December 2007 Edition
CAD/CAM
Nightmare on Outer Drive West
Even with 3D visualization, designs can sometimes require nightmarish manufacturing contortions. A shop with the right software and hardware beat the competition in creating a tool to overcome a design bad dream.
In the time it took its competitors to develop and present CAD drawings for an assembly tool needed by Detroit Diesel, 3-Dimensional Services delivered a working prototype to attach a wiring plug to a socket in a new engine design
It's a race between engine designers and the price of fuel. Not only do engines have to run cleaner, supply more power, and provide more miles per gallon, they have to fit within the streamline confines of vehicle design. At times, the necessities of compactness can interfere with the realities of production.
Detroit Diesel Corp., Detroit, a subsidiary of Chrysler and a part of the Freightliner group of companies, is at the forefront of diesel engine design with its sixth-generation DDEC VI electronic engine control system. The system uses a microprocessor, memory, and diagnostic capabilities that monitor and manage engine functions, including the after-treatment systems required for emissions standards. Sensors are installed at each of the six fuel injectors on the top of the engine head and under the valve cover, which provide operational monitoring and control.
At times, Detroit Diesel needs help to complete the assembly procedures of its engine designs, according to Ken Zalucki, sales engineer for the rapid prototyping firm 3-Dimensional Services, Rochester Hills, MI. Such was the case with the DDEC VI.
"Connecting the sensor terminal into the engine during the pre-production build stages – completing engines for various testing and trials while coordinating the necessary assembly procedures – turned into a challenge for Detroit Diesel," Zalucki said.
The terminal required the insertion of a wiring plug into its receptacle at the injector location, a position between two valve springs and so close to the engine wall that there was limited hand access.
"The location made it almost impossible to put enough pressure on the plug while securing the retaining clips to successfully engage the parts," Zalucki said.
In the few instances where it was possible to force the plugs into the sockets, connector blades were bent or misaligned, requiring repair or replacement.
Zalucki said a Detroit Diesel engineer called it an ergonomic nightmare. Since this was a pre-production build, development of specialized tools and assists for production runs 12 weeks into the future.
Finding a Solution
Detroit Diesel turned to 3-Dimensional Services and other prototyping firms for help designing a tool that would let engine builders snap the plug into the socket easily and without damage.
3-Dimensional Services provided about 12 prototype parts for this latest engine variant, and worked with Detroit Diesel on other projects. Typical prototype parts 3-Dimensional constructed for Detroit Diesel included stamped support brackets, injected molded plastic brackets, and harnesses for routing and securing wiring.
"We've worked with various part configurations in almost all types of manufacturing disciplines," Zalucki said, "but developing a tool was different. I presented the application specifics to our engineering team. Within three days we presented to Detroit Diesel a working sample. Our competitors provided just CAD drawings of their proposals."
Rising Above the Competition
3-Dimensional Services specializes in rapid prototype services with design, engineering and analysis, in-house tool construction, and complete build of first off parts and low- to medium-volume production runs.
By using advanced process methods, manufacturing technologies, and the talent of its staff, 3-Dimensional Services provided delivery of a fully-useful tool up to 70 percent faster than conventional prototype shops.
The prototype tool had multiple step surfaces to locate and grasp the plug and depress the locking flanges. 3-Dimensional incorporated a stop-pin, preventing excessive pressure that would crush the terminal, plug, or contact blades.
3-Dimensional Services provided delivery of a fully-useful tool up to 70 percent faster than conventional prototype shops
"Detroit Diesel used the tool and provided feedback," Zalucki said. "When we got the input, we fine-tuned the design. Modifications included making sure the tool met ergonomic criteria such as the handle curve, distance between handles so it would fit the largest percentile of hand sizes, and the force and tension required to operate the spring-loaded handle grips."
The first finished tool met specifications and measured about 10" long. 3-Dimensional added a rubber coating to the handles and delivered the upgraded tool about seven days after the original prototype was delivered. Three more tools were completed in the next week. Zalucki said he expects more orders.
To beat the competition, 3-Dimensional Services relied on its production process resources, including laser-cutting capabilities. With its 17 laser processing systems it could cut and trim the handles from 3/8" steel and cut and shape the workholding jaws.
The jaws were also machined using CNC machining centers. Each jaw tip was welded to the handles.
Handles were drilled and tapped, and springs were fastened. Where necessary, surfaces were hardened, ground, and polished to provide a finished appearance. The tools were given an acid bath for a rust-resistant gunmetal gray color.
"The three-day response may seem fast to most, impossible to others," Zalucki said, "but it's our way of doing business."
Founded in 1991, 3-Dimensional Services is known for rapidly manufacturing complete, production-ready prototype parts. With its subsidiaries – Urgent Plastic Services and Urgent Design & Manufacturing – the firm can handle laser cutting and welding, machining, stamping, hydroforming and tube bending, vehicle frame fabrication, injection molding, vibration welding, castings, rapid modeling, and exotic alloy high definition stamping and assembling. 3D Services
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