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From model to prototype

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It's late in the evening, just outside the conference room at the headquarters of 3-Dimensional Services, a rapid prototyping firm located in Rochester Hills, Michigan. It's the night before the company will make a critical presentation to a potential customer, and from inside the room, voices resonate as a very frank and open discussion is held regarding the tools and technologies that will sway the decision in the firm's favor.

"There's no doubt about it," one voice injects into the conversation, "plastics are continuing to gain more importance in virtually every sector of manufacturing. At the presentation, we have to emphasize our ability to produce plastic prototype components fast."

"Let's not overlook one of the oldest processes," a second speaker presses forward, "because, since the Bronze Age, mankind has been forming and shaping metals. Our stamping capacities should be heavily stressed."

"The flexibility to cut and weld myriad shapes and contours," a third speaker says, "using lasers is critical to the speed and precision for today's rapid prototype operations. Laser processing abilities should be the priority of our presentation."

"Lasers, shmasers," someone from the back says, "that's old technology...give them something new, like hydroforming. Explaining the advantages of hydroformed parts is at the top of my list."

"Wait, lest we forget," cuts in another, "machining, turning and milling operations - make parts. Machining is the strength we should highlight."

At this point, the speakers all at once toss out opinions, and among the jumble are heard words like vibration welding, reflex tooling, high definition stamping, stereolithography, tube bending, and more. Just when it seems that a consensus will never be attained, a distinguished-sounding voice brings order to the room.

"Everyone, please, settle down," this elder voice pitches to the others. "We need unity to present a strong message that today's rapid prototype shop has to be a combination of technologies, a combination of manufacturing disciplines, and a combination of knowledge and experience. I know. I've been sitting in this room for over 10 years, almost since the beginning, and virtually every project I've witnessed has been completed with teamwork, not individuals.

"For you younger guys, you for example, the portable barbecue grill in the corner and the lawn mower deck hiding over there by the plant, of course stamping and deep draw dies are important to you. That's how your components were created in just three weeks. Or you two, the plastic toy boat and the taillight lens assembly for the '03 SUV, plastic injection molding is in your blood. I've seen you all created...the intake manifold that reduced automotive weights by approximately 90 lbs...components for a digital audio receiver in just 13 days...you, the plastic and stamped parts of aircraft seats made in six weeks rather than the normal eight-month time period...or you guys that went to med school to aid in tissue biopsies and joint replacements. Everyone here is an example of what this team of people and technologies has put together over the years. If you'll listen, I'll explain."

Qualified design engineers work with the latest CAD software to achieve design and manufacturing intent.

So, the story goes. It began in 1992, when a group formed a new rapid prototype shop, modest in the beginning with only five employees, and an initial capital equipment list that included a few CAD workstations, a single SLA machine, and some laser processing centers for cutting and welding applications. Right from the start, though, the shop's objective was to redefine 'rapid prototyping' to provide production-like parts, using as near to production-like materials and processes as possible, and in as short a time frame as conceivable.

That prototype shop was 3-Dimensional Services (Rochester Hills, MI) and, today, it is joined by affiliated companies Urgent Plastic Services and Urgent Design & Manufacturing that together occupy three buildings exceeding 200,000 sq. ft. and employing over 200 staff members. Their combined resources and expertise now provide rapid prototype services for stamping, hydroforming, tube bending, and high definition stamping; high speed machining; laser processing; vibration welding; EDM plus casting, injection molding and assembly.

The company has always made it a priority to acquire the most advanced technologies available. This is evident by the 30 high- speed CAD/engineering workstations and advanced CAM software in place, from the dozen laser processing centers, the more than 30 presses including a 7,000-ton unit on the floor, or with the over 30 CNC machining systems with top spindle speeds of up to 40,000 rpm, to in-house injection molding machines.

In addition to technologies, the firms have created an atmosphere that encourages employees to develop ideas, then to implement them into workable process improvements.

Rapid prototyping systems include stereolithography, laminated object manufacturing, selective laser sintering, and metal lamination.

An example of this capability is the recent design and build of an ultra high-speed laser cutting system that was not otherwise commercially available. The self-made system allows 3-Dimensional Services to cut sheet metal components of a prototype assembly at speeds of up to 50,000 mm per minute. It is a marriage of technology and employee dedication that have helped 3-Dimensional Services and its partners cut prototype build times by 70 percent in most applications, as compared to firms still using conventional, outmoded technologies and thinking.

Though one of the company's very first projects required more precision than quickness-cutting 3/8' thick armor plating for a law enforcement vehicle, a subsequent project set the tone for what has become the benchmark for prototyping quickness.

