Rapid prototyping began as a way to produce three-dimensional prototypes directly from digital CAD files. Yet proponents have always maintained that faster prototyping machines and better materials could allow companies to manufacture short-run production parts economically.

This has begun to happen. From hearing aid ear inserts and sunglasses to jet fighter ductwork and medical implants, companies are using direct manufacturing to reduce costs, speed new products to market, and produce short runs without molds or dies.

Improved rapid prototyping materials play a large role in this push into the manufacturing mainstream. In the past, such materials involved compromises. Users could make parts fast,
accurate, or durable, but rarely an optimal combination of all three. Recently, materials developers have been trying to bridge those tradeoffs.

Better materials, like DMX-SLT resin from DSM Somos, are enabling rapid prototypers to make production parts for more demanding applications.

DSM Somos of Elgin, Ill., a division of Dutch chemical giant DSM N.V., says its new DMX-SL 100 is the first stereolithography resin to combine durability and accuracy. According to the company, parts made from the new resin have the durability of sintered nylon, the stiffness of ABS, and the impact strength of polypropylene.

This is a big step up from products usually made by stereolithography, a process known for dimensional accuracy. It uses ultraviolet light to solidify liquid resins into solid parts. Unfortunately, those parts are more brittle than conventional engineering resins (such as ABS, nylon, or polycarbonate), and they grow increasingly brittle as they age, said product development manager Brian Bauman.

Parts made from the new DMX-SL resins, on the other hand, are as stiff as conventional ABS, but have twice its impact strength and up to 20 percent elongation at break. Bauman said they can compete with parts produced by other rapid prototyping systems that melt or sinter thermoplastics. Those parts are durable, but do not have the aesthetics or dimensional consistency of pieces made by stereolithography.

Meanwhile, Stratasys Inc. of Minneapolis introduced a metallic prototyping material for use with the Arcam electron beam melting rapid prototyping system from Arcam AB in Gothenburg, Sweden. Stratasys is the exclusive North American distributor of the technology.

The metal powder ASTM F-75 cobalt chromium is commonly used in hip and knee implants, as well as in aerospace applications. It complements two titanium alloys already offered by Stratasys.

Electron beam melting produces parts by rapidly melting and fusing powders. By doing this under vacuum, the parts come out fully dense and without imperfections caused by oxidation. According to Stratasys sales manager Kirby Quirk, electron beam melting produces cobalt chrome parts three to five times faster than other metal additive-fabrication methods.

Robotic welding cells are getting affordable enough for small-run job shops, automotive suppliers, and even community colleges to buy.

A perfect example is the eCell from Lincoln Electric Co. in Cleveland. Priced at $49,900, eCell ships preassembled and ready for immediate use. According to the company's engineering manager, Geoff Lipnevicius, most users can teach the robot to do simple welds with only a half-day's training (although Lincoln's complete training course runs three full days).

The robot is designed for metal inert gas short arc, spray, synergic, and pulse welding, or flex-cored arc welding. Its footprint is 4 feet x 8 feet, and it is light enough to move with a forklift or to drive around on a one-ton pickup truck.

Lipnevicius makes a powerful case for robot productivity and quality. A welder with a steady hand can join 20 inches of metal per minute, he said. Along a single arc, the eCell robot moves fives times faster, and will even reach 200 inches per minute when it's fed two flux-cored wires at a time.

Robotic welders are coming down in price, making them more affordable for job shops and other small manufacturers.

Robots are also steadier and their welds are more repeatable and easier to monitor using statistical process control software. Unlike workers, robots have no turnover, sick days, or health care coverage.

Lincoln says its robot is relatively easy to program. To set up a job, the operator uses a handheld remote with buttons that control the position of the arm. For a simple weld, the operator starts the arm at a safe point away from the part, picks the start and end of the arc, and then goes to a safe point at the end.

"Software tells the robot how to connect the dots," Lipnevicius said. "Most people learn to do simple welds like that in half a day. Then we spend the next few days teaching them about their options, like getting the welder to weave back and forth to fill a gap or move the welding head to a cleaning station."

Given gains in productivity, many small job shops could pay for the robot within two years, Lipnevicius said. Community colleges are buying robotic welding cells for their vocational programs to encourage computer-savvy students to take up welding as a technology-oriented career.

Lipnevicius also sees applications among Tier II and III automotive suppliers. "Many of the Japanese transplant companies put several welding cells in a circle, and then progressively add components as they pass subassemblies from welder to welder," he said.

Lincoln teamed with Japan's Fanuc Ltd. to develop the cell. It is based on Fanuc's ArcMate 100iBe robot. Fanuc provides the six-axis articulated arm, controller, and software. Lincoln provides the welding heads, feeds, and controls.

Companies in the business of making tools to order usually juggle a number of different jobs at one time. At least, they hope to do so, because that's what keeps them prosperous. What's more, at small and midsize companies, the budget may not be able to handle a large software system devoted to budgeting a project and tracking all the work going through the shop.

That's the scenario that Sescoi had in mind when it developed a product that could be described as enterprise resource planning for the little guys. Sescoi, headquartered in Mâcon, France, has offices in several countries—the U.S., U.K., Spain, Germany, India, and Japan—from which it sells software like a full-size ERP system called WorkPlan that costs in the tens of thousands. The product for small companies is MyWorkPlan and the price starts at $5,200 to license five nodes, according to Jeff Jaje, marketing manager for Sescoi USA in Southfield, Mich.

Starting with information imported from Excel or other sources, a user can outline the steps a job will take. The program follows the job through the shop, providing a quick reference to check on the progress of each project.

Sescoi recently published a story about one of its satisfied customers, ABM Moldes. The company, based in Barcelona, Spain, makes molds for plastic blow molding. ABM uses MyWorkPlan to budget jobs, track their progress, and create a record to see if anything unexpected made a job less profitable than it should have been.

As Sescoi describes it, when a quotation is accepted by the customer, ABM converts it into a job to which all costs are allocated, including employee hours, purchased materials, and subcontracted work. A job-tracking module lets ABM identify variations between the budget and actual costs. As a result, ABM knows the profit margin on each job.

Jaume Gumà, ABM's managing director, said, "In the past, we thought we knew more or less if we were making or losing money on the job. Thanks to MyWorkPlan, we now know precisely and reliably."

According to Jaje, Sescoi created MyWorkPlan from scratch. It isn't a module unbundled from the full-scale ERP software. It is designed to be familiar to users of Excel spreadsheets and Windows in general, and makes use of such features as drag and drop and the right click of the mouse.

Jaje said the company liked the user interface so much that it is now rewriting the big ERP system in order to make it easier to use and quicker to learn.

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