Stacking the material deck for the 787

  • 03-Mar-2011 05:20 EST

Radio frequency identification (RFID) chips are relatively inexpensive and robust. Shown is an Orbital motor with an embedded RFID antenna in the nosepiece.

Portable tool manufacturers are being encouraged to incorporate smart technologies into their equipment that will process checks to reduce the potential for human error, perform self-checks on the equipment functions, and interact with databases to ensure the mechanic is using the most current release of product definition.

One of the forerunners of portable tools with these smart capabilities is the portable orbital drill units currently being developed by Novator and Boeing for introduction on the 787. These machines incorporate the ability to read passive radio frequency identification (RFID) chips that are relatively inexpensive, robust, and easy to embed into drill plates or other unique locations.

By using this capability, the machine’s controller logic can associate a specific process program to each unique location that calls for a particular series of orbit speeds and axial feeds and also lubrication methods at various depths through the stack of materials being drilled. This allows machines to feed at the optimum rates through the stack and travel no further than is required at each location, not only ensuring a consistent quality for the hole but also eliminating the wasted time that occurs with traditional portable tools where the motor is set to travel through the entire stack at slowest speed needed within the stack. Also, as the stack thickness changes from hole to hole, the traditional machine is not able to adapt and so is set to travel the distance required for the thickest stack the motor will encounter, thereby increasing process times.

To reduce the risk of human error causing defects, the RFID technology is used in combination with the machine’s logic to keep track of the number of holes that a cutter is used for and prevents the machine from drilling more holes than the cutter is allowed to drill. The RFID reader is also used to keep track of which holes have been drilled and prevents the mechanic from drilling the hole a second time. RFID also ensures the correct hole size is drilled at every location and the correct program is used to drill each hole to the correct depth.

Air logic sensors are used to measure air pressure at various parts within the machine to ensure sufficient vacuum pressure is available to effectively remove the metal chips and carbon dust as created. Air pressure checks are also used to ensure the machine is properly clamped in place on the drill plate with controls that prevent the machine from operating if any of the parameters are not met.

Some smart portable machines incorporate sensors that measure or compare thrust and torque forces to interact with the machine’s logic controls to enable rapid advance by the machine until contact is made. Others also measure changes in speed whenever an increase or decrease in resistance is encountered, allowing for optimization or improvements in the cutting parameters for each material within the stack and greatly reducing cycle times.

By incorporating sensors and programmable logic into the controls of portable tools in aircraft assembly, it is possible to effectively insert quality management into the drilling process that allows the opportunity to eliminate many quality checks that are currently used during the drilling process to prevent mistake propagation from occurring, which is often described as “inspecting quality into the product,” probably the most inefficient method of attaining quality.

With the introduction of cell phones, smart phones, texting, and twittering into everyday society, it can be argued that the public at large, as well as the aerospace workforce, has become more tech savvy. As such, many technologies and capabilities have become intuitive to the everyday person. In fact, many mechanics use their cellphones to communicate with each other, reducing the amount of walking required within the very large buildings used to build airplanes.

The down side to all of this technology in the workplace is that the probability of the mechanic being distracted during the critical times of hole generation in these exponentially more expensive aircraft structures has become almost a certainty. What this creates is stress.

Instead of making life simpler for a more tech savvy population, we have hi-tech devices introducing distractions in a low-tech workplace. This increases the probability of errors and mistakes.

We must bring our aircraft manufacturing equipment and processes into the twenty-first century. The technology is ready and available; the workforce is ready and capable. As material technologies continue to evolve in this ever-changing industry, so must the processes used to make airplanes out of them; this is the greatest opportunity we have before us.

Information for this article is based on SAE technical paper 2010-01-1867 by Eric Whinnem and Gary Lipczynski, Boeing.

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