Abstract
The increasing interest towards intelligent systems has led to a demand for the development of zero-defect strategies, with a paradigm shift from off-line and dedicated to in-line metrology with integrated robotic systems. However, a major barrier preventing the systematic uptake of in-line metrology is the lack of evaluation of system capability in terms of accuracy, repeatability and measurement time, when compared to the well-established coordinate measuring machine (CMM). In this study, a robotic Laser Radar (LR) solution is assessed in the context of automotive dimensional inspection of Body-In-White (BIW) applications. The objective is both to understand the effect of robot re-positioning error on measurement accuracy and repeatability and to compare measurement results against a CMM. Eighty-one surface points, six edge points, twenty-five holes and sixteen slots were selected from an industry standard measurement plan. Whilst LR exhibits a lower measurement accuracy than twin-column CMM, its repeatability is well within the specification limits for body shell quality inspection. Therefore, as a real-time in-line metrology tool, it is a genuine prospect to exploit. This research makes a significant contribution toward in-line metrology for dimensional inspection, for automotive application, for rapid detection and for correction of assembly defects in real time, with subsequent reduction of scrap and number of repairs/re-works.
Highlights
In recent years, there have been significant cycle time reductions for production technologies, especially joining technologies, to improve right-first-time (RFT) capability with a minimum waste of resources and reduced product defects in pursuit of zero-defect manufacturing (ZDM)
The results showed that the Laser Radar (LR) accuracy and repeatability are well within the specification limits of typical automotive BIW inspections
The results show a significant reduction in measurement cycle time, reduced by 83% to 6 min
Summary
There have been significant cycle time reductions for production technologies, especially joining technologies, to improve right-first-time (RFT) capability with a minimum waste of resources and reduced product defects in pursuit of zero-defect manufacturing (ZDM). By using off-line measurement (taking off the assembly line), for car manufacturers, it is more difficult to predict defects before they occur or identify trends in the production line due to limited sample size. Is this time consuming, and it cannot identify the root cause of any faults. There is a growing desire to move away from off-line sample measurement to in-line data collection, and this will only be possible with fast, accurate measurement technologies This leads to a common trend in Europe (and worldwide) regarding research into in-line. CMMs are often considered a bottleneck in the quality process due to the ever-increasing product complexity, leading to an increase in the number of measurement points and the measurement time and in some cases only providing partial information on the measured area rather than the full product data
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