By Brad Cleveland, Protomold
Once upon a time prototyping was a labor-intensive manual process. Originals were laboriously carved out of wood, modeled in clay, or machined by hand. The cost of creating a prototype may have been small compared to that of setting up machinery for mass production, but prototyping was still a slow, costly, labor-intensive process …
Then came digital automation. One of the first areas impacted was machining. Highly skilled machinist/programmers could develop toolpaths that would produce identical items in a variety of materials through computer numeric control (CNC) of machine tools. Suddenly, machining became an unattended process and skilled labor moved from manufacturing to the programming of toolpaths. The problem was that developing the program for the computer took a great deal of specialized skill and a great deal of the programmer’s time. That made the process cost-effective for production, but still not economical for prototyping, where the small number of copies couldn’t justify the cost of developing the program.
To overcome what was essentially a software problem (i.e. the lack of computationally efficient automated toolpathgeneration algorithms for multi-axis CNC machining), clever engineers invented new manufacturing processes such as stereolithography (SLA), selective laser sintering (SLS), and fused deposition modeling (FDM) that were easier to support from a toolpath conversion point of view, due to the way they built plastic-like parts in even, predictable layers.
So in this manner, the software problem became dramatically easier, and the result was an automated ability to convert CAD models into a complete set of toolpaths for these new processes, which fundamentally enabled the entire “rapid prototyping” (RP) industry to flourish.
Unfortunately, the parts produced by RP processes are still something of a mixed blessing. Rapid prototyping processes are indeed fast and inexpensive, and they eliminate a lot of expensive labor, but they support very few resins, leave jagged steps at the edges of the layers, and offer little in the way of surface cosmetics. And while they can approximate the desired shape, the layering process often leaves parts weak and brittle compared to parts injection molded or machined from solid stock. They are certainly sometimes adequate for early, conceptual stages of product development, but tend to come up short when any kind of functional testing is required.
Fortunately, the same trend in software development that enabled additive rapid prototyping has been extended to the automated development of toolpaths for CNC machining. Using a 1.9 teraflop multi-node compute cluster, First Cut Prototype developed proprietary software to convert customers’ 3D CAD models directly to toolpath files for machining. The result is the best of both worlds: high-quality parts machined directly from solid stock in a wide variety of resins at speeds and prices comparable to those of rapid prototyping. These are strong enough for functional testing, have excellent cosmetics, can use most standard production resins, and can be made in as little as one day. Pretty much everything we ever really wanted in a prototyping process in the first place.
About the Author
|Brad Cleveland, President and CEO
The Protomold Company, Inc.
1757 Halgren Rd.
Maple Plain, MN 55359 – USAPhone: 763 479 3680
Fax: 763 479 2679
|Brad Cleveland has been the president and CEO of The Protomold Company, Inc. since November of 2001. Prior to Protomold he was cofounder and vice president of AeroMet Corporation, a laser additive manufacturing company and subsidiary of MTS Systems Corporation.Protomold®, a Proto Labs service, is the world’s fastest source for custom injection molded parts. The company fills a unique niche in the manufacturing of plastic parts, using a combination of advanced, proprietary software and sophisticated equipment to produce prototype and low volume runs of custom injection molded parts. The material properties of Protomold’s real molded parts surpass those of parts produced by additive prototyping processes. At the same time, delivery is faster and costs are lower than those associated with traditional injection molding.|
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