Rapid Manufacturing System

  • RMS Description
  • RMS Description MPH mobile modules are designated as Rapid Manufacturing System (RMS). A RMS is a mobile manufacturing system that can produce parts rapidly near the point of need.

    The current RMS prototype consists of two twenty-foot International Standards Organization (ISO) containers, each housing one primary piece of fabricating equipment. Each of these modules meets the size and weight requirements for C 130 aircraft transport and can be moved overland on Army trucks. One module contains a Directed Material Deposition (DMD ®) machine that utilizes a patented process called Laser Engineered Net Shaping (TM) (LENS ®)developed by Sandia National Laboratories.” This machine can create a fully dense metal part from a Computer Aided Design (CAD) model, which is converted to a Standard Triangulation Language (STL) file. After a part is built “near net shape” with this process, it is directed to the other module that contains a 5-axis multi-task machining center for final finishing and dimensioning. In addition to the major machines inside each module, there is also an engineering workstation with both engineering and manufacturing software, a satellite communications system, and a reverse engineering capability including laser-scanning equipment to capture part geometry from old parts in need of replacement.

    • DMD ® The Laser Engineered Net Shaping (TM)(LENS ®) process is considered a Directed Material Deposition (DMD ®) process because powdered metal is directed into the path of a laser beam where it is melted and then solidified on the workpiece to create a part particle-by-particle and layer-by-layer. The properties of metal parts created using this process can be made equivalent to and potentially better than those of wrought material of the same composition. Also, the time to create a part using this process, compared to casting or forging, is greatly reduced. The LENS ® process is an emerging process technology still in need of maturing and consequently remains under both development and testing in the MPH program. A Design of Experiments (DOE) is underway to relate process variables to resulting material microstructures and mechanical properties. In addition to relating the process variables to material properties, the experiments are designed to identify methodologies for increasing processing speed, improving surface finish and maximizing the configurational capabilities of the process. Key process variables include laser power, powder feed rate, weld pool size, and beam path control strategy.
      A major asset of this process is the ability to make fully dense metal parts with free-form flexibility. This provides the ability to make a wide variety of parts as is required by the MPH system. In addition, this process enables the attainment of the mobile processing requirement for reducing the logistics footprint. Because the process is based on powder technology, the material inventory can be dramatically reduced, as there is no need to store wide varieties of solid stock. In addition, the ability of the process to consolidate a number of high performance alloys (e.g. high alloy steel, Titanium) powders permits a strategy of reducing material compositional inventory by building parts to better than original part properties. In this strategy, a single high performance alloy is employed for a whole family of parts yielding mechanical properties equal to or better than those in the original parts. Consequently, the compositional varieties of powder stock can be kept to a minimum in the materials inventory. Finally, the near-net-shape capability reduces scrap to a minimum and consequently reduces the need for any significant inventory quantities to make up for wasted material. The goal of the MPH program is to carry a single powdered metal to the battle space that would meet all part property requirements.
    • Multi-task Machining Center Post-processing of parts made by the LENS ® process requires the use of a second piece of manufacturing equipment, the 5-axis multitask machine to meet surface finish and tolerance specifications. The second ISO module of the RMS contains this 5-axis multi-task machining center. This machine is a multi-axis mill that is set up primarily as a lathe.
      Work pieces such as gears and camshafts that normally would require separate turning centers, and both vertical and horizontal machining centers, can now be completely machined with efficiency and accuracy in the multi-task machining center. All axes are direct motor driven with no belts, pulleys, or gears, and tool exchange speed is nearly instantaneous. The machine incorporates an integrated 64-bit PC controller, color graphics display, and a simple programming language. In addition to having the capability of directly inputting machine code (CNC), the programmer can also simply inputs the dimensions in a logical machining sequence (guided by the machine), and the video display unit shows a shaded model of the work-piece for each stage, including a model of the cutting tools in action. This can be seen dynamically for an entire program prior to cutting material and while the actual machining is in progress. During programming, the controller immediately flags any x-y-z interference or an unfeasible operation as an error, and the corresponding program line is highlighted for correction.
      The 64-bit controller is capable of making tool path adjustments on the fly (OTF) to compensate for tool wear. Any manual adjustments (tweaking) done by the operator while the program is running can be recorded by the controller and immediately incorporated into the master program file, if desired. Another capability of this machine is the ability to record cutting path data in the event of a tool breakage. These data (up to 5 motions) are recorded as the operator manually guides the tool away from the work-piece for changing. At the restart command, the stored cutting path data guides the tooling back to the interrupted stage position, and the original program continues. There is no need to return to the program beginning, this saves significant time over conventional methods.