A natural extension of RP is rapid manufacturing (RM)
For short production runs, however, RM is much cheaper, since it does not require tooling. RM is also ideal for producing custom parts tailored to the user's exact specifications. A University of Delaware research project uses a digitized 3D model of a person's head to construct a custom-fitted helmet. NASA is experimenting with using RP machines to produce spacesuit gloves fitted to each astronaut's hands. From tailored golf club grips to custom dinnerware, the possibilities are endless.
The other major use of RM is for products that simply cannot be made by subtractive (machining, grinding) or compressive (forging, etc. ) processes. This includes objects with complex features, internal voids, and layered structures. Specific Surface of Franklin, MA uses RP to manufacture complicated ceramic filters that have eight times the interior surface area of older types. The filters remove particles from the gas emissions of coal-fired power plants. Therics, Inc. of NYC is using RP's layered build style to develop 'pills that release measured drug doses at specified times during the day' and other medical products.
14. 5 Future Developments the way companies design and build products. On the horizon, though, are several developments that will help to revolutionize manufacturing as we know it.
One such improvement is increased speed. 'Rapid' prototyping machines are still slow by some standards. By using faster computers, more complex control systems, and improved materials, RP manufacturers are dramatically reducing build time. For example, Strategy's recently (January 1998) introduced its FDM Quantum machine, which can produce ABS plastic models 2.5 ~ 5 times faster than previous FDM machines. Continued reductions in build time will make rapid manufacturing economical for a wider variety of products.
Another future development is improved accuracy and surface finish. Today's commercially available machines are accurate to 0. 08mm in the x-y plane, but less in the z (vertical) direction. Improvements in laser optics and motor control should increase accuracy in all three directions. In addition, RP companies are developing new polymers that will be less prone to curing and temperature-induced war page.
The introduction of non-polymeric materials, including metals, ceramics, and composites, represents another much anticipated development. These materials would allow RP users to produce functional parts. Today's plastic prototypes work well for visualization and fit tests, but they are often too weak for function testing. More rugged materials would yield prototypes that could be subjected to actual service conditions. In addition, metal and composite materials will greatly expand the range of products that can be made by rapid manufacturing.
Many RP companies and research labs are working to develop new materials. For example, the University of Dayton is working with Helisys to produce ceramic matrix composites by laminated object manufacturing. An Advanced Research Projects Agency/Office of Naval Research sponsored project is investigating ways to make ceramics using fused deposition modeling. As mentioned earlier, Sandia/Stanfords LENS system can create solid metal parts. These three groups are just a few of the many working on new RP materials.
Another important development is increased size capacity. Currently most RP machines are limited to objects 0. 125m3 or less. Larger parts must be built in sections and joined by hand. To remedy this situation, several 'large prototype' techniques are in the works. The most fully developed is Topographic Shell Fabrication from Forums in San Jose, CA. In this process, a temporary mold is built from layers of silica powder (high quality sand) bound together with paraffin wax. The mold is then used to produce fiberglass, epoxy, foam, or concrete models up to 3. 3m x 2m x 1. 2m in size.
At the University of Utah, Professor Charles Thomas is developing systems to cut intricate shapes into 1. 2m x 2. 4m sections of foam or paper. Researchers at Penn State's Applied Research Lab (ARL) are aiming even higher: to directly build large metal parts such as tank turrets using robotically guided lasers. Group leader Henry Watson states that product size is limited only by the size of the robot holding the laser.
All the above improvements will help the rapid prototyping industry continue to grow, both worldwide and at home. The United States currently dominates the field, but Germany, Japan, and Israel are making inroads. In time RP will spread to less technologically developed countries as well.
With more people and countries in the field, RP's growth will accelerate further.
One future application is Distance Manufacturing on Demand, a combination of RP and the Internet that will allow designers to remotely submit designs for immediate manufacture. Researchers at UC-Berkeley, among others, are developing such a system. RP enthusiasts believe that RP will even spread to the home, lending new meaning to the term 'cottage industry'. Three-dimensional home printers may seem far-fetched, but the same could be said for color laser printing just fifteen years ago.Cheap Merrell Shoes
Finally, the rise of rapid prototyping has spurred progress in traditional subtractive methods as well. Advances in computerized path planning, numeric control, and machine dynamics are increasing the speed and accuracy of machining. Modern CNC machining centers can have spindle speeds of up to 100,000r/min, with correspondingly fast feed rates. Such high material removal rates translate into short build times. For certain applications, particularly metals, machining will continue to be a useful manufacturing process. Rapid prototyping will not make machining obsolete, but rather complement it.