Practical and Portable Automated Machining
Published September 16, 2014 by SAE International in United States
Annotation of this paper is available
The utilization of new materials and tightening of desired tolerances has driven the advancement of Practical and Portable Automated Machining. Increased demand in volume within the aerospace industry not only requires minimizing the amount of manual operations, but also applying automation inside existing manual fixtures. In the past, manual labor, with drastic limitations on achievable accuracies, has been utilized in areas that machine tools cannot either access or the limited amount of work does not justify the expense of additional machines. Assemblies requiring critical hole alignment or drilling through stack materials often are difficult to achieve using manual operations.
The solution is a practical and very portable machining unit that is small enough to fit into otherwise difficult areas and is lightweight enough to be either moved into position by small machines or quickly disassembled/assembled with each subassembly capable of being positioned manually.
The criteria for the developed machine were that it be;
- Lightweight - Under 250 lbs allowing for manual positioning or easy mechanical positioning
- Accurate - Maintain accuracy achieved with current PKM technology
- Rigid - Capable of drill/mill/orbital of titanium
- Flexible - Can be mounted in any orientation and is adaptable to rail, vacuum, fixed leg, gantry, etc.
- Inexpensive - affordability should be compared to high-end manual tools instead of machine tools
The XMINI Parallel Kinematic Machine developed uses the major benefits of Parallel Kinematics which presents an excellent rigidity to weight ratio, high accuracy, very flexible. This was combined with the new construction of the PKM, redesigned to reduce the size weight of the unit by scaling the unit down in size as well as replacing previous heavy components with aluminum and carbon fiber components. The XMINI has an expandable work envelope by combining mechanical methods of moving the machine (i.e. - tracks, rails, etc) along with the utilization of cross lasers, cameras and/or probes for accurately establishing the new position.
Applications for the new XMINI are currently underway with multiple major aerospace manufacturers. These applications take advantage of the portability as well as the flexibility in the mounting orientation. All of the programs included requirements of being manually portable, and drilling/milling. Highly accurate holes in aluminum/titanium/Carbon Fiber stack materials are being achieved for many of the projects. Exploration is continuing on other potential uses in welding, laser cutting and fastening.