Clay, 3D printing, and a little Geomagic make handheld controller prototype
FORCE America had a problem familiar to many companies: How do you improve on a previous design, yet retain the familiar look and feel that customers love about your products?
The answer came from Advanced Design Concepts. ADC combined clay modeling with digital shape sampling and processing (DSSP) using Geomagic Studio software and rapid prototyping with an Objet 3D printer. The result: a complete physical prototype of a new controller handle in half of the scheduled time.
Combining function and form
For nearly 50 years, FORCE America has been creating motion and control products for mobile hydraulic systems incorporated into work trucks and agricultural equipment used for snow removal, logging, mining, harvesting, and other heavy-duty tasks.
The controller handle modeled by ADC will be used by municipal snow plows. It is designed to accommodate three different joysticks for controlling plow blades, three switches for salt distribution, and the electronics to control and light the device.
Reliability is obviously an overriding requirement in FORCE America’s designs, but its controllers also have to be ergonomically flexible to accommodate interaction with different-size hands.
David Zech, mechanical project engineer at FORCE America, thought ADC was perfectly suited
“In previous projects, ADC had proven it has the design engineering skills to produce a final product design that is both structurally sound and cost effective,” says Zech.
There is also the added advantage of ADC having all the tools to do the job in one place.
“Because the design, moldmaking, and part manufacture are located in the same ADC facility, we are able to reduce the time needed from conception to manufacture,” says Zech. “The setup also decreases the cycle time when unforeseen changes arise in new product design.”
The tools to make a leap
The controller handle project epitomizes ADC’s expertise in DSSP, which describes a group of technologies that enable users to move efficiently between physical and digital worlds. At the center of the process is Geomagic Studio software, which ADC has used in design engineering projects for a diverse range of customers, from Harley-Davidson to Fiskars to American Blimp.
“Geomagic Studio fundamentally changes the way you can design,” says Mark Schaefer, ADC president. “It provides the tools that enable you to make a quick leap from a physical model with a shape and feel everyone likes to an accurate CAD model for manufacturing.”
FORCE America started the project by giving ADC the internal components that would be required in the new design and a rough clay model of the shape. Using Pro/ENGINEER, Schaefer created CAD models of the buttons and circuit board areas based on existing drawings and 3D scans. He then created a volume model around the components to provide a clearance guideline for the clay work.
Saving a month in iterations
ADC used the Objet system to produce a rapid prototype of a volumetric clearance model for the controller’s internal components. This allowed Chris Mulhall, a senior engineer at ADC, to add clay to the RP model and guarantee that the final offset (the wall thickness of the part) would not interfere with any of the pre-designed internal components. Mulhall then added clay to create the intended shape of the controller, sculpting it to meet FORCE America’s ergonomic and styling requirements. Changes were made to the clay by hand until the look and feel was right.
“Making a part that feels and looks good is very difficult,” says Schaefer. “Using clay as the media to get the shape right saved about a month in CAD and physical prototyping iterations.”
Greg Groth, reverse engineering manager at ADC, captured the geometry from the clay model using a GOM ATOS white-light scanner. He saved the data as an STL file and imported it into Geomagic Studio software. Within Geomagic, he smoothed out inconsistencies in the clay surface, made the button area flat, and created models for the top and bottom shells of the controller handle and a safety switch for the back of the controller. The models were turned back over to Schaefer, who generated parting line surfaces and curves in Pro/ENGINEER.
The Pro/ENGINEER models were then brought back into Geomagic Studio, where Groth modified the parts to meet tooling draft requirements. Once the drafts were set, Groth created offset surfaces to maintain the wall thicknesses of the parts. He then used Geomagic Studio to create surfaces of the final parts and define the offset internal geometry.
From Geomagic, the surfaces were brought back into Pro/ENGINEER, where structural ribs, holes, and assembly features were added. The final models of the handle — top, bottom, and safety switch — were printed on the Objet system, and the parts were assembled for final approval.
“Once the clay model was perfected, it was only a matter of days to move from scan data to a final, tool-ready prototype with switches and components ready for installation,” says Schaefer.
Much of the speed of the project can be attributed to the interchange between Geomagic Studio and Pro/ENGINEER throughout design stages.
“The combination of Geomagic Studio and Pro/ENGINEER enabled us to quickly capture the clay model, check the draft, and modify the surface geometry to make the controller manufacturable,” says Groth. “This is a perfect example of Geomagic and CAD working together to generate a high-quality design very quickly.”
The job, scheduled for six weeks, was completed in just three weeks. While ADC was completing the handle design, engineers at FORCE America were able to work on other parts of the new system assembly. Most importantly to Zech, ADC was able to ensure design quality in the early development stages.
“By allowing ADC to design and build the parts and the molds we were able to utilize the knowledge they have from many previous projects and make quality an integral part of the initial design,” he says. “ADC allowed us to provide a product that is new and improved from the previous product, yet has the quality look and feel that customers expect from FORCE America.”
About the author
Bob Cramblitt is principal of Cramblitt & Company (www.cramco.com) in Cary, NC. He writes about technologies and processes that dramatically impact the way products are designed, engineered and manufactured.
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