improve windshield installation efficiency.

"We asked the design engineers to come up with a quick-drying adhesive urethane that would make the T680 windshield leak-free and could also be used on other Kenworth vehicles," Tisdale says. "The process resulted in a one-piece bonded-in panoramic windshield for the T680 that offers a leak-free design, a 27° rake angle for improved aerodynamics, and thicker glass for greater rock chip resistance. We found that the windshield takes about a quarter of the time to replace."

The Kenworth - Chillicothe plant must be flexible to handle the assembly of Kenworth's different Class 8 trucks with various day cab and sleeper configurations. Plant engineers designed new robotic cells and assembly lines for the Kenworth T680 to work within the existing facility. For example, the robotic cell that applies adhesive and installs the T680's panoramic windshield can be switched out with a robotic cell that does similar work on the T700 cab trim assembly line. Multi-tasking robots also perform hundreds of programmed steps required to build the T680 cab.

The Kenworth T680 uses advanced design and manufacturing techniques but also takes advantage of technology developed for building other Kenworth trucks, such as electrostatic painting. With this technique, electrically charged paint particles are magnetically attracted to the truck's surface when the vehicle is grounded, creating a uniform and durable undercoat for better adhesion of the topcoat for a quality finish.

 

 

 

 

To make the manufacturing process on the Kenworth T680 more efficient, manufacturing teams at the Chillicothe plant developed a two-step plan to adapt the plant for the T680. Since product and manufacturing designs happened on parallel tracks, changes were being made right up to the production of the first line units to take full advantage of the latest technology. "New engineering software combined with simultaneous manufacturing and design engineering enables us to produce the T680's features more efficiently," Tisdale says.

"Product design has to be part of the manufacturing design, and manufacturing design has to be part of the product design for a new product like the T680 to be successful. The days of designing a new product and then handing it to manufacturing are over. It really must be done simultaneously because of the complex nature of building an aerodynamic truck as well designed and engineered as the Kenworth T680," says Tisdale.

Source: Kenworth

Published April 2012

Rate this article