"That job, started in 1992, was me," remarks the senior storyteller. "The eompany designed, developed, and manufactured a portable natural grass playing surface used at a World Cup soccer match held indoors. We produced the Turfbox pallets, a series of shallow boxes that held sod and could be set outdoors for sun and watering, then brought by forklift into the stadium prior to a match. The system, consisting of 92,000 sq. ft. of grass and using more than 1,000,000 pounds of steel, was completed within three months. I'm the small, sample piece that was used to demonstrate the system's viability to the organizing committee.

"That was then-a small company making a big impression. Today, people, the services of these three companies are as diverse as the customers we serve," the sample box explains and continues his tale.

Design and engineering services that work in partnership with customers to verify design intent validate prototype function, fit, and manufacturing intent. Also on hand are multiple CAM software packages, specialized to meet the wide variety of complex processes including multi-axis machining, welding, tool, mold and pattern work.

3-axis laser processing affords the power to cut through thick armor plate yet the precision to trim metals and other materials to tolerances of plus or minus one thousandth. For complex contours, 5- axis laser cutting systems, guided by CAM-generated beam paths, follow the most intricate of profiles to provide exacting fits and quality finishes. In addition, a powerful 8 kW laser welding system is used to join similar materials, dissimilar materials, and stocks of different thickness.

CNC machining centers with up to 5 ft x 10 ft travels manufacture prototype parts as well as dies and tooling. CAD/CAM files are downloaded to generate accurate tool paths, tool geometry, fixturing data, and locating points that assure setups are quick and dimensions consistent. A new, extremely rigid vertical machining center allows high-speed cutting of hardened steels to 60 R^sub c^ coupled with feed rates of up to 20,000 mm per minute, and positioning accuracy to 1.5 micron. A high-speed 5-axis machining center provides improved finishes and reduced secondary work for complex three-dimensional shapes of many tool-making jobs. Two other machining centers, with 40,000-rpm spindles and feed rates, even allow finish-grinding operations in single setups.

Rapid modeling has its place at the shops, too. This includes two stereolithography systems, two laminated object machines, two selective laser-sintering systems, and a new metal laminating system that can produce a finished aluminum part or tool in a single process. At the prototype facilities, these models not only give customers solid parts to review, but in many casting applications, the models are often used to make patterns and mold tooling. These part replicas can also be used as a tool for tryouts of fixtures, machining and assembly operations.

The company's electrode department houses six ram-type die sink units and five wire machines.

Stretching prototype build capabilities to their limits, the companies' forming and stamping capabilities rival many production fabricating and stamping houses. One such process is high definition stamping that maximizes a material's elongation properties through the use of special lubricants and lubricating methods, die design, and heating of the dies, allowing intricate forms and optimum mater\ial performance. The relatively new process of hydroforming is not new here, with both a low and high pressure range-up to 60,000 psi capacities available-and up to 200 tons of end feed capacity for axial feed applications in a variety of materials. Used with hydroforming or as a stand-alone process, advanced CNC tube bending machines provide forming of complex shapes, curves, twists, and compound arcs. All tooling is built in-house for no-delay fabrication.

The company developed its own high-speed laser cutting system with speeds of up to 50,000mm per minute.

With mechanical and hydraulic presses from 60- and 7,000-ton capacity, even deep draws and large pieces are not beyond the realm of the comnanies' forming capacities.

Besides the 8 kW laser, other welding technologies used for assembly operations include production-typical equipment such as articulated-arm, robotic-welding cells that simulate various assembly routines while providing data on weld quality and the process.

At the heart of the companies' injection molding and casting operations is an in-house pattern and model shop. Using urethane, sand, wood and plaster, positive or negative molds and cores, tools are made economically yet are production-like as to quality, process, and manufacturing intent. A new spin has been added, too, with spin-cast technology. Spin casting allows the use of low-cost, fast-to-complete dies made of rubber polymers, so prototypes are produced quickly and at lower costs.

Injection molding of plastic prototypes is accomplished through the use of over a dozen molding machines from 30 to 1,500 tons, in vertical and horizontal configurations. Shots are controlled to production standards and can include embedded parts such as reflex tooling, clips, and fasteners. An in-house injection mold tool department features eleven EDM machines, and high-speed bench top machining centers and grinders for electrode production.

A new vibration-welding machine has been added that uses an accelerated vibrating motion to create friction and heat between two surfaces and results in a fusion of the parts.

"Look kids, we've set the standard for rapid prototype work, now and into the foreseeable future," notes the old-timer as he wraps up his story. "It's not just one method or procedure but a host of technologies and expertise that made us. We are now the ambassadors for rapid prototyping. For a variety of products and a diversity of industries, we all have two commonalities. We were finished quickly, and in most cases, were produced using processes and materials as close to production as possible."

A hush falls over the room as the cleaning crew enters to make sure the area is ready for the next day's presentation. 3- Dimensional Services

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Source: Tooling & Production

Copyright Nelson Publishing Dec 2003

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