Article: Appliance Magazine
Article from “Appliance” Magazine, October 1, 1993 by Tim Somheil
“A sense of urgency; engaging suppliers, empowering employees, re-orienting facilities, and harnessing technology add up to a broad ADS profile. (U-Line Corp.’s appliance cellular manufacturing process) (The Best in Accelerated Design Strategies)”
A facility newly configured for cellular manufacturing was the outgrowth of U-Line Corporation’s growing engineering flexibility. In recent years it has invested heavily in integrating CAD/CAM into engineering and taking other measures to enhance product design, all with the goal of improving quality and decreasing product development cycle time. These accelerated design strategies have earned the company a reputation among its suppliers as one of the fastest product developers, and the company is unapologetically demanding of its own suppliers in this regard.
“We haven’t necessarily had a conscious program to reduce product development time; it has just always been our nature to be extremely aggressive and to operate with a sense of urgency,” says W.A. “Buzz” Reed, vice president and chief engineer. “When a supplier tells us it will take 6 weeks to provide samples, we tell them that is not acceptable–we need them in 2 weeks. When a supplier says I’ll get back to you first thing in the morning and we don’t hear from him, we rattle his cage.
“Our veteran suppliers know how to attack a project with us. And I am sure they deal with our projects on a different time scale than they do with other companies.”
Mr. Reed says the relatively small size of the company may facilitate accelerated product development to some extent. “But I don’t think for a minute that large companies could not operate using the same philosophy,” he declares. “I worked for years with big appliance producing companies, and I don’t think there is any question they couldn’t operate under the same sense of urgency.”
Accelerated Combo Bucket Design
This sense of urgency is illustrated in a recent redesign of a combo bucket used to store ice in some of the company’s units. The part development, from first drawings to production, was less than 20 weeks.
The combo bucket was originally drawn, reviewed, and released by the company within about 2 weeks. Be-cause it had been decided to go with an Eastman Ektar copolyester material for the part, the company sent its CAD data to Eastman for analysis.
Tom Deaderick, applications specialist, Eastman Performance Plastics, first performed the mold fill analysis on the combo bucket, using the Kodak Glyph Visualization System.
The process started with the development of a wire-frame model, which includes lines, points, and curves. “We put surfaces on it as needed,” Mr. Deaderick explains. “If a part has a sculptured surface, we build those into it. The initial concern during the mold fill analysis is ensuring the part will fill. Then we make sure we have walls sized properly and the sprue located correctctly for a balanced fill. If the part has to have a weld line, we can modify its location using the software.”
A finite element model was developed. Up to this point, according to Mr. Deaderick, the process is similar to other mold fill analysis systems. Now, the company’s software comes into play. Mr. Deaderick says it is the only software that can simultaneously animate five components of injection molding data.
“A typical mold-filling software package will take a snapshot in time after perhaps 1 second into a 5-second fill,” he explains. “It will then give you five or six plots. You have a picture that will tell you the pressure, another picture to tell you temperature, another shear temperature, another flow front, and another flow velocity.” The Glyph system, on the other hand, shows a continuous animation of all these components on the screen simultaneously. It graphically displays the information and allows different data to be related. If a feature is changed all the effects of the change can be noted at once.
“I kept in contact with U-Line and Production Plastics regularly as the analysis was conducted, asking for their input as needed,” Mr. Deaderick says.
The part required 128 hours of computer simulation time, or about 4 hours each for 30 runs.
Once the mold-filling analysis was complete, a narrated analysis videotape was presented to U-Line engineers. The videotape contained suggested wall thicknesses and sprue location as well as optimum processing conditions for the tool.
Eastman further supported U-Line’s accelerated design strategy by providing a structural analysis on the combo mold steel. Deep mold cavities combined with significant injection pressures can produce considerable stress within the mold steel. Occasionally, a mold cracks under these conditions. Eastman provided U-Line the anticipated steel deflections for the combo mold to ensure proper mold sizing.
While Production Plastics machines the finish surfaces of the steel, Eastman reviewed the tooling prints. Suggestions for a balanced cooling layout, sprue design, poppet location, and venting considerations were provided to U-Line as the finished surfaces were completed, allowing the lines to be evaluated without delaying the project.
“The tooling time for a part like this is 10-12 weeks,” explains Mr. Reed. “We can start the tooling before the flow analysis is complete–the tool maker can buy the steel and do some of the preliminary work.”
Many years ago, he added, when the company was not using CAD, the initial drawing stage would have been about twice as long. In addition, without a CAD drawing, flow analysis is not possible. Flow analysis saves the company the time and expense that would have resulted if it had to make adjustments to tooling to achieve proper filling and good-looking parts.
“We saw a need years ago to implement computer-aided design (CAD),” says Mr. Reed. “We researched a number of systems and finally selected Hewlett-Packard hardware and software from Cimlinc.
“Accuracy is also better with CAD,” he adds. “We can assemble components on the CAD screen to help assure accuracy. We still build prototypes, but we can eliminate the first few iterations by doing them on the screen.”