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Te conventional inspection process based on 2D draw-


ings, still very much the norm at many manufacturing compa- nies involves the following steps: • Receive model from customer. • Have CAD engineer or quality engineer make blue- print.


• Have approved by inspection department. • Make hard copies to be used in manufacturing and inspection.


• Inspect and manually fill out inspection report.


ment tools means that a part can be measured anywhere and at any time—on the machine, beside the machine or in the quality lab. Since the measurement soſtware is based on the CAD model and sometimes embedded in a CAD or CAM en- vironment, it is easy to create measurement subroutines for in- process gaging or complete inspection programs in the same environment used to create CNC manufacturing programs. By the same token, inspection data may be viewed within the CAM package to make toolpath adjustments based on graphi- cal MBI feedback. Tis makes it far easier to troubleshoot


For too long, manufacturing subdisciplines existed in their own little kingdoms, using tools and data sets unique to their own specialties.


Here is the breakdown of hours involved using a CMM to


inspect a relatively small and uncomplicated aerospace part using the conventional 2D drawing process: • Drawing creation (2-6 hours) • Drawing on paper and printing (1–4 hours) • Drawing based inspection—includes annotating draw- ings with GD&T information and writing the inspec- tion program (2–10 hours)


• Ambiguity or uncertainty waste (1–100 hours) Te range of time presented here (6–120 hours) is broad


because time costs in the last category (ambiguity or uncer- tainty waste) can easily be blown out of proportion when inappropriate or misunderstood tolerancing information results in bad parts that are accepted, or good parts that are rejected because tolerances are too inflexible. Both of these situations, however, happen frequently and they add hours to inspection processes.


Systemic Advantages In addition to eliminating many of the disadvantages of


conventional inspection protocols, MBI also introduces sub- stantial advantages not only within inspection processes but also throughout all manufacturing processes. Measurement Device Independence: MBI need not be asso-


ciated with any particular measuring device either in terms of device type or manufacturer. Tis means data collected using the most appropriate devices for the purpose at hand— hard gages, hand tools, height gages, CMMs, portables, laser trackers, laser radar, white light sensors and spindle probes. Good MBI soſtware can be programmed to integrate data collected from all of these sources, so users only need to be familiar with one soſtware product. Measurement devices may also be used in combination to collect data for the same inspection task. Measure Anywhere, Anytime: Te universality of the mea- surement soſtware along with the portability of the measure-


first-piece manufacturing processes or refine them during pro- totype manufacturing. Integration with Manufacturing Processes: Measurement tools


aren’t just for inspection. Te same model-based tools can be used for scanning artifacts for reverse engineering as well as locating components such as fuselage skins during assembly. Because the soſtware is based on and integrated with the CAD model everyone in manufacturing including design engineers, manufacturing engineers, CNC programmers and quality ana- lysts have access to the same familiar operating environment. Laser trackers are an example of measurement equipment


that may be tightly integrated with manufacturing processes. Airframe manufacturers frequently use them to locate com- ponents during assembly. Te component is located, attached and then the location is once again confirmed. No further inspection is required at this point because an inspection step was an integral aspect of the manufacturing process. Breaking Communications Barriers: For too long the vari-


ous manufacturing subdisciplines existed in their own little kingdoms, using tools and data sets unique to their own specialties. When their work was done it was passed along to the next user in a form that would have to be translated into another unique set of tools and data sets, and so forth for the life of the program. Not only was this process terribly inefficient, it also inhibited interdepartmental communication of information that could be used in partnership to greatly improve the total manufacturing outcome. With MBD/MBI the primary tools and data sets are now


identical and shared. Finally everyone, for the most part, is speaking the same language. Tis makes it possible for design, manufacturing, and quality assurance folks to get together in front of the same graphical MBD information to quickly iron out ways to modify designs or incorporate less rigid true-po- sition tolerances, so that the manufacturing process can make parts far more economically without sacrificing any of the critical dimensions necessary to the design intent. ✈


Aerospace & Defense Manufacturing 2013 105


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